PINNED - ADD ON PACK Step By Step 30ah Pack build / pictures

[shirley_hkg]

I think others might be interested too.

should he charge using the bounder chair XLR using the bounder charger ?

would it still charge full the ADD ON this way ?
thanks

I suppose you have the cells balanced and fully charged via PL8, and the Bounder is full also .

do i have to connect the balance leads to the pack first then connect it to the BMS ?
Connect balance leads to terminals. Check XH connector to ensue all volts are correct . Connect to BMS.


the bounder has a BMS also - doesnt he have to disconnect both packs first - - charge the bounder with the bounder charger and charge the ADD ON with a dumb charger ?
NO he doesn't have to.
Both batteries will be charged simultaneously, no matter which battery you charge .


or are you saying to leave it all connected and then just use the bounder charger on the bounder XLR ?
Yes. Also you can charge at high amp, if you've made the add-on a stronger plug.


would that work ? how can i known if the ADD ON got charged up that way ?
Of course . You will see the bms LEDS light up, near the end of charge .


Can i purchase the same BMS again - do you know the make model ? if i need a new one

You finished this one first .

thanks
Claudio

[expresso]

Pics have been deleted by mistake

here they are - if any one interested -

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[expresso]

dont forget to add a fuse also -

this may not make any difference since we are using newer Cells now - no longer headways but in any case - if it helps someone else try it -

[Potty]

Are there any pre-made items that can be turned into an add-on with minor alterations please? Or anywhere that actually sells them ready to go?

Thanks.

[Burgerman]

Not really.
At least not how we want.
Dont be scared its easy.

[Potty]

Dont be scared its easy.

Hmmm

Wonding if you would mind checking through my current understanding/questions please Aiming for something that works and is safe, being 100% optimal is not important to me.

Steps:

1: Buy hobby charger / 8x lifepo4 3.2v Xah(depends on size, probably thinking 40-80ah at this point) prismatic cells / SB50 connector.
2. Fit the SB50 to back of wheelchair, so that the connection between current Lead batteries and add on, once connected, forms a parallel connection, i.e. one big "24v" battery.
3. Connect all 8 lifepo4 cells in parallel and set charger to 3.65v.
4. Connect all 8 lifepo4 cells in series to form a "24v" Xah brick.
5. Create a box to protect the brick from damage and add a Male SB50 connector with enough wire. (not sure yet which gauge of wire to use)

Assumptions:

The lifepo4 being higher starting volts does not matter, you can use a "normal" Mobity charger like when it was just Lead alone?
I will be able to leave said charger on overnight, like I have been doing with lead?
The Lead and lifepo4 will "balance" with use/charging, to settle on the slightly lower lead voltage? (with some "lost" ah from the lifepo4, but wont really matter)
No BMS needed?
It's safe? (wishing to avoid going.... booooom xD )


Questions:

Will this effect insurance? (mostly care about the public liability/home insurance part)
Ordering from aliexpress or similar Chinese site is best for the cells/charger? Or there is somewhere else(ideally UK) that sells them?

Sorry for the long post! Just trying to make sure I get everything right from a safety aspect.

Thanks again for all the help!

[Burgerman]

Assumptions:

The lifepo4 being higher starting volts does not matter, you can use a "normal" Mobity charger like when it was just Lead alone?

No.
While both the lead and the lithium use the same CHARGE VOTAGE at 28.80V for AGM or 28.2V for Gel (both work for lithium) you cannot charge with a dumb 2 wire charger.

You can do that ONLY if you disconect the lithium first.

But you CAN set up a hobby charger and use that to charge the lithium, with balance connector connected, to charge the lithium. Which will also charge the lead providing you set the thing in a way that will do both. Which you can. If you get the right charger. The PL8 is out of production, so you would need to use a different one and others will advise as I dont use these. But not cheap... Probably an 8S iCharger with some power. And some very careful setup.

