Shape of Lithium batteries (1 Viewer)

[Otter Spotter]

Most Lithium Leisure batteries are shaped like traditional lead acid batteries, does anyone make flat batteries (ala Tesla car style) ? The space under my bed frames is quite tall and 4ft.6in long so I was thinking a long flat battery would be a better use of space than the existing battery. I think I am right that the cells are around 3ins long which along with a case would really work for me so does anyone have any ideas?
Cheers

 

[68c]

I think you may be have mixed up the 18650 Li-Ion cells with the larger LiFePo4 cells used in leisure batteries. The LiPo cells do not carry the fire/ explosion risk that the 18650 cells do.

 

[Otter Spotter]

I think you may be have mixed up the 18650 Li-Ion cells with the larger LiFePo4 cells used in leisure batteries. The LiPo cells do not carry the fire/ explosion risk that the 18650 cells do.

OK so how tall are LiFePo4 cells ?

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[Gromett]

Most Lithium Leisure batteries are shaped like traditional lead acid batteries, does anyone make flat batteries (ala Tesla car style) ? The space under my bed frames is quite tall and 4ft.6in long so I was thinking a long flat battery would be a better use of space than the existing battery. I think I am right that the cells are around 3ins long which along with a case would really work for me so does anyone have any ideas?
Cheers

Look at the bare cells and see if they suite. If they do come back and ask about building your own

LiFePO4 Prismatic Cells | Fogstar Batteries

We offer a wide range of LiFePO4 Prismatic Cells purchased directly from the manufacturers. Legitimate cells that come with a QC certifications to state that the voltages, capacity and sizes are all matched.

www.fogstar.co.uk

 

[Otter Spotter]

Look at the bare cells and see if they suite. If they do come back and ask about building your own

LiFePO4 Prismatic Cells | Fogstar Batteries

We offer a wide range of LiFePO4 Prismatic Cells purchased directly from the manufacturers. Legitimate cells that come with a QC certifications to state that the voltages, capacity and sizes are all matched.

www.fogstar.co.uk

Cheers for this link, looking at the 280ah at £99.99 each they look as though standing upright, you could make up a 840ah pack for a similar size to my 110ah if stood upright, but if you could lay them on their sides then 72mm isn’t much and I suspect it may be possible to fit 5 or 6 along the base of one side of the bed cupboard though it may unbalance the van. I could take photos of the space tomorrow and you could tell me your thoughts

 

[Gromett]

Cheers for this link, looking at the 280ah at £99.99 each they look as though standing upright, you could make up a 840ah pack for a similar size to my 110ah if stood upright, but if you could lay them on their sides then 72mm isn’t much and I suspect it may be possible to fit 5 or 6 along the base of one side of the bed cupboard though it may unbalance the van. I could take photos of the space tomorrow and you could tell me your thoughts

For a 12v pack you need to buy in sets of 4. Just in case you didn't know.

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[Otter Spotter]

For a 12v pack you need to buy in sets of 4. Just in case you didn't know.

No didn’t know, Am I being thick but will 4 be 1120AH or do you need 4 cells to produce 280AH ?

 

[Gromett]

No didn’t know, Am I being thick but will 4 be 1120AH or do you need 4 cells to produce 280AH ?

You have 4 in series to make a battery. The voltage is added but the AH stays the same.
If you want more AH. you can either
a) get bigger cells.
b) put 2 or more in parallel.

 

[Otter Spotter]

You have 4 in series to make a battery. The voltage is added but the AH stays the same.
If you want more AH. you can either
a) get bigger cells.
b) put 2 or more in parallel.

So to get a 500AH set up how many cells would I need and I presume a BMS and some form of heating? I am thick Cannot get my head around Volts and AHours etc

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[LithiumConvert]

I Cannot get my head around Volts and AHours etc

You need 4 LiFePO4 cells (technically, connected in series) to give 12 volts.
The cells are nominally 3 volts each. (In practice a bit more).

This has nothing to do with battery capacity (Ah).

Think of it as 4 cells connected tohether (in series) to make a battery.

Now the more batteries you have connected together (in parrallel), the more capacity (Ah) you have.

For example, Sterling Power say that I can connect an unlimited number of my 60Ah batteries together (in parallel). I currently have 3, so 120 Ah.
Plenty for me and well over double the capacity I had with the original AGM battery.

------------------------------------------

Don't forget that with lithium you do do have keep the batteries upright. So to to get them in the space you have you can lay them on their side if it helps.

