PINNED - Lithium battery conversion/info

[Scooterman]

I want to buy 16 105Ah cells, but I'm wary about buying from sellers from Aliexpress as I don't want returned/used cells.

Steve

If and when you manage to source some cells Steve, can you let me know (if you remember).

[steves1977uk]

Sure SM! Might see what RJ-Lithium have to offer.

Steve

[Scooterman]

I'm going to get 8 of these for my salsa. I need to double check measurements but I reckon they'll just squeeze in. Constant discharge is 1C but will be fine for my ultra-light chair with 90A controller.

There's still life in my 4 year old ex-scooter lead-acids (now in salsa), but am sorely tempted by lithium, it's sexy

Product Name: Lithium iron phosphate cell
Shell Material：Aluminium
Rated capacity:150Ah
Minimum capacity:150Ah
Internal impedance:0.2~0.3mΩ
Nominal voltage:3.2V
Dimensions(L*W*H):174*48*171mm
Weight:2.95±0.10kg
Recommend Constant Current:150A(1C)
End-of-Discharge Voltage:2.5V
Recommend Constant Current:75A(0.5C)
Charge Voltage:3.65V
Maximum Pulse Discharging Current：228A（3min）
Maximum Pulse Discharging Current：300A（30S）
Charge Voltage:3.65V
Max Continuous Discharge Current:150A(1C)
Cycle life (80%DOD):4000 cycles
Charging Temperature：-5~60°C
Discharging Temperature：-30~60°C

[saker98]

Add 10 days going nowhere in customs, waiting for them to rip you off and then being held to ransoe by royal mail who will also add another fee for the privelidge of collection from customs till you pay the bill before they even bother to turn up

John: The order is from door to door, no additional fees.

I will confirm when they are delivered.

James

Hi everybody, my batteries arrived today. Paid on 01/10/2019- shipped 19/10/2019 - Received 29/10/2019. £1239 for 18 delivered to my door all fees paid.

Reading 3.24 lowest to 3.31 highest Unboxed and warming up in my heated shed.

[Burgerman]

Good. All undamaged? Charge each seperately. And test a couple, to find capacity to 2.9V.

[stevelawiw]

https://www.aliexpress.com/item/4000126563901.html?spm=a2g0o.detail.1000060.2.39bb6597LsMXrD&gps-id=pcDetailBottomMoreThisSeller&scm=1007.13339.146401.0&scm_id=1007.13339.146401.0&scm-url=1007.13339.146401.0&pvid=4031e9b5-1521-4da6-bf1f-d0ec8def4f72
24v 300ah for £866? But I can't see any mention of 3C in the spec, are they lower quality?
And they are big!

[foghornleghorn]

https://www.aliexpress.com/item/4000126563901.html?spm=a2g0o.detail.1000060.2.39bb6597LsMXrD&gps-id=pcDetailBottomMoreThisSeller&scm=1007.13339.146401.0&scm_id=1007.13339.146401.0&scm-url=1007.13339.146401.0&pvid=4031e9b5-1521-4da6-bf1f-d0ec8def4f72
24v 300ah for £866? But I can't see any mention of 3C in the spec, are they lower quality?
And they are big!

Look like 2C max burst current

Discharge Current:150A (1C)
Maximum Pulse Discharging Current：228A (3min)
Maximum Pulse Discharging Current：300A (30S)

You'll never fit 16 of those in a wheelchair, and you seem to be using Burgerman's misleading ignore the shipping cost pricing.

US $1,097.25 + Shipping: US $588.95 to United Kingdom
= $1686.20 = £1300
Plus whatever import fees you get hit with.

[shirley_hkg]

But I can't see any mention of 3C in the spec, are they lower quality?
And they are big!

[stevelawiw]

You'll never fit 16 of those in a wheelchair, and you seem to be using Burgerman's misleading ignore the shipping cost pricing.

Yeah, I think I had my rose tinted glasses on

[Scooterman]

I ordered 8 of them (150Ah) for just over £600 incl shipping so fingers crossed. My lead 3.5 year old lead acids nearly died on me today and I was only out for a couple of hours and much of that was on the bus.

I need to get something quick with limited funds, and me and my chair are super-lightweight so I'm hoping they'll be okay . At that price they're only slightly more than leads and will just squeeze in lengthways. Plenty of room on height and width. If not them I would have had to buy lead acid which is what I didn't want to have to do...

As BM says sometimes you just gotta go for it and take a chance.

And my mob scooter is much heavier than my powerchair and it's fine with 180Ah lithium. In the summer I get a safe 75 miles before recharge, but tend to recharge after 65 miles or so.

[Scooterman]

Why can't I find a 4 digit LCD voltage display that can be left permanently connected? I think the BatGo checker is LCD but it can't be left permanently connected.

I don't want LED as it gets washed out by sunlight.

If anyone can find one 0-30V dc please post the link

[Irving]

Why can't I find a 4 digit LCD voltage display that can be left permanently connected? I think the BatGo checker is LCD but it can't be left permanently connected.

I don't want LED as it gets washed out by sunlight.

If anyone can find one 0-30V dc please post the link

Why cant it be left connected?

Whats wrong with this one?

