A topic I made with advice on what charger to use among other discussions about batteries has vanished - I really don't think it was breaking any rules but if so I didn't receive any kind of warning. I was just wondering if maybe it was something server-side?
Topic vanished?
- Thread starter No_Shorty
- Start date
This is a list of all your posts, accessible from your profile:
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This is a list of all threads you've posted to, accessible from the search page:
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Is any of them the thread you're looking for?
EDIT: I did a google search for your username, and this forum site domain, and compared the topic list with the above list, and found one that doesn't show up on ES anymore (dunno why??). At least some of it is cached on google, linked here until that disappears, and then I quoted the whole text of each page below (doesn't include the images that still show up in the cache though):
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If you went that route then I would advise a completely separate HVC for failsafe redundancy.
noted, thanks.
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john61ct 100 GW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by john61ct » Jun 22 2020 3:35pm
No_Shorty wrote: Is there any way to effectively program this in to the BMS? Monitoring battery SoC on set simply isn't going to happen, so any levels I want to cease using the battery at have to be controlled by the battery itself if at all possible.
Do NOT trust BMS estimates of SoC, notoriously inaccurate. Even $200+ purpose designed battery monitors are lucky to stay within 5-8% accurate
But a simple "wattmeter" counting Ah used if reset at 100% stop-charge point works well enough so long as you are targeting DoD with a decent cushion
and then the lower BMS cutoff is there (as I said) as a failsafe last ditch protection.
Do not rely on BMS for normal operations without redundancy, in this case consequences are, your pack is instantly rendered basically scrap, very dangerous (fire risk) to use any further.
Auditory alarms or flashing lights can also be rigged for voltage levels approaching the hard cutoff point.
But nothing substitutes for a diligent human familiar with the systems' usual behaviours, watchful for anomalies.
The more you try to automate everything, the more complex, the less reliable the system.
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No_Shorty 100 mW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 22 2020 3:43pm
For sure, the realities of on-set life rather preclude battery monitoring however, and if I were ever to take this down the route of making batteries for others then they would need to show as 'dead' so that they were disconnected by the user.
Always happy to put in extra fail safes, in fact the more the merrier - if having a wattmeter in line to indicate battery low and/or disconnect is the best approach I'm happy with that.
All that said, why would the BMS coulomb counting be any worse than that of a simple wattmeter? They rely on the same technique do they not?
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john61ct 100 GW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by john61ct » Jun 22 2020 11:29pm
Generally yes
but devil's in the details
lots of factors **should** be taken into account, CEF & Peukert coefficients, ideally an internal database of chemistry-specific tables & behaviours, falling Ah capacity over time.
With lead banks a device called Merlin SmartGauge is best for SoC%, and it doesn't even count coulombs! No shunt based BM comes closer than 5-8% even with frequent manual resets at 100%
SG does not work with LI chemistries though.
Everything at this guy MaineSail's site to do with electrickery is worth close parsing
https://www.google.com/search?q=battery ... arinehowto
He has a great article on LFP care there, much will apply to other LI chemistries.
This thread is also long but very informative
http://www.cruisersforum.com/forums/f14 ... 65069.html
Also came across this in my notes
Image
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No_Shorty 100 mW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 23 2020 10:33am
Cheers, I'll look in to all of this, I think the general rule of thumb seems to be that both 'ends' of the battery charge cycle are where its life gets shortened.
Is it incorrect to look at a discharge graph as a representation of how much mAh are represented by the 'top' 0.1v [4.2-4.1v]?
I ask because on a discharge graph 4.2-4.1 seem to represent barely 200mAh at low discharge and close to nothing at all at higher discharges - this wouldn't line up with your graph suggesting 10%. Does this mean that the immediate 'sag' you see on a discharge graph isn't representative of starting the discharge at a lower (4.1, 3.9 etc) voltage.
He has a great article on LFP care there, much will apply to other LI chemistries.
I actually have one of his articles saved from a year or so ago from when I first entertained this idea. Very thorough and well written.
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john61ct 100 GW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by john61ct » Jun 23 2020 8:29pm
Sorry, I've lost track, what graph do you mean?
The % of capacity between two voltage points (**must** be V at rest not under load)
will vary by chemistry, even model battery concerned.
Leaving 10-15% at the bottom, and 5% at the top, would be a good goal, lots of extra longevity without too much sacrifice of capacity.
