Alec's DIY Powerwall

I was going to post a pic of my second pack in the Battery section and instead decided to start my own little thread to document my build.
I am planning a small 7s20p 24v build to start. I like the idea of smaller packs for a number of reasons. I realize there is the potential for greater loss at scale, and may end up rebuilding larger packs later. We shall see. For now I'm focused on getting one string together, panels mounted, and all the rest of the fiddly things going.





This is my first pack. I am using cells from cheap replacement laptop batteries from fleabay. In this pack all cells are 1800mAh.





The second pack is ready to solder! I got a bit better at bending the bus bar. This whole thing is a learning journey for certain! I knew virtually nothing about electricity prior to this adventure. I am a clinical scientist and have always wanted to learn but just never had the right situation. Well Mr HBPowerwall cured that! His adventures spurred me into action. I thought to myself if this Aussie bloke can do it I certainly should be able to figure it out! [emoji12].

So my bottleneck is cell testing. Well money too! This is so far a hobby so my accountant (read wife) has throttled my build slightly. I am using an IMAX b6 AC to charge the cells.





Once they are charged I do a test for capacity on the Opus.





So far with only 1 Opus I am finding cell processing to be the slow point. Again my accountant needs business (Read household) justification for additional capacity!

I think once I actually get this system operational and she sees the advantages this can bring the checkbook will begin to open more. Lol!

I need more cells, holders, bus bar copper, sleeves for some cells needing re sleeved, and a few more odds and ends. The list is growing! I also need solar panels, cable, a charge controller and an inverter. So like I said I am at the very beginning of this build. I will update as progress continues.

Any and all advice is welcome. I don't get butthurt easily, so if you see a glaring error please point it out to me. I don't claim to know a lot about this.





My modest little work area.

Alec

Second pack complete!

Wow, so clean it looks like a machine did it! *thumbsup*

Korishan said:

Wow, so clean it looks like a machine did it! *thumbsup*

Click to expand...

Thanks!

Third pack is together, but still needs soldered. I would love to get the cells tinned tonight but I am knackered. If I start I won't stop and will pay the price tomorrow at work! Lol!

More to come!

Fourth pack is together. Now I need more cells. It'll be a couple weeks.

My soldering iron took a crap so I will be replacing that. It was a cheap one anyway. Now I have the excuse to buy a nicer one!

I need more bus bar copper too and I think I found a much cheaper source than before.

I need more cell holders and solder as well. This post is turning into a shopping list! The only thing I seem to have in abundance is fuse wire and 10g wire.









I'm getting better at bending the bus wire I think.





Well that was a short catch up on where I am. Short on substance also unfortunately! Maybe the pics were interesting at least!

Have a great evening gents.

I think you could make some $$ making packs. They are so clean!

Small update. Finished my 5th pack. I have more cells on the way. It's slow but steady. I can't wait to get 7 packs done. My plan is a small'ish but expanding wall that we will use as a charging station for phones and laptops and so forth. At least to start. I have grand plans long term. 1 step at a time.

I like the zip tie holding the bus.
I looked at doing that but didn't think about running it clear thru both sides.

1958 greyhound said:

I like the zip tie holding the bus.
I looked at doing that but didn't think about running it clear thru both sides.

Click to expand...

Thanks. It takes a bit of messing around but it works well.

Looks all around good to me. I like your approach - starting small and keeping it clean. I wonder if using 3 12g instead of 2 10g would keep the windings tighter on the buses. Looks great!

kazbach said:

Looks all around good to me. I like your approach - starting small and keeping it clean. I wonder if using 3 12g instead of 2 10g would keep the windings tighter on the buses. Looks great!

Click to expand...

I didn't think about doing 3 instead of 2. That might work well also.

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I got two of these scooter packs. Man they were a nightmare to disassemble. I'd much rather laptop batteries.



Turned them into the beginning of 2 more packs! Still need a bit more clean up, and testing.

Alec_J said:

I got two of these scooter packs. Man they were a nightmare to disassemble. I'd much rather laptop batteries.



Turned them into the beginning of 2 more packs! Still need a bit more clean up, and testing.

Click to expand...

Interesting to see that you too have the same date of manufactory in those 22PM cells on the right (5FX4)
All 1560 of my 22P M cells have the same date code. Ive google and posted everywhere to find out if they are genuine Samsung as I still dont really know
Those packs are a small pain to disassemble but trust me you will get good at it with time; I figured out a good system with those and they are a great source of cells as its 20 cells all at once with probably identical usage and thus capacity / internal resistance. In that sense perfect for your 20p packs.