I will be able to leave said charger on overnight, like I have been doing with lead?
The Lead and lifepo4 will "balance" with use/charging, to settle on the slightly lower lead voltage? (with some "lost" ah from the lifepo4, but wont really matter)
No BMS needed?
It's safe? (wishing to avoid going.... booooom xD )

Yes. Its the BMS that will if anything CAUSE any issues and fires. Thats why we dont use them...
So yes and Lithium Ion Phosphate does not burn. Dont confuse these with Lithium ion as in laptops, teslas, phones, etc. Those are fireworks!

Questions:

Will this effect insurance? (mostly care about the public liability/home insurance part)
Ordering from aliexpress or similar Chinese site is best for the cells/charger? Or there is somewhere else(ideally UK) that sells them?

All kinds of options. Getting good A grade cells is the hard part. There are a few reasonable otions though and people or me will advise.
Insurance? No idea about your insurance...

[shirley_hkg]

But you CAN set up a hobby charger and use that to charge the lithium, with balance connector connected, to charge the lithium. Which will also charge the lead providing you set the thing in a way that will do both. Which you can. If you get the right charger. The PL8 is out of production, so you would need to use a different one and others will advise as I dont use these. But not cheap... .

If you find PL8 is your best choice, I have brand new units (New-in-box) to offer.

[Burgerman]

Which I would buy. At least 2. But only with a bunch of balance connector plugs/cables. And a FUIM3 USB connection gadget. Those are all essential and also all but impossible to find now.

[shirley_hkg]

They are ALL available, balance wires with JST connector, and FUIM3 usb interface.


https://www.wheelchairdriver.com/board/ ... 49#p202249

[Burgerman]

Get them while they are hot!

[shirley_hkg]

I don't know why you choose add-on, instead of full lithium. The hustle and bustle involved in both case are the same basically.

It's always easier and simpler to handle one battery type than two .
Storage of LFE need no maintenance for months to a year.

[Burgerman]

I agree. But maybe just to learn?

For many people, probably most powerchair users range is never an issue. They never use a chair much and sit around watching TV or whatever. For active users then no lead battery is even close to being adequate.

So that leaves a few real options.

1. Addon which is heavy, nusance to carry, charger etc seperately. Which depending on range needed can be huge and heavy.

2. Swap to safe liffepo4 from lead, charge with hobby charger. To replace a typical 80Ah GRP 24 means that you end up with a battery that will outlive the chair and probably you. And 500% gain in usable range. So if used carefully 100 miles? At least 50 miles even if you are an animal and heavy with a properly programmed heavy rehab chair.

3. Drop in lead brick replacements. These CAN work with unpredictable reliability issues. You CAN gain up to 100% range increase wih say 135Ah dakota lithium and those can do adequate current so that you wont keep cutting out due to the BMS protections. Others, not so much! So not much range gain, definite reliability issues and nowhere near the lifespan expected because of heavy C rate use and possible BMS issues.

4. An addon made from the firework cells. For e.g Lithium Ion "tesla" style cells with a voltage regulator charger setup to continually charge the lead. These can be smaller and lighter as an addon, these cells are (can be if correctly choosen) more energy dense. But more "engineering" CC/CV buck/boost board and possible kaboom danger is the result. But as an addon you are not sitting on it so it could be thrown away like a phone or laptop.

5. Use your lead. With a rapid charge boost halfway through the day in the short term. Lead lasts longer and you get a 2nd chance, to go out in an evening!

[fabrasil]

Folks, i have doubt!

I've using lifepo4 cells to make some batteries to my clients (26650, terrain, etc) BUT today one bring me an Ottobock's B400 with 7SP15 (18650 panasonics 3.4A) with dual BMS 80Ah.

When battery fully charged, its 29.2V. The vwheelchair is running @ 11km/h instead of 7~8km/h as usually.
Two times stoped due high voltage (10 leds bkinkng - 1600 @ software).