You will see people talk about only using from 20% to 80% that's just silly, or more likely they do not know how to actually judge SoC% accurately.
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No_Shorty 100 mW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 28 2020 9:01pm
john61ct wrote: ↑
Jun 23 2020 8:29pm
Sorry, I've lost track, what graph do you mean?
I was just generally referring to a 'discharge graph' when a cell is tested, so for example:
Image
The % of capacity between two voltage points (**must** be V at rest not under load)
But I think you have just answered this anyway - as the above graph is under load, so the initial 'sag' is not representative of its capacity at this voltage?
Leaving 10-15% at the bottom, and 5% at the top, would be a good goal, lots of extra longevity without too much sacrifice of capacity.
Defo achievable. Still 3800mAh out of a 50E at 1C discharge [5753mAh rated]
You will see people talk about only using from 20% to 80% that's just silly, or more likely they do not know how to actually judge SoC% accurately.
Well it's good to know I don't need to go to these lengths even if I was targeting cycle life. As it is cycle life is a secondary thing that it a balance between the benefits and cons, and making the battery last 2-4x the time is certainly worth the 20% additional size and weight.
I have also recently been reconsidering LiFePO4 - but only because I never properly looked into pouch cells. In Prismatic or Cylindrical (e.g.26650) they are super expensive and super big and heavy. In pouch form they are a similar cost per Wh and about 30% heavier and only 15% or so bigger than a 20-90% DoD LiPo pack.
It's still yet more weight and size, but the safety and temperature resilience advantages bring them back in to the fold.
The biggest disadvantage by far is that these pouch cells are not at all widely available and I can find very little information on proper pack build procedures or reputable suppliers (my thread on this here: viewtopic.php?f=46&t=107029&p=1567230#p1567230). I don't think it's going to sway me away from LiPo cells. But it may convince me to build one pack of each to see how they both play out.
Lastly - I think I have decided on my charger once and for all. I'm think I'm going to go with the Mean Well RCB-1600. I have vague plans to make a touch screen controller with saved profiles to interface with it, but for now I can just adjust it with pots and adjust profiles with their nice friendly GUI. I didn't get the two outputs I wanted but que cera.
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Is any of them the thread you're looking for?
EDIT: I did a google search for your username, and this forum site domain, and compared the topic list with the above list, and found one that doesn't show up on ES anymore (dunno why??). At least some of it is cached on google, linked here until that disappears, and then I quoted the whole text of each page below (doesn't include the images that still show up in the cache though):
https://webcache.googleusercontent.com/search?q=cache:LhLkpMt4rUsJ:https://endless-sphere.com/forums/viewtopic.php%3Ff%3D14%26t%3D106810+&cd=1&hl=en&ct=clnk&gl=us
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48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
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No_Shorty 100 mW
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48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 16 2020 1:46pm
So I have done a lot of searching on this front, and either what I wan't doesn't quite exist or it's just hard to find.
A quick/brief background on what I'm doing:
I am building a swappable battery pack to power computing equipment in the field (I work in TV) - this is going into a 48v 1600VA inverter and 4xDPS5020 programmable bucks (outputting between 12-20v), all told a maximum possible draw of 50A (it will normally be well, well under this, more like 10A, but flexibility is important). Will be built with Sanyo 18650GA which have a 500 cycle life at 6A per cell, but with a max draw of 10A per cell. This should cover me for just about all my use cases as well as any inverter spikes even during peak usage. Driven by TinyBMS
I could go in to the ins and outs of this more but it's not really relevant to my question - that being:
Batteries will be charged 'off-board' and I am aiming for a 2hour 'fast charge' with the ability to reduce this down to an overnight slow charge and save the batteries, and then additional profiles are a bonus.
It will be a modular and flexible system (so potential for bigger batteries or other chemistry), and I would like to at least start this project with a charger capable of matching this ideal. I will be 'open sourcing' the plans and build process to my industry (any anyone who wants a read) as well.
This is what I'm looking for:
-48v Lithium Charger so CC/CV with adjustable/programmable current/profile (range needed 2-15A, but the higher possible current the better in case of bigger packs)
-Ability to have at least 2 preset profiles for slower/kinder charging that are selectable on unit or possible to install switch to do so.
-I would love more than one output, or managed outputs that auto switch to the next battery (are there products deigned to take over the latter part of this? Can I just make a parallel 'dock' that halves the charging current if I connect two?)
