Johan
Off-grid energy systems enthusiast.
This post shows how I opened the case of the EG4-WP 48V 100Ah (5.12kWh) battery without damaging any cells or other electrical components. This voids your warranty. First try to contact Signature Solar to see if a less invasive solution exists. In my experience they do their best to help you.
Read this post if you want to:
Procedure:
![PXL_20220506_182823829.jpg PXL_20220506_182823829.jpg](https://diysolarforum.com/data/attachments/94/94060-4508439ee20cbe616fe178d4832d865c.jpg)
Clearances (as measured):
If you only want to reset the BMS:
Instead of sawing the entire lid off, You could also make a small hole in the lid of the case. I recommend not using a drill (unless in a very controlled manner) because the clearance between BMS and lid is small. Instead, use a soldering stick or a router if you have one. Where to make the hole... this may very well vary 0.25in (6mm) per battery!:
@Will Prowse @electric @Trkarl @RichardfromEG4
Notes
*This happens, for example, after connecting to an inverter without pre-charging. In my case, the BMS retried connecting roughly five times (each followed by a 4-min protect-mode-time-out) with a Cotek SD-3500-148. I tried reviving the BMS by charging is 24h using a an EG4 charger: unsuccessful. SS sent me a replacement.
** the Overkill BMS may have the same cell tap connectors, but the JK BMS may be a good alternative too.![PXL_20220506_183226902.MP.jpg PXL_20220506_183226902.MP.jpg](https://diysolarforum.com/data/attachments/94/94061-782281c58de23583152edbbdfbb644c4.jpg)
This is what it looks like inside.
![PXL_20220506_183307261.jpg PXL_20220506_183307261.jpg](https://diysolarforum.com/data/attachments/94/94062-c1cd42d54f14916c3da42423ce7a460c.jpg)
What BMS is this? How to access?
![PXL_20220506_190706119.jpg PXL_20220506_190706119.jpg](https://diysolarforum.com/data/attachments/94/94063-154618961e578d40392c6f69c5ec63b9.jpg)
Distance from reset switch to handle outer edge (the ruler's zero is right above the switch center!).
![PXL_20220506_190947806.jpg PXL_20220506_190947806.jpg](https://diysolarforum.com/data/attachments/94/94064-868a27204d496aa65693deb9290b39dc.jpg)
Distance from reset switch to case long outer edge.
Read this post if you want to:
- reset the BMS from being stuck in "protect" mode back to "stand-by" mode*, or
- replace the BMS by a different BMS**, or
- see what's inside
Procedure:
- First remove both plastic handle ropes (can be done fully non-destructively);
- cut the case all around using an oscillating saw (the famous Will-Prowse tear down method),
- Carefully saw right above (!) the seam (in my case this worked without touching cells - in your case it may not - it's your risk!
- The case wall thickness is 5/8in (8mm) all around (see photo).
- Apply multiple saw passes, gradually increasing the kerf depth.
- carefully pry the lid off with chisel (re-solidified debris may "weld" the lid a bit to the case's body locally).
![PXL_20220506_182823829.jpg PXL_20220506_182823829.jpg](https://diysolarforum.com/data/attachments/94/94060-4508439ee20cbe616fe178d4832d865c.jpg)
Clearances (as measured):
- from cutting plane to cells: 1/4in (6mm); ? OMG
- between case long inner wall and cells: zero
- between BMS circuit board green top surface and lid bottom surface: 3/4in (20mm)
If you only want to reset the BMS:
Instead of sawing the entire lid off, You could also make a small hole in the lid of the case. I recommend not using a drill (unless in a very controlled manner) because the clearance between BMS and lid is small. Instead, use a soldering stick or a router if you have one. Where to make the hole... this may very well vary 0.25in (6mm) per battery!:
- 7 5/8in from the handle outer edge (see photo),
- 4 3/4in from the case long outer edge on the negative terminal side (see photo)
@Will Prowse @electric @Trkarl @RichardfromEG4
Notes
*This happens, for example, after connecting to an inverter without pre-charging. In my case, the BMS retried connecting roughly five times (each followed by a 4-min protect-mode-time-out) with a Cotek SD-3500-148. I tried reviving the BMS by charging is 24h using a an EG4 charger: unsuccessful. SS sent me a replacement.
** the Overkill BMS may have the same cell tap connectors, but the JK BMS may be a good alternative too.
![PXL_20220506_183226902.MP.jpg PXL_20220506_183226902.MP.jpg](https://diysolarforum.com/data/attachments/94/94061-782281c58de23583152edbbdfbb644c4.jpg)
This is what it looks like inside.
![PXL_20220506_183307261.jpg PXL_20220506_183307261.jpg](https://diysolarforum.com/data/attachments/94/94062-c1cd42d54f14916c3da42423ce7a460c.jpg)
What BMS is this? How to access?
![PXL_20220506_190706119.jpg PXL_20220506_190706119.jpg](https://diysolarforum.com/data/attachments/94/94063-154618961e578d40392c6f69c5ec63b9.jpg)
Distance from reset switch to handle outer edge (the ruler's zero is right above the switch center!).
![PXL_20220506_190947806.jpg PXL_20220506_190947806.jpg](https://diysolarforum.com/data/attachments/94/94064-868a27204d496aa65693deb9290b39dc.jpg)
Distance from reset switch to case long outer edge.
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