My DIY battery storage system

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jonescg
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My DIY battery storage system

Post by jonescg » Sep 04, 2017 9:30 am

I have converted several lead-sled scooters to LiFePO4 over the years, including these shitty E-max "Sport" scooters.
Emaxsport Pb to Li 001.jpg
Another lead to lithium conversion. Too bad the scooters themselves sucked balls.
Emaxsport Pb to Li 001.jpg (158.93 KiB) Viewed 787 times
They worked, but they only do 55 km/h, take a calendar month to get there, and they're really badly made. So after years of them not selling, I ended up picking up a couple of them for very little. I recovered the lithium I put into them and will be using them to make a load-shifting system for charging my scooter (which is not shit).
Future powerwall.jpg
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The scooter to be charged of an evening.
Plates on.jpg
My good scooter - 3 kWh onboard, 60 km range
Plates on.jpg (182.83 KiB) Viewed 787 times
I hope to rig the solar panels on the shed to charge the 6 kWh LiFePO4 battery, so I can then dump charge from it to the scooter at night.

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Monstarr
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Re: My DIY battery storage system

Post by Monstarr » Sep 14, 2017 7:26 am

You can use a Meanwell ISI-500 MPPT charger & inverter with those LiFePO4 cells. They somewhat have the same charge voltage as lead.

http://www.ebay.com/itm/Mean-Well-350W- ... XQvV9SMITK

There are more on ebay btw.

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jonescg
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Re: My DIY battery storage system

Post by jonescg » Sep 18, 2017 8:23 pm

Thanks for the tip!
I have a couple of ways of doing this, and they cost about the same. But going down the MPPT charge regulator / inverter route might be the best for an 'off-grid' system.

Got two more scooters to rip apart this weekend :D

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jonescg
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Re: My DIY battery storage system

Post by jonescg » Sep 26, 2017 7:53 am

All of the cells ready and willing!
20170926_202906.jpg
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Next step is to get some busbars cut up. Only needs to be about 1 mm thick, if that.

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jonescg
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Re: My DIY battery storage system

Post by jonescg » Oct 15, 2017 4:42 am

Only a little bit of progress to report - welding up a nuggety little cabinet to house the cells. I want it to be self contained. There's room for another 2 cells in parallel (8 kWh total).
Power cabinet.jpg
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The aim is to have two lower shelves filled with cells and the upper shelf with the inverter and battery charger. If I had an inverter/charger I'd hook the battery right up to it, but I don't. So for the meantime I'll just charge it off the mains while the sun shines (set a timer from 9 am to 3 pm) and use the inverter to run the scooter charger.

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jonescg
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Re: My DIY battery storage system

Post by jonescg » Oct 28, 2017 5:34 am

Well the shelf part is complete. I'm going to put two sheets of 9 mm plywood down and glue them together for added strength.
There's room for about 8 kWh of these cells (I only have 6 kWh) but with any other chemistry you could probably fit closer to 16 kWh.
Power cabinet 2.jpg
Next step is the busbars.

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jonescg
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Re: My DIY battery storage system

Post by jonescg » Oct 29, 2017 9:12 am

Just going to get these laser cut from 3 mm aluminium since that's what the terminal posts are made of.
Sure, I could drill them myself, but sending a file by email and picking up finished busbars is so much easier...
Power Cabinet Busbars.jpg
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jonescg
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Re: My DIY battery storage system

Post by jonescg » Nov 18, 2017 7:01 am

I got the aluminium busbars made to suit 9 cells in parallel, since that's what the cabinet can easily fit. I figured at the time I could just leave them there and populate them as I get more cells...

...but then I got greedy :twisted:

So I'm buying another 45 cells. It's not the ideal situation as I didn't want to spend too much on this battery, but what the hell. 9 kWh is more useful anyway.
Busbars going on sml.jpg
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