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Incomplete Charging Cycle

PostPosted: Sun Mar 02, 2014 5:58 pm
by Grady
I installed an Ample Power alternator high capacity alternator and NS2 regulator recently last year. After struggling with the existing batteries, I very recently changed them out for new batteries. The problem still exists and is getting worse. The amp hours are never completely replaced and the run time on the batteries is becoming lower and lower with each charge cycle. Here are the facts that I have.

When I first installed the new batteries one week ago, the voltages and electrolyte levels were perfect. When I started the engine for the first time I briefly saw a voltage of 14.1. Since then, the absorption phase seems to be too short to see any voltage above 13.6, which slowly rises to 13.85 during the charge cycle. The output of the alternator then completely shuts down at that point, recovering only about 90% of used battery capacity on each discharge / charge cycle. This is cumulatively reducing the available Ahrs available to me. Out of a 3 group 27 battery capacity of 270 Ahr, I am now down to 210 Ahrs and dropping with each cycle. About two hrs after charging is complete, the battery voltage has dropped from 12.8 to 12.65 under normal loads.

I read in Ample Power literature that this situation is sometimes attributed to new batteries that have not been “broken in”. I have never heard this from anyone else in the battery or marine business. But let us assume it is a factor and needs to be done. I am cruising and at anchor; I have no shore power available to utilize with my Zantrex / Freedom / Heart Interface controller. How can I control the alternator’s charge current to the low level required after a full 10.5 volt discharge? Can my new NS2 regulator do it? Or must I cruise to some destination with shore power available?

Are there any other issues that can cause the system behavior described above other than the bad battery story? What are the factory presets on the voltage and time setpoints? I am unsure the installer changed anything on the NS@ regulator.

Re: Incomplete Charging Cycle

PostPosted: Sun Mar 02, 2014 9:18 pm
by Coulomb
First, please read this article on the forum:

I suspect you have one of those Amp-hour meters which can't be trusted.

Are your batteries actually getting full? It takes 2 hours under normal load to drop from 12.8 to 12.65. The later voltage is typical of a liquid electrolyte battery after it has been fully charged and rested a bit.

Increased capacity after 5-30 cycles of "break-in" use is reported in several battery books for professionals. You can find references listed in the back of "Living on 12 Volts with Ample Power.

The factory set absorption voltage for 14.4 Volts and float at 13.5, which are typical for liquid electrolyte units, and gel batteries. AGM units require slightly more.

Al regulators should be adjusted after installation to match the battery types.

You can play with the absoprtion setting to limit current, but you'll have to make frequent adjustments.

The best piece of information regarding battery management is knowing when a battery is full based on voltage and current -- in fact there is not other accurate way.

Re: Incomplete Charging Cycle

PostPosted: Mon Mar 03, 2014 12:56 pm
by Grady
A follow-up question then: if I never see a charging voltage in the range of 14.4, or really never much above 13.85, am I OK? Or should I see 14.4 for what period of time during on board charging? The voltage readings on the Link 10 monitor are accurate vs my digital meter. After charging, should I ignore the -42 Ahrs reading?

Re: Incomplete Charging Cycle

PostPosted: Mon Mar 03, 2014 3:08 pm
by Coulomb
The absorption voltage and the absorption time are both adjustable. Typically the voltage is set for 14.4 and the time set for 45-60 minutes. See the manual for adjustment information.

The Link 10 may be fairly accurate during the first discharge after a full charge, provided you reset it to zero at the end of charge. It gets increasingly in error during recharge, and subsequent discharges. Reset it at the end of each full charge, or ignore it.