What charger to use for 8s4p lithium ion

HI guys I’m from London, I am having trouble finding a charger for my lithium ion battery pack.

My pack is 8 in series and 4 in parallel using samsung 25r meaning my pack is = 33.9v max charge

I have a bms and I will charge through the bms.

My question is what charger/port shall I use. I can’t seem to find a 33v charger. Also do I need 1A, 2A, 3A or 4A because I don’t know. I don’t need a balance charger because the bms does that, so all i need is charging port and a charger.

Cant I use a 36V charger? and unplug it earlier so my pack doesn’t exceed 33v? is that even possible? Will my house blow up?

if u want to charge a bit faster then choose with higher A… 3-4A should be good… but you might as well go with 2A and wait about 4-5hours till charging is complete…

u should look for one’s with adjustable voltage… you wil have to search around a bit…

Take a look at what @PXSS offered in his group buy… it might be possible to downgrade the voltage enough for your system…

keep looking :wink:

Great thanks man, theoretically what would happen if I used a 36v charger?

10s charges till 41v… unless u can turn it down to 34 or so… u.will overcharge.your.cells.

Full charge for an 8s pack is 33.6 not 33.9 4.2v x 8 = 33.6 Using a 36v charger could be dangerous. You could get a variable power supply to charge it. It would have to have adjustable voltage and current with constant current and constant voltage modes. Then if you decide to build a bigger battery later, you’ll be able to use the same charger up to 12s

SKYTOPPOWER STP6005 Precision Variable DC Power Supply 0 - 60V / 0 - 5A Digital Adjustable Regulated Lab Grade Safe Circuit Design - US Power Cord https://www.amazon.com/dp/B01MQFCFMN/ref=cm_sw_r_cp_api_zuCWyb6VJC6PG

best case scenario: Your BMS might not work if you use a higher voltage than it was designed for. worst case scenario: :volcano:

I got tired of my cheap brick chargers cutting off before my battery was fully charged and got a 60v 5a adjustable Linear power supply to charge my batteries. And it works like a dream!!!

It starts in constant current mode and slowly brings the voltage up until the battery reaches around 90% then it switches to constant voltage mode and as the battery fills up the current gradually decreases until it gets to zero at which point the battery is full.


I got a lab power supply a few years ago too - like @Namasaki has in his pic.

I’ve thought about building another from components… Here’s a cool option for those who want to make their own variable power supply:

Do you have a special charger between your batteries and the supply? I got myself a bms but the manufacturer told me I have to buy a cv cc charger. I don’t really get it :thinking:

If you already got yourself a bms maybe this is something for you: http://www.ebay.com/itm/Intelligent-Smart-33-6V-2A-Charger-for-8S-28-8V-29-6V-Li-ion-Li-Po-Battery-EU-/321471399664?hash=item4ad93046f0:g:YXAAAOSwKIpWBgVj

I am using a BMS installed on the board and my power supply is CC/CV It has to be Constant Current/ Constant Voltage to work properly

Ah, okay. I thought it just would supply voltage or current and you have to switch manually between the modes.

It switches automatically. All you have to do is set the max voltage and current like I said, It works like a dream!

Just saw it under your post. I think I over read it…my fault :confused:

The problem I was having is that my BMS would not start balancing until my 10s pack reached 42v and then the brick charger would turn off. At this very moment I’m charging my board. the pack is showing 42v but my power supply is still sending 55ma of current because the bms is balancing. When all the cells reach 4.2 the power supply output should be at zero. Or I could stop it at 50ma and call it good enough.

Do you have a link to your power supply? I have not bought the brick type charger yet because I’m still building up my board. But I think I could get the same scenario.

I have 2 brick chargers. One is 2a the other is 5a both do the same thing. They cut off when my battery gets to 41.8 or 41.9v and never fully charge the battery. The Power supply I got was a little pricey but not bad it was $179 +tax on Amazon I posted a link earlier in this thread for one that is only $75 on Amazon Mine is this one: https://www.amazon.com/gp/product/B00G0HAY3U/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

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Here is the one for $75 Thats a real bargain for a 60v 5a supply. they both have CC and CV modes https://www.amazon.com/dp/B01MQFCFMN/ref=cm_sw_r_cp_api_zuCWyb6VJC6PG

Sorry it’s to late here in Germany. I should get some sleep or I will over read even more links :stuck_out_tongue:

Great thankz guys, i ended uo buying a 8s brick charger from America specifically for charging 8s lion pack at 4a.

Thanks getting some real value from you guys