Legend for Diary
**ML** :: Morning Low ~ The reading before sunrise.
If there is no overnight use this is an indication of battery charge and is the parameter for setting the length of time the next Absorption charge will run
**DL** :: Daily Low ~ The minimum voltage the battery reaches during a 24 hour period of use from sunrise. Unless the batteries are unused and assuming there is some sun to maintain charge then this figure will be lower than ML
**Ft** :: Float level reached ~ though this is adjustable
**Ab** :: Absorption level reached ~ again adjustable ~ see Rolls Guide
**Bk** :: Uncontrolled charging until Absorption reached
Fallback from Ft > Ab and/or Ab > Bk hasn't yet been determined ?? TO DO!!!!
V is Volts:: A is Amps :: W or KW |is watts or kilowatts: (**W = V × A**)
Y is total daily yield from panels including use and storage etc. in Wh or KWh (watt or kilowatt hours)
Thursday 6th Nov 2014
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.
Results of the tests: Battery temp estimated at 11°
sg1 to sg6 are results for specific gravity from negative to positive terminal
ID Voltage sg1 sg2 sg3 sg4 sg5 sg6 1 12.86/7 1.250 1.250 1.250 1.240 1.240 1.240 2 12.88/9 1.255 1.260 1.255 1.250 1.250 1.250 3 12.88/9 1.250 1.250 1.240 1.255 1.250 1.250 4 12.82/3 1.245 1.250 1.245 1.242 1.237 1.235
Only one cell reached the 1.260 I was hoping for. Battery 4 was not charged as well as the others
Connected Batt 4 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 Batt 4 reached the float charge today I disconnected it and connected Bat3 which is now the load battery.
When Batt 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.
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