PINNED - Lithium battery conversion/info

[expresso]

Or 200Ah ... an additional 10 miles...

https://szaspower.en.alibaba.com/produc ... 1f41HzY08D

nice - i missed that one - well i have some 100ah Cells on the way shipped already - we see how those do - will be testing for Cap. no rush since i dont have another chair for them just yet. few ideas - those above cells would be easier with just 8 - but cost alot more than my way with 16 Cells -

also since we dont go below 2.9v - if you read the specs - some are rated to 2.0v to get there rated Cap. - which we never will get -

but some cells are rated to 2.5v to get there full Cap. those are a better bet for us - since we wont have as much unused Cap. at 2.9v - at best 10ah less than rated Cell - since they do round them off the numbers - i was told my 100ah cell would be at Min. 92ah to 96ah - - so its already not 100ah to begin with - but was told this before hand. so honest seller so far.

i expect no less than 85ah - but hoping for 90ah and over - we shall see -

[Gnomatic]

My set of 75Ah cells, charged at 3.6v, then discharged to 2.9v, yielded 66Ah/cell or so. Figuring we're not using the last ~10% by not discharging to 2.5v, my cells seem pretty close to their advertised capacity. I bought 18(so I had a spare or two) and they were all pretty consistent with with their capacity yields. Much more consistent than the set of 100Ah Sinopoly cells I purchased last summer.(and later sold)

Those 100Ah Sinopoly's are really more like a 90Ah cell. I got like ~82Ah out of them on most. And on one cell only out 74Ah down to 2.9v. Their 100Ah rating was inflated, and their yields were much less consistent than the batch I have now. The batch I have now were advertised as manufactured by CALB, for what that's worth.

[terry2]

So looking at my graph. I need to bring cells 7\8\2\4\6\1 up to match 5\3 ?

[Burgerman]

The charger already has. It does that every last time you charge. Look at the line where its charged. All cells are at 3.600V
.

Its USING it that may cause it to become unbalanced. For E.G if some cells are higher impedance, they wast some as heat. Or if some have a naturally higher self discharge evel then they will require more time to reach full. Or when charging, if theres a connection somewhere that is higher resistance the charger sees a false voltage. It corrects itself as the current drops as it becomes charged.

As long as it doesent get worse then no problem. You are actually talking about a small amount.

[terry2]

The charger already has. It does that every last time you charge. Look at the line where its charged. All cells are at 3.600V
.

Its USING it that may cause it to become unbalanced. For E.G if some cells are higher impedance, they wast some as heat. Or if some have a naturally higher self discharge evel then they will require more time to reach full. Or when charging, if theres a connection somewhere that is higher resistance the charger sees a false voltage. It corrects itself as the current drops as it becomes charged.

As long as it doesent get worse then no problem. You are actually talking about a small amount.

Now I have swopped over the cells. It does look better.
Would you make new connectors and try again?

Thanks BM.

PS the torque in my chair is out of this world now

[Burgerman]

No I would use it! You are looking at a tiny fraction of an Ah on a 176Ah battery.

[terry2]

No I would use it! You are looking at a tiny fraction of an Ah on a 176Ah battery.

Thanks again.

I have learnt not to start my chair off in high power.
Crossing a blind corner I put it in to top power. And my back wheels done a small burn out

[Burgerman]

Because of much less weight. And because with lead the voltage drops when you accelerate.

[Scooterman]

BM - I went for a 34 mile ride yesterday. It was full throttle all the way, uphill and down. I've averaged 8.8mph for the trip. The scooter has about 0.5mph more top speed but where it really gains is the average speed, because there is hardly any drop off in speed except going up really steep hills.

I was wondering if you could work out the say a 70% DoD range for me from my mileage? (During normal use I won't be pushing the scooter quite so hard).

The 2 x 90Ah packs deliver about 160Ah before the volts start to drop off.

Also is the CV time a little short? Learning from what you've said previously I could reduce the TC to less than C/500. But I was wondering if reducing CV to 3.55v or even 3.5v (bal @cv) might increase the CV time and also give me a few more cycles?