So far my searching has come up with the following:
-I'll pop in the Cycle Satiator first - it's just a smidge under powered, but in a pinch the 8A would do. At the very least it will likely be going in my writeup as the 'best' plug and play option I have found and still a decent charge rate.
- 1500W fully programmable V+A via CAN -(no experience with this) https://greenwattpower.com/product/1500 ... e-charger/ - this thing is by far the closest solution I have found, but "coming soon". I have emailed to inquire. Can't find any third party sellers. edit: These guys got back to me, the are a supplier to large industry and don't sell to end users or startups without large MOQs. This product will be like some of the other brands that integrate it with a system, very unlikely to be an end user product but I encouraged them to consider finding a supplier for such a purpose
- Many of Victron's products. Any of their smart chargers/multiplus units/smart solar MPPT controllers etc. Two problems with Victron - the first is cost (they do a lot more than I need) and the second is changing profiles means going through an interface wholly designed for solar - I just really don't like the idea of that.
-Finally my current 'winner' a 'DPM 8616' PSU from AE/Juntek:
https://www.aliexpress.com/item/3302805 ... 7ec09YlZZN - This can output 60v@16A (so a little breathing room) CC/CV, coupled with this PSUhttps://www.aliexpress.com/item/4000402 ... 9d35OyMwOF to drive it. (edit - just realising that 60v is too close to 58.8 after power conversion, so maybe not this PSU)
These are cheap enough and vastly programmable, so that I can buy two driving them both from the same PSU for dual battery charging on independent CC/CV. As many profiles as I like, and the wireless controllers can pair with multiple supplies.
My only real problem with it is buying these PSUs from 'Juntek' - I can find nothing else like them bar a bench power supply, reviews on YT are decent though. I would need to build them into some kind of box with the PSU to make it into one 'charger' unit.
Ultimately I really want a plug and play solution, but I feel like that may be asking a bit too much if my Googling is of any repute.
Last edited by No_Shorty on Jun 19 2020 9:44am, edited 3 times in total.
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goatman 1 MW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by goatman » Jun 16 2020 4:24pm
I think the Cycle Satiator from Grin
https://www.ebikes.ca/product-info/cycle-satiator.html
I think I read here you can stack them to up the amps im not sure, here
viewtopic.php?f=14&t=60169&p=1506981&hi ... s#p1537630
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No_Shorty 100 mW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 16 2020 6:28pm
Hmm, interesting, but it somewhat puts it in the 'really rather expensive' range.
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goatman 1 MW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by goatman » Jun 16 2020 8:25pm
yes it does but Ive been wondering if you can use other identical chargers "stacked" to double the amps of a charge?
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No_Shorty 100 mW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 17 2020 7:51am
I really can't see why not!
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amberwolf 100 GW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by amberwolf » Jun 17 2020 8:32am
While they are not programmable per-se, there are the Meanwell LED PSU chargers, that can be used to provide the power. They are CC supplies when below their set voltage, and CV when at that voltage, so if they're set for the fullcharge voltage of the pack, then they are effecdtively CC/CV chargers...without a shutoff point. The HLG series are sealed and potted if you need that, or the ELG I think are open-frame, and they have other series.
"programming" is done by using the adjustment pots for current and voltage limits.
There are individual devices out there that can be used to shut off a device above a certain voltage, and probably also when a certain current is reached--the ones I've seen were to shut off the output if current was *above* a certan point...but I expect they could be modified to do the opposite, if no one makes one that does that.
Alternately, the Cycle Analyst could be used to sense current and voltage, and then use the throttle output via a relay control board to shut a relay off when charging is complete. There is a battery test station Grin makes to do that sort of thing for testing batteries, and AFAIK you can download and install the firmware on any CA, and then build your own relay control box. There's a thread about it somewhere around here.
Not sure if this will really do what you want, but it's another avenue to explore. (or rabbit hole to waste time on).
If you found this advice helpful, supporting contributions are accepted here.
"if it ain't broke, improve it till it is"----Dog-Hauler Cargo eTrike SB Cruiser----The HI-Lebowski: a Lebowski SMD brain running a zombified Honda IMA Inverter: a HOW-TO guide----Cargo eBike CrazyBike2----General Blog
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No_Shorty 100 mW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 17 2020 10:32am
Hey, yes Mean Well are on my radar, not really quite as 'programmable' as I would like and I think I have only found one supply that goes over 60v (The HEP100-1000, adjustable pots on the enclosure), but they are a potential. edit: just checked the HLG/ELG, they both top out at 54V.
