LiFePo4 15s Charger?

Skirmish

100 mW
Joined
Mar 18, 2021
Messages
44
What chargers will work with LiFePo4 in 15s configuration?
Will any 54.75v lithium charger work?

Thanks!
 
I would not go above 52V unless current at 0.5C or a bit higher, 54.0V max at say above 0.1C,

CC-only is fine.

Or for occasional cap testing to judge SoH%, 54.0V even if below 0.5C

holding CV then, a high current rate doesn't matter, hold until amps trail to 0.2C.

So adjustability is important.

If going for cheap then use a PSU or DCDC and have an HVC circuit cut it off at source

and a BMS as backup failsafe.
 
What lifepo4 cell ? No need to go above 52v or 3.5 v per cell. The cell and capacity or ah with determine at what amps you can charge this battery at. Along with the limitations of the BMS if you're running one.
 
999zip999 said:
What lifepo4 cell ? No need to go above 52v or 3.5 v per cell. The cell and capacity or ah with determine at what amps you can charge this battery at. Along with the limitations of the BMS if you're running one.

k2 26650 lifepo4 in 15s 8p.
I think I've been searching for the wrong thing, I haven't had a lot of luck finding a charger at around ~54v.
 
Skirmish said:
k2 26650 lifepo4 in 15s 8p.
I think I've been searching for the wrong thing, I haven't had a lot of luck finding a charger at around ~54v.
Yeah, that's an unusual configuration. 16s is the common "48V" standard. Can you rebuild the pack to 16s 7-8p? That would open up a lot of safe, cheap options.
 
999zip999 said:
Yes 16s is common and 15s is something you have do on your own. Why why 15s ?

The cells I bought came only in bulk, in a number divisible by 15 not 16.
 
Skirmish said:
The cells I bought came only in bulk, in a number divisible by 15 not 16.
It's less than 7% loss of Wh to reconfigure to 7p16s. Or just buy 8 bare cells for 8p16s for a 7% Wh gain.
I would design the pack around the charge and discharge profiles, not an arbitrary number of cells.
 
The programmable Satiator by Grin will work fine. A bit pricey but will solve your issue.
 
fatty said:
It's less than 7% loss of Wh to reconfigure to 7p16s. Or just buy 8 bare cells for 8p16s for a 7% Wh gain.
I would design the pack around the charge and discharge profiles, not an arbitrary number of cells.
Is there an advantage to running 16s vs 15s if the controller + motor + charger work fine with either configuration and the power available with 15s is adequate?
 
No, just easier to find cheap chargers.

Highly reco Satiator, very flexible for future proofing

model# 4808 labeled "24V-52V", I believe output range is 24-63V @8A (manual states 12-63V)
 
The Satiator looks great! $600 dollary-doos though :eek:

Could I use the Mean Well HLG-320H-54A for 15s and 16s?

It lists the constant current region from 27-54v and an adjustable output range of 49-58v https://www.meanwell-web.com/content/files/pdfs/productPdfs/MW/HLG-320H/HLG-320H-spec.pdf
 
That is a a good unit, and yes that V range will cover both 15S & 16S ranges, decent flexibility.

Note there is another step up in the HLG series for power, 600W iirc.

But the HLG is a power supply, not a charger as such, no automated stop-charge

best to look for an adjustable HVC to cut its AC input, set to your desired V setpoint and the PSU just above that.

Unless you are going to sit there and watch a DMM / ammeter to stop charging manually.

 
Will the PSU overcharge the cells if it's configured to output 54v for 15s?
I was planning to add a cheap Volts / Amps display from aliexpress, eg. https://www.aliexpress.com/item/32788030454.html and checking for it to hit 54v / low current and then turning the PSU off.

If I can stop charging automatically that would be really handy though. I'm not familiar with HVC, I had a bit of a poke around but couldn't find an example. Do you have a link to somewhere I could find a suitable one or some more information?

Thanks in advance!
 
High voltage cutoff, just a circuit that controls a relay / solenoid / contact switch when the specified voltage is reached.

Most BMS types could be rigged to work, Arduino etc, some OTS adjustable units out there, "battery protect" "DIY UPS" circuits.

Results in CC only charging, which is fine for LI chemistries for daily cycling.

Some even here claim so long as the Vmax is held there is no danger, it does no harm for cells to just go down to zero current.

Not me, afaic automated stop-charge (with backup failsafe) is required even if I plan to sit and watch.

But LFP is much safer than li-ion it's true.
 
Can't you buy a few more cells from battery hookup. Is that where you got these ? I find them to be nice reasonable people when I bought a box of 36 I asked for for more cells and they are able to put 40 cells together for me even though the boxers 36. 200amp cell.
16's is the way to go to make it easy on you and into the future.
Are you going to run a b m s ? If it's your first battery build I would definitely run a b m s.
 
