Battery charger help needed

Hi Dave,

Running a battery charger, your alternator or power supply through a 3 stage solar regulator will not allow the regultor to operate according to its programmed charge profile for optimum charging (it will work though to a certain degree but will never get off the 'bulk" stage). The reasons for this is that all the above only pump out around 13.5-14 volts (alternator will be higher but as its voltage increases it current decreases so will not be of any help) and a smart charger usually operates at around 14.2-14.5 volts during its bulk and absorbtion stages. The exception is if you found a power supply that supplies a higher voltage (idealy 17-22 volts) with maximum current supply at above 15 volts (if you do not use the equalise function of the regulator). This would enable the solar regulator to perform as it was designed. The problem with this though is having some sort of current limiting in either the power supply or regulator (such as the PL20 which you can program max current setting) as a solar regultor during its bulk stage operates as constant current so will suck as much as it can from the source. No protection means blowing fuses or worse, equipment.

I have gone through all the above, even built a power supply but my regulator (which is 20A) cannot be programmed for current limiting so I kept blowing fuses on the power supply as it tried to suck up to its max rating of 25A (this is why you never have solar panels that can supply more current than the regulator can handle unless you can limit the current in some way). A realy good site is this siteas it describes how to go about exactly what you want to do.

I ended up buying a 30A 3 stage charger from ebay for $370. It does everything I want but without the cost of similar items (Xantrex for example). It is identical to the Durst type and works extremely well.

Regards
David

Dave,
what power output do you get with cloudy conditions ??
What loss of power do you suffer in cloudy conditions ??

Why won't you run the 20 amp charger direct from the genni to the caravan battery ??
As you say 20 amp charger will not deliver the full current at all times, why not get an automatic charger that will deliver 'bulk' and then 'float' charge as required by the battery, will be faster and no problems of overcharge or even undercharge for the battery system!!