PINNED - Lithium battery conversion/info

[Scooterman]

They're neat, I've not seen them before

[terry2]

You can re use the centre fuse, or breaker if it has one. But it will now not go in the centre, it will go in the + 24V end of the battery. Its likely easier to just throw all the olf stuff away, and fit a new fuse in your new wiring.

A 100A or 125A midi fuse (ebay) and 2 ring terminals and a bit of heatshrink is all you will need. About 2 uk pounds...

https://www.ebay.co.uk/itm/MIDI-STRIP-L ... zCXWSQFKKw

You can add the fuse holder too if you want instead of heatshrink. But its a bit bigger and not so neat.
The ring terminals you need are ones with a 6 ot 6.6mm bolt hole and a 10sqmm cable size. And you will solder them on. You will crimp them, first to hold in position to make it easy. One of those turbo cigarette lighters with a small pencil flame. Takes 5 seconds per joint.

I will buy 2 of them.
Here is my wiring. Mine is the DX2

[Burgerman]

Thats all just confusing. Chick all that away in a corner for now, and ignore it. The only bit you want to use is the 24V input connector, with its wires later on.

YOU connect your lithium 24V to the power module. You dont need to figure out how they managed to over complicate it all with 30 wires!

[terry2]

Thats all just confusing. Chick all that away in a corner for now, and ignore it. The only bit you want to use is the 24V input connector, with its wires later on.

YOU connect your lithium 24V to the power module. You dont need to figure out how they managed to over complicate it all with 30 wires!

So every thing in the picture that is yellow. I don't need.
Then from the modal plug I put 1 earth and 1 live both with 100amp fuses

[Scooterman]

I’ll reply just in case BM is at church.

Yes

[terry2]

I’ll reply just in case BM is at church.

Yes

Thanks.

[shirley_hkg]

I have 24 cells and would like to group them into 3P8S, with the least deviation in capacity.

My score is △c=809， between the two extremes

Can anyone help ?

[Burgerman]

I am rubbish at maths.

But you need to add the lot up, div by 8. Then pick any 3 that add up to that number.

But it more important to group by self discharge rate.
Then by impedance.
Then by capacity.
And all 3 if you have the patience!

[Scooterman]

Would this work?

If they were sorted least to most, then group centre 3 cells, and work way out???

or

[Burgerman]

Approximately.

[Scooterman]

In 2P8S for example

Rather than capacity testing and matching cells that way, could you...

Arrange two groups of 8S

For each group, charge/discharge to 3.6v/2.9v, and note the order which cells shot up towards 3.6v. And also the order they fell away towards 2.9v.

Then group them that way assuming the cells that shot up first and fell away first would be weakest.

Obviously the cells would have to be balanced before you started, so balance them at the top, discharge a bit, then charge/discharge 3.6/2.9v cycle?

I doubt if it would be as good though, but a lot quicker.

But I don't know enough about lithium, it was just something I thought of...

EDIT: When in use, if you never allow the cells to discharge below about 30% SoC, does it even matter if they're not capacity matched?

[Scooterman]

This what I've managed to do so far, it's not too bad a job but I've not finished yet. Before sticking the bottom and sides on I plan to stick doubled sided tape (gotta buy some) on each cell so as to stick them to the rubber. Then I'll stick on sides and bottom and reinforce with gaffer tap.

Hopefully it won't turn into a sticky mess, ha! ha!

But first I need to work out easy way of roughly matching the cells...

[Gnomatic]

Looks really good, Scooterman. What is that material you are using between the cells?

[Scooterman]

Thank you

It's this https://www.ebay.co.uk/itm/Black-Solid- ... ect=mobile

I bought 2.5mm as I felt it represented best value for money

PS: Superglue sticks the edges of rubber together really well.

[Burgerman]

You should have made one seperatot longer. To go around the complete pack. But you can do that like a big ring, with some overlap to glue.
And you must have a sheet under the battery too.

[expresso]

thats for sure very good thickness between the cells - you seem to have alot of spare room then - my problem is very little room to spare if i try to fit the most in there - how thick is that rubber 2mm ?

looks nice

[Burgerman]

So every thing in the picture that is yellow. I don't need.
Then from the modal plug I put 1 earth and 1 live both with 100amp fuses

Correct. Just feed the power module 24V with a fuse in the positive wire. Better to use 10 sqmm cable ideally. How thick is the wire coming out of your plug? You may be able to reuse that.

[Scooterman]

thats for sure very good thickness between the cells - you seem to have alot of spare room then - my problem is very little room to spare if i try to fit the most in there - how thick is that rubber 2mm ?

looks nice

Hi Expresso, the rubber is 2.5mm thick. I have a bit more room to play with. I have two battery trays measuring 276mm x 177mm.

