What charger to use for 8s4p lithium ion

ESK8 Electronics
, , ,
21

Hi guys! Is it possible to use this regulator: https://www.amazon.ca/Converter-Transformer-Regulator-Controller-Regulated/dp/B00E8D7XYG/ref=sr_1_6?ie=UTF8&qid=1490102218&sr=8-6&keywords=regulated+power+supply+60v

powered from 210w 19.5v laptop brick like this (I already have one)?

I also have a good 550w PC power supply, but it is limited to 12v…

The thing is now I am working on dual motor build with 8s7p battery (with used laptop cells) for this summer, but for next year I am going to build a solid 12s battery with new high drain cells. So I don’t want to buy a charger to use it only for one summer and then put it on a shelf. I would prefer to build a good variable power supply/charger to use for various projects… Looking for your advice. Thank you!

22

Be careful - that is just a step down converter. It says in the description:

This makes this hard to use as you can’t use any PSU and when you do have a lab supply you would not need this in the first place.

You should use this for your purpose (that is what I did): http://www.ebay.com/itm/DC-DC-900W-0-15A-8-60V-To-10-120V-NC-Boost-Power-Supply-Module-CC-CV-LED-Driver-/182029384354?hash=item2a61cbfaa2:g:1gAAAOSwezVWxxrE

23

read this thread (especially at the end it gets interesting and describes your plan):

1 Like
24

Thanks, That’s exactly what I was looking for!

25

Hi man! What BMS do you use, and what charger did you find? :slight_smile:

26

Do those brick chargers cut off both with BMS and w/o BMS at 41,8v? What would happen if the chargers do not cut off at 42? Could they just be ‘dumb chargers’ and idle at 41,8-42 like all night, and letting BMS balance all nice and dandy?

Thanks!

Edit: Could I just use DC-DC ‘universal’ converter for normal charging to get my 42v charger to 40/41? and some time scer the converter to 42 for balancing?

Like this 8.5-50v input - 10-60v output cheap Aliexpress DC-DC converter?

Although they do mention something about for charging you’d need this and that, in the description

Oor just use a fully adjustable, probably €€€ bms from the start?BesTech

27

Namasaki, do you know whether if using a one of those ‘dumb’, power supplies with voltage regulator (43-40v) on them and voltage on 41v, when do they cut off? Do they just idle all night at 41v after the battery doesn’t take current in anymore? does a SuPower BMS make difference when charging with 41v with it? Would it be possible to add a cut-off measures?

Thanks!

28

I use a Lab power supply to charge my batteries. If you use a power supply it should be a CC/CV power supply Voltage is like water pressure Current is like water flow Current will only flow into the battery as long as the voltage in the battery is lower than the voltage your charging it with. So when your charger is set to 41v and as your battery reaches 41v, the flow of current drops. When I charge my batteries, my Vesc’s are on so they take a littler current. So the current on my charger never drops below 50ma at full charge. If your Vescs are not on during charge, then it’s possible that your charge current would drop to zero at full charge. So even though the charger stays on, it’s not overcharging the battery.

I looked at the power supply your linked. It only outputs 36v If I’m not mistaken, a regulator will reduce voltage output but not increase it so you’ll need a supply with higher output.

29

Yes that’s what i wanted to hear, that although I could use timer, there wouldnt be anything bad happening if it would just idle at that 50mA

Haha yo yeah I had looked on too many different 10s/36v/42v chargers that I automatically though “hey that fine!”

Thanks

30

When the charge voltage and battery voltage equalize, current can no longer flow because the pressure being equal will stop the flow. If you do not have any load on the battery, Vescs on for example, the charge current should drop to zero.

Check out this video about charging a Lipo with a power supply: