PINNED - Lithium battery conversion/info

[Burgerman]

If you are only discharging one cell, then it should be set to DISCHARGE 10A. And the single cell preset.

That will be more than twice as fast.

[terry2]

If you are only discharging one cell, then it should be set to DISCHARGE 10A. And the single cell preset.

That will be more than twice as fast.

Yes it is set to 10.00A
It has been going for 38 mins and the counter is at 6260 mah

[Burgerman]

Hopefully you remembered to stop it at some point, and then do the same amount out, from the other cells. If you go too far, just put the right amount back in (charge) to make up the difference. Take 23Ah out by mistake? Add 3Ah back.

[Scooterman]

I wouldnt use copper. Once you clean all that oxide off, and watch for an hour it goes dull again. Why? It oxydises fast. Oxides dont conduct at low voltages well... And thats why the ones you buy are plated in zinc cadmium etc. But nobody listens! Its why I use that tinned marine cable, tinned ring terminals. Tinned anderson connectors, etc etc. Copper conducts great. Its a bad contact surface.

i listen - because i see my contacts also - which i used copper on my ring terminals at first - you can see how they become - the wiring on my first full pack - i used copper rings - i am not worried because it works fine - BUT if i had to remove the pack or i see its not showing up good in the graphs etc, - i would redo the wiring with tinned copper terminals -

i found good ones - thick walled for crimping and deeper - i like them much better -

Petroleum Jelly

The oldums are the bestums

Fish?
Do you mean gasket paper?

What is it made of? Dont say fish...

No wonder I couldn't find it on All I could find was fish patterned wallpaper!

[shirley_hkg]

Are we wearing different googles ?

[terry2]

Hopefully you remembered to stop it at some point, and then do the same amount out, from the other cells. If you go too far, just put the right amount back in (charge) to make up the difference. Take 23Ah out by mistake? Add 3Ah back.

A friend done 3 cells for me as I had to go to bed.

I have 3 left to do. Them I can wrap them up. I have 1mm plastic sheet coming this week.

I did forget about the bottom of the battery tray. So I will get some 0.5mm plastic sheet this week for that.

[Scooterman]

Are we wearing different googles ?

Okay smart arse!

I did forget about the bottom of the battery tray. So I will get some 0.5mm plastic sheet this week for that.

1/2mm don't sound very thick?

[terry2]

Are we wearing different googles ?

Okay smart arse!

I did forget about the bottom of the battery tray. So I will get some 0.5mm plastic sheet this week for that.

1/2mm don't sound very thick?

It's just to stop the cells touching the metal bottom.
I'm already wrapping each cell in Kapton tap.
I am going to put Grey Pipe Insulation Foam Pipe Lagging around the edges of the battery compartment.
I already have a Velcro strap to hold the pack in place.

[Scooterman]

I'm using a Velcro strap too

[terry2]

I have bought one of these https://uk.banggood.com/ISDT-BattGo-BG- ... rehouse=CN


Is there away to test to see it it works with one cell\battery we have?

I have a 8S connector wired up for my 8 cells. But I want to make sure it works before installing it.

[expresso]

I'm using a Velcro strap too

what kind of velcro strap did you use - do you have a pic or link to it ?

i been trying to find some sort of strap with handle etc, that can be used to lift a pack out of chair -

thanks

[terry2]

I'm using a Velcro strap too

what kind of velcro strap did you use - do you have a pic or link to it ?

i been trying to find some sort of strap with handle etc, that can be used to lift a pack out of chair -

thanks

Mine strap was already in the chair to hold 2 MK gels.

[Scooterman]

I'm using a Velcro strap too

what kind of velcro strap did you use - do you have a pic or link to it ?

i been trying to find some sort of strap with handle etc, that can be used to lift a pack out of chair -

thanks

Mine strap was already in the chair to hold 2 MK gels.

I,vs got a few 50mm x 1000mm velcro straps. I will wrap one or two straps around each 12V pack and PULL! Tightly pulling 8 cells together into a snug pack, hopefully.

Note, it's a scooter NOT a powerchair. Much better access to batteries

[LROBBINS]

Expresso,

Since you are in the U.S., take a look on McMaster-Carr for "cinching straps". These pass the belt through a ring and then back to tack the velcro and are much more secure than a simple overlap.

