Tuesday, Oct 11, 2011 at 15:41
Hi Lenita,
no need to apologise, I'm glad to help.
Yes,
solar charging works in tandem with alternator charging, but one after another.
Driving means bulk charging (high current, rapid increase of state of charge up to 80~85% of full). Followed by
solar charging while stationary (low current, slow increase of SOC to 100%).
Ideally, you'd be driving for a couple of hours in the morning, and the
solar panels do the topping up for the remainder of the day while pulled up somewhere.
But if the
solar panels are of sufficient size and the
solar regulator is of the MPPT type, then you might not need to drive at all, or you could skip a day or two and rely on
solar only. As a guide, your alternator returns charge at the rate of 1Ah/minute.
E.g. if there's a daily shortfall of 20Ah, you'd drive (or fast idle) for 20~30 minutes the next morning.
To get an idea of state of charge, you can observe battery voltage which should reach 14.4V by 2pm.
If it doesn't get there in time, run the alternator a bit longer next morning.
You've gotta love your red dust lol.
Photos show batteries are pretty likely AGM around 100Ah each.
Battery size gives a good indication of its capacity, so yours would be around 300Lx175Wx200H?
For selecting battery size (Ah capacity), you'll need to find out your daily Ah requirement.
Multiply by 2.5 and that's the recommended battery size.
14.4 or 14.7V boost voltage:
Rule of thumb for AGM batteries: if they're being discharged more than 50% on a daily basis, select 14.7V, otherwise 14.4V. You can select 14.7v regardless once or twice per fortnight for a mini equalisation charging stage.
But if there's no battery temperature sensor, select 14.4V in summer regardless of depth of discharge.
The way the regulator's charging algorithm is designed also determines what setting to use, and also how accurate the actual voltage is controlled. Sometimes 14.4V setting only results in 14.2V battery voltage in which case you'd select 14.7V giving you 14.5V actual.
Indicator lights:
these only signal the presence of charging current/voltage, but not how much of it.
A basic voltmeter/multimeter reading taken off directly at the battery terminals is a good proxy of actual state of charge. But this varies with any load currents. An easy way is by using a
solar regulator with a remote control/display unit.
Hope to have explained everything?
cheers, Peter
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