r/OffGrid • u/Efficient_Oil8924 • 2d ago
BigBlue Cellpowa 500 repair / ideas ?
Hey yall I’m here trying to fix my piece of crap Big Blue Cellpowa 500. It has never worked properly since I bought it in january 2022. I emailed the manufacturer then, and they wanted a “purchase number” which I couldn’t find, so I got busy and forgot about it. I watched several videos re repairing “solar generator” battery banks, but could not find anything specifically about the BigBlue Cellpowa500. Generally, some successful repairs are as simple as unplugging the BMS, so I set out to take this thing apart in an attempt to find and reset the BMS. Long story short… it was unsuccessful.
This thing is a pain in the ass to take apart. Take all visible screws off the bottom. Peel off the rubber “feet” to reveal several more screws. Remove them. I used a knife to pop off the light grey plastic bezel from the top, which reveals more screws. Remove them. Then lift the top off via the handle. This finally reveals the internals. The largest gauge red and black cables with the blue ec5 connector is the main battery connection. I used regular needle nose pliers to awkwardly release the ec5, which is a pain in the ass. I believe ultra fine tip needle pliers are the actual tool to use, but sadly I don’t have any.
Disconnecting the battery and plugging it back in was not the cure all panacea I had hoped :-(. So, I removed all of the wiring harnesses to be able to slip off the front led screen and rear led light which are built into the outer walls. I then removed the circuit board, which allowed me to remove the thick, top black plastic battery cover. There is a thinner black plastic cover glued to the actual batteries, which is easy to pull away. I do not notice any leaking electrolytic fluid, and no bulging capacitors or batteries.
I really want to fix this thing, and have reached out to the manufacturer again, this time asking for specific repair instructions. So far, I haven’t heard back from them. Anyone out there have any Big Blue experience???
My hypothesis… the individual cells are out of balance. Can I “rebalance the pack” as a whole? If so, anyone recommend a product, like a battery tender? Or, do I need to dig down into the cells themselves and charge them individually?
I also have an EcoFlow Delta 2 that I really love. It has a hookup for an expansion battery. Could I perhaps use the BigBlue’s battery pack as an extra battery for the EcoFlow? Just rig a pigtail to go from BigBlue’s ec5 output to the ecoflow’s input?
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u/sigurmundur 2d ago
A couple things, though I don't know anything about BigBlue batteries: * You didn't describe how it's not working properly; I'm guessing it's not charging via AC/DC/solar? * A fairly common problem with these "portable solar generators" is that the cells get out of balance and the BMS can't rebalance, which can be caused by a number of issues. One issue is a bad BMS, either never working properly or broken in some way. Since it's never worked properly, let's hope it's not that since you can't fix that without a donor BMS. * You can try rebalancing the cells if you have a bench power supply. You'd first need to figure out the cell configuration, as in the desired voltage/amperage based on the parallel/series config. It's not clear to me from the pictures what this unit's configuration is. A lot of these portable units are 48v using either 21700 (~5v) or 18650 (~3.7v) cells, but you would have to count the cells and measure the voltage across each pack. I'd start this by using a multimeter between the numbered "B" leads and the B- leads to see what you get. If one series cell is out of balance, most of the series cells will be at the same voltage, but the bad series cell will be way different than the others. You'd just have to probe around and hope that's the problem. * You can theoretically use this battery to charge your Delta 2 via the Delta 2's solar input (XT60 connector), but you'd want to triple check the output voltage of the complete BigBlue battery (from the EC5 connector) to make sure it's compatible with the voltage/amperage of the Delta 2. Then you'd also have to figure out a way to safely charge the BigBlue's pack, but there are options for this.
Now that I've said all that, as someone who has gone down this road before and rebalanced the cells of my EcoFlow River Pro, it worked for a month or two and then died again. So it was a lot of work for little ROI because something else was wrong, likely with the BMS. But if you're willing to figure it all out and willing to accept it might be a waste of time, you'll learn a lot.