6w PV unregulated Trickle Charger.

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Hi Marty, when you measured the 19.1 volts I assume that the battery was not connected to the charger, nor any other load connected. If so, you would be measuring the open-circuit voltage of the PV.
It is more appropriate to measure the voltage with the battery connected and after being on charge for a time. I would expect it to be in the range of 13 to 14 volts.
What matters is the current going into the battery once it is fully charged and I would expect that to be around 20 to 50 milliamps.

You should not need a 'voltage controller' in the circuit with just a 6 Watt PV.
As you say, it has been keeping the battery "topped up".

Consider that the 6 watt solar panel has a maximum output of half an amp .... the 100AH battery should be able to suck that up and keep the panel loaded down sufficiently so voltage does not get out of control.

Bear in mind that 6 watts ..... will only be between 10m and 4pm, in summer in the northern part of Australia in full sun.

It would be worth checking the terminal voltage with the battery connected at midday with a clear sky.

cheers

Back in the early '80's, I purchased a Solarex 36w panel for about the same $$$'s that would now get me over 600w, or maybe more, of solar output. Had it mainly to charge a battery to run an HF transceiver, and a few lights, in our caravan.

Some years later, I set it up on the roof of the station homestead, where it did duty charging an N70Z battery, to run both an HF and a UHF, until we had the phone on, and the HF was eventually consigned to a storage cupboard. No regulator was fitted and the batteries gave good service for many years.

Bob

Thanks Alan, that is reassuring. Soon after connecting the PV , measured 12.8v at battery. Will check for a few days.
cheers marty.

Thanks TB, I will check as you suggest.
cheers marty.

Thanks Bob, very reassuring as I have only 6w.
cheers marty.