I know it is a lot to absorb and to comprehend. Much of it I know will go directly against what you thought you knew about Ah counters, and I' apologize for that.


How did I arrive at all this? It's what I do and part of my job to understand this stuff. I have also been using Ah counters on my own vessels since the original eMeter (Link 10) was introduced back in 94/95. I actually test an awful lot of batteries for 20 hour capacity. All my tested batteries are run through the paces in a controlled temp "water bath" set for 77F (unless testing certain GEL batteries) and tested with laboratory grade calibrated test equipment. The battery being tested in this image is at the very tail end of a 20 hour capacity test. It is a Lifeline GPL-31T rated at 105Ah's. As can easily be seen it delivered slightly over 105Ah's and the 5.25A load is just about to cut off at 10.499V..


With this information an Ah counter can be more accurately programmed. Without accurate programming you can use your Ah counter but just don't expect more than a general ball-park accuracy. Is this bad? Heck no, but I think you'll agree we can always do better.


Don't fret it though, there are many way to look at this:


#1 You now have a better understanding of Ah counters and will be more careful trusting yours empirically as you may have in the past.


#2 You are perfectly happy with your banks performance already so if you can tweak it just a bit, and get better life, you'll be in 7th heaven.


#3 You're a a geek at heart and you want this damn thing to be as accurate as you paid for.... Good luck.. (wink)


#4 There must be an easier way?


There is now an easier battery monitoring product for monitoring SOC called the Smart Gauge. The Smart Gauge gives you less information but a far more accurate representation of SOC. In the whole realm of battery health, and your system running efficiently, SOC is the only parameter that really matters. You can add a Smart Gauge and use it side by side with any Ah counter but if you do that I would suggest that you ignore the Ah counter for anything more than amps and volts, unless you want to go all tech geek and actually program it accurately....


This article does not change anything about Ah counters, they have been like this since they were invented. I am hopeful it did give you a better understanding of how they actually work and how and why they become out of sync with your bank or develop counting errors over time. It is my hope that you can use this information to make your Ah counter more accurate for your battery bank. Oh and BTW I use a a Link-Pro Ah counter on my own boat.



Good luck!



P.S. In order to keep this site FREE I do sell a few products that I think represent a good value. The Victron BMV battery monitor below is one of them. Before you purchase a battery monitor remember where you learned about installing and programming them, in an in-depth manner.