Fukuokian
New member
- Joined
- Oct 15, 2024
- Messages
- 29
I'll use this place to document my build... It's gonna be a long, slow project, but I'm excited and enjoy the research, design & DIY that is going into it.
I have a small second house in the Japanese countryside; eventually I may retire there. The motivation for the project is to be completely off-grid with no bills. (other than property tax and maintenance.) I've already cut off the electrical service, and am running on 2 solar panels, 2500w inverter, victron 100/20 MPPT, 4 agm 12v batteries 2s2p for a 24v system. It's good enough for lights and a small fridge, and even a spot air conditioner during summer days. It's time for an upgrade!
Onto the project...
I've purchased 2 Nissan Leaf Gen2 packs (8 bars - 61-66% capacity) for around $220 usd each after shipping. Would have preferred 9 or 10 bars, but that would have doubled or tripled the price at best, if I could even find them. Also, I was only gonna do 1 pack, so I'm very happy with the new total capacity. It should give me 30kWh.
The packs have been disassembled. *** ...best advice I found was to use a multi-tool on the clamshell seam to cut through the rubber/glue holding it together. Had it open in 5 minutes. Most of you already know, but I'll put out this Warning: The pack is High Voltage (400v-- or 2 x 200v with the service plug removed) Enough voltage to kill you. Use insulated tools and gloves (rated for the voltage), eye protection, etc. I wrapped my socket wrench and extension with thick rubber hose and used several wraps of electrical tape on the sockets. I also took everything apart in steps that reduced the voltage of the connected parts as quickly as possible.
For my 48v system, I decided on 7 stacks connected together in series each stack will have 13 modules connected in parallel. The first pack of 48 modules came discharged to about 7.2v, the second stack's modules are all at 7.8v. My plan is to use about half of each to make a stack. --> Warning... they must be the same (or within 0.1v? for Lithium ion) voltage before connecting in parallel. (Double-check the voltages just before making the parallel connections, they may settle a bit after charging, or you might have mixed in a different module. I'm currently charging the first pack's modules up to 7.8v before I make the parallel connections. After that, I can let them sit for a good week or more to balance themselves.
Where am I at now... I'm still charging the modules 1 by one using a step-down converter (buck converter) and an old 9v 3a power supply. It's painfully slow, but cheap. About $7 for the converter, and the power supply was free. (Yes, my crimping is cringe! ! Need to redo, or at least tape. Connection is good though!)
Still deciding on the terminal connecting busbars. WIll reuse the copper bars that came with the pack... but still need to source more. I got a lot of good advice here... https://secondlifestorage.com/index...arallel-cell-module-copper-connections.12888/ I'm considering flattening copper pipe, but I've tried this before and gave up because the surface was still too rough; I didn't like to possibility of a reduced terminal connectivity. I may do some more testing with a hydraulic jack/or modified crimping tool. It would only need to be very flat/smooth at the terminal connection points.
That's it for now... I'll update as more gets done!
Your advice, personal experience, and pointing out things you feel are, or could be unsafe, is appreciated. I'm learning as I go.
I have a small second house in the Japanese countryside; eventually I may retire there. The motivation for the project is to be completely off-grid with no bills. (other than property tax and maintenance.) I've already cut off the electrical service, and am running on 2 solar panels, 2500w inverter, victron 100/20 MPPT, 4 agm 12v batteries 2s2p for a 24v system. It's good enough for lights and a small fridge, and even a spot air conditioner during summer days. It's time for an upgrade!
Onto the project...
I've purchased 2 Nissan Leaf Gen2 packs (8 bars - 61-66% capacity) for around $220 usd each after shipping. Would have preferred 9 or 10 bars, but that would have doubled or tripled the price at best, if I could even find them. Also, I was only gonna do 1 pack, so I'm very happy with the new total capacity. It should give me 30kWh.
The packs have been disassembled. *** ...best advice I found was to use a multi-tool on the clamshell seam to cut through the rubber/glue holding it together. Had it open in 5 minutes. Most of you already know, but I'll put out this Warning: The pack is High Voltage (400v-- or 2 x 200v with the service plug removed) Enough voltage to kill you. Use insulated tools and gloves (rated for the voltage), eye protection, etc. I wrapped my socket wrench and extension with thick rubber hose and used several wraps of electrical tape on the sockets. I also took everything apart in steps that reduced the voltage of the connected parts as quickly as possible.
For my 48v system, I decided on 7 stacks connected together in series each stack will have 13 modules connected in parallel. The first pack of 48 modules came discharged to about 7.2v, the second stack's modules are all at 7.8v. My plan is to use about half of each to make a stack. --> Warning... they must be the same (or within 0.1v? for Lithium ion) voltage before connecting in parallel. (Double-check the voltages just before making the parallel connections, they may settle a bit after charging, or you might have mixed in a different module. I'm currently charging the first pack's modules up to 7.8v before I make the parallel connections. After that, I can let them sit for a good week or more to balance themselves.
Where am I at now... I'm still charging the modules 1 by one using a step-down converter (buck converter) and an old 9v 3a power supply. It's painfully slow, but cheap. About $7 for the converter, and the power supply was free. (Yes, my crimping is cringe! ! Need to redo, or at least tape. Connection is good though!)
Still deciding on the terminal connecting busbars. WIll reuse the copper bars that came with the pack... but still need to source more. I got a lot of good advice here... https://secondlifestorage.com/index...arallel-cell-module-copper-connections.12888/ I'm considering flattening copper pipe, but I've tried this before and gave up because the surface was still too rough; I didn't like to possibility of a reduced terminal connectivity. I may do some more testing with a hydraulic jack/or modified crimping tool. It would only need to be very flat/smooth at the terminal connection points.
That's it for now... I'll update as more gets done!
Your advice, personal experience, and pointing out things you feel are, or could be unsafe, is appreciated. I'm learning as I go.