I would not be making my own batteries by buying the cells.

 

[Two on Tour]

I would not be making my own batteries by buying the cells.

I have built three LifePo4 battery packs from buying cells because at the time of building them it was the cheapest option and it was a good way of learning and understanding about Lithium batteries in general.
This is my current home built battery pack which is in our van and built from CatL 271Ah cells. I have now replaced the Daly BMS and active cell balancer with a JK BMS.

 

[MisterB]

RogerIvy can make you a battery to a specific shape, if the standard sizes dont work for you.

a quick google search - The batteries can be mounted in any direction, even upside down. Since there is no liquid in them and they are solid the battery will work however you mount them.

i think LithiumConvert had a typo/auto text mishap ???


ive built two 14.3KW batteries, for home battery use and the 16 lifePO cells are placed on their side, one on top of each other, in two columns, though i dont see the 'need' for placing them upside down!

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[MisterB]

I have built three LifePo4 battery packs from buying cells because at the time of building them it was the cheapest option and it was a good way of learning and understanding about Lithium batteries in general.
This is my current home built battery pack which is in our van and built from CatL 271Ah cells. I have now replaced the Daly BMS and active cell balancer with a JK BMS.

View attachment 880277

Loving the home made busbars aswell, almost a work of art !!

Otter Spotter - although the cells are in two rows of two, you could just as easily have one row of four, even end to end if you make your own busbars. you would of course need to look at how you can contain the cells to prevent swelling when charging, but as you would want protection of the cells anyway it shoildnt be an issue.

 

[Otter Spotter]

You need 4 LiFePO4 cells (technically, connected in series) to give 12 volts.
The cells are nominally 3 volts each. (In practice a bit more).

This has nothing to do with battery capacity (Ah).

Think of it as 4 cells connected tohether (in series) to make a battery.

Now the more batteries you have connected together (in parrallel), the more capacity (Ah) you have.

For example, Sterling Power say that I can connect an unlimited number of my 60Ah batteries together (in parallel). I currently have 3, so 120 Ah.
Plenty for me and well over double the capacity I had with the original AGM battery.

------------------------------------------

Don't forget that with lithium you do do have keep the batteries upright. So to to get them in the space you have you can lay them on their side if it helps.

I would not be making my own batteries by buying the cells.

I wouldn’t try and build my own, I am always tinkering with my van and there quiet a bit of floor space under my bed/bench seats (rear lounge) hence my brain fart ( Why can’t I have a long slim battery under the benches?). Why are batteries the rectangular block shape when maybe a flat one would be space user friendly. I maybe can see why when you look at Two on Tour ,s home made battery, it’s to save on cable but surely the power drop caused by cables running between the cells would not lose much ?

 

[MisterB]

I wouldn’t try and build my own, I am always tinkering with my van and there quiet a bit of floor space under my bed/bench seats (rear lounge) hence my brain fart ( Why can’t I have a long slim battery under the benches?). Why are batteries the rectangular block shape when maybe a flat one would be space user friendly. I maybe can see why when you look at Two on Tour ,s home made battery, it’s to save on cable but surely the power drop caused by cables running between the cells would not lose much ?

not sure it was done to try and save cable?? only he can answer that, but i suspect at the time it was cost effective to bild his own and he learnt a lot from doing it (as i have) - PS you can have one long slim one if you want, though it appears, not a readily available off the shelf one - PPS it wasnt a brain fart, it was a sensible thought to 'push the envelope' rather then be told what you can have my the manufacturers.

im sure RogerIvy built a long slim one for someone, it was on youtube - it will give you an idea of whats possible ,,,

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[Two on Tour]

not sure it was done to try and save cable?? only he can answer that, but i suspect at the time it was cost effective to bild his own and he learnt a lot from doing it (as i have) - PS you can have one long slim one if you want, though it appears, not a readily available off the shelf one - PPS it wasnt a brain fart, it was a sensible thought to 'push the envelope' rather then be told what you can have my the manufacturers.

im sure RogerIvy built a long slim one for someone, it was on youtube - it will give you an idea of whats possible ,,,

The reason I used cable for busbars was that the cells expand and contract with charge and discharge and my feeling was that using a fixed copper or aluminium type busbar tightened down onto the cell terminals could put load on the terminal post with this expanding and contracting. The cable busbars I made are fitted with a slight curve to them to eliminate any chance of a load being applied with this expanding and contracting.

