HF 1.5w Solar Panel for trickle charge dual battery system?

[hostage]

I am curious if anyone uses these to help maintain the battery, while away from the boat on a dual battery system? I am going to be installing a second battery with an isolator, I am curious how this would impact things.

 

[dingbat]

I am curious if anyone uses these to help maintain the battery, while away from the boat on a dual battery system? I am going to be installing a second battery with an isolator, I am curious how this would impact things.

1.5w at 12 volts is 0.125 amps.
Pretty useless as a battery charger

 

[tpenfield]

For a single or dual battery set-up, and just maintaining the batteries, not really charging them up, I would go about 15 watts.

You may only get about 60% of the panel rating, as you will want a solar charging regulator.

Many trickle chargers (battery maintainers) are about 400ma. That's what you would get with a 15 watt panel after all was said & done.

I did a 100 watt system for the 7 (seven) batteries in my boat. It does the job, but is by no means overkill.

https://forums.iboats.com/threads/solar-power-installation.757735/

 

[hostage]

For a single or dual battery set-up, and just maintaining the batteries, not really charging them up, I would go about 15 watts.

You may only get about 60% of the panel rating, as you will want a solar charging regulator.

Many trickle chargers (battery maintainers) are about 400ma. That's what you would get with a 15 watt panel after all was said & done.

I did a 100 watt system for the 7 (seven) batteries in my boat. It does the job, but is by no means overkill.

https://forums.iboats.com/threads/solar-power-installation.757735/

Yeah, not looking for charging, just for maintaining. More so worried about not getting on the boat for a few weeks and having the battery hard to start, especially as battery ages.

I read the whole thread. Are you isolating the batteries so it won't overcharge a specific battery? Also are you using an isolation relay so they alternator will charge the other batteries, when the engine ia running?

If I put the panel on the starting battery, then the voltage should activate the relay so the both batteries will get charge. I don't know how to isolate this, unless I put a switch between the starting battery and relay.

 

[tpenfield]

Battery isolation is so that the batteries are not joined by the single solar panel. It is fairly common to have isolators with shore power or solar where a single voltage source is charging several batteries that need to be independent, unless joined by other means (battery switch, etc)

 

[KD4UPL]

1.5 watts is completely useless.
Too trickle charge 2 G27 batteries I would think 20 watts would be about right.

 

[boataway]

I disagree with some of the sentiment on this thread. Many trickle chargers are less than one watt and do just fine keeping the battery topped off, if that's what you are after. Average resting discharge rate is well below that level.

 

[tpenfield]

I took a look at an AC powered battery maintainer that I have and it's output was rated for about 6 watts (500ma @ 12 volts) IIRC. The 1.5 watt is probably fine as even at 60% of its rated power, it will deliver about 70ma to the battery(ies). That may be a bit low. Of course if you want a little bit of headroom to charge the batteries then you may want more wattage.

When I was designing my solar charging system, I wanted to have some extra capacity to actually charge the batteries, since there is a small current draw from various things in the boat that stay active. The 100 watts vs 7 batteries (15 watts/battery) seemed quite adequate to both maintain and do some charging as needed. Some folks suggested I needed more, but the system would have worked fine with even a 50 watt panel (7 watts/battery).

 

[tpenfield]

The self-discharge rate of these batteries at full charge is about 25ma (right?) (1% of capacity per day at 'room' temperature).

 

[hostage]

The context is for a battery in a smaller run about, not a crusier. I shut off the battery, as I put it on the trailer. I just don't want to be gone for a few weeks and have issues starting the boat.

 

[tpenfield]

Try it and report back. The 1.5 watt chargers certainly work, based on the consumer reviews. Probably not enough for dual batteries, and assumes you have good sunshine.

Keep in mind that the self discharging of the battery happens continuously, so during the daylight hours, the solar panel will be playing catch-up for a while.

 

[Scott Danforth]

I would just get a solargizer kit