SPIM08HP batteries for Solar Generator

[alfaeric]

So I found what seems to be some amazing prices for these LiPo battery packs- where the cost is less than $0.20/W-hr. Actually way less.

After finding them, it sounds like they are capable of 200A continuous, but being fearful of fire, I would want to limit that to 40A, so for the system I have that has 4400W peak output, I would need 11 packs of 14.8V. Which would be 44 battery packs.

Anyway. has anyone used these cells for a power wall or a generator?

And for a power limiting BMS that I would need a lot of- what would a good BMS be?

Doing this would let me expand my system to do a little more than I had originally planned, which is actually a good thing. Or maybe make a super light battery for a race car- which a poster did a few months ago with these....

Thoughts?

 

[FilterGuy]

Link?

 

[JoeHam]

I don’t think those are LiPo (LiFePO4)

 

[alfaeric]

I don’t think those are LiPo (LiFePO4)

LiPo and LiPO4 are not the same thing- Lithium Polymer vs. Lithium, Iron, Phosphate.

These are LiPo batteries, which still have the risk of overheating and catching on fire. Which is why I'm wondering if they would make a good power wall or not. When you do a search, it does not seem that anyone is making large scale storage devices out of these- even though they seem to have come out of buses.

 

[alfaeric]

Link?

B-grade - 70 pack - 3.7V 8AH 200A LITHIUM ION POWER - SPIM08HP

70 pack of Silver 3.7V 8AH 200A LITHIUM IONModel - SPIM08HP Most of these are considered B-grade due to the fact that many have thermal paste stuck to them. Some may have minor amounts of flexibility, bends and/or wrinkles. There is absolutely no severe damage such as ballooning, rips...

www.batteryclearinghouse.com

While they seems really, really cheap, the system I am building is a few thousand miles from be being able to watch it closely- so I'll keep looking for alternatives. But in terms of original storage for the cost, this is a pretty hot deal, and they have free shipping for now (I checked yesterday).

 

[SolarRat]

I used them for scooter/bike battery packs. Nice batteries for small projects but hooking them together is a headache. I thought of using them for a large battery bank, but after working with them I decided against it.

 

[Supervstech]

Can it be done? Sure... but lipo seems too riskk

I don’t think those are LiPo (LiFePO4)

terms are confusing aren’t they?

LiPo is for Lithium polymer... where LiFePO4 stands for Lithium (Li) Iron (Fe) Phosphate compound molecule (P-phosphorus ,O4-Oxygen compound)

many use a short acronym LFP to easily associate the name.
LiPo batteries use various chemical plates and electrolytes for the chemistry, and are usually flammable but light for the capacity.

 

[alfaeric]

Can it be done? Sure... but lipo seems too riskk

terms are confusing aren’t they?

LiPo is for Lithium polymer... where LiFePO4 stands for Lithium (Li) Iron (Fe) Phosphate compound molecule (P-phosphorus ,O4-Oxygen compound)

many use a short acronym LFP to easily associate the name.
LiPo batteries use various chemical plates and electrolytes for the chemistry, and are usually flammable but light for the capacity.

About the risk- seems like most of the risk is when you start to push them near their limits. So if I throttled both the charging and the discharging, would they be much safer?

When I run the calculations, even if I went to just the needed rated storage of 1200W-hr, that's about 50 batteries. And the peak output of my inverter (for short periods) is 4400W, for easy math, call that 400A from the entire battery pack. And lets be conservative to down that to 40 batteries, or 10 cells- 400A over 10 battery cells is 40A peak needed. Way under the rated 200A.

In the reverse, it would be quite easy to just charge the entire system with 40A, too- and make sure that the charging cut offs were well under the dangerous voltage.

Seems like those safety margins would make them safe.

But I'm very much not sure, and safety is a pretty key part of the generator I built.

 

[SolarRat]

Can it be done? Sure... but lipo seems too risky

I couple cells came dead and internally shorted, otherwise they looked "normal". I ran some high drain tests on one pack and got one of the cells to do the same. No fire, or explosion, but the terminal ends heated up enough to melt through a few layers of heat resistant kapton tape and a few layers of electrical tape (used for cushion between terminals). Fusing these individually would be highly recommended.

 

[SolarRat]

About the risk- seems like most of the risk is when you start to push them near their limits. So if I throttled both the charging and the discharging, would they be much safer?

When I run the calculations, even if I went to just the needed rated storage of 1200W-hr, that's about 50 batteries. And the peak output of my inverter (for short periods) is 4400W, for easy math, call that 400A from the entire battery pack. And lets be conservative to down that to 40 batteries, or 10 cells- 400A over 10 battery cells is 40A peak needed. Way under the rated 200A.

In the reverse, it would be quite easy to just charge the entire system with 40A, too- and make sure that the charging cut offs were well under the dangerous voltage.

Seems like those safety margins would make them safe.

But I'm very much not sure, and safety is a pretty key part of the generator I built.

40 cells could make a 10p4s pack that would be 80ah at 16.8v (fully charged). These seem to be happy running at about 1.5C (so far), but when I pushed it to 3C I had a meltdown. 1.5C on the 80ah pack would be 120 amps. I wouldn't push these old cells past that. I get a lot of cell deviation at 1.5C, so for a long term big battery bank I would want to keep the load below 1C (really 0.5C). That goes for any battery really, but more so on old used cells that can no longer safely run near their rated load.

They are cheap enough to just swap out any bad cells, but you'll have to come up with a way to build these banks so they are serviceable. When I was planning on making these into a big pack, my plan was to use 1/4 inch aluminum bars and 1/4 plastic insulator bars and use a long through bolt to clamp everything together. It got past the point of practicality.

