07-19-2021, 03:03 PM
Any dashboard mounted solar panel has the potential to overvolt a battery.
it depends not only on the actual output of the panel at that time, but the state of charge of the battery at that point.
And not only that,, assuming it is 98%+ charged it depends on the battery, its health, temperature, and original design.
some maintenance free starter sealed but flooded batteries, act like AGM in that they taper to near zero amps at high absorption voltages. Even just 2 unregulated watts on such a battery can push it well over 15.5v, and that is not doing the battery any favors when it occurs several hours each day.
How much each battery self discharges changes for the worse as a battery ages, so the dash wattage might not even be able to keep up with self discharge, much less any parasitic draws, or just some overnight DC loads drawing from starter battery versus the house.
Mainsail has a video showing a 10 watt unregulated panel overvolting a pair of lifeline GC-2s, 220Ah.
https://marinehowto.com/do-i-need-a-solar-controller/
The owner of a dashboard panel needs to insure their panel is not overvolting their specific battery.
The newer the battery, the more likely it is that the unregulated panel can overvolt it
Just check the voltage, it does not need to be high 13's or higher all day, day after day.
If you can remove the caps, monitor water usage.
I'm getting used to having re incorporated a separate house bank. When I want the uncycled starter bank to see some time at absorption, I turn my solar switch to both. I've been setting my phone timer for late afternoon re isolation.
Mostly my G31 Northstar AGM is being used for starting. That thing holds 13+ volts for days after a top charge.
The Dekas settle to 12.84v in 24 hours when isolated from all loads.
if I discharge these banks in parallel the Northstar provides more than half its share of amp hours consumed, and if the load is tiny the Dekas are a load on the Northstar,
So proper isolation is highly desirable, though forgetting is hardly instant demise.
it depends not only on the actual output of the panel at that time, but the state of charge of the battery at that point.
And not only that,, assuming it is 98%+ charged it depends on the battery, its health, temperature, and original design.
some maintenance free starter sealed but flooded batteries, act like AGM in that they taper to near zero amps at high absorption voltages. Even just 2 unregulated watts on such a battery can push it well over 15.5v, and that is not doing the battery any favors when it occurs several hours each day.
How much each battery self discharges changes for the worse as a battery ages, so the dash wattage might not even be able to keep up with self discharge, much less any parasitic draws, or just some overnight DC loads drawing from starter battery versus the house.
Mainsail has a video showing a 10 watt unregulated panel overvolting a pair of lifeline GC-2s, 220Ah.
https://marinehowto.com/do-i-need-a-solar-controller/
The owner of a dashboard panel needs to insure their panel is not overvolting their specific battery.
The newer the battery, the more likely it is that the unregulated panel can overvolt it
Just check the voltage, it does not need to be high 13's or higher all day, day after day.
If you can remove the caps, monitor water usage.
I'm getting used to having re incorporated a separate house bank. When I want the uncycled starter bank to see some time at absorption, I turn my solar switch to both. I've been setting my phone timer for late afternoon re isolation.
Mostly my G31 Northstar AGM is being used for starting. That thing holds 13+ volts for days after a top charge.
The Dekas settle to 12.84v in 24 hours when isolated from all loads.
if I discharge these banks in parallel the Northstar provides more than half its share of amp hours consumed, and if the load is tiny the Dekas are a load on the Northstar,
So proper isolation is highly desirable, though forgetting is hardly instant demise.
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