6w PV unregulated Trickle Charger.

Submitted: Monday, Oct 31, 2016 at 12:10
ThreadID: 133699 Views:2079 Replies:6 FollowUps:1
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Is my battery being damaged?
I have been using a 6 watt PV as trickle charger, for a year or so. Works well and keeps the 12v 100va AGM van battery topped up when not in use.
Checked output voltage yesterday, and found 19.1v. I looked at what I thought was the faulty voltage controller, but it is only a junction box. Should I include a voltage controller in the circuit?
cheers marty.
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Reply By: Allan B (Member, SunCoast) - Monday, Oct 31, 2016 at 12:41

Monday, Oct 31, 2016 at 12:41
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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".
Cheers
Allan

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AnswerID: 605555

Follow Up By: Kazza055 - Monday, Oct 31, 2016 at 18:41

Monday, Oct 31, 2016 at 18:41
I fitted a 5W panel directly into the TV 12V outlet with the panel sitting in the skylight.

Worked a treat and as Allan stated, no regulator is required.

I now have 2 x 150W panels so don't use the 5W panel anymore.
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FollowupID: 875307

Reply By: The Bantam - Monday, Oct 31, 2016 at 20:04

Monday, Oct 31, 2016 at 20:04
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
AnswerID: 605575

Reply By: Bob Y. - Qld - Monday, Oct 31, 2016 at 21:26

Monday, Oct 31, 2016 at 21:26
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

Seen it all, Done it all.
Can't remember most of it.

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AnswerID: 605587

Reply By: martycon - Tuesday, Nov 01, 2016 at 10:52

Tuesday, Nov 01, 2016 at 10:52
Thanks Alan, that is reassuring. Soon after connecting the PV , measured 12.8v at battery. Will check for a few days.
cheers marty.
AnswerID: 605601

Reply By: martycon - Tuesday, Nov 01, 2016 at 10:55

Tuesday, Nov 01, 2016 at 10:55
Thanks TB, I will check as you suggest.
cheers marty.
AnswerID: 605602

Reply By: martycon - Tuesday, Nov 01, 2016 at 10:59

Tuesday, Nov 01, 2016 at 10:59
Thanks Bob, very reassuring as I have only 6w.
cheers marty.
AnswerID: 605603

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