PINNED - Lithium battery conversion/info

[LROBBINS]

What about using that along with a ZDS supply attached directly to the battery set to 3 stage: 3.7 (or a bit more) volts till low current when it would go to 3.6V and the balancing supply just used to drain high cells? Would it be able to actually see cell voltage when the charger is also connected? So far in my filling and partly discharging my new 200 AHr cells, a voltmeter on the cell sees an average of charger voltage and cell voltage - actually biased toward cell voltage.

[Burgerman]

Dont know. But dont exceed 3.65v and only for a short time on first charge. And after this dont exceed 3.60v for more than an hour if possible. If out of balance or for general daily use set balance to start at either CV or 3.50v not less. And charge to 3.55V where its safe to maintain for 4 or 5 hours no problem.

Any less than 3.5 to 3.55V doesent balance properly or as well. And or takes a lot longer.

I tend to use 3.550V or 3.600V and set balance to 3.500V and CV termination to whatever it takes to give me balance + 20 to 30 mins. That generally tends to be around 1000thC to 350thC depending on cell type, quality, age. So you can fine tune this by adjusting the actual charge termination current.

If that charger does this or allows this then you could probably use in place of the PL8 although it lacks the PC software. But as a stopgap? maybe.

[ex-Gooserider]

Is there an English version of the video? I'm sure the guy in the one Shirley posted is informative, but I can't understand a word he says...

However a second use case that I could see for a charger like this is for keeping it in the car or other secondary location as a backup to do a top-up charge if you find that you are getting low when away from your PL-8....

It also seems pretty small, so useful if traveling?

ex-Gooserider

[terry2]

Good for low quality Chinese cells, this new charger may worth a look ;
1S -- 12S , 20A Charge current , 4A balance , 9-58V input.


youtu.be/bcBLamrWd8c

Does anyone know the name of that charger?

[Burgerman]

Yes... 유나 Una6 Una9 신형 밸런스 충전기 A12 Pro

Or Dave.

[LROBBINS]

Thanks for the clue. Here's the result of an AliExpress search and a few individual listings. Unfortunately there's not too much usable information in any of these, at least for someone who doesn't know Chinese, and probably none of the details we'd need even for someone who does.
https://it.aliexpress.com/wholesale?catId=0&initiative_id=SB_20210414020413&SearchText=A12Pro+

https://it.aliexpress.com/item/1005002328086618.html?spm=a2g0o.productlist.0.0.5f322fcfOeVxj8&algo_pvid=713cade5-eabb-4bed-9317-4ef1a1631185&algo_expid=713cade5-eabb-4bed-9317-4ef1a1631185-4&btsid=2100bb4716183946536002969e0db2&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

https://it.aliexpress.com/item/1005002329201206.html?spm=a2g0o.productlist.0.0.5f322fcfOeVxj8&algo_pvid=713cade5-eabb-4bed-9317-4ef1a1631185&algo_expid=713cade5-eabb-4bed-9317-4ef1a1631185-2&btsid=2100bb4716183946536002969e0db2&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

https://it.aliexpress.com/item/32946424223.html?spm=a2g0o.productlist.0.0.5f322fcfOeVxj8&algo_pvid=713cade5-eabb-4bed-9317-4ef1a1631185&algo_expid=713cade5-eabb-4bed-9317-4ef1a1631185-1&btsid=2100bb4716183946536002969e0db2&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

https://it.aliexpress.com/item/32863307378.html?spm=a2g0o.productlist.0.0.5f322fcfOeVxj8&algo_pvid=713cade5-eabb-4bed-9317-4ef1a1631185&algo_expid=713cade5-eabb-4bed-9317-4ef1a1631185-0&btsid=2100bb4716183946536002969e0db2&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

From here Aliexpress pages come up in pretty bad Italian, but I assume that if you are elsewhere they will come up in some approximation of your local language.

[Burgerman]

I tried to find info too. That really is the name by the way. (Not dave, the other one!) I was looking for maybe a handbook or PDF like the one with the PL8.

The problem is that the devil is in 2 things. The firmware/software. And the DETAILS. And there are almost non as usual. So you dont really know how programmable or what it will ACTUALLY do in reality. What will cause errors. Its designed for hobby use, so like the PL8 it may error on large capacity Ah. Or time limits not allowing a full charge at 20A. A 200Ah battery will heed 10 to 11 hours at 20A. Many have a 2 or even 8 hour limit. Scared of lipo fires. Does it end charge when current reaches some level of mA? Or when balanced, or does it keep going! Can you choose termination conditions? Balance current level end point, etc. If not and its expecting a small Ah hobby pack it wont go well... And does it error after a 150mA cell voltage gap like the PL8 did before I interfered with the software guys? And a few other questions.