I'll follow your advice

PS: The lipo cell checker I bought is useless, it gives false readings and I nearly didn't go on trip, I thought I was going to have to. But I checked voltages with PL8 and they were okay. I was still nervous though, so took the PL8 with me and powered it from XLR. IR looks good so I guess my connections are holding up for now, and I clobbered a few pot holes on the trip so shook the packs up a bit.

[Burgerman]

Everything looks perfect.

BM - I went for a 34 mile ride yesterday. It was full throttle all the way, uphill and down. I've averaged 8.8mph for the trip. The scooter has about 0.5mph more top speed but where it really gains is the average speed, because there is hardly any drop off in speed except going up really steep hills.
I was wondering if you could work out the say a 70% DoD range for me from my mileage? (During normal use I won't be pushing the scooter quite so hard).

The 2 x 90Ah packs deliver about 160Ah before the volts start to drop off.

So its safe to use 160Ah.
You did 34 miles. And returned 59Ah. So your safe 160Ah div by 59Ah returned for 34 miles is 2.71. So you can drive for 2.71 x 34 miles = 92.2 miles...
And that 92 miles is a safe figure as driving slower means going a little further. And you always return a little more than you take out too so you actually used less than 59Ah by say 3 or 4%. And that should leave 20Ah (about 10 miles) in reserve.

However, cold days, low tyre pressures, hills all mean less miles so thats not guaranteed.

Also is the CV time a little short? Learning from what you've said previously I could reduce the TC to less than C/500. But I was wondering if reducing CV to 3.55v or even 3.5v (bal @cv) might increase the CV time and also give me a few more cycles?

If cells all balance easily, then CV time can be short. And they look spot on. No dodgy connections or bad cells there. But if some are crimped it will not stay that way...

I'll follow your advice
PS: The lipo cell checker I bought is useless, it gives false readings and I nearly didn't go on trip, I thought I was going to have to. But I checked voltages with PL8 and they were okay. I was still nervous though, so took the PL8 with me and powered it from XLR. IR looks good so I guess my connections are holding up for now, and I clobbered a few pot holes on the trip so shook the packs up a bit.

None of those cell checkers will be accurate. As I said its purpose is to detect when a cell goes below 2.9V and tell you! It is NOT a fuel guage as it wont tell you anything useful. So as long as all the cells are balanced and healthy theres no need to plug it in at all for the first 50 miles, and then only as a LOW CELL VOLTAGE ALARM. As a fual guage it will tell you that the pack is all low and unbalanced...

[Burgerman]

Everything looks perfect.

BM - I went for a 34 mile ride yesterday. It was full throttle all the way, uphill and down. I've averaged 8.8mph for the trip. The scooter has about 0.5mph more top speed but where it really gains is the average speed, because there is hardly any drop off in speed except going up really steep hills.
I was wondering if you could work out the say a 70% DoD range for me from my mileage? (During normal use I won't be pushing the scooter quite so hard).

The 2 x 90Ah packs deliver about 160Ah before the volts start to drop off.

So its safe to use 160Ah.
You did 34 miles. And returned 59Ah. So your safe 160Ah div by 59Ah returned for 34 miles is 2.71. So you can drive for 2.71 x 34 miles = 92.2 miles...
And that 92 miles is a safe figure as driving slower means going a little further. And you always return a little more than you take out too so you actually used less than 59Ah by say 3 or 4%. And that should leave 20Ah (about 10 miles) in reserve.

However, cold days, low tyre pressures, hills all mean less miles so thats not guaranteed.

Also is the CV time a little short? Learning from what you've said previously I could reduce the TC to less than C/500. But I was wondering if reducing CV to 3.55v or even 3.5v (bal @cv) might increase the CV time and also give me a few more cycles?

If cells all balance easily, then CV time can be short. And they look spot on. No dodgy connections or bad cells there. But if some are crimped it will not stay that way... You could reduce the TC slightly, by say 15 or 20%?

