PINNED - Lithium battery conversion/info

[terry2]

Scooterman, how do you get all those cells to stick upside down and the laptop too?


Terry, yes it looks balanced and well full.

Now choose discharge, for 2 to 3 hours. And post a screenshot.
All cells should be very close like a single line almost.

Then choose recharge, and they should all be almost completely balanced straight away as soon as the charging finishes.
And another screenshot.

Discharging now.
All the cells are 3.318v as I have been discharging for 40 mins.

I wont be needed soon. We have expresso and scooterman, all figuring this stuff out and 3 or 4 others.

Not a chance

[Burgerman]

Shirley too. He was doing addons and emailed me before this site existed.

[terry2]

I had to stop discharging as it's my meds time.

All the cells was 3.318v after 40 mins

[expresso]

I wont be needed soon. We have expresso and scooterman, all figuring this stuff out and 3 or 4 others.

Oh not a Chance - always learning from your and others here - wont let you go that easy i finally started testing my range on the bounder with the famous BMS you love so much we see - i am inching my way up to see how much range i can get.

so far so good - i might have done about close to 28 miles to 30 today - recharging now -

[Burgerman]

Oh not a Chance - always learning from your and others here - wont let you go that easy i finally started testing my range on the bounder with the famous BMS you love so much we see - i am inching my way up to see how much range i can get.

so far so good - i might have done about close to 28 miles to 30 today - recharging now -

But with a BMS to interfere range is going to be inconsistent. Depends on balance, which may well be good, or after a few weeks stored, miles out. And on cell temperature. And on load. So slopes or hills. Just because you get 30 one day doesent mean it wont stop at 20 another day.

[steves1977uk]

I wont be needed soon. We have expresso and scooterman, all figuring this stuff out and 3 or 4 others.

You'll always be needed BM Who else would we have to teach us!

Steve

[expresso]

Oh not a Chance - always learning from your and others here - wont let you go that easy i finally started testing my range on the bounder with the famous BMS you love so much we see - i am inching my way up to see how much range i can get.

so far so good - i might have done about close to 28 miles to 30 today - recharging now -

But with a BMS to interfere range is going to be inconsistent. Depends on balance, which may well be good, or after a few weeks stored, miles out. And on cell temperature. And on load. So slopes or hills. Just because you get 30 one day doesent mean it wont stop at 20 another day.

i am aware of that - for instance today i went a bit more just to see - but i also had to go up a hill steep which seemed to last for ever the chair did slow down Alot for the whole slope - so i know this is one hill i like to avoid next time - i will figure out a different to get to the bridge and avoid this one hill - i am starting to use the chair now so its getting charged more often - hopefully that will keep the pack balanced better -

[shirley_hkg]

Shirley too. He was doing addons and emailed me before this site existed.

Faded memory , and couldn't recall what I asked .

1.5 decade ago .

To friendship

[Furio]

Hi BM,
I dismantled my pack and measured the cell voltages on no load and on load.(Used 3 24V, 90W halogen lamps in parallel as load) The results are:

Cell # (from +ve) No load V. Load Amp Load V.

1. 3.330 3.12 3.324
2. 3.331 3.42 3.326
3. 3.330 3.15 3.325
4. 3.331 3.44 3.320
5. 3.330 3.15 3.325
6. 3.330 3.16 3.327
7. 3.330 3,39 3.320
8. 3.328 3.25 3.300

The connections were fairly corrosion free and no crimp connections. Cleaned all connector contact areas and cell terminals, reconnected the cells again. Checked pack voltage. The result:

Pack 26.63(Open V) 9.90(Load A) 26.46V(Load V)

When the pack was loaded as above, the cell voltages:

1. 3.302
2. 3.305
3. 3.303
4. 3.299
5. 3.303
6. 3.304
7. 3.298
8. 3.305

The readings are fairly good, it seems.I am yet to put the pack back in the chair and see the result on actual load.

What is BM's opinion/advise.

Thanks.

Furio.

[Burgerman]

Likely a bad connection. Charge and balance and post screenshot. Then do a discharge test, to 2.9VPC. And post that too.

[terry2]

Here is a pic of the re-charge of my pack.

[Scooterman]

Before your meds you discharged your pack by about 6.5Ah (a tiny percentage of 176Ah pack).

Then this morning you put back in about 7Ah (another tiny percentage).

IMHO it doesn't really demonstrate much apart from your cells re-balance again at 3.6v after a tiny discharge.

If I was you, I would discharge the pack a bit, then dismantle it and re-assemble it in your chair. If it won't take long (i.e. a few days) to install the pack in your chair then leave the pack as it is, i.e. fully charged. If you won't be installing the pack for many weeks then discharge it a bit. About 50% is good for long term storage (months) but you obviously won't take that long to install it. You're not a slowcoach like me!

But as I've said numerous times before I'm just starting out with lithium so am not that sure of my ground

But everything you've done looks good to me

EDIT: But if you want to test the capacity of your pack Ah, then discharge it to 3.0v or 2.9v, but it'll take a blooming long time. I recently discharged two 90Ah packs they each took about 22hrs to discharge to 3.0v. Although I have got two PL8s so could discharge both packs at the same time.

[terry2]

Before your meds you discharged your pack by about 6.5Ah (a tiny percentage of 176Ah pack).

Then this morning you put back in about 7Ah (another tiny percentage).

IMHO it doesn't really demonstrate much apart from your cells re-balance again at 3.6v after a tiny discharge.

