another source for agm batteries

pianotuna wrote:
Any truth to AGM's REQUIRING high charge rates to survive?

pianotuna;

I totally screwed up my previous reply because I missed that you were asking about Amps and not Volts. I revise my reply:

Lifeline 5.4, wrote:
For repetitive deep cycling, chargers should have an output current of at least 0.2C (20 Amps for a 100 Ah battery). If the output current is less than this value, the cycle life of the battery may be negatively affected.

I believe what they are saying here is that in a cyclic use as opposed to a standby use that there may not be enough Amp replacement between cycles. A cycle is use then charge activity. That is exactly the case when we are RVing.

just previous to the above quote

Lifeline 5.4 wrote:
The charging current during the Bulk stage should be set as high as practical; higher current levels mean faster recharge time.

Note that there is no encouragement to change from their regular 14.3V temp-comp. If you are not getting to full charge then increase Amps.

Further down:

Lifeline 5.4 wrote:
full charge state should be verified using the
criteria(I quote: time to full charge formula) given above (current drops below 0.5% of rated capacity).

There seems to be a belief that AGMs must be fully charge with each cycle. I don't see that in the Lifeline manual. I do believe in sulphation. I believe I monitor sulphation progress by observing morning Volts with my Turnigy. I observe two Voltages, morning and overnight low. If they are trending down, I am sulphating. When they hit my low threshold, out comes the genny and I run it until the solar takes over. I look for the solar controller to show float sometime that day. The longest consecutive days doing this is 31 when I retreated to shore power.

Now there is Lifeline's paragraph 5.5 Conditioning which describes a use of high volts to recover a battery that is exhibiting a loss of capacity AFTER a regular charge cycle. There is nothing routine or scheduled here. (Contrast to that to the regular process of bubbling wets.) In fact, Lifeline goes on to explain that this is not to be confused with wet-equalization.

I have not felt the need to recover my AGMs as described by Lifeline. There is nothing wrong with the procedure.

I do feel the Deka is below its 79AH spec because it drops to 13.8V after resting over 24hrs. One Optima drops to 13.84 and the other drops to 13.02.

I can assure you I have used these batteries as lab rats in my driveway. I am very comfortable with their performance.

YMMV and IMHO. :)

HTH;
John