Not enough info to find out. As I say the devil is in the ones and zeros and the details. Even the menu's. Yes it does chinese. But does it do english? Or even chinglish? One thing that bothers me is that for reasons that baffle me the usual way of setting termination current is not mA. As it should be. But a percentage of charge current. Which means every time you change charge current you also over or undercharge the cells... And often it will not go low enough anyway so you are forced to charge at a lower current like on the iChargers. So again. more info needed!

[shirley_hkg]

I got mine today .
@ £85 .

[shirley_hkg]

Maximum balance current is 4.5A actually .

[bghil]

Hi all,

I have converted my powerchair to LiFePO4 last year, based on great advice from this site. My pack is 6P8S of 10Ah headway cells (I have no more space, and could not find enough 12Ah cells).

All was fine until recently. The 3rd group (made of 6 cells) did take longer and longer to balance. For my safety, I removed the battery from the chair for some testing and individual group charging. All but the third groups were very similar, with the third 2Ah lower.

Some discharge/charge cycles (only a few Ah) and all seemed good again.
I put back the pack into the chair and used it for 2 weeks, with increasingly longer time for balance: same problem again.
When I charged each group (but the third), I put back 10Ah.
On each of the 6 cell in group 3, I put back 5Ah, so the imbalance was 20Ah!

Thinking one cell was bad, I charged them individually, the problem should be obvious.
But no, they look fine in isolation. I could not pin-point the faulty one.
I then monitored the voltage just after disconnecting the charger, and one cell drops must faster than the others, up to -50mV. I replaced this one.

I rebuild the pack and let it rest for 2 days.
Just before reinstalling in the chair, I made a little discharge and charge again as a pack... and the group 3 was lagging behind by a lot.
I charged it separately and put back 13Ah. 13Ah of unbalance after just 50h of rest, how is that possible?

Yesterday, I started to think about cabling issue, maybe a little short (not strong enough to destroy anything fast). My ohm meter does not find anything suspicious.
I also suspected of one cell "leaking" and discharging the others. I separated one cell at a time and put the amp meter to measure some current between the just separated cell and the rest of the group. No more that 0.1mA.

I am really lost with this.
I plan to dismantle everything and start back from beginning:
measuring the auto-discharge of each cell, grouping to make the discharge of groups as close as possible...

But I suspect I could hit the same problem again if I don't understand was is wrong.
Any help would be greatly appreciated.

[Burgerman]

You have a PL8?

Test all cells on the failing group.
Charge FULLY at 3.600V until its been at CV until current falls to 200mA. Each one seperately.
Then mark as A B C D E etc,

Wait for at least a week.
Now recharge each one with a termination current of 200mA
Write on each cell the exact mAh returned. You will find one that has a high self discharge current compared to the rest. This will be a small difference and just a few mAh on good cells. Should not take long to charge.

Discard any that have high self discharge rates.

Replace with new.

CAPACITY test at 10A from 3.600v to 2.9V and you should see the same capacity from each cell. To within say 2%.



Why has a cell deteriorated?
I dont know. But a 60Ah pack is not enough for a powerchair really even with headway cells. Too high loading per cell. So problems occur.
Where did your cells come from? eadways are now old. And many sold as new when in fact not. And many copies that are not genuine. Also if you have a bad connection on your pack all sorts of weird stuff happens.

Tell me you are not using a BMS! Battery Murdering System? That could easily be your problem.

And never exceed 3.600V unless in very controlled conditions on initial charge.
And never drop below 2.9V unless you want to murder the cell.

[bghil]

Thanks BM.

I don't have a PL8, where can I find one?
I use an ISDT Q8. I cannot change the termination current, but it looks like 0.1 or 0.2A anyway. Or does it depend on the max charging current?

No, I do not use a BMS, I have read your site ;-)
I always set charge voltage to 3.6V and never dropped below 2.9. The lower I got was 3.2V before charging, about half capacity.

Before replacing any cell, I did test the self-discharge for 4 days. Not that much difference between the cells (but higher than the initial measurement I did one year ago during 2 weeks).
I also did this the second time (after replacing one cell), and not any more differences either.

I did not do a capacity test on all cells either, just a few ones at build time, which were good (but none in group 3 were tested)

What I did not do is charge them separately, I charged as a group, then disconnected the group and let rest for a few days.

I will test by charging separately, but I do not understand what difference it could make.

[Burgerman]

If you charge in parallel as a group, and one cell has failed by going high resistance you may see the group as charged, and that one cell may not be.

