Bulk charge setup choices

[nutnspecial]

Mornin all, I would love some confirmation and any input on this subject.
I read neptronix's tuturial on lipo and the wiki, and alot of other threads but have not found what I'm looking for.

Battery 'packs' to be charged: 18s of 6s 5.8ah or 16s of 4s 5ah. Each pack may in the future be doubled in capacity to 11.6 and 10ah respectively.

For universal low priority charging and balancing: an icharger 106b 6s 250w. I see this as an essential part of charging and maintanence, but definitely slow and a pain to rewire the series packs for charging, and I believe it's unnecesary to do so on every charge.

Enter bulk charge. If you wanted to charge 64-80v batteries having 5-11ah, what is the setup of choice?

before anyone mentions, no I don't want an expensive 4 channel charger and am not considering a bms. (these are great, but I prefer to be my own bms, because I find kiss is always more reliable)

I am considering 2x of one of these. One is a used meanwell brand with a little less current, the other is a little less$, new, and more current.
http://www.ebay.com/itm/High-Performance-36V-DC-9-7A-350W-Regulated-Switching-Power-Supply-36-Volt-/181633106482?pt=LH_DefaultDomain_0&hash=item2a4a2d4232
http://www.ebay.com/itm/Mean-Well-36Vdc-8-8A-Switching-Power-Supply-SP-320-36-Very-Clean-/271750208652?pt=LH_DefaultDomain_0&hash=item3f45931c8c

If there is a tuturial thread on these in series please link it!

Here are my questions: what would be a better choice? (ie is the namebrand more important than the other criteria?)

Do most of you target your batt charge rating specifically for charging? Mine are 2c, and I assume 1c is double the time to charge.

So if one planned on 10ah batts, would one seek a 20amp charge setup? Examples?

If there is no chance of exceeding the 2c batt rating (as in the case of my proposed setup), I assume a board like fetcher's limiter is not desirable and/or necessary? Why would you use one, in what circumstance?

My assumptions are that either of the linked psu is considered cc/cv and to series them for proper voltage I will at least need to isolate grounds. Is there anything else to know?

 

[Ykick]

SP series meanwell utilize "hiccup mode" over current protection. You'd need a current limiting circuit or scheme of some sort. I've used them and still do every once in a while but knowing what I know now, I'd stay away and look for chargers designed to be chargers.

https://bmsbattery.com/16-alloy-shell-charger

I've had good experience with the 400W version. About $85-$90 shipped last I bought.

The other PSU is a clone - who knows what it's capable of doing, how long it may last or if it even works at all?

You say don't wanna hear it but without a BMS you're literally playing with fire bulk charging RC Lipo naked. We've probably all done it and have gotten away with it for periods of time but it's a dangerous and reckless game to play. I'm not gonna contribute any further to that activity. Good luck...

 

[nutnspecial]

Thanks Ykick, the 900w version is 90$ and delivers about the same current as the meanwell psu's. I like that it's one unit and assume it's better suited for this purpose? So it doesn't use hiccup mode then, it uses cc/cv?

Is there an abbreviated version of 'what you know now' on psu vs chargers that would help my decision?

Also, you use battmedics on your 4s right? They are considered a management system, yes?
That was my plan too- along with low voltage alarm and the ca for when under discharge.

My comment was referring to a dedicated automated bms mated to each battery set- I believe that's the common interpretation of bms here. I don't trust it, don't want it.

https://bmsbattery.com/ebike-charger-ev-charger/457-alloy-shell-900w-lifepo4-li-ion-lead-acid-battery-ev-charger-charger.html#/ac_voltage-90v132v

Looks tempting, although it's unclear how much the voltage is adjustable, and i place little faith in user friendliness based on spelling and syntax errors just on that page. Do these even come with any documentation for their designed use?

 

[miuan]

I'd stay away and look for chargers designed to be chargers.
https://bmsbattery.com/16-alloy-shell-charger
I've had good experience with the 400W version. About $85-$90 shipped last I bought.
You say don't wanna hear it but without a BMS you're literally playing with fire bulk charging RC Lipo naked. We've probably all done it and have gotten away with it for periods of time but it's a dangerous and reckless game to play. I'm not gonna contribute any further to that activity. Good luck...

I've had horrible experience with the BMS Battery 400W chargers. I've had about 4 of them, ONE still works, others smoked.
On the flipside, the 360W equivalent of GreenBikeKit seems to run cooler and more reliable.
Both set at 4A stock.

I'd say if you MUST buy the BMS Battery model, I'd run it at less than rated amps. Otherwise get another brand of same looking charger.
DO get the BMS circuit for your lipo if you can. You don't need to power your bike thru it, just use it for charging to keep your home and workspace safe.

I've had the 900W BMS Battery charger once... it broke too.. it was quite noisy while it worked though. And since I've been using the 400W units, I've come to the conclusion that they are just so much more practical:
- less noisy
- more portable
- still fast enough
All of those chargers are well adjustable for both current and voltage.

 

[Ykick]

nm.....................

