Rolls BatteriesUpdated: April 6th, 2017
23-25 March 2017: Problem with Battery 4: See comment 17
21-25 March 2017: Rearranged batteries to use all four: See comment 16
19th January 2017: Previous swap of 3&4 for 1&2
On receipt of the batteries, after checking the containers were intact, I measured the voltage of each and found one at 12.83 the others at 12.88. I then numbered each one and measured the specific gravity of the acid to obtain a better measure of the state of charge.
The hope was that each was fully charged as they are new models and shouldn't have been hanging around the retailers for long and who should have fully charged them before sale. I was clearly already a bit concerned that one was at 12.83.
The expected sg of acid in a fully charged battery would be at least 1.26. On an older battery an sg of over 1.27 may indicate water loss and concentration of acid.
Here are the results of the tests on Thursday 6th Nov:
Battery temp estimated at 11°
sg1 to sg6 are results for specific gravity from negative to positive terminal
Only one cell reached the 1.260 I was hoping for. Battery 4 was not charged as well as the others
Connected Bat4 via Victron MPPT controller. At the end of the day the LED indicated float charging i.e. battery at or over 80%. I used this as load battery.
Once Bat4 reached the float charge today I disconnected it and connected Bat3 which is now the load battery.
When Bat 3 reaches float charge early one afternoon I will disconnect it and reconnect Bat4. Once I have done this to each a few times I will check the specific gravity and if they are compatible will connect them in parallel.
See comments 8 to 14 :- delayed swap and Bat 2 at 8.3v after 8 months
See comments 13 :- delayed swap and Bat 3 at 11.9v after 3.25 months