Anyone got a charger for top balancing cells higher than 5amps.

ddonq1412

Looking to see does anyone have a charger to balance 16 cells. Willing to pay some money for assistance on it. Based in northern ireland but willing to travel to collect charger. As i think i have a bad cell but wanting to confirm.

on_the_roots

Easier (and probably cheaper) buying a brand new from Amazon for ~£51.00 and re-sell it afterwards.

ddonq1412

i have one on these at 5 amps and it doing nothing at all been connected to a set for over a week and it still shows 3.32v

slave1

Use car jump leads, generally they are supplied with “weak” cables

unkel

https://www.boards.ie/discussion/comment/121189216#Comment_121189216

Nature of the beast I'm afraid. If you have 16 300Ah cells and they came 50% charged, even with a 10A charger that would actually charge all the way up to 3.65V with the 10A (it won't - not even close) with 30W (10A times 3.2V) will take 7500Wh / 30W = 250 hours. In practice a lot more than that, as the amperage goes down towards zero when the cells get more and more charged, so up to 3-4 weeks. Double that if you have two cells in parallel in your pack!

My solution: forget about top balancing. It's a fool's game. Every week you spend top balancing the cells, you lose time and you lose money. Bang the cells into a battery, make it work for you and make it start paying its way and let the BMS top balance the cells over time

ddonq1412

Have 14 cells in parrallel and it's been 9 days so far. And getting no where with it. I do have a set of cells in a seplos mason and it won't allow them to charge or discharge.

Big Lar

If you parallel 4 cells and then connect each of your 4 paralleled cells in series to make a 12v battery you could get the majority of your charging completed with a car battery charger @ 12v to do the majority of the charging and then split them again to balance them.

unkel

https://www.boards.ie/discussion/comment/121192418#Comment_121192418

That would speed things up, but your cells would have zero protection, so you have to know what you are doing and regularly monitor the individual cells. Didn't one of the regulars on here damage some of his cells by exactly doing this recently from accidentally overcharging them?

ddonq1412

Not sure if I fancy a car battery charger. A bit of money in these if they start blowing up.

on_the_roots

What if you just mount the 16 cells in series, connect the BMS as normal and let the inverter charge them? Then unmount all cells and balance with the DC power supply? This would speed things up and you might not need to balance all of them, right?

Of course, if your BMS doesn't balance automatically....

unkel

https://www.boards.ie/discussion/comment/121192587#Comment_121192587

This! And if your BMS has active balancing, you don't need to unmount and top balance. It is overrated.

My theory is that this is a self-perpetuating old wives tale. Based on the past where BMS did not have active balancing and cells were very expensive, so it was important to get every last Ah of capacity out of every cell. A bit like people saying you need to way oversize your array of solar panels for your inverter as your inverter is very inefficient at lower loads. Another old wives tale that has been around for many years, totally false now.

ddonq1412

My problem is I have a seplos BMS connected all cells read 3.2v but the packs switches off after 5mins. And it only drawing 2ah out of it.

unkel

https://www.boards.ie/discussion/comment/121192862#Comment_121192862

Seplos doesn't have active balancing. So in your case I would do as @on_the_roots suggested, hook up the inverter and try get the battery (in series) charged as much as you can with it (the Seplos will protect cells from overvoltage) and when it won't charge no more, dis-assemble battery, connect cells in parallel and wait however long it takes before all cells are 3.65V. Could still take weeks.

Alternatively, leave the battery connected in series and attach an active balancer. There's a cheap one for sale on adverts from one of the forum regulars (it used to be mine). It will do the job for you and once top balanced, just remove it and either keep it or sell it on...

ddonq1412

I have set me seplos inverter to user defined and had it at 18 amp charge slowly creeping it up to 22amp as I was trying to watch the cells shooting the voltage didn't want it to get to 3.650v or near that to any cell. Got about 5kw pushed to it most cells reading over 3.4 the last 2 were reading 3.381v so slowly getting there.