It’s a beautiful day in a string of beautiful days, certain not to last, and I thought I’d better duck into the powershed and give my batteries a bit of maintenance while I can be outside and still feel my fingers.
I have two 232 amp/hour Interstates that will turn 4 years old in January, which puts them near the end of their predicted service life though they’re working fine and might last another 2-3 years without deterioration – or might not. Currently they’re only running the Lair’s 12v lighting, so they’ve been lightly used all this year. Before then they saw almost daily 25%-40% discharge cycles.
And I have 4 225 amp/hour Trojans, whose age I don’t know but I believe they’re at least a year older than the Interstates.
I got these in December of last year from some neighbors who just wanted them gone. They were discharged at the time and probably had been for some time, so I assumed they were scrap and originally took them just to be polite. But they accepted reconditioning with my BatteryMinder, and have worked fine since I installed them in March. For the past seven or eight months they’ve powered the Lair’s inverter and I have no complaints. This battery bank being almost twice as big as the Interstate bank, the daily discharge cycle has been much less extreme: Typical morning voltage even near the winter solstice is 12.6v.
In terms of my actual experience with the two battery brands, there’s not a lot to choose between them – I’ve been perfectly happy with both. There are signs, though, that the Trojans might give you more quality for the money.
I check electrolyte levels at least once per month, more usually twice since it’s so convenient. The Interstates definitely outgas more than the Trojans, using more distilled water. It’s easy to find them exposing the tops of their plates with just a very little neglect. The Trojans are more stable. They’re also cleaner…
…where there’s junk floating on top of the electrolyte and what looks like goo on top of the cells under the surface of the liquid. I don’t know what that means, but it has definitely grown progressively more so over the life of the batteries. Is it a sign that the Interstates are more likely to short a cell at some point? Time will tell.
One thing I don’t like about the Trojans, and this is a personal peeve, is that the level indicators inside the filler holes make it impossible to get the probe of my digital hydrometer into the electrolyte. So I have no way of testing the specific gravity of the Trojans’ individual cells, something I very much like to do. I may need to invest in a hydrometer built in this century: No way I’m going back to an auto parts store turkey baster.
In general, then, both brand of battery has served me well in a small solar power installation with reasonable maintenance and moderate use. I can’t point to any definite flaw in either. But the Trojans have proven they can shrug off a period of definite neglect, and I do not have the impression the Interstates would have done as well.
They’re both golf cart batteries, and not made for this specific application. I really have had people tell me I’m doing it all wrong. But golf cart batteries are built to be severely discharged and quickly recharged over and over, and survive long enough to make money for a golf course. They might not be exactly the right purchase for a large household power system but experience has proven that they work extremely well with moderate use, and for much less money than the big Rolls Surrette gold standard.
And now if you’ll excuse me, I have to stop putting it off, glove up and go clean off the tops of my batteries.