Re: understand 12v electrical
I have the same battery monitor and it does the same thing on my installation.
I am "playing with" the settings (look in the little green manual that came with the system) to make sure I have them set right. I'll let you know if I have a breakthrough and please let me know if you have one.
I have 2-6V EGC2s in series as a house bank and a thirty watt solar panel hooked through a cheap shunt controller and it's more than enough to keep the system fully charged - it's always charged when I get to the boat - but after a half hour or so of running a couple of Caframo fans and charging my iphone through a small inverter the voltage is down to 12.7 from the 12.9V it was at my arrival on the boat and the capacity bar graph indicates 85 percent. The load on the bank is about 1.5 to 2.5A discharge depending on the solar panel output so I've only used about 1 A-H max out of the 100 that I have told the system that comprises 100 percent (50 percent discharged) of available by the time it indicates 85%.
I'm thinking that the Clipper BM-1 is perhaps too cheap/simple a system to give accurate indications.
I am going to load up the system at maximum discharge rate (everything on except A/P and transmitting on the VHF radio) and plotting a test discharge - voltage and current vs time (and taking sp. gr. periodically) as well as BM-1 voltage and discharge rate and capacity vs time and compare them.
Going to take a while since - using LEDs - I have got my total hotel load (excluding A/P and VHF-transmit) down to less than 10A with EVERYTHING on including nav and anchor and spreader and all cabin lights/Furuno GPS/sounder/fans/computer inverter so it's going to take 10-12 hours to do the discharge. Stereo/radio/weather instruments/backup electronics are all portable and dry cell powered.
I'll post the results later in the week.
"It's not what you know that's important...it's what you do with what you know." -H.G. Rickover