LiFePo4 for Permobil C500S

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Re: LiFePo4 for Permobil C500S

Postby quadcopter » 04 Aug 2019, 13:50

Intersting question:
Can LiFePo4 cells be mounted upside down?
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Re: LiFePo4 for Permobil C500S

Postby Irving » 04 Aug 2019, 14:10

quadcopter wrote:Intersting question:
Can LiFePo4 cells be mounted upside down?

Don't see why not, they're solid electrolyte.

But don't rest them on the terminals, they won't like that loading..

But why would you want to?
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Re: LiFePo4 for Permobil C500S

Postby Burgerman » 04 Aug 2019, 16:18

The electrolyte is like oil, thin, clear and a bit like vegy oil. Not solid like in the lipo packs or lithium ion cells. But theres not much in there, a few CC, and theres no reason they should work any better any particular way up. But probably better to have the vent not at the bottom. It will puke oily electrolyte rather than what looks like smoke/steam out if drastically overcharged or shorted out or heated up. Its on the pos end of the headway style cells and the top of the prismatics. It wont matter unless the pressure release vent is needed...

If you want to see this oily stuff, put a headway on the fire. When hot enough it leaks out via the vent. And like cooking oil it will burn if hot enough and ignited by external source.
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Re: LiFePo4 for Permobil C500S

Postby quadcopter » 05 Aug 2019, 22:50

Irving wrote:
quadcopter wrote:But why would you want to?

I reworked my pack after Burgerman note about isolation between cells. I added isolation tape and special isolation film.
The cells were placed in powerchair case but they stay very tightly. Also there are welding seams on walls of the case.
I'm sure that isolation will be damaged one day.
So I want to rework the pack again: 4 cells inside the case and 4 outside at the back + thick good isolation between cells and case.
I'm thinking how to place them to have shortest interconnections.
Lay them on a side seems the best for me right now.
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Re: LiFePo4 for Permobil C500S

Postby quadcopter » 09 Aug 2019, 22:18

Can I use AWG 10 and these fuse holders with rectangle fuses 40A instead of Revolectrix 40A Safety Banana Plug Cable?
fuse_holder.png
Fuse holder
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Re: LiFePo4 for Permobil C500S

Postby Burgerman » 09 Aug 2019, 22:55

Screw connectors?

I wouldnt. You just need a normal ring terminal and solder it, midi fuse, and a M5 nut/bolt. Covered in heat shrink. Its smaller neater and wont screw up, come loose, or be a high resistant point.

Will it work? Yes. Is it as good, no its bulky, and less good. And more expensive. Those are really for boy racers adding car sterios. Or just use blade fuses, and solder + heatshrink. Or if you are careful, skip the fuse. I have given up fitting any on charge cables. Because I am careful...
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Re: LiFePo4 for Permobil C500S

Postby expresso » 09 Aug 2019, 23:08

BM - how big of M5 nut and bolt would be needed ? to make a good contact and keep it flush ? do you know the length size -

etc, -

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Re: LiFePo4 for Permobil C500S

Postby Burgerman » 09 Aug 2019, 23:33

Use a domed (round head type) M5 stainless bolt, 8mm long and an M5 nyloc. No washers. Not nylon!!!
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Re: LiFePo4 for Permobil C500S

Postby expresso » 10 Aug 2019, 00:20

any reason a M6 screw wont work - i have the m6 nut already

https://www.amazon.com/10-M5-10mm-Stain ... =1-13&th=1

like this but 8mm long ?
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Re: LiFePo4 for Permobil C500S

Postby Burgerman » 10 Aug 2019, 01:12

You could. But the hole in those fuses is designed for M5 bolts and so is drilled to 5.5mm. You would need to drill 6mm or a fraction bigger, and then the bolts and nuts are physically bigger and will stick out more. Probably better to use 5mm bolt.

Yes as above. With nuts.
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Re: LiFePo4 for Permobil C500S

Postby expresso » 10 Aug 2019, 01:25

ok - will look around if i can find a few here -
i have a fuse holder but this would be less bulky - mines is compact though

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Re: LiFePo4 for Permobil C500S

Postby expresso » 10 Aug 2019, 03:32

BM are you sure 8mm is good enough size - what if the ring on the wire end is a hefty size - not very thin ?
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Re: LiFePo4 for Permobil C500S

Postby Burgerman » 10 Aug 2019, 07:25

On M5mm bolt it should be perfect, as the nut is smaller too. And on a ring terminal for 5mm bolt there should be no problem. The next size is 10 or 12mm. But bolts are cheap. So order a few different lengths if your ring terminals are thicker metal. Or order 10mm long. Or measure yours... The nut is 1.5 x the 5mm (so 7mm tall) The bolt is 8mm long... So 1mm left for the ring... Order 10mm. If you can find any. Or 12mm but there will be 2 or 3mm sticking out extra.

https://www.westfieldfasteners.co.uk/Da ... High_M.pdf


Looking at this, then ideally you will need 10mm for a nyloc nut inc fuse/ring.
Or 8mm for nornal nut including ring and fuse.

But I dont think 10mm is easy to get. So you have a choice of 8mm (normal nut) or 12mm which is a little longer than needed, for nyloc.

So probably better to use normal M5 nut and a dab of loctite, and 8mm long bolt. Because that keeps it all thinner and neater easy to heatshrink.
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Re: LiFePo4 for Permobil C500S

Postby expresso » 10 Aug 2019, 16:35

this is a compact fuse holder - smallest i can find - but still would be larger than without using it - i think maybe 8mm 5M size can work - will order a few - fuse holder is about 20mm high - - i was thinking of using it but maybe will see without - depends on space - this makes it easier to change out fuses if ever needed without cutting up heatshrink
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Re: LiFePo4 for Permobil C500S

Postby quadcopter » 27 Aug 2019, 19:54

How should I charge my pack?
I.e. what is better - charge it every time I return home or let it stay till next trip and charge only before?
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