Six months ago, we started a test of AGM batteries from LifeLine to see if, by implementing recommendations from that manufacturer, we could solve the problem of short life that we, and many other live aboard voyagers, have experienced with AGM, and in fact all, lead acid batteries.
It’s still early days. But on the other hand, our last set died in a year, so if we have improved things it should be showing by now.
Results of AGM Battery Test
Drum roll…can I have the envelope please… A discharge test indicates that the batteries, after some hundred 50% discharges, are performing at near-new levels.
A true discharge test as documented in the LifeLine Batteries manual requires pretty sophisticated test equipment that we don’t have. However we were able to get a satisfactory measurement for our purposes simply by leaving our computers and lights on for a total draw of between 10 and 20 amps (depending on what we were doing) on each battery until the voltage dropped to 10.5 volts and then reading the number of amp-hours used off our Link 2000 digital meter.
Both batteries (tested separately) were able to supply 230 amp-hours, give or take 5 amp-hours, before turning their little lead toes to the sky. Their rated capacity is 255 amp-hours over 20 hours—a current (amperage) draw of 12.75 amps—or 206 amp-hours at a draw of 15 amps, so our result was pretty respectable and in line with what we got from the same test when they were new.
It is also encouraging that the performance of these two house bank batteries is near identical, indicating that our technique of keeping the combiner switch on “both” (parallel) except when equalizing, is working out well.
So what do we attribute the dramatically better performance of this set when measured against our last three house battery banks? Well, you can read the whole series of posts on the changes we made. But in the next post in the series we will summarize all that mind numbing detail, as well as revealing a couple of other things we changed but have not posted on yet.