I suspect part of the problem is that some of Don's numbers don't make much sense..
Originally Posted by Don Lucas
a couple of weeks ago I recorded the resting voltage for a few days and it varied around 12.58 to 12.4 with SOC between 99 and 92%
If that was a true "resting voltage" reading then your monitor
is either off or giving you what it "thinks" is the Peukert corrected SOC, in which case the voltage should be much higher than 12V under load..
12.4V is about 72% SOC 12.58V on a Trojan is 86% SOC not 99% - 92% full. A Trojan wet battery, after resting, (this means fully disconnected from everything for 12-24 hours) should read 12.73V.
It appears the monitor is out of calibration which could be due to an incorrect Peukert #, CEF etc. etc. or the solar
panel tricking it into thinking the bank is full. Solar panels
very often trick the monitors into re-setting to full as they are below the "full" current
threshold for the specified period of time needed for a re-set to 100%.
When re-setting, based on 2% acceptance, it is important to determine this with absolutely no loads on and no other charging
sources.. All DC loads should be shut off and the solar
panel also turned off before determining the accepted current
to the bank. The solar panel has the potential to trick the regulator
into cutting back if the absorption voltage is set slightly higher than the alts voltage regulator
. This can cause you to "think" your batts are only taking 2%.
Had this exact situation a short while ago and the VR was actually cutting field output to 0% because the bank voltage was higher than the solar controllers setting. The solar panel was supplying the "current" not the alt. Owner thought bank was full because it was only taking a few amps. Shut off solar charge controller and the alternator
kicked back on and was supplying current again... Simply adjusted the VR to .2V higher than the solar controller and all was well..
As Bill mentioned a 450Ah bank of Trojans's should not be anywhere near 12V based on your description. I suspect your bank is not as charged as you think and have some monitor calibration issues causing the confusion. You may also have another load on there not being counted by the shunt. Can you post a picture of the house bank wiring
between house bank neg and the shunt?
I am sure we can get this sorted out...
P.S. Just for grins I just ran the Peukert Exponent calcs for a bank of 450Ah T105's.
At a 6A draw, if you drew the bank to 10.5, volts you'd get 626 Ah's out of the bank..
At a 22.5A load your bank would deliver 450 Ah's before falling to 10.5V or what is considered the cut off for a 20 hour capacity test...