If I was you, I would discharge the pack a bit, then dismantle it and re-assemble it in your chair. If it won't take long (i.e. a few days) to install the pack in your chair then leave the pack as it is, i.e. fully charged. If you won't be installing the pack for many weeks then discharge it a bit. About 50% is good for long term storage (months) but you obviously won't take that long to install it. You're not a slowcoach like me!

But as I've said numerous times before I'm just starting out with lithium so am not that sure of my ground

But everything you've done looks good to me

EDIT: But if you want to test the capacity of your pack Ah, then discharge it to 3.0v or 2.9v, but it'll take a blooming long time. I recently discharged two 90Ah packs they each took about 22hrs to discharge to 3.0v. Although I have got two PL8s so could discharge both packs at the same time.

It was discharging for just under 2 hours.
I will do 3 hours now. I will be using BMs profile which works and is safe

The pack is built and wont be coming apart again until it dies.
After more testing and BM says it's good to go. I will clean up all contacts using IPA Isopropyl.
Then I will use a very fine amount of Loctite.

I can't wait to see your cells. Are they going in your scooter?

[Scooterman]

Understood, sorry I don’t know how far you are into your build. :Thumbup: My cells are hooked up temporarily while I wait for parts to arrive

Using internal discharge the PL8 can only discharge about 3.5Ah @ 24v. Takes a LONG time for a big pack.

Yes, the cells will be going in the demon mobility scooter

[Burgerman]

Just 1 hour is enough. To see if that gap dissapears. If not you have a dirty connection somewhere. When you clean dont use IPA use a that green scotchbright cloth. On connector and on terminal. The connectors are not crimped are they ?? Soldered hopefully or theres the issue.

Probably be perfect next charge regardless. Cell 4 seems to think its full faster. And has the lowest loaded voltage. So I suspect dirty connection on cell 3 4 or 5.

[Scooterman]

Sorry BM I’ll butt out as I’ll confuse terry. From the time stamp I saw you were up late last night so I thought you might not be up for a while

[terry2]

Just 1 hour is enough. To see if that gap dissapears. If not you have a dirty connection somewhere. When you clean dont use IPA use a that green scotchbright cloth. On connector and on terminal. The connectors are not crimped are they ?? Soldered hopefully or theres the issue.

Probably be perfect next charge regardless. Cell 4 seems to think its full faster. And has the lowest loaded voltage. So I suspect dirty connection on cell 3 4 or 5.

All connectors was made using 10 sqmm and soldered. Which was a pain
All the balance leads was crimped then soldered.

I will go over connection later and re-test.

Thanks BM.

I will wait for the BMs seal of approval before fitting

[Burgerman]

May be fine next charge. Or after a quick clean woth abrasive paper or scotchbright. Also all connectors, spray with switch cleaner like deoxit or whatever. And bananas. And balance connectors. Then fit them. Test! You should have 4.4 times the range. Dont run the lowest cell below say 3 volt. And then you will have a very long lived pack. Remember they drop very fast at the end.

[terry2]

May be fine next charge. Or after a quick clean woth abrasive paper or scotchbright. Also all connectors, spray with switch cleaner like deoxit or whatever. And bananas. And balance connectors. Then fit them. Test! You should have 4.4 times the range. Dont run the lowest cell below say 3 volt. And then you will have a very long lived pack. Remember they drop very fast at the end.

Will do.

Plenty of time to get them right.

[Furio]

Hi BM,

Here is the charge grafs after reassembly of the pack. I am out of the woods. The improvement in IR looks good. It seems that there was some corrosion in the connectors.

Thank you BM .

[Burgerman]

If you discharge now say 10Ah. Then recharge it SHOULD look almost perfect.

Corrosion, bad connections, oxydisation in stupid crimped connectors, etc is what causes all of these problems. We are looking a tiny mV differences.

Thats why AVOID unplated copper bus bars or terminals. Clean all contact surfaces with an abrasive. Dont just crimp its rubbish unless you have a production line and correct types of crimp connectors and some kind of quality control!!! SOLDER them.

Also set the termination current to approx 30% to 40% less than now.

[shirley_hkg]

if you want to test the capacity of your pack Ah, then discharge it to 3.0v or 2.9v, but it'll take a blooming long time. I recently discharged two 90Ah packs they each took about 22hrs to discharge to 3.0v. Although I have got two PL8s so could discharge both packs at the same time.

I'm dumping a 75Ah pack into my empty chair , via XLR port.

It can take 20A , if freshly cleaned eg. WD-40 .

6 times faster .

[steves1977uk]

Are you using an external XLR socket directly connected to the batteries Shirley? I'd be very surprised if you're pushing 20A through the pod's XLR port!

Steve

[Burgerman]

He may well be. But it wont end well!

He maybe hasnt seen how small the wires are inside the various pods/modules/pm etc. I have. 12A is OK. More and I would worry...

[Scooterman]

If using Regen discharge and the PL8 runs out of space to put Ah into, what does it do?

[terry2]

Discharge picture

[terry2]

Recharge picture after cleaning all the connectors.

[Burgerman]

Get it fitted. Still check cell connections on 3 4 5 but its good enough.

[Scooterman]

There's only 2% difference between IN and OUT.

Lithium is very efficient

[Burgerman]

Yes.

Usually about 5% on a full charge. And usually lead needs around 30 to 40% extra on a charge... Its why lithium is a no brainer on solar setups. You can use a third less panels!