Batteries–Bigger is Better

Sometimes bigger really is better.

It is raining, today. What to do? I’m in the middle of a huge upgrade of my solar power system, but most of the work will be outside and I don’t care to get wet. Wet, as in a hot tub is ok. Being cold and wet does not appeal to me.

I guess I can water batteries. It is time for some of them. In my various independent and blended systems I have a lot of cells that are AGM and don’t require water. I also have 168 cells that do need to be watered. This is nuts, but it is just the sort of thing that can happen if you start small and gradually grow the system. Things can get out of hand.

I recently acquired a couple of forklift batteries in the Mobile Solar Generator trailer I bought and I am impressed. Mine had been serviced, but another set belonging to a friend had not…for over 4 years. They still had water above the plates. Granted, we had to add 12 gallons to top up, but if they can go 4 years without being damaged, getting overlooked for a month will never be a problem. In fact, these are designed to be checked every 3 months in heavy service.

I started off with so-called golf car batteries. Exide calls them electric vehicle batteries, which I like as a better term. Many people refer to GC batteries as “starter” batteries. Not in the sense that they are used for starting a vehicle. More like in the sense of training wheels on your kid’s bike. I resent that term, but I suppose it is true.

Many people use GC batteries, like the Sun230 that Sun Electronics sells. That’s all they need or that’s all they can afford. The difference between a Sun230 and a Trojan T105 or an Eveready or Exide GC2 is basically the price. The Sun230 is cheaper and has a few more amp hours. Also, you buy them from Sun Electronics, you pay no tax and need no core. Florida exempts solar stuff, but try telling Sam’s Club or WalMart that. Starter batteries? Fine. You gotta start somewhere.

If you have a big budget, then by all means think big. It can save you in the long run. That’s the big holdup on solar, though, isn’t it? You can get electricity from the PoCo for $250 per month, whereas the sun’s free electricity might cost you $15,000 or $50,000 more up front, unless you do-it-yourself. I heard from a guy the other day with a $350 power bill and a quote for a $130,000 power system. I understand why folks start small. I started small, actually intending the system as a test bed for stuff I was doing with my solar boats. It just got out of hand, after a while.

So what’s the difference with the bigger batteries? For years, the L16 was the battery you aspired to have. Some scrounged them from floor scrubbers and some bought retail. Comparing to a GC2, the L16 is a lot more expensive in $/amp hour. They may be cheaper in the long run, though, because they have thicker plates and hold more acid. Thicker plates generally equate to longer life and more liquid means you are less likely to get low and ruin the thing.

My first visit to Sun’s old Miami warehouse was a hoot. Oh, the new store is nicer, but I don’t think it has the character of the old place, especially when the grafitti artists had been at work. In the showroom there were these huge Rolls batteries. Actually, they were hollow demo dummies, but huge all the same. Just 2 volts, but lots of lead, acid and amp hours if you got the real thing. A hand truck is required to move them, the real ones, not like the featherweight 64 pounds of a GC2. Put 24 of them together to make 48 volts and you had serious storage and longer life. Also, you only had 24 cells to water, as opposed to scads of them for the same power in a stack of GC2s.

The big 2 volt scheme is pretty good, I think. They are still hand truck portable, yet retain the advantages of scale. My new batteries are 510 ah at 48v (8 hr. rate) and weigh a ton each. It’s like a set of the semi-portable Rolls cells soldered together in a steel box. Actually, though they are new to me, they are 5 years old, which in big battery life is just broken in good. They are not very portable, though. My big tractor might lift them, but it is out of order. The smaller tractor will not. Getting them off the trailer was easy enough with a chain fall and an oak limb. I used old tech and sledded them to the Solar Shed. There is not much room to maneuver behind the shed, so the wimpy tractor is little help. Jacks and cleverness prevailed, though.

At my friend’s house, he has stripped 2 of the solar trailers. He has a better infrastructure setup. He offloaded with an I-beam and trolley setup, then used pipe rollers to move the batteries through the garage. He is starting with 2160 amp hours of battery in his new system. That is super for a house his size. At a ton each, the batteries are still moderately portable, given his circumstances. I hope the garage doesn’t settle on one side and tip over.

In Texas, where everything is bigger, one of our correspondents shared photos of his 800+ ah Bulldog battery (if I remember right). Now that was one big battery and he has a forklift and a trolley to move it.

I’m starting to ramble, I suppose, but the point is, the more battery you have the better your system will perform and the longer the batteries will last. If you use large batteries, instead of lots of little batteries, they are likely to last longer and require a lot less maintenance.

As for my upgrade, with over 2000 amp hours of storage I am easily rolling through multiple cloudy days without hitting the dreaded 50% depth of discharge. 10 more solar modules are waiting to squeeze a few more watts out of the clouds, too, but the huge reserve seems to have solved a lot of issues. I have also added an automatic diesel generator, just in case, but so far it has only had monthly exercise run time.

–Neal