[Scooterman]

I have bought one of these https://uk.banggood.com/ISDT-BattGo-BG- ... rehouse=CN


Is there away to test to see it it works with one cell\battery we have?

I have a 8S connector wired up for my 8 cells. But I want to make sure it works before installing it.

BM - Can this balance a large pack? I'm doubtful

[Scooterman]

I’m using this to wrap my cells

[Burgerman]

Can it balance a large pack? In maybe a month. And to balance LiFePO4 you MUST be above 3.45V or it will UNBALANCE them by capacity as it tries to balance by voltage... So forget about that balancing anything LiFePO4 altogether.

[elryko1992]

I have bought one of these https://uk.banggood.com/ISDT-BattGo-BG- ... rehouse=CN


Is there away to test to see it it works with one cell\battery we have?

I have a 8S connector wired up for my 8 cells. But I want to make sure it works before installing it.

https://m.youtube.com/watch?v=y0IZh7_egmU

[Burgerman]

https://www.ebay.co.uk/itm/ISDT-BG-8S-S ... Swl29b7jkm

These look OK as a battery monitor. Dont use the so called balance, it will take 2 hours to balance a 1Ah battery. So 200x longer to balance a 200Ah one! And it cant anyway unless its already fully charged and balanced as the voltage will be too low.

Also dont expect it to tell you with any accuracy how much you used or how much is left. Because thats impossible on LiFePO4 anyway. At best its a GUIDE!!! It will show if you have trouble somewhere. It will show that they are full. It will show that they or 1 cell is at the end of its chage before you damage it. But as a reliable accurate fual guage it will be useless. Still a helpful thing to give you some idea though. And prevent damage and with a big pack thats all thats required.

[terry2]

I have bought one of these https://uk.banggood.com/ISDT-BattGo-BG- ... rehouse=CN


Is there away to test to see it it works with one cell\battery we have?

I have a 8S connector wired up for my 8 cells. But I want to make sure it works before installing it.

https://m.youtube.com/watch?v=y0IZh7_egmU

That video would be good if I had the batteries he had.
I have sent for a lipo battery now to test it and update the firemware.

https://www.ebay.co.uk/itm/ISDT-BG-8S-Smart-Battery-Checker-Balancer-Signal-Tester-Quick-Charge-XT60-Plug/382632655199?epid=12025933201&hash=item5916aef95f:g:D7wAAOSwl29b7jkm

These look OK as a battery monitor. Dont use the so called balance, it will take 2 hours to balance a 1Ah battery. So 200x longer to balance a 200Ah one! And it cant anyway unless its already fully charged and balanced as the voltage will be too low.

Also dont expect it to tell you with any accuracy how much you used or how much is left. Because thats impossible on LiFePO4 anyway. At best its a GUIDE!!! It will show if you have trouble somewhere. It will show that they are full. It will show that they or 1 cell is at the end of its chage before you damage it. But as a reliable accurate fual guage it will be useless. Still a helpful thing to give you some idea though. And prevent damage and with a big pack thats all thats required.

I've got the same one. But only to keep an eye on the pack.

[expresso]

Expresso,

Since you are in the U.S., take a look on McMaster-Carr for "cinching straps". These pass the belt through a ring and then back to tack the velcro and are much more secure than a simple overlap.

thanks will take a look

[terry2]

Expresso,

Since you are in the U.S., take a look on McMaster-Carr for "cinching straps". These pass the belt through a ring and then back to tack the velcro and are much more secure than a simple overlap.

thanks will take a look

These look good

https://www.ebay.co.uk/itm/Ozark-Trail- ... SwKXhcQv0d

[Scooterman]

Expresso,

Since you are in the U.S., take a look on McMaster-Carr for "cinching straps". These pass the belt through a ring and then back to tack the velcro and are much more secure than a simple overlap.

thanks will take a look

These look good

https://www.ebay.co.uk/itm/Ozark-Trail- ... SwKXhcQv0d

I
Yes very robust. I just realised as well as pulling the cells together in a tight pack I need to strap them down so they don't jump around going over bumps and loosen the connections.
That must be a particular problem with add-ons connected to chair via a flying lead.

[terry2]

I have got these https://www.amazon.co.uk/gp/product/B01 ... XQVE9KK595
and some Loctite 243 from amazon as a add-on.

Now to find out how to put 8 cells together.
I've got my 1 mm plastic coming Tuesday.


