[paw_by_paw]

Hi Guys,
Hope I am posting in the right place now.
Here is my dillema:
I have a PBE charging system installed with Battery Monitor and extra battery pack and box supplied by PBE.
I have also installed a Nat L battery monitor on batt box to monitor batt box seperately as the PBE system shows al three batteries and batt in box as alternative battery though.
I had to remove the system due to vehicle replacement and this weekend had to go without the PBE system.
I charged alternative battery which was in back of my van before leaving home. Our destination was outside of Warmbaths.
About three hours traveling to warmbaths further with a 60 Litre Campmaster Fridge set at position one about 4 dgrees I saw the Nat L monitor shows only about 50% power left in battery.
So I decided to let it run flat to see what will happen.
On Friday evening the monitor shows battery is at very low level 27%.
So I decided to charge with generator which charges at 8 amps and kept generator running for three hours. After 1 hour the Nat L monitor showed battery full at 100%.
Long sstory short on arrival back home today I immediately took my tester and tested battery and it was at 11.75 Volts.
The Nat L monitor was dead at this point. When I took battery pack out of vehicle suddenly monitor comes on again showing only two red lights. I am now seriously baffled . When we left this morning the Nat L monitor was at htree red lights and one yellow. The fridge was still working when I arrived home and the PBE dischrge controller installed in box had not tripped out the fridge as yet as it would if battery power is too low.
My question now? Can the battery be faulty? How will I know it is faulty?
Can the Nat L monitor be faulty?
Why would the monitor come on again when battery was shaken a bit?
How would a bateery be tested to have fault in the battery it self? Meaning loose plates or something?
Just a short note: There is always a 30 to 40 % difference in batt strenngth between the PBE Monitor and Nat L monitor.
PBE says their monitor is accurate as it gets calibraded at factory?
Any suggestions?
Thanks

[Bigwill]

I suggest you also measure the battery voltage with a multimeter and compare that to your other instruments.
However I'm afraid your battery is shot by now. One should never use it with no yellow lights on. The red lights are coloured red for a reason. Never let the battery below 12.0 volt I am told. You will be very lucky to recover this one.

[paw_by_paw]

Bigwill.
Yes that is what is so confusing.The NL Monitor showed no voltage at all but when tested with mulimeter it showed 11.75 volts Only after a bit of a shake the NL monitor came on again.

[Bigwill]

Well 11.75 volts is a very very flat battery. I am not surprised that the NL monitor did not pick up any charge initially. The shaking and consequent mixing of the electrolyte could have resulted in the 11.75 volts being generated. I wouldn't worry too much about the discrepancy of the meters. The percentage shown by the meters is based on the voltage of the battery with a zero draw. Once a battery goes faulty it could show 100% based on volts but could have very little stamina. Also to fully charge a good condition battery you will need a longer time and if you depend on the car's alternator to charge while running the fridge and possibly headlights you will need to travel a much longer distance. Any battery shop will test your battery's stamina (ie. continuous delivery) free of charge. If it holds the charge under draw the battery is fine, if it drops under draw buy a new one.