Opening the package I was a little less impressed. Two steel plates with a circuit board between them. There was no mounting hardware. The only documentation was an index card with a wiring diagram that looked super simple. There were some instructions on how to download a cellphone app and connect to it. There was a QR Code, when you point your camera at it, takes you to web page of the same wiring diagram I was holding in my hand. No links to any manual or additional documentation.
Ok, this must be simple I thought. —I hate being misled in this fashion.
Once in a while when you think something is simple it turns out to be the case. Not this time. First off, I needed to mount the circuit board somewhere within fairly close range of the batteries. Not just the circuit board either, I needed some extra room for wires coming and going on the two sides. I didn’t really have that kind of space on my back control panel of the van. But, I did have some stuff on the panel that was no longer in use, and I had some wires inefficiently routed. I took a day off work and drove to a Lowes parking lot and went to work.
It was a big job just clearing the space. I think it was two in the afternoon before I started putting everything back together. I know I looked at the sun sinking lower and put some speed on. It was a lot of work moving all the stuff and of course I never would have gotten around to it had it not been for this incentive. I realized it had been needing to be done for a long time. It is really much, much better now.
Installing the BMS I hooked it up like the diagram showed. I MacGyvered a mounting system using some lumber splicing staples and flexible tubing. I ran all the wires and got things laid out better than they were before. The BMS hooks up to the ground side of the cells via three fairly big wires. Then it also has a little skinny wire going to each individual cell and a skinny wire on each end of the group. I got all those things wired together. More MacGyvering. Finally just before dark I finished. Happy with myself for meeting deadline, I flipped the switch.
Nothing. I traced all my connections. I did the connect, disconnect, reboot lots of times. Nothing. I connected to it with my phone. There I saw a bunch of error messages all about low individual cell voltage levels and so it was offline and would not turn on. Nothing I did made any difference. I gotta admit, that was a pretty low night. I was so tired. I drove to a Walmart parking lot where I went in and bought some candles. I sat in the van, in candle light, trying to figure out what I was going to do. It was a bummer of a night.
I had no options, I had to take the next day off too and I knew by the end of the day I had to have something working. I was in Baton Rouge and my time to be in Louisiana was nearly up. In coming days I had to be able to login to work somehow. I needed to travel north soon, back to Minnesota, where fall lasting into January had suddenly turned to winter that very day. There were rumblings this winter blast could stretch into the south where I was and with no power I had no furnace. It was a “had to be successful” day.
Let me tell you how desperate I was for success. I turned to Reddit, the wild, wild west of computer forums. Where posting a question *can* get you an answer, or you can get ten thousand brutally angry replies because you messed up a verb tense. I found a Sub-Reddit for OverKill Solar, the brand of BMS I had purchased, and posted my questions, including a screen shot and begged for help. Then I went to coffee.
I had a few replies when I got back. I had a few suggestions. Only a couple negative ones pointing out my stupidity and predicting doom, so a pretty good haul. From those suggestions I went to work. Everyone at that point felt it had to be a loose or bad connection. I like to think I do better work than that but before I could go back and ask more questions I had to confirm it. I traced every wire. I disconnected everything and I reconnected. Same problem. I took it all apart again. I changed out some wires. Hooked it all back up. Same problem. I took it all apart a third time. Cleaned every single connection with an emery board, reversed the cell order to see if the voltage values in the phone app changed(they didn’t) and I hooked it all back up. Still it didn’t work.
Again it was after dark. I was sitting in the van under candle light, thinking the next day I would need to remove the BMS and cobble it back together to hook it up the way I had it before. After all, it had been working fine until I added this new hardware. It was in the process of thinking all that through. About what wires would have to go where, I came up with a hack.
The black ground wire coming from the van and solar charge controller come to the BMS and then out the other side of the BMS going then to the negative pole of the battery. But, because the BMS thought the cell voltages were wrong, it would not allow any current to pass through. My hack was to attach two spring clips and a short chunk of wire to the BMS. From one side of the BMS to the other, essentially bypassing it. Bada-bing! I had lights. Lucky thing too. By the next afternoon my furnace was running often.
It wasn’t the *right* thing to do but it got me working. That’s where I stand to this day. I have no new ideas. It is possible the BMS is defective. I don’t feel confident in saying so until I have tried all the instructions people gave me. The timing works out well for one of the suggestions. In addition to the hints people gave me, one person sent me a link to the full manual for the BMS. Why wasn’t that on the index card included in the box? I have no idea.
In the manual it is suggests if there is any discrepancy of the initial voltage between cells (and there is some on the order of 0.05volts) it might cause problems for the BMS. A Reddit suggestion by one person said the cells be balanced by hooking the four cells up in series. Then, over time, the voltage will equalize between all the cells. I am going to be out of the van and living in the real world for the next month and a half. Before leaving I pulled them out and put them in the corner of my son’s basement to allow them time to do so. Hopefully this is the cure!
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