PINNED - Lithium battery conversion/info

[ex-Gooserider]

Hadn't thought about Shirley quoting in HKD instead of USD, my bad.... Part of it is that I did get a very wide range of quotes that were supposed to be in USD for shipping my cells, with the range getting up towards $700, so it didn't sound totally unreasonable... I'd agree that converting HKD to USD gets under $100, which is much more reasonable.

ex-Gooserider

$700 is on the VERY high range of what I got for quotes, especially for 'slow-boat' post...

ex-Gooserider

Unless I'm mistaken, Shirley is quoting HKD, not USD. Unless I'm mistaken, the HKD/USD ratio right now is 7.78/1, so not so bad.

I'm still interested.

You are right ...

[shirley_hkg]

:D First try of PL8 on my lithium . It's a 72P8S pack with Sony 26650 cells . TWO years old and has been with BMS .

[Burgerman]

Pretty good. Bet your charger is set to a lower voltage than recommended though...

The pack in my mower is 2 year old and was with its BMS. And miles out. And defective.

[Gnomatic]

:D First try of PL8 on my lithium . It's a 72P8S pack with Sony 26650 cells . TWO years old and has been with BMS .

How many Ah is your pack, Shirley?

[Burgerman]

Top of graph, says 215Ah. Bottom of graph says 140Ah...

[shirley_hkg]

BM , would you please include the followings in your suggestion list to REVOLETRIX

1,more balance starting points
2,Soft start for all charge current ; for sake of power supply and initial charging for deeply discharged cells . ( now I enter low charging rate in preset and change to higher amp after start . It then increases at around 0.5A steps . )

[Burgerman]

I already have. 2 years ago...

[steves1977uk]

Found these on ebay... http://www.ebay.co.uk/itm/LITHIUM-ION-L ... SwTM5Y6p0d

Might be ok to use in a demo chair to show people how much better Lithium is... 40 cells would build a 24v 75Ah pack which I use.

Steve

[Burgerman]

To make up a 90Ah pack means buying 2. Thats 600. Plus bars, orange blocks, and you don't know what state they are in... I wouldn't.

[Gnomatic]

BM would you post a preset for the PL8 for an LiFePO4 24v 8S7P 105Ah pack? Basically a clone of expresso's.


Thank you!

[Burgerman]

24V, (3.600v per cell) 8S 105Ah, 20A Charge, 500thC (210mA) termination (to be changed to 300mA after first few charges), Wide cell voltage extreme error limits, and cell gap limit, relaxed cell balanced accuracy to prevent hunting on large pack (4mV). 16 hour total charge limit.

Remove .zip

[expresso]

24V, (3.600v per cell) 8S 105Ah, 20A Charge, 500thC (210mA) termination (to be changed to 300mA after first few charges), Wide cell voltage extreme error limits, and cell gap limit, relaxed cell balanced accuracy to prevent hunting on large pack (4mV). 16 hour total charge limit.

Remove .zip

Any Difference between this preset and the ones you made me in the past ?

[Gnomatic]

Thank you. Discharging the pack a bit with my 25A load dump. Then will charge the pack for the first time with that preset. I'll post the charge graph later today. I'm a bit nervous!

[Burgerman]

Nope.

[Gnomatic]

Here's the graph from my packs first charge. Cell Group 6 started to run away a bit from the rest of the pack ~45min in.

[Gnomatic]

.... and here's the whole PL8 charge file

105Ah Pack Initial Charge.CP8.zip

(41.07 KiB) Downloaded 224 times

[expresso]

that looks fine - theres always going to be that One group that dosnt behave as the rest - over time i think its more important how they discharge -

lets see what BM says

[expresso]

if you see my first charge - much worse - i dont believe i did the whole discharge recharge etc, after a few rides - it got in shape

it changes over time here and there - not always the perfect line -

[Burgerman]

1st charge balances them. 2nd charge will be better. 3rd better still. And its already practically perfect. Its why we need balance chargers.

[Gnomatic]

Good to hear. It was only cell group 6 that was a little out of balance with the rest, on the high side which I assume is better than the low. I'll post the second charge graph to compare.

Feel like I'm finally getting somewhere with this. It's taken me awhile. That said, I can't wait to get the pack installed in my chair. The weather is turning nice!

[expresso]

Good Job Genomatic - you be ready to ride soon -

[steves1977uk]

You'll love the power of lithium Gnomatic, less voltage drop under load when tackling ramps and hills, plus you can venture further

Steve

[Burgerman]

I had forgotten how much chairs slow under load with lead when it gets a bit discharged. Been using an old BM1 today...

[Gnomatic]

I'm looking forward to trying out the pack on hills and offroad. Actually that was the main reason I decided to go lithium. I like hiking on trails of of many types, walking, ATV, horse, you name it. If I'm offroad in a a hilly area, brand new fully charged lead bricks last me ~3hrs, if I'm lucky. Then I'm done for the day even though I'd really to keep going

[expresso]

you would double that range - and if thats not enough - build a ADD ON and Connect it to your chair -

[Gnomatic]

I monitored the pack as I discharged it a little over 3hrs with my my 25A load dump. Here's what that looked like.

[Burgerman]

Why did you stop?

And did you discharge through the PL8? Or monitor it as you did the discharge externally?

[Gnomatic]

Why did you stop?

And did you discharge through the PL8? Or monitor it as you did the discharge externally?

I was getting ready to eat and didn't want to forget about it so I stopped.

I did not discharge through the PL8, I just connected the pack externally to my 25A load dump and monitored with the PL8. Eventually I want to use regenerative discharge feature of the PL8 with the load dump in parallel on the PSU side like you do.

[Gnomatic]

Here's the graph for my second charge.



Cell Group 6 is all over the place and the rest of the lines don't seem as tight as the first charge. Not what I was expecting to see. BM, any idea what is going on here?

Here's the .CP8 file from the charge.

105Ah Pack 2nd Charge.CP8.zip

(70.12 KiB) Downloaded 223 times

It seems I took about 55Ah out of the pack with the load dump. A little less than I was expecting.

[Burgerman]

No...

But I suspect a loose bolt, or something. crimped connectors somewhere? Are these all new cells?

Check every bolt that you think you already did. You will be amazed.