For a larger battery I'd look into their 18650 modem packs instead, make a spot welder and build with these:

NICKEL FUSE 5P WIDE CONTINUOUS ROLL BY THE FOOT! 18650 CELL LEVEL FUSING

ONLY $3 PER FOOT! Each foot equals 75 cell connections, 5 wide by 15 long. Just 4 cents per cell connection! FINALLY!!! The wait is over! A custom cell level fused nickel design that can be spot welded with ease, works perfect, and is super cheap. Battery safety just reached a new affordable and...

batteryhookup.com

 

[alfaeric]

Have to run those through my energy storage calculator. For the LiPo packs, I was getting a pretty amazing deal, but still feared the fire danger. And there are some simple ways to connect them together- with a copper rivet.

But there are a ton of the 18650 kits out there- which would make assembly a little more straight forward. I'll look into those.

Too bad the LiFePO4 cells are quite a bit less in storage capability....

 

[SolarRat]

And there are some simple ways to connect them together- with a copper rivet.

I saw Jeru's video about that...I think that would be fine for very small loads only. He was using cheap brass grommets...

 

[alfaeric]

I saw Jeru's video about that...I think that would be fine for very small loads only. He was using cheap brass grommets...

Don't forget that the entire strip is conductive, so once you firmly get them attached to each other, you are done. The current does not pass through the grommets, it would just use the sheet contact.

If there was a cheap clamp, or even a press fit plastic band covering that, it would work, too.

 

[SolarRat]

Don't forget that the entire strip is conductive, so once you firmly get them attached to each other, you are done. The current does not pass through the grommets, it would just use the sheet contact.

If there was a cheap clamp, or even a press fit plastic band covering that, it would work, too.

After seeing the Jeru video with the grommets, I was thinking of doing that to just mechanically hold them together, then soldering. By themselves I don't think there is enough mechanical force over a large enough area for anything more than maybe 0.5C. The tabs are flexible, so the clamping force will not be spread out.

One tab is what I believe to be aluminum, and the other I think tinned copper. A special aluminum solder/flux would probably have to be used.

I gave up on the idea because it won't work on a larger scale. I was planning on paralleling at least 10 together. The max you can parallel with this method would be maybe three cells. You'd need a 1/4" bar stock "spacer" between each cell to parallel more than 3. For my 1p3s and 6s packs, no more than two tabs needed to be connected with one fastener, so I could have done it...but I wouldn't have "learned" anything about how to scale it up. 1/4" aluminum spacer bars with two holes drilled through, and then long thru-bolts would be the way to go for each parallel pack.

They are cheap enough, give it a shot. If it doesn't work for your project you will find many other uses for them. They are perfect in 3s for my small 12v LED light projects. But the pack comes out much bigger than a similar rated pack made out of the 18650s.

 

[alfaeric]

After seeing the Jeru video with the grommets, I was thinking of doing that to just mechanically hold them together, then soldering. By themselves I don't think there is enough mechanical force over a large enough area for anything more than maybe 0.5C. The tabs are flexible, so the clamping force will not be spread out.

One tab is what I believe to be aluminum, and the other I think tinned copper. A special aluminum solder/flux would probably have to be used.

I gave up on the idea because it won't work on a larger scale. I was planning on paralleling at least 10 together. The max you can parallel with this method would be maybe three cells. You'd need a 1/4" bar stock "spacer" between each cell to parallel more than 3. For my 1p3s and 6s packs, no more than two tabs needed to be connected with one fastener, so I could have done it...but I wouldn't have "learned" anything about how to scale it up. 1/4" aluminum spacer bars with two holes drilled through, and then long thru-bolts would be the way to go for each parallel pack.

They are cheap enough, give it a shot. If it doesn't work for your project you will find many other uses for them. They are perfect in 3s for my small 12v LED light projects. But the pack comes out much bigger than a similar rated pack made out of the 18650s.

For sure cheap enough, especially when you factor in all of the other systems things needed for the 18650s to assemble enough.

I actually found some double sided electrically conductive tape, so add that to some rivets to keep them compressed will be an interesting experiment. I'm pretty sure that soldering to aluminum would be a major challenge, if at all possible.

The other idea I was thinking about is to pair cells together, which would also match the nominal current limiting of decent BMS modules. So it would be 8 cells in a 4S arrangement. Which would cut the number of BMSs required in half. And some copper bar would work fine for that.

BUT, before I do that, I need to do proper research on the 18650 option. Probably this evening.

 

[Josh Gibson]

So I found what seems to be some amazing prices for these LiPo battery packs- where the cost is less than $0.20/W-hr. Actually way less.

After finding them, it sounds like they are capable of 200A continuous, but being fearful of fire, I would want to limit that to 40A, so for the system I have that has 4400W peak output, I would need 11 packs of 14.8V. Which would be 44 battery packs.

Anyway. has anyone used these cells for a power wall or a generator?

And for a power limiting BMS that I would need a lot of- what would a good BMS be?

Doing this would let me expand my system to do a little more than I had originally planned, which is actually a good thing. Or maybe make a super light battery for a race car- which a poster did a few months ago with these....

Thoughts?

Hi, Josh here. For the past 3 years I have been building a power wall with the SPIM08HP cells. In fact I am about to order 180 more cells! I currently have 5.7Kwh worth of storage and I am very happy with them. www.batteryhookup.com has outstanding bus bars for the SPIM08HP cells along with cell holders, all thread bolts.