It is my understanding that the BMS (Tiny BMS) will control the cut off and disconnect from the charger. So a very basic CC/CV power supply will be suitable as it will not continue to charge the battery after target V/A is reached.
I have also realised today that the Chargery C10325 is capable of this output. The only thing it lacks is easy to use profiles as you have to manually set them yourself. Again the BMS should handle any foul ups as you can set the max amperage and voltage on the charge circuit, but the idea of being able to switch the profiles with just a button press is very useful if I ever choose to sell a charger as part of a kit to my industry.
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No_Shorty 100 mW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 17 2020 10:46am
Ooo you know what - I have just been poring through the Mean Well specs again and have spotted the RPB-1600-48
Programmable curves and tops out at that magic 58.8v. Definitely need to look in to it more.
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No_Shorty 100 mW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 17 2020 11:40am
I think the Mean Well requires the SBP-001 to interface with the PC to change profiles. So switching between multiples would require this and at least something like an Arduino to issue commands. The output amps can be adjusted by "applying external voltage" but I dont really know what this means or if it would work as a simple "profile changer".
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amberwolf 100 GW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by amberwolf » Jun 18 2020 12:37am
No_Shorty wrote: ↑
Jun 17 2020 11:40am
The output amps can be adjusted by "applying external voltage" but I dont really know what this means or if it would work as a simple "profile changer".
That means you could use an external pot to change the limit to anything in it's range. ( the same way you can use internal pots to do so).
Alternately, you can make "current profiles" by using a switch to change one resistor in a voltage divider. A rotary switch would give you as many profiles as there are positions on the switch. If you only need two, a simple 1P2T (spdt) toggle would work.
For the HLG/ELG, you can series them for higher voltages. Been done successfully as chargers numerous times here on ES. The ones I have here, before they came to me, were used as a set of 4, 2p2s, for about 58v24a charging of a motorcycle. I"m just using one on the SB Cruiser trike, mounted under the cargo area with the controllers and stuff.
If you found this advice helpful, supporting contributions are accepted here.
"if it ain't broke, improve it till it is"----Dog-Hauler Cargo eTrike SB Cruiser----The HI-Lebowski: a Lebowski SMD brain running a zombified Honda IMA Inverter: a HOW-TO guide----Cargo eBike CrazyBike2----General Blog
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goatman 1 MW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by goatman » Jun 18 2020 3:01pm
No_Shorty wrote: ↑
Jun 16 2020 6:28pm
Hmm, interesting, but it somewhat puts it in the 'really rather expensive' range.
I just remembered, Andy Kirby sells a charger on his Cloudsto,
https://cloudsto.com/ebikes/chargers/ch ... etail.html
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No_Shorty 100 mW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 18 2020 5:20pm
amberwolf wrote: ↑
Jun 18 2020 12:37am
No_Shorty wrote: ↑
Jun 17 2020 11:40am
The output amps can be adjusted by "applying external voltage" but I dont really know what this means or if it would work as a simple "profile changer".
That means you could use an external pot to change the limit to anything in it's range. ( the same way you can use internal pots to do so).
Alternately, you can make "current profiles" by using a switch to change one resistor in a voltage divider. A rotary switch would give you as many profiles as there are positions on the switch. If you only need two, a simple 1P2T (spdt) toggle would work.
For the HLG/ELG, you can series them for higher voltages. Been done successfully as chargers numerous times here on ES. The ones I have here, before they came to me, were used as a set of 4, 2p2s, for about 58v24a charging of a motorcycle. I"m just using one on the SB Cruiser trike, mounted under the cargo area with the controllers and stuff.
So does the external pot actually need to be supplying VDC? So in order to adjust you would need another AC/DC converter to apply the voltage but with a pot inline?
I actually think I may have made my mind up, I have been going back and forth between using two of the Juntek bucks for two outputs and supplying them with a power supply and using one of the Mean Wells. The problem with the Juntek idea is that you need to be able to supply 58.8v+10% for efficiency loss at the buck, so you need a PSU of 65v+ and 20A to supply both bucks at 10A load. This is no common thing. I was also worried about the longevity of the Juntek bucks.