I'll follow your advice
PS: The lipo cell checker I bought is useless, it gives false readings and I nearly didn't go on trip, I thought I was going to have to. But I checked voltages with PL8 and they were okay. I was still nervous though, so took the PL8 with me and powered it from XLR. IR looks good so I guess my connections are holding up for now, and I clobbered a few pot holes on the trip so shook the packs up a bit.

None of those cell checkers will be accurate. As I said its purpose is to detect when a cell goes below 2.9V and tell you! It is NOT a fuel guage as it wont tell you anything useful because while its got a fancy display it does not know how much you have left based on voltage alone! So as long as all the cells are balanced and healthy theres no need to plug it in at all for the first 50 miles, and then only as a LOW CELL VOLTAGE ALARM. As a fuel gauge it will tell you that the pack is all low and unbalanced... Its an emergency low warning device on a cell level.

Yes you can safely set charge volts to 3.550 or 3.525V. Since it balances easily and all cells are happy... Dont set to 3.500 unless you also set the balance to only balance at CV. So disable 'balance entire charge' to NO. then 3.500 is also OK but borderline too low. I use 3.550.

[Burgerman]

What did you get with lead bricks? Miles?
25?

[terry2]

BM - I went for a 34 mile ride yesterday. It was full throttle all the way, uphill and down. I've averaged 8.8mph for the trip. The scooter has about 0.5mph more top speed but where it really gains is the average speed, because there is hardly any drop off in speed except going up really steep hills.

I was wondering if you could work out the say a 70% DoD range for me from my mileage? (During normal use I won't be pushing the scooter quite so hard).

The 2 x 90Ah packs deliver about 160Ah before the volts start to drop off.

Also is the CV time a little short? Learning from what you've said previously I could reduce the TC to less than C/500. But I was wondering if reducing CV to 3.55v or even 3.5v (bal @cv) might increase the CV time and also give me a few more cycles?

I'll follow your advice

PS: The lipo cell checker I bought is useless, it gives false readings and I nearly didn't go on trip, I thought I was going to have to. But I checked voltages with PL8 and they were okay. I was still nervous though, so took the PL8 with me and powered it from XLR. IR looks good so I guess my connections are holding up for now, and I clobbered a few pot holes on the trip so shook the packs up a bit.

CV.PNG

Those graphs are way better than mine
What Terminal Connectors did you use?

[Scooterman]

What did you get with lead bricks? Miles?
25?

Yes about that. So lithium gives me about x4 the range and about 30-35% more oomph judging by how scooter feels now, so definitely worth doing and a good learning experience. But I couldn't have done it without your and Shirley's help.
Next time i will wait until I've covered more mileage before charging and try charging at 3.55v

I totally agree with you about the crimped connections. I'm annoyed with myself that I only crimped them because I'm so much better at soldering now . But if the graphs stay okay for the summer, in the winter I will strip off all the links and terminals and redo everything with soldered connections and neater wiring, I always make mistakes BM. The one part of the build that I was happy with was totally encasing both packs in that thick rubber gasket material. It made for two solid stout 12v packs, not dissimilar to lead bricks to look at.

I will also fit an Anderson to the back of the PSU like you. I noted what you said and may try and fit it inside the case flush with the backplate.

[terry2]

What did you get with lead bricks? Miles?
25?

I can tell you with my Puma and 2 MKs. I got about 8 mile at 6 mph then the battery bar would be at it's lowest.

[Scooterman]

Those graphs are way better than mine
What Terminal Connectors did you use?

I think it's more luck than skill terry. Don't follow my lead, I plan to redo the connections in the winter.
The 6mm^ pvc flex I bought looked a bit thin so I wired everything in parallel (included series links) which made for a LOT of links with 16 cells . Also the lugs I bought were 6mm^ but too big for the cable and I didn't have the right sort of crimpers so I'm embarrassed to say I crimped them as hard as I could using pipe grips.
But I've learnt a lot from my mistakes, so when I redo them and convert my powerchair I will know what not to do.