 

[MisterB]

The reason I used cable for busbars was that the cells expand and contract with charge and discharge and my feeling was that using a fixed copper or aluminium type busbar tightened down onto the cell terminals could put load on the terminal post with this expanding and contracting. The cable busbars I made are fitted with a slight curve to them to eliminate any chance of a load being applied with this expanding and contracting.

i suppose in a contained structure that isnt so much of an issue, but yours is 'taped' so might be different. a sensible approach non the less .. and as you did it before commercially available batteries were available at an 'affordable' price it really did (and does) make sense!

 

[Two on Tour]

i suppose in a contained structure that isnt so much of an issue, but yours is 'taped' so might be different. a sensible approach non the less .. and as you did it before commercially available batteries were available at an 'affordable' price it really did (and does) make sense!

A while back there was a lot of talk and controversy about compressing cells or not and I'm in the not compressing camp as the cell cans are already pre compressing the cells according to the cells spec sheet of my cells, hence my cells are held together with Kapton tape.

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[treblid]

I used Kapton tape when bench testing our 4 calls pack but I ended up placing them in a box compressed slightly when discharged using the method RogerIvy showed on his video.

Also used flexible busbars that our laminated copper and can expand and contract between the fixing points.

 

[LithiumConvert]

i think @LithiumConvert had a typo/auto text mishap ???

Thank You Mr B for pointing that typo out. You are quite correct. You do NOT have to keep lithium batteries uprght.
Too late to edit/correct post #10 now.

 

[Otter Spotter]

Inside of one of my Bench seats measurements are 12ins x 41ins + space being used by existing battery. My thoughts are lay the batteries flat and put a piece of Plywood on top as false floor, what do think you all think? Would weight be a major factor and cost versus capacity, is it worth it?

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[Two on Tour]

Inside of one of my Bench seats measurements are 12ins x 41ins + space being used by existing battery. My thoughts are lay the batteries flat and put a piece of Plywood on top as false floor, what do think you all think? Would weight be a major factor and cost versus capacity, is it worth it?View attachment 880353View attachment 880354

RogerIvy nigelivy , what do you recon you could do with that space?

 

[MisterB]

Inside of one of my Bench seats measurements are 12ins x 41ins + space being used by existing battery. My thoughts are lay the batteries flat and put a piece of Plywood on top as false floor, what do think you all think? Would weight be a major factor and cost versus capacity, is it worth it?View attachment 880353View attachment 880354

Check the dimensions of the cells ....you can check on Fogstar for the cell dimensions. I wouldn't just put plywood over it though i would enclose it completely.

 

[Gromett]

So to get a 500AH set up how many cells would I need and I presume a BMS and some form of heating? I am thick Cannot get my head around Volts and AHours etc

If you can't get your head around volts and Ahours I would suggest this is probably not a DIY project.

But. Here you go anyway.
You either need;
4 x 500AH cells 1p4s
8 x 250AH cells (2 strings of 4 which each string having it's own BMS then connected in parallel)
16 x 125AH cells (4 strings of 4 which each string having it's own BMS then connected in parallel)
etc...

I haven't built one, so you perhaps should ask RogerIvy or Wissel if you have any questions.

But my point would be, building a custom battery so you can fit it to specific dimensions is possible, practical and cost effective.

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[steven2002]

What about off-grid power solutions custom battery build options.

Custom built LiFePO4 Battery — Offgrid Power Solutions

If you’re looking for a custom built LiFePO4 battery that offers you more than you’d get from a standard LiFePO4 battery that you’ll find on the market, this is a fantastic option for you! We have build custom LiFePO4 batteries for many different applications (such as narrow boats, yachts &amp

offgridpower.solutions

 

[Two on Tour]

What about off-grid power solutions custom battery build options.

Custom built LiFePO4 Battery — Offgrid Power Solutions

If you’re looking for a custom built LiFePO4 battery that offers you more than you’d get from a standard LiFePO4 battery that you’ll find on the market, this is a fantastic option for you! We have build custom LiFePO4 batteries for many different applications (such as narrow boats, yachts &amp

offgridpower.solutions

Funsters RogerIvy and nigelivy mentioned in this thread are off-grid power solutions.

 

[RogerIvy]

Eve cells are:
200mm high without the terminals
135mm wide
72mm thick

These are 280ah and 300ah cells. It would include the cells with slightly more capacity (up to about 220ah, more than that and you need to be careful about false claims).

Eve 230ah cells are 54mm thick (height and width are the same as 280 and 300).