So rather than give them their own PSU or start putting them in series I have more or less chucked that idea in favour of the much simpler Mean Well charger with easily accessible pots for CC/CV. If I want to charge two batteries I just get two chargers and it comes in at a similar price to the bucks with their own individual PSUs.
So I think its: Mean Well HEP-600C https://www.meanwell.com/webapp/product ... d=HEP-600C
I can make up a case for this, bung two pots on the front and wire them in place of the pots on the board and have these be the 'profiles' of the charger. If two batteries were used I would just stack them giving them their own isolated programmable supplies.
They can be picked up for about £163 a pop so not going to break the bank either.
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john61ct 100 GW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by john61ct » Jun 18 2020 7:17pm
Did not read the whole thread.
If Grin is just "a bit expensive" for you, definitely the way to go.
The key distinctions you need to be decided on:
actual charger? IOW self terminates, in theory set it and forget it?
DC converters and PSUs can be adapted only set the voltage setpoint, with outside devices handling termination through contactors.
The units must be designed for paralleling if you need that, not just any model can do so.
CC-only actually works just fine, makes for simplicity, only an HVC needed to handle stop-charging.
ex-telecom gear is top notch and pennies on the dollar for big amps
Elcon makes good stuff, failsafe CAN control.
Meanwell HLG units with the "A" suffix work well, I have a stack of the 54A model at 240W available for $40 each plus shipping
output voltage- 54v (adjustable 50-57v, 12S LI
output current- 4.45A (adjustable 2.23-4.45)
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No_Shorty 100 mW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 18 2020 9:10pm
john61ct wrote: ↑
Jun 18 2020 7:17pm
Did not read the whole thread.
If Grin is just "a bit expensive" for you, definitely the way to go.
It's not that it's expensive, it just doesn't really fit what I'm after.
The key distinctions you need to be decided on:
actual charger? IOW self terminates, in theory set it and forget it?
I'm afraid I don't know this acronym? "IOW"
DC converters and PSUs can be adapted only set the voltage setpoint, with outside devices handling termination through contactors.
The units must be designed for paralleling if you need that, not just any model can do so.
Yes I would be relying on the TinyBMS to terminate the charge if I were simply using a PSU
CC-only actually works just fine, makes for simplicity, only an HVC needed to handle stop-charging.
Again, sorry, I don't know the acronym "HVC"
ex-telecom gear is top notch and pennies on the dollar for big amps
Elcon makes good stuff, failsafe CAN control.
I'm trying to put together a 'guide' for other professionals in my industry to allow them to purchase their own parts and chargers etc if they wish. Therefore I am trying to avoid looking for second hand gear.
Meanwell HLG units with the "A" suffix work well, I have a stack of the 54A model at 240W available for $40 each plus shipping
output voltage- 54v (adjustable 50-57v, 12S LI
output current- 4.45A (adjustable 2.23-4.45)
Just to be clear, would this allow for an output of 58.8v@10A?
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john61ct 100 GW
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by john61ct » Jun 19 2020 12:29am
IOW in other words
HVC high voltage cutoff
GIYF google is your friend
No_Shorty wrote:It's not that it's expensive, it just doesn't really fit what I'm after
It does if you stack them.
True chargers, terminating accurately, with full adjustability of current and a wide voltage range, are very very rare.
> Yes I would be relying on the TinyBMS to terminate the charge if I were simply using a PSU
Best to have the relay cut off the mains input.
Elcon makes good stuff, failsafe CAN control.
I'm trying to put together a 'guide' for other professionals in my industry to allow them to purchase their own parts and chargers etc if they wish. Therefore I am trying to avoid looking for second hand gear.
Then pay 10x more, Elcon is sold new, as are telecom grade gear.
Meanwell HLG units with the "A" suffix work well, I have a stack of the 54A model at 240W available for $40 each plus shipping
output voltage- 54v (adjustable 50-57v, 12S LI
output current- 4.45A (adjustable 2.23-4.45)
> Just to be clear, would this allow for an output of 58.8v@10A?
See that "50-57v" there? The first number is the bottom of the range, the second one is the top.
So for 14S 57V would give you termination at 4.07V
For some that might be way "too low" but it certainly would be good for cell longevity, not really sacrificing much capacity, depends on the chemistry of course.
As for current, that 4.45A gets doubled by stacking.
The HLG-600H-54A will give you your 10A.