 

[MrDude_1]

if you're going to run 16s, you can wire them up as two 8s batteries. Get an iCharger 208 and you'll have 350w of charging... you can just plug in ONE and balance charger, then plug in the other. Or at the very least, make it a single plugset to change between series and parallel.... less chance of messing it up.

as far as bulk charging.. I like my Meanwell SP-500-27. Its set for 33v for 8s bulk, and you can run two of them for 16s bulk. It does take one simple mod to let the amperage be adjustable. I recommend charging below 1c... this means that if you're totally discharged, it will take about 1 hour. 2c would be a half hour. it IS a CC/CV power supply/charger.

I have 20ah of lipo, and I charge it at about 15amps max.
the SP-500 is really rated for 486 watts..
33v @ 15amps is 495watts.. so I am already pushing it a tad... however it seems to handle it without issue.
Ive pulled 600 out of it before(about 18A), but only in cold weather with an eye on temp. I wouldnt do it in the summer.

Because I never have my pack run down too far, I always end up mostly charged in 20mins or so.
Also, please note that this is a dumb charger.. so as your pack gets closer, it lowers the amperage.. until its all so low that you would be better off with the iCharger... the icharger is smart, in that it looks at the pack, sees its low, and raises the voltage to let the full amperage in. The meanwell goes slower the closer it gets to full.... so by the time you're 90% charged, you might as well unplug it unless you have time to kill.

 

[nutnspecial]

Thanks Ykick but the last comment I don't understand. Some one can mix up pos and neg just connecting a battery. (in fact there was just a post where someone tried to parallel 5s with 15s)

In my mind, you'll never be able to protect the disrespectful users from themselves. I see it all the time with the way the building codes go, and the mindset of the officer.
They have a million rules to protect people, but there is no substitute for teaching a kid that an outlet will shock them, that a stove will burn, that it hurts to fall down.

Giving them a bms is never gonna keep them safe- Without knowledge and respect of/for a device, it can still end badly because that device can fail. Infact, my point is one should never rely on tech alone to protect them from danger.

If that's your thinking then fine, I do understand where you're coming from. (it's the american mindset- dare I say) Let's face it though, this stuff is dangerous, but no more so than gunpowder or gasoline.

Mr Dude
as far as bulk charging.. I like my Meanwell SP-500-27. Its set for 33v for 8s bulk, and you can run two of them for 16s bulk. It does take one simple mod to let the amperage be adjustable. I recommend charging below 1c... this means that if you're totally discharged, it will take about 1 hour. 2c would be a half hour. it IS a CC/CV power supply/charger.

Thanks Dude! That answers the questions I asked, and helps alot.
You recommend charging at half the c-rate? Is that because you have the 20ah and the charger is maxed before 1c?
I've read to stay around 60% max of C for continuous discharge, but hadn't heard anything about staying 1/2 C for charge. (and in my mind the charge C-rate is already 1/10 or less of the discharge rating.)
Any idea where to find a funtional write-up on doing them in series?

 

[MrDude_1]

Thanks Dude! That answers the questions I asked, and helps alot.
You recommend charging at half the c-rate? Is that because you have the 20ah and the charger is maxed before 1c?
I've read to stay around 60% max of C for continuous discharge, but hadn't heard anything about staying 1/2 C for charge. (and in my mind the charge C-rate is already 1/10 or less of the discharge rating.)
Any idea where to find a funtional write-up on doing them in series?

Theres a HUGE meanwell thread on here somewhere... buried in that I found out all the info I needed for my meanwell mod. The only mod is replacing a very easy to get at resistor with a 5k linear pot. I ran my pot up to the front of the case and stuck a knob on it.

As far as the charging goes, theres a couple things at play.
The slower you charge, the longer your batteries are going to last.
The ratings of RC batteries are for sales, not for actual hard use.
We often use our batteries more than the RC guys. Most guys pull out their large 8s choppers once every other weekend or whatever... and they have multiple batteries they swap... they then quick charge them in the field... one goes bad, its $40-$100 and lasted a year.... On the otherhand, we have several batteries, run them all the time, and if we treated them like that, we could only get a few months of use, then its alot more money as we run several at once.

So you will see claims of charging at 5c or whatever.. and thats insane. they get hot, and they just dont last if you do that.
I always stick to 1C or less, any faster and you're shortening the battery life to save a few minutes.

That said... yeah, my charger can only push 15amps and 1C is really 20amps... so I am only charging at 3/4C rate. I am often tempted to turn it up higher, but there are two large MOFSETS on a heatsink in there... when its set at 33v, they dont get much hotter pushing 15amps... but when I turn them up to 16 they get noticeably hotter over time... if I crank it to 18 they get very hot instantly. So I am going to stick to 15amps... Keep in mind, if you dont fully discharge the battery, your charge time is much shorter... I always try to run as much amp-hours as I can stuff in there...that way I can go farther, lose less voltage on short trips, and I can charge faster... everything works easier if you oversize the battery a little.

 

[nutnspecial]

Thankyou!