Sooner or later, you gotta do it, whether it is the clock, the smoke detector in the hall, the car or your solar power system. Oh? You have grid tie and don’t have to change the battery? We’ll talk about that, too.
The batteries that I had on the main bank were in great shape, but there weren’t enough of them, especially now that the brutal air conditioning season has begun. One of the auxiliary banks in my EVs was getting punky. I think I got that desulphated and it is feeling much perkier.
No, the main thing is that I wanted to test a specialty battery before adopting them in the Solar Yacht project. I’m a big fan of GC2/T105 type golf car batteries, like Sun’s inexpensive Sun230 model, but dealing with acid and hydrogen generation in a closed area of the boat was presenting technical issues with which I did not care to deal. The easy way out is to eliminate acid and hydrogen generation.
That left a choice between lithium and some sort of sealed lead acid (SLA or VRLA). The cost of lithiums, if considered over the long term, is a great deal, but it is a bunch up front. This boat only has to last a year, and lithium might outlast me. My government funding budget, which is to say my Social Security check, demands a lower up front cost. John sells sealed batteries at a fraction of what they go for at the Marine store (the one out West) but doesn’t have the size I needed for the boat.
I found some used ones from a guy in Georgia. I don’t normally go for used batteries, but since I was testing durability and on a budget, what the heck? I figured I would get 8 for the main bank, four for the grid tie and one spare. The spare would give me an age-matched replacement should one of the others fail and, in the mean time, provide a robust power source for my 12v Solar Boxcar system. (It is actually a 40′ cargo container, but my wife thinks it looks like a boxcar, so it is The Boxcar.)
I thought to do a reality check. It seems that you can’t actually put 13 of these in the bed of an Avalanche. If you could, you’d break the axle. I settled on 9, which fit nicely and was only a wee bit over gross weight.
It was a nice outing for my brother and me. With Andy navigating, the 514 mile trip became 667miles, but we saw some interesting countryside. Two blocks from our destination there was a minor fender bender. Minor for us, that is. I got a silver smudge on my trailer hitch ball, which tore the fascia off the front of the RAM that rammed us. After acquiring our load, we headed to Talbot County, where I showed bro an old cemetery in the bounds of the old family plantation. He’d not seen it, before. I sprayed 200 year old tombstones with tombstone cleaner and he learned a little genealogy.
On the way to another family plot in Harris County, we passed a new solar farm under construction. It looked like progress may have been halted by virus worries. There were some neat, shiny rows and there were some torn up acres still piled with stumps, but no activity. After cleaning up some more great-great grandparents’ rocks we limped back to Florida, as a tire had gone bad somewhere along the way.
Then the fun began. Saturday, between old coming out and new going in, I moved over a ton of batteries. Literally. Another 500 lbs would wander over to the grid tie project on Sunday afternoon.
I was in luck. I had most of the cables I needed, already. Nice fat 00 cables with marine shrink tube on the terminals. I had to make one cable to join banks, but had the wire and connectors. When you buy supplies like this, always buy a few extra. If I hadn’t had these, then I would have been delayed for a week or two, waiting for them to come in the mail.
Overall, I only had to switch the house to the grid for a few hours and everything came back online without a hitch. It really pays to check everything twice, from voltage to polarity.
OK, listen up! This is where we get to the educational stuff.
The main bank is two strings of sealed VRLA batteries and the two auxiliary EV banks, when they aren’t elsewhere, are flooded lead acid (FLA). THEY HAVE DIFFERENT CHARGING CHARACTERISTICS. Time to reset the charge controllers.
Let’s go back in time a bit and I will tell you why I have been hesitant about sealed batteries. Tom, my nearest solar neighbor to the west (12 miles by air, 20 by road) bought 3 strings of the nice Outback VRLA batteries. He connected them to a 10kw array and fried them within two years. There was way too much charging current. There IS a specification for that. After some experimentation, I was able to bring most of them back. One gave its life to science. OK? So, you see that I am not wanting to kill my new batteries.
Reading the fine print (always RTFM*) I learned that you should not exceed 40 amps charge rate per string on these new batteries, should float them at 54.4 volts per string and you can bulk charge for a while at a higher voltage. Now the fun begins because I have 4 charge controllers, three different models and I haven’t been into the menus of two of them in quite a while. I set the twins at 54.4 and 54.3. I offset them a little so they don’t just drop out at the same time. Another controller had a menu selection for VRLA battery, but it has only one button and you have to combine short and long pressings to get where you want to go with it. Mo’ buttons = mo’ better, I have decided. Then there is the FM60. It is wonderfully adjustable, but there is a password and there is a trick to getting into hidden menus. Hint: shut it all down, press and hold the correct TWO buttons and turn on the breaker to the battery. There’s a whole new world of menus in that thing! Save yourself some grief…RTFM.
Next morning, I kept a close watch on charge rates and float voltages. All was well. Nailed it!
What about the EVs? They will be perfectly happy with the VRLA settings, but they won’t get into the equalization stage. They will have to be taken offline every now and then for equalization, which is basically a quick overcharge. DO NOT equalize sealed batteries! They burp out the gases, which cannot recombine to replenish the electrolyte. They dry up and die a horrible death. You mourn their death when you have to buy more. Don’t kill your batteries.
Now, as for the Sun230 batteries that I moved to the grid tie system, I think I will save that story for later. If interested, do your homework and look back through the blog for the GTIL or grid tie limiter stories. But yeah, we’re gonna put batteries on Grid Tie.
*Read The Freakin’ Manual