Friday, Jun 14, 2013 at 12:09
G'day again, adell s
I've looked at the data sheet and operating instructions for your solar reg. It's old, but in my opinion it is good and
well engineered for what it is, an earlier, superseded solar controller.
From what you say, I agree with the possibility that one of the three batteries is stuffed and is pulling the system down overnight. It is possible that they are all below par to varying degrees, with the same result. The best way to
test them is to remove them, take them to a battery place and have them individually load-tested.
It is possible for the batteries to have little capacity (ie, be worn out through age or abuse) but still appear to be taking a charge normally when hooked to a charger (mains or solar). So it is quite possible that everything will look hunky-dory with the solar working, but as soon as you put a decent load on the batteries they go flat quickly, or rapidly self-discharge.
The Steca has a Gel setting and a Flooded setting. You have gel batteries. Is the Steca set to Gel? If not, that will have overcharged your Gel batteries and contributed to their poor performance. Also, the Steca will apply a periodic Equalisation charge if set to Flooded. That is a definite no-no for sealed batteries and if it happened would further contribute to their present state.
Also, Steca's data says that your gel batteries will be held at 13.9V by the solar charger. That is a float charge and is higher than a fully charged battery's resting voltage, so it is natural for the voltage to come down to 12.6 or so with no sun and no load. Even a good battery will do that. (I'm not sure of the resting voltage of a fully charged gel battery, but the principle is valid).
A good quality three stage PWM charger would theoretically be better than your 2-stage Steca, and a 3 stage MPPT better again, but I'm not sure it's worth the expense to change just yet until we know more of your requirements, such as useage, loads, how long you want solar to support your batteries without access to mains - eg long boat trips - etc. I suspect your Steca will be adequate in combination with good batteries and a good multi-stage mains charger. But if you have a big wallet, I would tend towards a new, up-to-date MPPT multi-stage solar regulator.
In the Xantrex, the reference to charging three batteries means it can look after three different battery sets, or banks. If you connect two or three batteries in parallel, the Xantrex will see them as one battery bank. You would connect that bank to one of the three outputs on the charger. You could connect an engine battery to another of the outputs, and a third, auxiliary battery or set of batteries, to the third pair of outputs. The Xantrex has the ability to look after all three sets of batteries as if it were three separate chargers. (You would have to
check the instructions on that, as there may be restrictions, like maybe they all have to be the same type - gel, flooded, AGM, etc. I know the principle, not the details.)
So your batteries must be hooked up in parallel to keep the overall voltage to 12V and that set of parallel batteries connected to one of the outputs of the Xantrex. The Xantrex will then see them as one battery and charge them simultaneously.
DO NOT hook them up in series. Series will add the voltages of the batteries - 2 will give 24V, 3 will give 36, etc. It's a 12 volt charger, it cannot charge 24 or 36 volts battery banks and could be damaged if connected to higher than 12V.
Cheers
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