EDIT= I will be using the foam that came with the batteries on the corners for protection.

[Scooterman]

Can it balance a large pack? In maybe a month. And to balance LiFePO4 you MUST be above 3.45V or it will UNBALANCE them by capacity as it tries to balance by voltage... So forget about that balancing anything LiFePO4 altogether.

This got me thinking...
So after a charge cells are balanced both in respect of voltage and capacity (somewhere near 100%)
As they discharge the same amount of current is drawn out of each cell (cos wired in series), for a period of hours (Ah out)
So cells should stay balanced in capacity (at least during large middle part of their discharge curve). Good cells/well matched cells should also stay balance in terms of voltage.
BUT with not so good, or poorly matched cells, they will stay in balance (capacity wise), but no so well balanced voltage wise. So if you try to balance them by voltage you'll pull them out of balance capacity wise?
Does that someway explain what you mean?

[Burgerman]

This got me thinking...
So after a charge cells are balanced both in respect of voltage and capacity (somewhere near 100%)

EXACTLY 100% -- Every cell that is brought up above the 3.45V point till almost no current flows, is 100% full.

As they discharge the same amount of current is drawn out of each cell (cos wired in series), for a period of hours (Ah out)
So cells should stay balanced in capacity (at least during large middle part of their discharge curve).

No, during ALL of it! But the cell with the least capacity will be empty first. Good cells are very close though. And you should not be discharging to that point or even close to 100% discharged anyway. 95% is as far as you should ever go. 2.9V per cell UNLOADED and say 2.5V loaded.

Good cells/well matched cells should also stay balance in terms of voltage.
BUT with not so good, or poorly matched cells, they will stay in balance (capacity wise), but no so well balanced voltage wise.

Yes but we balance at the TOP so voltage below 3.450V is not important.

So if you try to balance them by voltage you'll pull them out of balance capacity wise?
Does that someway explain what you mean?

It explains part if it.
But theres even stronger reasons not to attempt to balance at lower than 3.45V. And theres 2 good ones.
1. The TEMPERATURE of the cell, has more affect on its voltage than its state of charge. So the cells at one end where the air can get to them may be cooler and those then "appear" to be lower. So the balancer tries to discharge the rest. When that wasnt actually out of balance. So in doing so it UNBALANCES the pack.

In addition you may have noticed that at the CC part of the charge, or discharge, the voltage may in fact go the WRONG way. As in under discharge for e.g. the voltage may drop low, then increase for an hour or so, then eventually begin to fall as you would expect. And the opposite under charge. This is because the cells have resistance and charging or discharging warms them up! And reduces resistance.

If you discharge 8 cells, and the voltage is RISING then the weakest cell is the one that has rissen more. That is, the cell with the highest resistance has warmed more, and shows a higher voltage. If you try to balance that, you will take MORE from the highest voltage cell, but that will just make it read even higher voltage. And so you keep going! And that keeps unbalancing the pack more and more. Because VOLTAGE is not an indication of state of charge!!! It cant tell you how many actual Ah out it is. It in fact will be exactly the same Ah used as every other cell regardless of its difference in volts by a few mV.

2. The typical BMS , charger, cell balancer is only accurate in its READING of the voltage to say 5mV. That means its total error can be 10mV. But the difference in charge on 8 cells may in fact be zero, and the balancers inaccuracy THINKS they are out of balance. If the voltage rise/fall is actually doing as you would expect, it will try to drop say 5 to 10mV from the highest cell as it sees it. That difference may be 40Ah, or MINUS 40Ah.. So it will spend all day long trying in vain to balance a perfectly balanced battery... While acually putting it many Ah out of balance.

[terry2]

This is how I need my pack to look like once it's wired up.
The problem is that I don't know how to do this.
I have been on you tube, but nothing so far. Can some kind person help please.

[terry2]

This is how I need my pack to look like once it's wired up.
The problem is that I don't know how to do this.
I have been on you tube, but nothing so far. Can some kind person help please.

Forget that picture. I have it wrong.

I haven't got a clue

[Scooterman]

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

[terry2]

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

Just found out they won't fit my chair

My battery bay takes 2 MK 72 amp which are MK Depth 6.7 X width 10.2 X hight 8.2

My cells are 2 inch X 6 3/4 X 8.2

The battery bay is just 11 in width.

Stupid me thought I could of fitted them.