# Trojan battery charge/discharge cycles



## TX_Dj (Jul 25, 2008)

As a general rule, most Lead Acid batteries perform about the same on their cycle lifespan, give or take.

The key thing is the less you discharge them, and the softer you discharge them, and the sooner you get them back to full charge, the more "cycles" they will survive.










This is pretty much what the cycle life charts look like, this one may be a little optimistic, but doesn't say what battery it pertains to. The deeper you discharge your batteries, the less cycles they will survive.


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## CCinBR (Aug 4, 2008)

Thanks, TX_Dj,

But I'm wondering about some of what I've read that makes these three batteries have possibly very different lives. Don't 6Vs, because they have only 3 cells instead of 6 as inthe 12v, have thicker plates resulting in longer lives (but how much longer?). Then, AGM's seem like a rather different kind of lead acid battery in a number of ways. Their big appeal to me is the low/no maintenance. I've done a spreadsheet for myself that compares all the batteries on $/WH. BUT if I can get a good enough estimate of the number of life cycles AND if there is a big enough difference (a much higher number for the AGM's, for instance), then my real winner will not be the lowest price per battery or lowest $/WH but lowest $/cycle. If they all have the same number of charges, I have my answer but I'm still hoping for more data....

I didn't include it in my first post but I anticipate 50% DoD.

Thanks,

Carlo


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## madderscience (Jun 28, 2008)

I had heard that Trojan T-105's at least are good for about 700-800 cycles to 80% DOD. I would expect the T-145s and T-1275s to be pretty similar and the above chart more or less backs that up.

I have had several of the "Old timers" in my local EV crowd tell me that the T-1275s and T-875 have identical plate designs and aren't quite as durable as the T-105s are but they did not quantify that with numbers but between these guys they've built literally dozens of EVs so hopefully they know what they talk about.

I also don't know for sure how they rate the number of cycles. I assume it is number of cycles to a certain percentage of original capacity but I don't know what that is.

AGMs tend to have less cycle life than flooded (maybe only a couple hundred cycles to 80% DOD) but it depends a lot on the quality of the battery. I hear a lot more complaining about weak/bad AGMs in my local EV group than I do people complaining about weak floodies.


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## CCinBR (Aug 4, 2008)

Thanks, Madderscience.

I was able to reach Trojan today. They confirmed what you and TX_Dj have said - that the life cycle profiles for T-145 and T-1275 are basically identical. Also that their AGM have approximately 2/3 life cycles of flooded. So...... after much enjoyable research, I know that I will have a 12 x 12V system (hooray!). Most of my design decisions flow from this one.

I've gotten rid of all fluids (in the car) and removed the muffler and tail pipe so I really feel like I've started.

I'll keep folks posted.


Carlo


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## adric22 (Jan 17, 2008)

CCinBR said:


> identical. Also that their AGM have approximately 2/3 life cycles of flooded. So...... after much enjoyable research, I know that I will have a 12 x 12V system (hooray!). Most of my design decisions flow from this one.


I remember spending about 2 months trying to decide what kind of batteries to use in my EV as well. I was investigating all kinds of different batteries and originally I was leaning towards AGM. But in the end I realized the cost of the AGM combined with the lower life expectancy really turned me off. I'd have been willing to pay the extra cost for the fact that they are sealed, but when factoring in battery replacements every 200 cycles, it just didn't make sense. In the end I used Trojan T875's.


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