You should have made one seperatot longer. To go around the complete pack. But you can do that like a big ring, with some overlap to glue.
And you must have a sheet under the battery too.

I did think of that BM, or even individually wrapping each cell in one piece rubber. I think either of the methods would work with thinner rubber, but this stuff wouldn't go round corners very neatly. I thought I could score the back to make it bend sharper but in the end did what I did. Your suggestion may be better, I usually discover the best method after I've finished a job and think, "Why didn't I do it like that? ".

What I've done will do, and I'll reinforce it with gaffer tape.

Noted about the bottom, I mustn't forget that! If I've got enough rubber over I might put a double layer on the bottom.

I did think of saving time and money by cutting one end off the individual cardboard boxes the cells came in and using them as insulators, but I thought you'd tell me off! : Plus I did think they could get all soggy in the english weather.

[terry2]

So every thing in the picture that is yellow. I don't need.
Then from the modal plug I put 1 earth and 1 live both with 100amp fuses

Correct. Just feed the power module 24V with a fuse in the positive wire. Better to use 10 sqmm cable ideally. How thick is the wire coming out of your plug? You may be able to reuse that.

I have bought the 10 sqmm wire you suggested.

I don't know how thick the wire coming from the plug is.
It is tucked away out of sight. And I won't know till I get both batteries out so I can see what's what.

The Puma 40 battery bay is very hard to get to. One is supposed to use a lift\jack when changing batteries.
A friend is going to use wood to raise the back wheels.
Then I hope we can sort out the new wiring.

[terry2]

@Scooterman
That looks awesome dude

[Scooterman]

@Scooterman
That looks awesome dude

Thank you Terry, but I've not finished it yet. Still plenty of opportunity to make a f*** up and end up with a sticky rubbery mess chucked in the dustbin (trash) in disgust and grumbling about wasted money

[Gnomatic]

I have a bit more room to play with. I have two battery trays measuring 276mm x 177mm.

Wow, you do have a spacious battery tray! I wish my chair's battery area had that much room to play with. Can't wait to see what it looks like when you have your pack fitted.

[terry2]

I have done my balance wires ready for the cells and the monitor.

Do the balance wires go on in a sequence. I know the red wire goes to positive and the black to earth.
But I am not sure about where to put the other wires.
Thanks

[Scooterman]

Look at page 62 in the PL8 manual, there's a diagram.

Sorry. I don't mean the balance wires on page 62. But where to put the connectors to hook up the batteries.

[Furio]

Hi,

Today when I started charging the lifepo battery, the PL8 tripped on SAFETY CODE 17 : Cells No Add Up. The charger starts and when the current reaches 300 mAH this happens; and repeatedly. I am lost. Could someone give any idea.

Thanks.

Furio.

[expresso]

terry if you post some pics of the Cells and how your doing it etc, - would be easier to see and notice if anything may be out of place etc,

might be easier for others to help you also. if you can -

[Burgerman]

Hi,

Today when I started charging the lifepo battery, the PL8 tripped on SAFETY CODE 17 : Cells No Add Up. The charger starts and when the current reaches 300 mAH this happens; and repeatedly. I am lost. Could someone give any idea.

Thanks.

Furio.

Cell balance lead connections or plugs not connected or bad connection maybe oxidised. Not using crimped connectors by any chance?

Wrong preset selected?

One or both charge cables not connected or fuse blown?

A group of cells that are dead?

A pack thats at too low voltage?

You selected dont use Banana plugs on the PC screen?

You changed the preset settings in the DETECT tab.

[Furio]

Hi BM,
I am using the preset you provided, without alteration. One thing I noticed, all the cell voltages are in 3.3v range except cell #5 which is just shy of 3.6v.

But now the charger is working on CV and current @ 1.1 Amp.

Other points you mentioned, I will have to wait.

[terry2]

terry if you post some pics of the Cells and how your doing it etc, - would be easier to see and notice if anything may be out of place etc,

might be easier for others to help you also. if you can -

Will do dude.

I'm just waiting for the plastic wrap to come tomorrow.
After I have done that I will post a picture of how I'd like the pack.

[Burgerman]

Then the pack is WAY out of balance. Why?
So it can only charge at the same rate that the 1000mA balance circuit can drain the 3.6V cell. So you have a problem. And may need to restart after 16 hours if its not already done. The full cell wont much like being full for long periods. So you can speed things up by connecting say an automotive headlamp bulb across the 3.6V cell for a few minites. Watch on screen. Its voltage will fall, and the charger amps will increase.

Hi BM,
I am using the preset you provided, without alteration. One thing I noticed, all the cell voltages are in 3.3v range except cell #5 which is just shy of 3.6v.

But now the charger is working on CV and current @ 1.1 Amp.

Other points you mentioned, I will have to wait.