Skirmish said:
Is there an advantage to running 16s vs 15s if the controller + motor + charger work fine with either configuration and the power available with 15s is adequate?
Higher voltage at same power = lower current = more efficient
But mostly just the ability to use a proper charger with charging safeties
 
Skirmish said:
Could I use the Mean Well HLG-320H-54A for 15s and 16s?
It lists the constant current region from 27-54v and an adjustable output range of 49-58v https://www.meanwell-web.com/content/files/pdfs/productPdfs/MW/HLG-320H/HLG-320H-spec.pdf


yes, this will work perfectly and is very safe, miles safer then any crap aliexpress "charger" you will find.

Skirmish said:
Will the PSU overcharge the cells if it's configured to output 54v for 15s?
I was planning to add a cheap Volts / Amps display from aliexpress, eg. https://www.aliexpress.com/item/32788030454.html and checking for it to hit 54v / low current and then turning the PSU off.

If I can stop charging automatically that would be really handy though. I'm not familiar with HVC, I had a bit of a poke around but couldn't find an example. Do you have a link to somewhere I could find a suitable one or some more information?

Thanks in advance!

just set the meanwell to 53V. there is no need to go higher. there isless then 2% of capacity to gain from going higher then 3.5V. your bms will do any balancing so the battery will be charged ferfectly no matter how long you keep the charger on.

ps: 3.4V float is also good, but you might not trigger the balance feature of the bms properly.
 
A 48 v sla charger might work. SLA's usually go to 55v which seems high but is less than what a similar lifepo4 charger will do. I have used sla's on my lifepo4 packs mostly at work. And this has been done without incident or damage to my knowledge. But I do use the
appropriate charger to fully charge & balance prior to a longer ride. Ideally, you take a workable charger and tweek down the voltage to around 53v. Or you can pull plug 10 to 15 minutes before batteries are full.
 
999zip999 said:
Can't you buy a few more cells

Good idea, I'll shoot them a message and see what they say. Just looking at their web shop shipping is going to roughly double the cost. If I absolutely have to do that I guess that's what I'll have to do ;)

I'll be using a BMS.
 
Skirmish said:
999zip999 said:
Can't you buy a few more cells

Good idea, I'll shoot them a message and see what they say. Just looking at their web shop shipping is going to roughly double the cost. If I absolutely have to do that I guess that's what I'll have to do ;)

I'll be using a BMS.

i you CAN fit and afford more cells you should. it increases everything from lifespan to range.

if you are someone that just wants to drive/ride the thing and leave it on the charger (wich is NOT a problem for daily use) you can just set your pack to charge at 3.5V per cell. no more, no less. well, you might want to dial it back to 3.4V per cell if you see the balance system on the bms activating contiusly when the battery is full. for actually filling the battery you only need 3.4V.
 
Yeah, definitely. I'm hoping the cell retailer can do a smaller order, otherwise it's going to get a bit expensive. Fingers crossed.

Would the extended life be from a shallower DoD?

I was wondering how the HLG-xxxH-54A would behave with it's max Vo set to below 58v: would that run CC up to the Vo set point? Would that affect the life of the cells?
 
Skirmish said:
Yeah, definitely. I'm hoping the cell retailer can do a smaller order, otherwise it's going to get a bit expensive. Fingers crossed.

Would the extended life be from a shallower DoD?

unknown, but generally the lower DoD the better. how much you gain is depending on your specific use case.

I was wondering how the HLG-xxxH-54A would behave with it's max Vo set to below 58v: would that run CC up to the Vo set point? Would that affect the life of the cells?

no, you set the current and voltage seperatly. you need the A version, this is VERY important. the B version has external leads and you need additional stuff to set voltage and current. the A version has internal pots under the black sillicone plugs.

i generally recommend setting the current to about 80% of its max rating. that keeps it a lot cooler. ps: you need to REALLY have a good look at the wattage you get. some models dont go as high as 58V, the 600W model only goes to 56.7V for example. be mindful and read the exact specs of that specific model. they differ between wawttages and the ELG or HLG version. the ELG is also an option as they are cheaper but less efficient and run hotter.

if you cant reach the voltage you want you divide the voltage by 2 and get that model and put them in series. dont forget that you need to divide the wattage also by 2.
 
Skirmish said:
Would the extended life be from a shallower DoD?

I was wondering how the HLG-xxxH-54A would behave with it's max Vo set to below 58v: would that run CC up to the Vo set point? Would that affect the life of the cells?
The V setpoint is maximum it should allow. CC is just a label for the first part of the cycle, before the setpoint is reached, aka Bulk.

Absorb / CV is after the set voltage is reached, charger keeping V capped, and amps start trailing, not regulated by any circuitry but the rising SoC / resistance of the battery.

Life cycles get maximised by 1 lower C-rates (higher Ah capacity),

2 avg DoD%, and

3 lower charge finish at the top.

And avoiding disastrous events of course.



 
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