Amp hours to fully recharge?

Hi Jim,

100 amp hours @ 13.2 volts takes 168 hours from 50% to 100%.

But you can't do better for efficiency by charging at low voltage and low amps for a longer time.

We all breath air and we all die. So if you want to live, stop breathing.

And in three hours there are quite a few situations at high charge rate you will return a touch more than the Ah used to the battery (say at 14.4-15v recharge voltage). But that's not 100% charged. Any time you see bubbles or feel warmth, you know a fair amount of your amp hours are not going to charging. Not a problem since it is often worth it for a fast charge or other reasons, but it needs to be factored into looking at Ah back in needing significantly more than Ah out.

Been reading all I can find on charge efficiency. It certainly does not seem to be common knowledge.

Jim

It's easy to see why I recommend 14.8 volts @ 20C when using a generator.

Muse this:

Last 15% charge rate 100 amp hour battery @ 8-10 amps at 14.8 volts

BUT TIMES THREE BATTERIES

8 X 3 = 24 amperes.

The generator is running...

What say you...?

Here is PROGRESSIVE Dynamics BROCHURE on how long it takes to charge a deep cycle battery.

"Progressive Dynamics ran this test on the amount of time it took a PD9155 (55-amp) converter/charger set to three different output voltages to recharge a 125 AH (Amp Hour) battery after it was fully discharged to 10.5-volts.

14.4-VOLTS (Boost Mode) – Returned the battery to 90% of full charge in approximately 3-hours. The battery reached full charge in approximately 11 hours.

13.6-VOLTS (Normal Mode) – Required 40-hours to return the battery to 90% of full charge and 78-hours to reach full charge.

13.2-VOLTS (Storage Mode) – Required 60-hours to return the battery to 90% of full charge and 100-hours to reach full charge."

What most of us do is to use the 14.4 smart mode charging method and re-charge the battery back to its 90% charge state in the three hour re-charge time frame. Then we can use the battery again right away and discharge down to its 50% charge state and expect it to perform as specified. Then we will need to re-charge again without delay to get it back up to its 90% charge state so we can do this all over again. I usually go about 10 days of these 50% to 90% charge cycles before I must re-charge to a full 100% charge state which takes around 12-hours to accomplish. This is usually the end of my camping trip so I can use the full 12-hours of charging at home sitting in the back yard where I park my camper when back from our trips..

Been doing this method of battery charging when camping off the power grid for many years now and are pretty successful keeping the battery bank in good working order.

Roy Ken

I think your are understanding correctly. As BFL13 said, you can't really recharge in 3 hours, you slow down at the end of charge. I know I can't recharge to 100% on trips; but when I am on shore power, my PD9260 brings me to 100% SOC in a day.

Doug

I wouldn't have the foggiest, but my PD wizard, and my solar controller knows !

CHARGE

EFFICIENCY

FACTOR

Google it.

100AH can't get restored in 3 hours anyway, where it takes so long to do that last few percent of SOC. But usually, they say to allow approx. 10% for heat loss on recharging.

I have seen that 115% figure in discussions about "overcharging" to ensure you get back to True Full. ISTR is was in that Lifeline AGM material mena refers to sometimes.