Keep it up!

The-J-Man said:

Alec_J said:

I got two of these scooter packs. Man they were a nightmare to disassemble. I'd much rather laptop batteries.



Turned them into the beginning of 2 more packs! Still need a bit more clean up, and testing.

Click to expand...

Interesting to see that you too have the same date of manufactory in those 22PM cells on the right (5FX4)
All 1560 of my 22P M cells have the same date code. Ive google and posted everywhere to find out if they are genuine Samsung as I still dont really know
Those packs are a small pain to disassemble but trust me you will get good at it with time ; I figured out a good system with those

Keep it up!

Click to expand...

Do you happen to know the date of manufacture?

Alec_J said:

The-J-Man said:

Alec_J said:

I got two of these scooter packs. Man they were a nightmare to disassemble. I'd much rather laptop batteries.
Turned them into the beginning of 2 more packs! Still need a bit more clean up, and testing.

Click to expand...

Interesting to see that you too have the same date of manufactory in those 22PM cells on the right (5FX4)
All 1560 of my 22P M cells have the same date code. Ive google and posted everywhere to find out if they are genuine Samsung as I still dont really know
Those packs are a small pain to disassemble but trust me you will get good at it with time ; I figured out a good system with those

Keep it up!

Click to expand...

Do you happen to know the date of manufacture?

Click to expand...

something like november 2015, Hang on

edit: check using this tool:
https://batterybro.com/pages/18650-date-code-lookup-tool
October 4th 2015.

but like I said no clue if they are genuine.
At one stage I got 5 cells that had the exact same infos printed on them but different font, and different codes on the cell can itself which made me doubt the authenticity of all others
all these packs are from the cheap knockoff hoverboards afterall

The-J-Man said:

Alec_J said:

The-J-Man said:

Alec_J said:

I got two of these scooter packs. Man they were a nightmare to disassemble. I'd much rather laptop batteries.
Turned them into the beginning of 2 more packs! Still need a bit more clean up, and testing.

Click to expand...

Interesting to see that you too have the same date of manufactory in those 22PM cells on the right (5FX4)
All 1560 of my 22P M cells have the same date code. Ive google and posted everywhere to find out if they are genuine Samsung as I still dont really know
Those packs are a small pain to disassemble but trust me you will get good at it with time ; I figured out a good system with those

Keep it up!

Click to expand...

Do you happen to know the date of manufacture?

Click to expand...

something like november 2015, Hang on

edit: check using this tool:
https://batterybro.com/pages/18650-date-code-lookup-tool
October 4th 2015.

but like I said no clue if they are genuine.
At one stage I got 5 cells that had the exact same infos printed on them but different font, and different codes on the cell can itself which made me doubt the authenticity of all others
all these packs are from the cheap knockoff hoverboards afterall

Click to expand...

I'm getting approximately 1900 mAh per cell in testing. Yeah don't know if they are knockoffs or original. I have a bunch of other new Chinese Lithium Ion at about the same capacity so they will work well with my packs.

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Balancing my little packs.

Alec_J said:

I'm getting approximately 1900 mAh per cell in testing. Yeah don't know if they are knockoffs or original. I have a bunch of other new Chinese Lithium Ion at about the same capacity so they will work well with my packs.

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Balancing my little packs.

Click to expand...

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Nice, That sounds about right for those cells at 1A discharge although as its results fromthe OPUS, sothey are even less in real as the results are a bit inflated.
My lowest were 2100 and up to 2400 on the OPUS for these 22P M cells.

It's a 6 pack now! Just 8 more to go [emoji52] I love doing this, but I really want to be done with the initial pack making. I want to move on to solar panels and charge controllers and inverters. Oh well it's the journey right?

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So my original intention was to build a 7s20p 24volt system. The more I read and learn the more convinced I am a 48volt system is really what I want. So I decided to be patient and just do it right from the start. It would be a waste of money to build a 24 volt system and then later upgrade.
Pete said in one of his videos that he wished he had started with a 48 volt.
At any rate it will just take longer. I have a hard time sourcing used cells and money is limited.

Good Job, yes 48V is the right way,more efficient, thinner battery cables, etc.
It would be better 96V, but 96V inverters are not common.

I agree that if you plan or think of expanding the 48V is better in most places. 12 and 24V should be for smaller systems and perhaps RV related and small cabins.