______
BTW, 14S is usually considered a "52V" pack, even called 56v sometimes.
nominal 48V with those types of Li-ion chemistries are usually 13S, but yes a bit lower setpoints than the "48V" you get from lead 24S packs.
If you can go down to 12S then more choices open up, even balancing chargers from the RC hobby market.
_______
And, GA aren't that great choice anymore, turns out can be inconsistent, often require rebuilding the pack
you'll be better off with M36, MJ1 or 35E cells
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by john61ct » Jun 19 2020 12:51am
Personally I'd reco going with LFP for this use case, 16S is a great 48V.
Yes a bit less energy dense, but much less likely to burn down the van and all the gear inside.
Can also just bolt together a single string of prismatics at the Ah capacity you want, no welding a big pile of tiny cells together.
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by amberwolf » Jun 19 2020 7:34am
No_Shorty wrote: ↑
Jun 18 2020 5:20pm
So does the external pot actually need to be supplying VDC? So in order to adjust you would need another AC/DC converter to apply the voltage but with a pot inline?
Generally there should be a voltage source pin from the PSU to do this. You'd have to check the pinout of the programming port. For instance, the Sorenson DCS55-55 I have here has this port:
DCS5555port.png
So I think its: Mean Well HEP-600C https://www.meanwell.com/webapp/product ... d=HEP-600C
I can make up a case for this, bung two pots on the front and wire them in place of the pots on the board and have these be the 'profiles' of the charger. If two batteries were used I would just stack them giving them their own isolated programmable supplies.
If this is like the HLG series that looks similar, then it is potted, so you won't be able to just open it and add new pots. You *can* add extensions to the knobs, using the shafts of screwdrivers pressed into it by the facing of the case, with a screw/etc into the handle of the screwdriver thru the facing of hte case, and a knob on the screw, etc. (or they make knobs with plastic or metal extensions specifically to do this sort of thing).
If you do have a case on them, and they aren't in free airflow, you will want to add a fan to pull air thru the case. Even if it's a big 5-inch "12v" fan running on only 5v to keep it slow and quiet, it would probably keep moving air thru enough to keep them cool. The HLG on the bottom of the trike gets pretty warm, but not hot, and is screwed to the wooden bottom panel from underneath, so it's in open air. (I also have another HLG of a different model and voltage up on a pole powering a 12V LED panel to light up the yard, and it also gets pretty warm in open air). Both of mine are running near their wattage limits.
If this is a potted one, and you prefer an unpotted type, like some of the "closed frame" or "open frame" PSUs like the SP320/etc., then you could remove the pot and wire it to an external one.
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 19 2020 9:05am
Cheers John, I have considered LFP but it's substantially less dense and these batteries will be moved from van to set between being charged and used so size and weight is very important.
Once the system is set up, V/A levels set, BMS configured etc the danger of the system is small.
Amberwolf-
Yes I saw this 5v line on a few of the PSUs and thought this, but then found one with no such line and that's what really confused me.
Can the pot not be removed from the circuit board and attached to the case? Or does this change its resistence too much?
The one I linked already has the holes for pot access so the extension wouldn't be the end of the world.
I will absolutelty be adding proper airflow to any case I make, and testing heat at high load.
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 19 2020 9:32am
Just realised I have let my numbers slip whilst being buried in what set up to go for with charging.
As mentioned in the first post, I was aiming for a 2 hour 'fast-charge', but the Ah of the battery is 30... so thats 3 hours. It was 15 amps I was supposed to be speccing for.
Time to dig back in
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by amberwolf » Jun 19 2020 10:02am
No_Shorty wrote: ↑
Jun 19 2020 9:05am
Can the pot not be removed from the circuit board and attached to the case? Or does this change its resistence too much?
I'm sure that would work fine...but as i said, these look like they're potted, which means to get the pot off the board you would have to cut open the aluminum casing along it's length and pry it off (because the potting will be adhered to the casing, so it won't slide out), then dig out the potting material around the potentiometers on both sides of the circuit boards, so you can desolder and remove them. Then you'll need to do something to re-adhere the remains of the casing to the potting in a way that lets heat pass thru it like it used to, or else attach new heatsinks to them.
If it's not potted, then you won't have this problem...but it is the same case style as my HLGs, and they are potted. The nonpotted Meanwells I have (like the SP series) have a more open style of casing that is also teh heatsinking, but is clearly open to airflow.
