PINNED - Lithium battery conversion/info

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Re: PINNED - Lithium battery conversion/info

Postby expresso » 12 Feb 2019, 18:49

BM - Would i be able to charge my chair - both have lithium in the chair and ADD ON - but BMS is in the chair - the bounder - i though about it - what if i charge the ADD ON fully connected to the Chair pack that has the BMS ?

the PL 8 would balance my pack - and the BMS would balance the chair pack - Can that work ? or would the PL8 give off errors at the end when trying to balance ?
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 12 Feb 2019, 19:35

Any. 15 to 24 is likely best?
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 12 Feb 2019, 19:36

BM - Would i be able to charge my chair - both have lithium in the chair and ADD ON - but BMS is in the chair - the bounder - i though about it - what if i charge the ADD ON fully connected to the Chair pack that has the BMS ?

the PL 8 would balance my pack - and the BMS would balance the chair pack - Can that work ? or would the PL8 give off errors at the end when trying to balance ?


No, the BMS will be bypassed.
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Re: PINNED - Lithium battery conversion/info

Postby expresso » 12 Feb 2019, 19:41

Ok so only charging from there XLR socket would engage there BMS ?

lets say it does bypass it - would it matter much ? since the PL 8 will balance anyway ?

seems as if this may be even a better option to charge it both at once and get a better balanced pack in the end ? assuming the PL 8 dosnt give errors

what harm can it do if it was tried once lets say ?

would i need a different preset from you ?

OH i think i see why it wont balance the chair pack - there no balance wires from the chair going to my PL 8 - i missed that part -
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 12 Feb 2019, 19:51

Ok so only charging from there XLR socket would engage there BMS ?

Yes
lets say it does bypass it - would it matter much ? since the PL 8 will balance anyway ?

It balances the addon perfectly, it has no connection to the seperate cells in the chair, so those will not be balanced at all.
seems as if this may be even a better option to charge it both at once and get a better balanced pack in the end ? assuming the PL 8 dosnt give errors

Wont balance the BMS pack, and neither will the BMS!
what harm can it do if it was tried once lets say ?

Who knows. Dont try it... Maybe non, if the pack is well balanced now. Maybe lots if not.
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Re: PINNED - Lithium battery conversion/info

Postby expresso » 12 Feb 2019, 19:57

https://www.youtube.com/watch?v=2cet0f4HZAU

in this video - at 7.50 mins into it - inside the battery box - i though maybe those power cables which at the end break up into many smaller cables soldered to the BMS would be balancing from those cables ?

if thats the case - it should work ? i also see those smaller wires which maybe the balance wires on the BMS - but if the charger goes in those larger cables into the BMS - maybe then it shoots out to those white smaller wires to balance ?

could it be ?
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 12 Feb 2019, 20:03

For the BMS to work it has to be able to DISCONNECT the charger repeatedly over and over as it tries to pull down the high cell. So no...
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Re: PINNED - Lithium battery conversion/info

Postby expresso » 12 Feb 2019, 20:06

Burgerman wrote:For the BMS to work it has to be able to DISCONNECT the charger repeatedly over and over as it tries to pull down the high cell. So no...


if would work if i use the XLR socket on the chair with the PL 8 - that would shut the pl8 on and off also - i dont recall if it did last time used it that way

i though maybe the BMS itself just shuts off that one cell leaving the charger going for the others - with the stock charger - i did see it hear it shut off and on -
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 12 Feb 2019, 20:16

if would work if i use the XLR socket on the chair with the PL 8 - that would shut the pl8 on and off also - i dont recall if it did last time used it that way

Yes.

i though maybe the BMS itself just shuts off that one cell leaving the charger going for the others - with the stock charger - i did see it hear it shut off and on -


Think about a pack with 8 cells. All joined up with cables or bus bars.
You CHARGE by adding power to the ends, the 0V and the 24V wires. The current goes through ALL cells.

The BMS watches the cell voltages, and when one cell is above about 3.65V it tries to stop it rising more by pulling that 1 cell down (shorting it out and wasting power) across a resistor.

Since the charger has 10 to 40A of power this fails dismally of course, and the voltage reaches 3.75, 3.85V and so the BMS panics, has no option but to disconnect the charger to ALL CELLS at once (your special connetion) while it tries to take power away from the highest cell and brings it back to earth...

It stays disconnected and not charging till that cell is about 3.5V... Then it reconnects the charger, and watches it do the same thing over and over for hours... sometimes very fast. It cant disconnect 1 cell, because that cell in in circuit for driving the chair with bus bars or cables.
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Re: PINNED - Lithium battery conversion/info

Postby expresso » 12 Feb 2019, 20:19

Ok i see - i though i had something there :) best to leave it as is and charge as before two packs each with its own charger and use the Chair XLR for the chair - thanks
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 12 Feb 2019, 20:20

I hadnt finished, read again. :cussing
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Re: PINNED - Lithium battery conversion/info

Postby shirley_hkg » 13 Feb 2019, 02:48

:clap Found these high conductivity T2 pure copper studs. Gonna implant it into battery terminals , with Loctile . Then use safety nuts to lock the connections .
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 13 Feb 2019, 11:01

Copper oxydises. Instantly. And oxides dont conduct. Better to use plated or stainless.
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Re: PINNED - Lithium battery conversion/info

Postby terry2 » 13 Feb 2019, 20:22

Burgerman wrote:Copper oxydises. Instantly. And oxides dont conduct. Better to use plated or stainless.



