Trojan Vs. Interstate: Long-term Battery Review

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.

That in turn got me to thinking about the relative quality of the two sorts of battery I’m currently running.

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

There’s no sign that things are coming apart inside the cells. Can’t say the same for the Interstates…


…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.

About Joel

You shouldn't ask these questions of a paranoid recluse, you know.
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5 Responses to Trojan Vs. Interstate: Long-term Battery Review

  1. Michael says:

    It has been my experience, that silicon jelly smeared on battery posts eliminates corrosion.

  2. NuclearDruid says:

    I’m assuming that you have a PDF of NSTM 223. Are you using grocery store distilled water? Do you have a portable water resistivity meter to check it? Just curious.

  3. B says:

    to be fair, you were also using the Interstates to a greater percentage of their capacity. Likely that is why they were outgassing so much.

    not really a true comparison.

    Having said that, the Trojans have a fairly good reputation for a reason.

  4. Norman says:

    Has anyone ever published data on like-to-like comparative long-term testing of deep cycle solar system batteries? Seems like a battery costing X% more might be worth it if it lasted 2X longer. Where’s Consumer Reports when we really need them?

    (Assuming, of course, that having won accolades, the $@#& battery company doesn’t change all the specs 2 years later and cut quality to make a buck.)

  5. Joel says:

    (Assuming, of course, that having won accolades, the $@#& battery company doesn’t change all the specs 2 years later and cut quality to make a buck.)

    Yeah, there’s that. How many products, popular because they’re good quality for the money, get sold to a different company and then downgraded and ridden to death to wring out all the bucks they can in a short time?

To the stake with the heretic!