I mentioned that the cells are 200mm high without terminals. When you add the laser welded terminals plus busbar, lug and bolt/screw you get to around 230mm. The standard cases that the OPS and FogStar batteries come in are 250mm high so very little spare room in the case. The BMS is at the end of the pack, again very little extra space. I don’t think a mouse could crawl around in one of those cases.

The 230ah batteries have a lot more free space at the end, around 70mm more than the 280 and 300. There simply isn’t another case available that is the right height and width so we have no choice but to use the bigger case.

I mention all this because it’s very difficult to make a custom case that doesn’t use quite a bit more space than the standard 280 and 300. Looking at those pics I’d suggest that two 280 or 300 on their side should fit with plenty of room. Otter Spotter (Dave) didn’t mention height of the locker as far as I can see. If the batteries can be upright that would probably be the best option (need minimum of 270mm, preferably a bit more).

If the choice is for two sets of 230ah cells to make up a 460ah battery then a custom case would probably be feasible to consider. Either as two separate batteries (each one a 4s configuration) or as a single battery (a 2p4s configuration). If you wanted to pack stuff on top you could make a sturdy case with ply.

If you placed two 280 or 300 batteries on their sides (or upright if it was a deep locker) it would be easy enough to build a false floor on top of them, it could hold heavy items.

Lastly, it’s more common to make a custom case where there is a small and/or unusual shape. Like an L shape, or a long thin battery to go over a wheel arch. Recently we built a custom 200ah battery using 8x105ah cells to go into a very small space under a seat. We’ve built 280ah 48v batteries to fit into specific spaces on a canal boat.

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[Otter Spotter]

If you can't get your head around volts and Ahours I would suggest this is probably not a DIY project.

But. Here you go anyway.
You either need;
4 x 500AH cells 1p4s
8 x 250AH cells (2 strings of 4 which each string having it's own BMS then connected in parallel)
16 x 125AH cells (4 strings of 4 which each string having it's own BMS then connected in parallel)
etc...

I haven't built one, so you perhaps should ask RogerIvy or Wissel if you have any questions.

But my point would be, building a custom battery so you can fit it to specific dimensions is possible, practical and cost effective.

I wouldn't DIY it, I would blow myself up

 

[Gromett]

I wouldn't DIY it, I would blow myself

Did you miss a word out there

 

[Otter Spotter]

Eve cells are:
200mm high without the terminals
135mm wide
72mm thick

These are 280ah and 300ah cells. It would include the cells with slightly more capacity (up to about 220ah, more than that and you need to be careful about false claims).

Eve 230ah cells are 54mm thick (height and width are the same as 280 and 300).

I mentioned that the cells are 200mm high without terminals. When you add the laser welded terminals plus busbar, lug and bolt/screw you get to around 230mm. The standard cases that the OPS and FogStar batteries come in are 250mm high so very little spare room in the case. The BMS is at the end of the pack, again very little extra space. I don’t think a mouse could crawl around in one of those cases.

The 230ah batteries have a lot more free space at the end, around 70mm more than the 280 and 300. There simply isn’t another case available that is the right height and width so we have no choice but to use the bigger case.

I mention all this because it’s very difficult to make a custom case that doesn’t use quite a bit more space than the standard 280 and 300. Looking at those pics I’d suggest that two 280 or 300 on their side should fit with plenty of room. Otter Spotter (Dave) didn’t mention height of the locker as far as I can see. If the batteries can be upright that would probably be the best option (need minimum of 270mm, preferably a bit more).

If the choice is for two sets of 230ah cells to make up a 460ah battery then a custom case would probably be feasible to consider. Either as two separate batteries (each one a 4s configuration) or as a single battery (a 2p4s configuration). If you wanted to pack stuff on top you could make a sturdy case with ply.

If you placed two 280 or 300 batteries on their sides (or upright if it was a deep locker) it would be easy enough to build a false floor on top of them, it could hold heavy items.

Lastly, it’s more common to make a custom case where there is a small and/or unusual shape. Like an L shape, or a long thin battery to go over a wheel arch. Recently we built a custom 200ah battery using 8x105ah cells to go into a very small space under a seat. We’ve built 280ah 48v batteries to fit into specific spaces on a canal boat.

I was just thinking that batteries laid down flat would possibly make a better use of space under the bench, which is used to store other stuff which currently has around 5ins clearance across the whole of the space so the 5ins would be the space for the batteries.

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