I am installing 2 85 watt solar panels with a charge controller wired directly to the house battery bank on my O'Day 31. The kit I purchased came with 1 inline fuse holder (30 amp) and a diagram showing the inline fuse between the controller and the battery. Is it also necessary to have a fuse between the PV's and the controller? Also, is it necessary to have a manual shut-off switch to disconnect the panels when the engine charging circuit is active or when the 3 stage battery charger is operational?
Solar panel inline fuse
- Thread starter Russr
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How stuff charges
The controller can't really effect circuits "down stream" (the batteries and other charging circuits) from itself. It only controls circuits upstream (the panels) If the batteries are at 14 volts for whatever reason it will not let the solar panel charge them at 13 volts. If it did then current would be flowing back into the solar panel.
What that means is you don't need to do anything to the controller when you use the alternator or battery charger. It will see the batteries as charged and not let the panels charge the batteries.
With that said, when the regulator (alternator charge controller) or battery charger turns the voltage down as the batteries reach full charge the solar charge controller will see the drop and try to start charging (assuming sunlight...of course)
The battery charger and alternator regulator shuts down for a few seconds every so often to check the resting voltage (don't flame me guys that is the only thing I can think to call it) so it can decide which charge stage to go to. If the solar charge controller "voltage sense" delay is longer than the battery charger's/regulator's "voltage sense" delay then there is no problem. If it does not have a time delay or it is shorter than the battery charger's then the battery charger/regulator will see the voltage increase from the solar panels as a more fully charged (than it is) battery and will go to the next stage or trickle charge mode.
This is not a big problem unless you are trying to charge the batteries rapidly with the battery charger or alternator. You would want to eliminate the solar panel from the circuit in this case. If you are leaving the boat for the week then you really don't need to do anything as the controllers will get the batteries charged but it may take a little more time to do it.
You don't need a fuse between the panels and the controller. the panels can't dump 100+ amps into the circuit so a short will not burn up the wires.
The controller can't really effect circuits "down stream" (the batteries and other charging circuits) from itself. It only controls circuits upstream (the panels) If the batteries are at 14 volts for whatever reason it will not let the solar panel charge them at 13 volts. If it did then current would be flowing back into the solar panel.
What that means is you don't need to do anything to the controller when you use the alternator or battery charger. It will see the batteries as charged and not let the panels charge the batteries.
With that said, when the regulator (alternator charge controller) or battery charger turns the voltage down as the batteries reach full charge the solar charge controller will see the drop and try to start charging (assuming sunlight...of course)
The battery charger and alternator regulator shuts down for a few seconds every so often to check the resting voltage (don't flame me guys that is the only thing I can think to call it) so it can decide which charge stage to go to. If the solar charge controller "voltage sense" delay is longer than the battery charger's/regulator's "voltage sense" delay then there is no problem. If it does not have a time delay or it is shorter than the battery charger's then the battery charger/regulator will see the voltage increase from the solar panels as a more fully charged (than it is) battery and will go to the next stage or trickle charge mode.
This is not a big problem unless you are trying to charge the batteries rapidly with the battery charger or alternator. You would want to eliminate the solar panel from the circuit in this case. If you are leaving the boat for the week then you really don't need to do anything as the controllers will get the batteries charged but it may take a little more time to do it.
You don't need a fuse between the panels and the controller. the panels can't dump 100+ amps into the circuit so a short will not burn up the wires.
Thanks for the info Bill. I'll definitely go with just a 30 amp fuse on the battery side of controller. I will however seriously consider a switch to disconnect the panels in the event that the batteries are deeply discharged and require a bulk charge from the 55 amp engine alternator (although only when away from the dock and shore power).
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