Quote:
Originally Posted by MarkInSpace
Hi mswhin63 -
These are AGM batteries - the one i bought is 8 Ah - turns out that is too little - it powered the scope for about 3 hours or so, then started beeping (beeps at 60%). When i bought it, the store guy said i could return it for a different model - which i will do.
They have a 12ooA and a 1700 A version. I’ll look at them and make up my mind.
I’ll post the results.
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As mentioned, you need to get Ah rating. The total current is not a measure of capacity on how much current is can push. 1200A may be able to blow a hole in a 3/16th spanner, 1700A may melt it in half. But if the Ah rating is on 8Ah then it won't be enough.
As you have already tested the 8Ah battery it is easy to determine how much you need. Simply multiply by the time you actually need to use it for and add extra 10% on top as a comfort zone.
For 12 hours - Ah required = (12 x 8)/3 = 32Ah plus 10% = 34.3Ah.
Anything above 34.5 Ah should give you approx 12 hours with leftover. AGM can go to 60% reasonably well although still better to go to 80%.