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 19 2020 12:08pm
Apologies, I am with you, I did not realise before what 'potting' meant and kept scanning over it as meaning it had potentiometers.
I guess that is what makes it rugged and IP rated, I had wondered how they achieved that.
Ok, well its pretty far down the list now, and I'm back looking at other options, I think with my power and current desired this leaves me the Chargery option, the RPB-1600-48 or putting 2 or more in series to achieve higher output.
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by john61ct » Jun 19 2020 1:43pm
No_Shorty wrote:Once the system is set up, V/A levels set, BMS configured etc the danger of the system is small
Unless something fails in a mode you did not anticipate.
If the battery modules get over say 40lb, just break it up into 24V or even 12V sub modules.
Then your choice of economical chargers gets much broader too.
With li-ion 3.6-37V chemistries, your users better learn to proactively predict State of Health decline.
LFP can go many thousands of cycles, does not get more fire prone with age.
Li-ion does, and lifespan can be just a couple hundred cycles.
EVs have gone over to these higher energy density formulations only for **propulsion** power levels, the weight savings translate to inherently better performance in the core use case.
Your weight savings are just adding a bit of convenience. Your system of course, but I **strongly** urge you to reconsider that bit of your design.
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 19 2020 6:42pm
Thanks John, I appreciate your thoughts on the matter but deciding on chemistry with weight, size, cost and the safety of each type in mind the right choice is lithium cells. We are talking nearly double the weight, over double the cost and poor availability of cells (at least in the UK). The 500 cycle life of the LiIon cells I have chosen at the max charge/discharge I will be using (so likely a much longer life) is adequate and worth the additional cost. It is the right choice knowing the purpose I am building it for and how it will be used. It is not just for convenience.
There are multiple fail safes in the system should the BMS fail for some reason but I have chosen Tiny BMS rather than a Chinese brand to avoid as much inherent quality issues as possible.
I appreciate that some people default to LiIon as they have heard about what goes in a Tesla and need a nudge in the 'right' direction. However, I have weighed the pros and cons of each and LFP simply doesn't cut it.
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by john61ct » Jun 20 2020 7:12pm
OK then, I warned you, I hope you never have cause to regret it. . .
Just FYI wrt terminology, LFP and many other widely varying chemistries, even LTO, all do fall under the umbrella term "lithium cells".
The many other chemistries more commonly used for propulsion use cases, including I believe NCA for your GA's, NMC, NCO, LCO, LMO etc, whether in cylindrical, LiPo style pouch / hard case prismatic form
all get lumped in as "Li-ion" even though there is a huge range of differences in the factors that determine suitability to a given use case.
I use "3.6-3.7V" as a general label to be a bit more precise, at least distinguish from the chemistries whose nominal voltages are far from that range
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by john61ct » Jun 20 2020 7:16pm
About GA consistency, longevity
https://bit.ly/3ddDA88
More recent threads tend to be more canonical
Last edited by john61ct on Jun 20 2020 7:16pm, edited 1 time in total.
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If you went that route then I would advise a completely separate HVC for failsafe redundancy.
noted, thanks.
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by john61ct » Jun 22 2020 3:35pm
No_Shorty wrote: Is there any way to effectively program this in to the BMS? Monitoring battery SoC on set simply isn't going to happen, so any levels I want to cease using the battery at have to be controlled by the battery itself if at all possible.
Do NOT trust BMS estimates of SoC, notoriously inaccurate. Even $200+ purpose designed battery monitors are lucky to stay within 5-8% accurate
But a simple "wattmeter" counting Ah used if reset at 100% stop-charge point works well enough so long as you are targeting DoD with a decent cushion
and then the lower BMS cutoff is there (as I said) as a failsafe last ditch protection.
Do not rely on BMS for normal operations without redundancy, in this case consequences are, your pack is instantly rendered basically scrap, very dangerous (fire risk) to use any further.
Auditory alarms or flashing lights can also be rigged for voltage levels approaching the hard cutoff point.
But nothing substitutes for a diligent human familiar with the systems' usual behaviours, watchful for anomalies.
The more you try to automate everything, the more complex, the less reliable the system.
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 22 2020 3:43pm
For sure, the realities of on-set life rather preclude battery monitoring however, and if I were ever to take this down the route of making batteries for others then they would need to show as 'dead' so that they were disconnected by the user.
Always happy to put in extra fail safes, in fact the more the merrier - if having a wattmeter in line to indicate battery low and/or disconnect is the best approach I'm happy with that.
