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Naio's avatar
Naio
Explorer II
Jun 21, 2018

Maximum amps for testing AGM capacity?

After a winter of being very sick, and a spring of catching up on farm chores, I am finally back to being able to work on the van at least once in a blue moon. Next step, testing the 100aH Fiamm telecom batteries I got used. I've been topping them off periodically, but otherwise haven't done anything with them since hitting them with the meanwell to recover capacity last year.

My question: How many amps are ok at continuous load, if I want to run them each down to 12 volts for testing? Is 30 ok? 60?

I have the van in storage, so I can't hang out for too many hours during testing. And, since I finally got this giant heavy batteries to the van, I don't really want to move them back to my house :-). But I have killed AGM deep cycle batteries before with too many amps, and certainly don't want to do that.

In case it matters, things I have available for load are a couple of 300 watt heaters, 600 or 900 watt ones, lamps with 60 watt bulbs, and assorted minor loads. I don't have anything 12-volt, so I will be running this off an inverter.

34 Replies

  • Capacity is usually spec'd at the 20 hour rate. So, if you want to see how they compare to their rated capacity, you'd draw down a 100 Ah battery with 5 amps. If you draw more, it's going to measure less than 100 Ah, even if it meets spec.
  • Are your loads 12 VDC appliances or 120 VAC?

    If 120 VAC, what inverter do you have to be able to run the 120 VAC appliances?

    Lastly, how many of these 100 amp-hr batteries make up your battery bank (or are they individual 100 amp-hr/not wired together)?

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