[Scooterman]

Nothing wrong at all with that one well done . 0.1V/8 = 0.0125V accuracy per cell so accurate enough to act as pack safety low voltage display.

The BatGo unbalances cells if left connected. Although I don't have one so am only going by what others say?

[Irving]

Nothing wrong at all with that one well done . 0.1V/8 = 0.0125V accuracy per cell so accurate enough to act as pack safety low voltage display.

The BatGo unbalances cells if left connected. Although I don't have one so am only going by what others say?

The BatGo BG-8S (if that's the one you're referring to) can't unbalance cells in its basic 2-wire setup, and it's expensive overkill just as a voltmeter. You need the additional add-on board built into the battery pack to read individual cells and that has a 'balancing function' which maybe gets misused hence it's 'reputation'.

The BG-8S is a good example of function creep - just because you can provide something doesn't mean you should!

BTW that LCD voltmeter I linked to is available here from a 'UK seller'

[shirley_hkg]

Has anyone built a lifepo4 pack using cells with an M4 threaded hole?

If so how did it go?

My long forgotten ultimate G24 form factor 280Ah is back on track, only one balance lead left.

Putting another 75Ah pouch cells together is a task.

No more bus bars. Wires and terminals only.

Initial balance was still messy.

Took two 15% DOD cycles, and now balanced in 10 mins and absorption period to 115mA termination is just another 20 minutes as well.

[Scooterman]

Wow! it's like spaghetti junction! Rather you than me Shirley

Is the spanner staying?

I did the same as you and insulated one of my 10mm combination spanners with electrical tape.

Sorry for the dumb question, but what are the resistors for, a BMS?

[shirley_hkg]

Preparing a reservior for an estimated 270Ah dump tonight .

Has anyone built a lifepo4 pack using cells with an M4 threaded hole?

If so how did it go?

[Dan]

BTW that LCD voltmeter I linked to is available here from a 'UK seller'

It says its measuring accuracy is only 3‰. Would we need something better? There are some cheap ones that claim a Measurement Accuracy 1%.

Ohhhh I just noticed the percent sign has an extra 'o' at the bottom. It means 'per thousand', rather than 'per hundred'.

I don't recall seeing that before, I had to google it.

‰
It's a percent sign with an extra 'o' at the bottom. It means 'per thousand', rather than 'per hundred'.
5% of 400 is 20, therefore, 5‰ of 400 is 2.

[shirley_hkg]

Is the spanner staying?



Sorry for the dumb question, but what are the resistors for, a BMS?

For taking photos only .

Resistors are meant to speed up an initial balance， while watching CCS graph.

A 0.5Ω / 50W resistor (£0.2) will dump the full cell @6A .

[Dan]

Shirley_hkg did you solder the balance wires directly into the middle of the bus wires? That would save on terminals.

[terry2]

How can we balance our cells with out charging?

Can our PL8 balance while discharging?

[shirley_hkg]

Can our PL8 balance while discharging?

Yes. That's exactly what it is for.

[terry2]

Can our PL8 balance while discharging?

Yes. That's exactly what it is for.

So I chose discharge from the menu. And that will do it?

I'm trying to equalise the cells with out charging
Thanks

[Scooterman]

Can our PL8 balance while discharging?

I'm trying to equalise the cells with out charging
Thanks

When cells are balanced at the bottom it is known as ‘bottom balancing’ as opposed to top balancing which the PL8 and BMSs do during charging provided you do a full charge to 3.6v and not a quick bulk charge

[terry2]

Can our PL8 balance while discharging?

I'm trying to equalise the cells with out charging
Thanks

When cells are balanced at the bottom it is known as ‘bottom balancing’ as opposed to top balancing which the PL8 and BMSs do during charging provided you do a full charge to 3.6v and not a quick bulk charge

OK. What I want to do it bring the highest cells down to the lowest.
The pack is coming out the chair next week.

[shirley_hkg]

I'm trying to equalise the cells with out charging
Thanks

No. You cannot. LiFePO4 can only be balanced WHEN THEY ARE FULL , or empty.

Usually we choose to balance it when it is full.

[shirley_hkg]

What I want to do it bring the highest cells down to the lowest.
The pack is coming out the chair next week.

Simple.


Hook it up to PL8 and set charge volt to 3.48V, balance starts @3.40V

If you see cell higher than 3.48v, discharge the pack first , via the internal mode , then recharge .

[Scooterman]

The pack is coming out the chair next week.

As an alternative... When the pack is out and on the bench, why not charge to 3.6v which will balance cells, then discharge to about 3.3v for storage, and they will stay balanced apart from slight variations in self-discharge rate.

That's what I did with my mob scooter a few days ago as I won't be using it over winter. But I left the cells in the scooter.

[terry2]

All sorted.

A friend of a friend that has cells like these.
Has lent me his Cell Meter 8. It's bringing the highest down to the lowest

[steves1977uk]

As an alternative... When the pack is out and on the bench, why not charge to 3.6v which will balance cells, then discharge to about 3.3v for storage, and they will stay balanced apart from slight variations in self-discharge rate.

That's what I did with my mob scooter a few days ago as I won't be using it over winter. But I left the cells in the scooter.

Yep, that's how I'd do it too SM.

Steve