EDIT: But the packs are built and strapped down really solidly, so I wonder if that helps keep the cells all in place going over the bumps, it's got to help if the individual cells are moving/flexing in respect to each other.

[terry2]

Those graphs are way better than mine
What Terminal Connectors did you use?

I think it's more luck than skill terry. Don't follow my lead, I plan to redo the connections in the winter.
The 6mm^ pvc flex I bought looked a bit thin so I wired everything in parallel (included series links) which made for a LOT of links with 16 cells . Also the lugs I bought were 6mm^ but too big for the cable and I didn't have the right sort of crimpers so I'm embarrassed to say I crimped them as hard as I could using pipe grips.
But I've learnt a lot from my mistakes, so when I redo them and convert my powerchair I will know what not to do.

EDIT: But the packs are built and strapped down really solidly, so I wonder if that helps keep the cells all in place going over the bumps, it's got to help if the individual cells are moving/flexing in respect to each other.

Sounds\looks great

My mate uses a hammer\chisel on battery connectors. Then solders the top bit.
He has never had a problem.

I know it's my wiring as I changed the cells and still had the graph go everywhere
If I could but some proper copper connectors I would try them. But I can't find my size.

[Scooterman]

If I could but some proper copper connectors I would try them. But I can't find my size.

Do you mean these? https://www.ev-power.eu/LiFePO4-accesso ... mto2oj9e94

[shirley_hkg]

@Scooterman , next is to find out your pack's terminal voltage, which varies pack by pack.

Drain it to 25.80V . Then use PL8 to discharge it till one cells hits 3.00V .

Note pack voltage , and never drain your pack beyond it .

A 4-digits voltmetre plus the rule of thumb is gonna be the best fuel gauge .

[terry2]

If I could but some proper copper connectors I would try them. But I can't find my size.

Do you mean these? https://www.ev-power.eu/LiFePO4-accesso ... mto2oj9e94

Yes.
But they don't stock the size I need.

[Scooterman]

These were the lugs I bought for the individual links, but the bell end wouldn't fit into my crimpers, that's why I had to use pipe grips. https://www.ebay.co.uk/itm/Copper-Tube- ... 2749.l2649. This was the cable https://www.ebay.co.uk/itm/6mm2-50-A-Am ... 2749.l2649

Also can you buy lugs without the hole at the end? When I tried soldering them upside down the solder ran out the hole.

Then when I tried soldering them the other way up, all the solder ran down into the strands of the cable . That's why I ended up crimping only

But I never tried crimping first AND then soldering as recommended by BM, so maybe that would have worked Also Shirley made the good point that if the link needs to be bent, bend wire before soldering, which i will do next time.

[terry2]

These were the lugs I bought for the individual links, but the bell end wouldn't fit into my crimpers, that's why I had to use pipe grips. https://www.ebay.co.uk/itm/Copper-Tube- ... 2749.l2649. This was the cable https://www.ebay.co.uk/itm/6mm2-50-A-Am ... 2749.l2649

Also can you buy lugs without the hole at the end? When I tried soldering them upside down the solder ran out the hole.

Then when I tried soldering them the other way up, all the solder ran down into the strands of the cable . That's why I ended up crimping only

But I never tried crimping first AND then soldering as recommended by BM, so maybe that would have worked Also Shirley made the good point that if the link needs to be bent, bend wire before soldering, which i will do next time.

I bought the same kind of thing. But it was 10 mmsq wire and lugs.

If I was you, I wouldn't touch the cells to needed.

[Burgerman]

And way too hot...

>>>>Also can you buy lugs without the hole at the end? When I tried soldering them upside down the solder ran out the hole.

[shirley_hkg]

And didn't cramp before soldering .