Good info.

So I have been watching the PL8 for most of the afternoon learning what's what. There is a lot to learn :)

My cells won't be here for 2 weeks, so can anyone tell me what other things I need to buy in advance please.
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Re: PINNED - Lithium battery conversion/info

Postby expresso » 13 Feb 2019, 22:18

https://www.electriccarpartscompany.com ... ePO4-XCell

this one looks as if with a little modification which BM does all the time - they can fit i think -

8 of them -
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Re: PINNED - Lithium battery conversion/info

Postby expresso » 13 Feb 2019, 22:23

https://smile.amazon.com/SELTERM-Gauge- ... g+terminal

on my first packs early when i first started i used these - thinking they are better - and they are fine and still work fine - but if i ever have to redo the pack or wiring etc, - i will use tinned - so my first 105ah pack is copper rings - my 45ah ADD ON is copper - my 36ah first ADD ON is copper

i always though it was best - but i see what BM is saying - it does tarnish over time - as long as my charge graphs are fine etc, i see no reason to replace them. my newer packs 60ah and 80ah i used much better nicer rings tinned copper and heavy walls to crimp solder works great.
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Re: PINNED - Lithium battery conversion/info

Postby terry2 » 15 Feb 2019, 14:08

Will this work?

I am going to buy 2 The 36" extension http://www.usastore.revolectrix.com/Pro ... sion-Cable

Cut the board off the one end and use the wires for balancing my 8 cells.
Then use the other one from the PL8 to the extension. Is this way ok?

And what's the best way to connect the earth and power to the PL8?
I mean what wire and what plug\socket is best?

Thanks
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Re: PINNED - Lithium battery conversion/info

Postby steves1977uk » 15 Feb 2019, 18:14

No problem! :thumbup:

The D-Sub connectors have tiny numbers near each of the small pins for the balance wires, so the wires from the PL8 would be:-

Pin 1 - Red
Pins 2-8 - White
Pin 9 - Black

Plus the two main thicker charge wires. Use the Safe banana plugs with the 40A fuse already put in place, you will need to extend these to match the length of the balance wires.

Hope this helps,

Steve
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Re: PINNED - Lithium battery conversion/info

Postby shirley_hkg » 16 Feb 2019, 12:55

Temporary measure. See what result I'll get . cheers
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 16 Feb 2019, 13:50

Lets hope the bad connections are not on the inside of the cells...
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Re: PINNED - Lithium battery conversion/info

Postby expresso » 17 Feb 2019, 04:08

https://enerbyte2016.en.made-in-china.c ... thium.html

another find today - can easily fit 200ah with room to spare
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Re: PINNED - Lithium battery conversion/info

Postby Scooterman » 17 Feb 2019, 10:30

shirley_hkg wrote: Temporary measure. See what result I'll get . cheers

Fingers crossed for you Shirley. I really hope you get good results, you've been good helping me out and deserve some good luck. :thumbup:

Now I've been getting better results with my tiny 600mAh cells in a 2P4S arrangement (I'll post results later).

I will try doing the same as you with the LF90s in a 2P8S arrangement on the bench and see what results I get. :thumbup:

EDIT: It'll take me few days to do it but I will get there and am confident of good results :joint
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Re: PINNED - Lithium battery conversion/info

Postby terry2 » 17 Feb 2019, 10:51

shirley_hkg wrote: Temporary measure. See what result I'll get . cheers



That looks complicated.
I hope it works out great in the end.
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Re: PINNED - Lithium battery conversion/info

Postby shirley_hkg » 17 Feb 2019, 11:22

Stored for a week. Bring it up to 3.6V again.
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Re: PINNED - Lithium battery conversion/info

Postby shirley_hkg » 17 Feb 2019, 11:24

Split lines for a very short period of time.
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Re: PINNED - Lithium battery conversion/info

Postby shirley_hkg » 17 Feb 2019, 11:27

Down to 3.0V . cheers
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Re: PINNED - Lithium battery conversion/info

Postby shirley_hkg » 17 Feb 2019, 11:31

Terminal voltage for this pack is :ambulance 24.2V ; " UNLOADED "
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Re: PINNED - Lithium battery conversion/info

Postby shirley_hkg » 17 Feb 2019, 11:48

Balance took couple of minutes only.

Less than an hour to reach a very low 60mA termination current .

Put back 172Ah.
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