Thursday, Apr 24, 2014 at 12:29
Hi Mike,
There are a lot of variables involved so I wouldn't initially suspect your panels.
First there' s the question of where your current (amps) meter is installed. If it's on the
panel side of the regulator, then under optimum conditions, and provided your batteries will accept it, I'd expect to see about 20 amps maximum. If it's on the battery side of the regulator, then 10-15% more, ie your 22-23 amps under optimum conditions, and again, if the batteries will accept it.
Secondly, the location of the regulator is far more important than generally recognised. It should be close coupled to the batteries by decent heavy cable so that the voltage drop between regulator and batteries is minimised. The regulator takes its
cue from what it sees as the battery voltage and if there is a significant voltage difference between regulator and battery not only will this result directly in reduced charging, it will upset the controller's calculations so that it will likely reduce the charging rate.
Thirdly, the batteries are an important element here. If they are in good condition and
well below being fully charged, then with your battery capacity they should accept (at least initially) all the current your controller can supply. They will not accept so much when approaching fully charged, indeed the controller will taper the charge rate anyway at this time in response to the increasing battery voltage.
Fourthly, the metering is important. If using an analogue style (moving needle pointing to a scale) accuracy may be pretty awful (probably within 10%). If it's a digital meter, properly installed, is probably within 1%.
A really important measurement is the battery voltage. When charging strongly, voltage will be below 14.4 volts for almost all deep cycle batteries. Voltage will rise as charge builds up until it reaches about 14.4 when the batteries are about 80% charged. The controller will then maintain this voltage while the charging current declines to a low level. The battery is then considered fully charged and good controllers drop the voltage down to about 13.4, which provides a trickle of current. (I've referred to 14.4V, though this is a typical figure and different battery types and different controllers may have slightly different thresholds.)
Another variable is of course just how optimally oriented are your panels? If horizontal and you are in southern Australia, you will not achieve anything like full output. (Reduction from the maximum is related to the sine of the angle from normal incidence, so near enough is ok, but larger departures from optimum can have a substantial effect.)
Suggest hang a voltmeter on your battery. If everythings behaving roughly as above, but you never see 20+ amps going in, then maybe panels, maybe batteries have an issue. It would be worth temporarily separating the two batteries - do both perform the same way? accept the same charge under similar conditions?
Sorry to be so verbose, but there really isn't a quick answer!
Cheers
John | J and V
"Not everything that can be counted counts, and not everything that counts can be counted."
- Albert Einstein
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