Normally the problem is a bad connection so that one cell is out of step or only partly connected as a pack. So it gets partly charged.

If no cell has higher self discharge than the rest. And no cell has a different capacity than the rest. Then the pack works. So you have either measured something badly or have a bad connection.

On many chargers they attempt to balance the cells below 3.500V during the whole charge cycle. That DISCHARGES the cell with the highest voltage. The problem is that the cell with the highest real voltage is NOT always the cell with the greatest state of charge. So this attempt at balancing UNBALANCES the pack by in your case 1.5Ah every hour the charger is connected. And so its quite possible that the charger is at fault.

So important question 1.
Does it try to do ANY balancing below 3.5V? If so throw it away.

Does it stop charge because current is low (.1 to .2A) BEFORE balance is completed?
Does it stop due to capacity or time limit reached before balance is achieved?

One problem with many chargers is that instead of ending charge at the correct termination current that YOU CHOOSE it does so at some percentage of charge current which is useless. Because its quite critical. And so if you charge at a low current it never ends! Of you charge at high current it ends way too soon.

Without looking at the charger I cant tell you if its any good.

[bghil]

The charger does nothing to try to balance until the first cell reaches 3.6V (my target voltage).

Then, it seems to discharge a bit the highest cell(s) (slowly) and the voltage drop to 3.59. Then restart charging but not at full Amps. And the cycle continues until all cells are 3.6.
I think it is a sound strategy, isn't it?

Then, the display turns green ("balancing") and continue for a few minutes and stops. I can see voltage going to 3.62 max in this phase, but only shortly.
Maybe this step should last longer?

There does not seem to be any timeout for the charge (I stopped it myself after 12h of balancing going nowhere).

So I may need to change the charging current to a low value to ensure the charge is not stopped too soon?
I will try that when testing the individual cells.

[Burgerman]

That can damage cells! 12 hours at a raised 3.600v is way way too long. They should be at peak voltage during charge for approx 15 to 20 mins max. If they are very unbalanced and it takes longer you should really be dropping down to 3.525v to 3.505v charge while it does that.

If all cells check out for self discharge. And capacity. Then you have a bad connection in the pack somewhere.

I don't have a PL8, where can I find one?

Shipping from revolectrix stores in US and singapore. And you will need a modified preset from me to play with. Hidden settings... And a FUIM3 and a handful of 36 inch cell balance connectors. All at the same time.

[terry2]

Maximum balance current is 4.5A actually .

How are you getting on with that charger?


I have done 45 miles going at 6-8-11 mph shopping and I've used 103 ah (2.7kWh) so far. Volts are still at 3.2 on all cells.

Think I will get the full 170ah out of them.

[shirley_hkg]

It can actually do 30A charging and 4.5A balance.

Good for imperfect Chinese batteries , though not accurate as PL8 .

[terry2]

It can actually do 30A charging and 4.5A balance.

Good for imperfect Chinese batteries , though not accurate as PL8 .

That's great news. Think I will order one.

Does it come with balance cables, or is it best to buy some. Or get the board as well?

Can you post pictures of your wiring please

Thanks

[terry2]

Is there website www.dc211.cn ? thanks

[ICEUK]

3D printing my new battery boxes, im going to do a lid as well . 2 days continuously printing (-:

[Burgerman]

Those are to stand prismatics in?

And a lid?

Excellent! If they are a tight fit. What are your cells? I see a new business in your future on here.

[ICEUK]

The pack I am making is based around 8x 202ah lithium cells, I have allowed 1mm extra to allow for any discrepancies in the battery cells. The base of the battery box is 150mm high, all sides are 2 mm thick. box looks sturdy. The lid is 48mm high again 2mm thick.

I am going to incorporate some cable management on top of the box to keep wires tidy and in place. Maybe some snap clip system or it may eve n be a simple channel for wires to run inside,







https://www.rj-lithium.com/sale-1184435 ... arter.html

[ICEUK]

Do I need the vent holes as shown in image?

[Burgerman]

Yes if only to drain water.

[ICEUK]

hi bm,

The last image I posted is of the lid, its upside down, didnt know if we need vent holes for the cells? but good point about some drain holes.

[Burgerman]

Vent holes probably wise.

[ICEUK]

Is it a good idea to have the cells a tight fit or give them a 1 mm gap all around?

[Burgerman]

A good fit and thin walls. In some installations 1mm extra makes things not fit...

[ICEUK]

I had my battery box on my wheelchair extended by 30mm, I'll get some pictures up when its finished printing

[shirley_hkg]

Can you post pictures of your wiring please

Thanks