[expresso]

@ Scooterman - Very good job - graphs look great and you are getting ALOT of range out of that - thats the sort of range i need -

tell me something - i am curious - those stubs you added to the cells sticking up - then you screws everything down - i like that idea - but i will be limited to how tall i can use - so can you tell me the size you used - how tall are they - and can you give me an idea how tall is actually needed to make a few ring terminals fit on one cell etc, so that when all screwed down - nothing or very little sticks up past the last screw holding it down ?

if you know what i mean - you used locktite to screw them down in the cells ? i though about it - if using those - then can use a nylon nut to bolt it all down and no need for lock washer or any more locktite either - would be secure tight connection -

i found using locktite can be a bit messy and sometimes i over do it - and can make it a worse connection then - using too much -

Like yourself - on my very first large pack - i ended up taking it out 3 times before i was done - first time - i replaced cables i didnt like how i routed them - and each time i fixed packed it better - then i had to take it out to replace one Cell that went bad - - then to add a breaker which i never had installed - thinking the chair was protected - it wasnt - i went the first summer with no protection

i learned - and each time i try to improve something - so if you can give me an idea how tall those screws are you installed on the cells first - with all the connections under them - or i may have to buy an assorted set of them and just test which are best - thats another
way -

good job - 34 miles nice ride - your ready for the summer now

[Gnomatic]

Scooterman nice job, its all coming together for you!

34mi was a nice first trek. And 59Ah returned. You now have massive range. Your charge graphs look fantastic.

[Scooterman]

And way too hot...

>>>>Also can you buy lugs without the hole at the end? When I tried soldering them upside down the solder ran out the hole.

I need to my iron a bit

Expresso -
Hi, I used what shirley got me. M6 thread rod cut into studs, washers, nuts, and nyloc locknuts. But if I did it again I would use these as it saves cutting rod into studs and you can screw them in with a hex key. https://www.ebay.co.uk/itm/M4-M5-M6-M8- ... 1471400574 They come in a variety of lengths.
I used studs because I don't like bolting into a shallow blind hole with a conventional bolt because if the bolt bottoms out it'll strip the thread, not good!

The threaded holes in my cells were about 7mm deep. So stud length = 7mm + lug/s + washer + Nut + locknut. Buy one of these, (or similar) they're cheap and cheerful and fine for what we do. https://www.ebay.co.uk/itm/150mm-Slidin ... SwFlxZaOsH the rod that sticks out the end is used for measuring depth of holes. As for overall install height = cell height (incl terminal) + nuts lugs & washers. I had bags of headroom and could have screwed 2.5 inch studs in the top of the cells without it foul on scooter bodywork, but that would have been silly

Scooterman nice job, its all coming together for you!

34mi was a nice first trek. And 59Ah returned. You now have massive range. Your charge graphs look fantastic.

Thank you I appreciate that Gnomatic

And didn't cramp before soldering .

I'm "learning all the time shirley"

[expresso]

thanks Scooter - the grub screws is what i though you used - i already have that measure thing - i am thinking i may try those on my next pack build -

on my current - i realized i needed about a 10 mm screw size to make sure with the ring terminals and washers etc, - its enough to hold them down and not over do it - i am not going to use locktite - this time - and use just the flat washer lock washer etc, with my wires for connections - and see how that works out - its an ADD ON - so worse case - i can redo it easier - but dont see why it wouldnt work

i shall find out -- i have 8mm 10mm and 12mm screws - so i can use any that may work - depending oh whats needed - all M6

[expresso]

https://www.amazon.com/binifiMux-35Pcs- ... way&sr=8-4


then i would need these ? would these be the correct size to fit the M6 grub screws ? i am not good at figuring this out - the pitch size also not sure - says 1mm pitch size -

i think this would be a better way to go - easier i think - locktite the grub screw and then use the above nuts - with flat washer only - screw it down - done - wont be coming off on its own

[Scooterman]

Espresso - I never used locktite for two reasons: 1) it's quite expensive

And 2) I thought it would act as an insulator so not good when we're after conduction

Re the nylocs in the link. Yes they're what you want, but check the pitch is compatible with your studs/grub screws. They generally come in two pitch sizes normal and fine. I think normal pitch spacing is probably best for our purposes, but I'm no engineer

BM will know.