setting absorption duration

For issues involving the NS2 regulator.

setting absorption duration

Postby tomsw on Wed Mar 23, 2011 12:10 am

I'd Like to learn what the best approach to set absorption duration might be, please. I was thinking of measuring the charge current close to the battery with my clamp meter*, with a target of maybe 5% (?) of my calculated 20 Hr rate. My typical day trip would find my two (flooded) 8D house bank down maybe 25-40% after a night on the hook with refrigeration, inverter, etc. The alternator is 120A hot rated. Usually engine rpm would be about 2000 for maybe an hour then <1000 for 8-10 hours while trolling. The wild card would be when we'd run at 2000 +/- for 3-4 hours before throttling down. I can see the absorption duration would like to be different for each case.................. Advice?

* This would be on battery side of the positive dist. post.
tomsw
 
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Re: setting absorption duration

Postby Coulomb on Tue Mar 29, 2011 2:26 pm

As you have discovered, there is no magic time that the absorption cycle should last for all circumstances. And the rules are different if you connect to shore power and change with how often you connect to shore power.

The time that it takes to decline to 5% or battery capacity under the most usual of circumstances is appropriate.
Coulomb
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Re: setting absorption duration

Postby tomsw on Sat Apr 02, 2011 8:53 pm

Coulomb; thank you for your response. I'd like to pose a follow up question if I may. First off let me say that shore power hook up would not be part of the puzzle. If, hypothetically, I found that 3 hours of my normal running/charging regimen was adequate time operating in "bulk' and 'absorption' modes to achieve the desired 5% current flow (i.e. 1 hour at cruise rpm and 2 hours at trolling rpm) and therefore I set the NS2 duration for 3 hours..........what would be the effect on my batteries if I were occasionally to run for 3 hours at cruise speed?

Thanks much,
Tom
tomsw
 
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Re: setting absorption duration

Postby Coulomb on Sun Apr 03, 2011 12:04 am

I think that 3 hours of absorption is too long under normal circumstances. A full--full charge isn't required every time. I'd suggest 2 hours normally, and maybe every couple of weeks, lock the regulator into absorption to get the full--full charge.
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