All that said, why would the BMS coulomb counting be any worse than that of a simple wattmeter? They rely on the same technique do they not?
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by john61ct » Jun 22 2020 11:29pm
Generally yes
but devil's in the details
lots of factors **should** be taken into account, CEF & Peukert coefficients, ideally an internal database of chemistry-specific tables & behaviours, falling Ah capacity over time.
With lead banks a device called Merlin SmartGauge is best for SoC%, and it doesn't even count coulombs! No shunt based BM comes closer than 5-8% even with frequent manual resets at 100%
SG does not work with LI chemistries though.
Everything at this guy MaineSail's site to do with electrickery is worth close parsing
https://www.google.com/search?q=battery ... arinehowto
He has a great article on LFP care there, much will apply to other LI chemistries.
This thread is also long but very informative
http://www.cruisersforum.com/forums/f14 ... 65069.html
Also came across this in my notes
Image
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 23 2020 10:33am
Cheers, I'll look in to all of this, I think the general rule of thumb seems to be that both 'ends' of the battery charge cycle are where its life gets shortened.
Is it incorrect to look at a discharge graph as a representation of how much mAh are represented by the 'top' 0.1v [4.2-4.1v]?
I ask because on a discharge graph 4.2-4.1 seem to represent barely 200mAh at low discharge and close to nothing at all at higher discharges - this wouldn't line up with your graph suggesting 10%. Does this mean that the immediate 'sag' you see on a discharge graph isn't representative of starting the discharge at a lower (4.1, 3.9 etc) voltage.
He has a great article on LFP care there, much will apply to other LI chemistries.
I actually have one of his articles saved from a year or so ago from when I first entertained this idea. Very thorough and well written.
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by john61ct » Jun 23 2020 8:29pm
Sorry, I've lost track, what graph do you mean?
The % of capacity between two voltage points (**must** be V at rest not under load)
will vary by chemistry, even model battery concerned.
Leaving 10-15% at the bottom, and 5% at the top, would be a good goal, lots of extra longevity without too much sacrifice of capacity.
You will see people talk about only using from 20% to 80% that's just silly, or more likely they do not know how to actually judge SoC% accurately.
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Re: 48v[58.8] 10A adjustable/programmable charger for 9s14p lipo packs
Post by No_Shorty » Jun 28 2020 9:01pm
john61ct wrote: ↑
Jun 23 2020 8:29pm
Sorry, I've lost track, what graph do you mean?
I was just generally referring to a 'discharge graph' when a cell is tested, so for example:
Image
The % of capacity between two voltage points (**must** be V at rest not under load)
But I think you have just answered this anyway - as the above graph is under load, so the initial 'sag' is not representative of its capacity at this voltage?
Leaving 10-15% at the bottom, and 5% at the top, would be a good goal, lots of extra longevity without too much sacrifice of capacity.
Defo achievable. Still 3800mAh out of a 50E at 1C discharge [5753mAh rated]
You will see people talk about only using from 20% to 80% that's just silly, or more likely they do not know how to actually judge SoC% accurately.
Well it's good to know I don't need to go to these lengths even if I was targeting cycle life. As it is cycle life is a secondary thing that it a balance between the benefits and cons, and making the battery last 2-4x the time is certainly worth the 20% additional size and weight.
I have also recently been reconsidering LiFePO4 - but only because I never properly looked into pouch cells. In Prismatic or Cylindrical (e.g.26650) they are super expensive and super big and heavy. In pouch form they are a similar cost per Wh and about 30% heavier and only 15% or so bigger than a 20-90% DoD LiPo pack.
It's still yet more weight and size, but the safety and temperature resilience advantages bring them back in to the fold.
The biggest disadvantage by far is that these pouch cells are not at all widely available and I can find very little information on proper pack build procedures or reputable suppliers (my thread on this here: viewtopic.php?f=46&t=107029&p=1567230#p1567230). I don't think it's going to sway me away from LiPo cells. But it may convince me to build one pack of each to see how they both play out.
Lastly - I think I have decided on my charger once and for all. I'm think I'm going to go with the Mean Well RCB-1600. I have vague plans to make a touch screen controller with saved profiles to interface with it, but for now I can just adjust it with pots and adjust profiles with their nice friendly GUI. I didn't get the two outputs I wanted but que cera.
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