What i should do, to solve it
Its using VR260, 2x HMC 200W 24V 2 poles motors.

Add two AGM/VRLA batteries in paralel?

Thanks
Fabio

[Burgerman]

He is using the firework lithium ion (cobalt type) cells that are higher voltage, and so 7S?
Thats borderline too high voltage. 4.2V x 7 = 29.4V
It will work under a load, but as you let go of stick to decelerate or as you decend a slope, the regeneration voltage will spike INTRMITTENTLY above the limit.

LiFePO4 8S gives a closer match for voltage. So doesent cause any issues. And its fire safe!

You could try adding a big ZENER diode, across the battery cables as they go to the battery. At say 30 to 31V, to clamp any regeneration spikes below this point.
But is it was me I would no want a lot of those lithium ion fireworks under me in a wheelchair or indoors. There are a few small ones in a phone or laptop. But the amount used in a pwerchair is quite dangerous.

[fabrasil]

Hi BM,

He is using the firework lithium ion (cobalt type) cells that are higher voltage, and so 7S?
Thats borderline too high voltage. 4.2V x 7 = 29.4V

It will work under a load, but as you let go of stick to decelerate or as you decend a slope, the regeneration voltage will spike INTRMITTENTLY above the limit.

LiFePO4 8S gives a closer match for voltage. So doesent cause any issues. And its fire safe!

You could try adding a big ZENER diode, across the battery cables as they go to the battery. At say 30 to 31V, to clamp any regeneration spikes below this point.
But is it was me I would no want a lot of those lithium ion fireworks under me in a wheelchair or indoors. There are a few small ones in a phone or laptop. But the amount used in a pwerchair is quite dangerous.

Yes, thats correct. Dangerous wheelchair...
Wheel, zener at high current never used before i will search about.

He already spend an amount for that battery thats him issue

Thanks

[Burgerman]

A zener diode across the battery will do nothing at all below the rated voltage. Above that voltage it will "short out" any voltage and only allow the safe voltage through to the battery.

You need a reasonably large one to sink the excess voltage/current.

[ex-Gooserider]

Having personally seen a lithium powered scooter (18650 battery powered) go up in FLAMES I'd second the notion of not wanting to be ANYWHERE near a wheelchair powered by them... I'm not sure I'd even allow it in my shop, at least not without a really BIG insurance policy! (The Asylum now prohibits lithium vehicles (scooters, e-bikes, etc.) in the building except for 'disability use'....)

If even ONE cell in that pack overheats, the entire pack WILL go up and you will NOT put it out w/ any readily available fire fighting equipment... From personal experience a standard "A:B:C" dry-chem extinguisher doesn't do ANYTHING useful - I tried one, twice - each time it damped the fire down for about 10 seconds before it started up again.

BM's description of them as "Fireworks" is very accurate, it was like watching a pack of firecrackers go in slow motion, about every 20-30 seconds, you'd get a big BANG, and a bunch of flaming debris shooting out as another cell exploded...

The scooter was not in use when it went up, but if it had been the person on it could have bailed and ran... If a cell phone starts going up you can play 'hand grenade' and make it someone else's problem... WE CAN'T RUN AWAY!!!!

ex-Gooserider

[fabrasil]

Dear

At software by c&w, exist OUTPUT VOLTAGE (devi-volts). May i use it to reduce voltage?
page 127 @ help guide of v16.x

Cheers

[Burgerman]

That only reduces motor output volts. It doesent remove an input voltage or regen voltage spike.

[BCrip71]

Is there a commercially available lithium add on pack?

[Burgerman]

Not designed as such.
Any 24V lifepo4 pack could be used.

[BCrip71]

Can you explain how an add on pack works? Does it charge your battery? Are they safe?

[Burgerman]

Read this thread.

Basically they work in the same way as a jump starter works on your car.

THE external battery is approx the same voltage as the lead. So connects its 24V in parallel.

Adding to the capacity and range.

Basically the same as having a bigger battery.