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Jehu García DIY Powerwall

DavidAnderman

New Member
Joined
May 1, 2020
Messages
36
I am terrible at soldering, so this new system offers a path to a DIY powerwall without soldering or welding. It’s a modular system based on 7S PCBs.

B4784161-54C2-4FD0-9691-4902FBA1FD35.jpeg

The building blocks are available in kit form on Jehu’s web site, but also available assembled on EBay. So, I ordered some components off EBay, and waited. Just to be sure, i ordered from different vendors on EBay.

i got my components and put them together using cells I have harvested from laptops. The result was a 7S board providing 29 volts, along with a 60 amp BMS, all connected.

i hooked the battery to my charge controller and everything worked. But, the next day, no power came from the XT60 connector on the BMS. There was 29V on the rail connectors, and the Positive connector on the XT60 had 29v, but the negative connector was not function all.

no problem, I had ordered more components from a second vendor so I put them together. Same problem with the BMS.

i tried a 3rd system with a 20 amp BMS. Same results, no power from the XT60.

note that none of these parts came from Jehu Garcia’s shop, they came from Chinese firms off EBay.

so, I ordered a BMS from Jehu’s shop. Unfortunately it’s a kit, so I may not be able to solder it together.

Anyone else using this system?
 
I am terrible at soldering, so this new system offers a path to a DIY powerwall without soldering or welding. It’s a modular system based on 7S PCBs.

View attachment 15900

The building blocks are available in kit form on Jehu’s web site, but also available assembled on EBay. So, I ordered some components off EBay, and waited. Just to be sure, i ordered from different vendors on EBay.

i got my components and put them together using cells I have harvested from laptops. The result was a 7S board providing 29 volts, along with a 60 amp BMS, all connected.

i hooked the battery to my charge controller and everything worked. But, the next day, no power came from the XT60 connector on the BMS. There was 29V on the rail connectors, and the Positive connector on the XT60 had 29v, but the negative connector was not function all.

no problem, I had ordered more components from a second vendor so I put them together. Same problem with the BMS.

i tried a 3rd system with a 20 amp BMS. Same results, no power from the XT60.

note that none of these parts came from Jehu Garcia’s shop, they came from Chinese firms off EBay.

so, I ordered a BMS from Jehu’s shop. Unfortunately it’s a kit, so I may not be able to solder it together.

Anyone else using this system?


I have the same system that I put together by soldering. It is not fun. Very time consuming to solder everything. With that being said, if you go to his online store, he now has the boards already pre-soldered. They are like a little bit more but if I was to do it again then that would be the option to go with. Spending at least half a day soldering..... The extra price is worth it.
 
I have the same system that I put together by soldering. It is not fun. Very time consuming to solder everything. With that being said, if you go to his online store, he now has the boards already pre-soldered. They are like a little bit more but if I was to do it again then that would be the option to go with. Spending at least half a day soldering..... The extra price is worth it.

He is selling populated PCBs, but mine are all okay. What I need is a functional BMS board, since none of mine work.

i realized that any high amperage 7S BMS would be plug compatible, so maybe I can scrounge one up.
 
while I love the design, it just seems very expensive when scalled very large. Its at best 60-70WHr per board. You'd need over 120 of these things to store 1KW.
 
168 for single sided board pre populated for 10 boards and BMS.

For some reason I thought it was more expensive. May have to give these some thought
 
So, $168 gets you 570Wh. I certainly hope that means populated with new cells.
With prismatic cells, a single 3.2V 280Ah cell is about $80 delivered. That is 896Wh and zero work to put it together.

You can get 4 cells and a BMS for under $500 and have 3.3kWh ready to go. (without soldering)
 
So, $168 gets you 570Wh. I certainly hope that means populated with new cells.
With prismatic cells, a single 3.2V 280Ah cell is about $80 delivered. That is 896Wh and zero work to put it together.

You can get 4 cells and a BMS for under $500 and have 3.3kWh ready to go. (without soldering)
At 3.2 volts.
 
The result was a 7S board providing 29 volts...
Charging to 29 volts / 7 cells = 4.2V per cell? Was that taken during the charge cycle or at rest?
Seems excessively high if at rest. What does the charge/discharge curve look like for your cells?
 
Wrap those suckers up with some Kapton tape.
That is a good idea. Seems like a strange thing to have to do to a battery holder.

There is one single battery holder and three dual battery holders. It is the dual ones that don't work
 
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