Solar and charging when RV attached to shore powerV

**terryriddle** · 03-16-2024, 05:22 PM

Last year I added a solar panel to my RV. I did that mainly to avoid taking out the flooded 57 lb battery and let the solar panel keep it fully charged. I also added a Bluetooth device that lets me read the solar usage and the battery voltage from my phone. This has worked well and is doing a great job of keeping the battery charged. I brought the RV down to the home to de-winterize and plugged it into the electricity from my home. I noticed that with the electricity from the home, the battery was kept charged and it appeared the solar was no longer being used to keep the battery charged. I am not an electrician and went with a basic solar panel, controller and Bluetooth monitor to see if the battery was in float mode or boost, usually in the morning.

When hooked up to shore power, am I correct in saying that the solar setup steps aside as long as the shore power is keeping the battery charged?

Terry

**Second Chance** · 03-16-2024, 06:29 PM

The battery doesn't know where charge current is coming from and neither the converter/charger nor the solar charge controller know the other exists. They both just see the voltage at the battery and respond accordingly. If the converter/charger is kicking in before the solar and keeping the battery charged, the solar system just thinks everything is fine and no charge is needed.

Rob

**terryriddle** · 03-16-2024, 08:03 PM

Originally Posted by Second Chance

The battery doesn't know where charge current is coming from and neither the converter/charger nor the solar charge controller know the other exists. They both just see the voltage at the battery and respond accordingly. If the converter/charger is kicking in before the solar and keeping the battery charged, the solar system just thinks everything is fine and no charge is needed.

Rob

Thanks Rob. That was my thought and I greatly appreciate the feedback. I just checked the app on my iPhone and it stated not charging (solar) yet the battery is at 13.6 volts, fully charged. Shore power has taken over, for sure, and the solar need not do anything... Thanks again for the quick response!

Terry

PS: We head to Jasper and Banff on June 2nd and return in mid-July with visits to some of the national parks we have visited before. We tried this in 2020 for our 50th anniversary and Covid canceled the trip. We were finally able to get several nights in Banff at an RV site and additional nights in Jasper. Just almost four years later. New battery, replaced the tires, and packing the bearings next week. Have a set of bearings/seals and tools to do a bearing job on the road, plus a slide motor if needed. Taking a cooler just in case I lose the frig due to a fan failure in the back of it, like last year. Very poor engineering for a frig to blow a 5amp fuse when one of the two fans fails. I has to remove the frig to replace the fan.

**terryriddle** · 03-16-2024, 08:36 PM

Originally Posted by Second Chance

The battery doesn't know where charge current is coming from and neither the converter/charger nor the solar charge controller know the other exists. They both just see the voltage at the battery and respond accordingly. If the converter/charger is kicking in before the solar and keeping the battery charged, the solar system just thinks everything is fine and no charge is needed.

Rob

One additional question. If I have the master electric switch in the RV turned off, does shore power still power the converter to charge the battery?

**Second Chance** · 03-17-2024, 06:35 AM

Originally Posted by terryriddle

One additional question. If I have the master electric switch in the RV turned off, does shore power still power the converter to charge the battery?

If you're talking about the battery cut-off switch, the answer is no for the converter/charger. The solar controller may or may not be wired directly to the battery. Be aware, too, that even with the battery cut-off switch off, there are still parasitic drains on the battery (CO detector, etc.). If you have shore power, leave the battery cut-off switch in the On position.

Rob

**terryriddle** · 03-17-2024, 09:46 AM

Originally Posted by Second Chance

If you're talking about the battery cut-off switch, the answer is no for the converter/charger. The solar controller may or may not be wired directly to the battery. Be aware, too, that even with the battery cut-off switch off, there are still parasitic drains on the battery (CO detector, etc.). If you have shore power, leave the battery cut-off switch in the On position.

Rob

The solar controller is wired directly to the battery and this morning it is in Boost Mode. If I understand your first sentence, with the battery cut-off switch in the off position, shore power will still maintain the battery via the converter/charger even if I did not have solar. Is that correct or does the battery cut-off switch also prevent shore power to use the converter/charger to maintain the battery? And yes, I do understand that even with the switch off, there are items that over time would drain the battery and it is best to disconnect the battery if I did not have shore power or solar power. I learned that the hard way years ago.

Sorry I am slow on the uptake... Appreciate Rob.

**Second Chance** · 03-17-2024, 09:49 AM

Originally Posted by terryriddle

The solar controller is wired directly to the battery and this morning it is in Boost Mode. If I understand your first sentence, with the battery cut-off switch in the off position, shore power will still maintain the battery via the converter/charger even if I did not have solar. Is that correct or does the battery cut-off switch also prevent shore power to use the converter/charger to maintain the battery? And yes, I do understand that even with the switch off, there are items that over time would drain the battery and it is best to disconnect the battery if I did not have shore power or solar power. I learned that the hard way years ago.

Sorry I am slow on the uptake... Appreciate Rob.

No - the shore power converter/charger will not charge the battery with the battery cut-off switch in the off position.

Rob

**terryriddle** · 03-17-2024, 10:02 AM

Thanks, Rob for the clarification. That I did not know, and before solar, I took the battery out of the RV after each trip and kept it in the garage on a trickle charger. But lifting 57 lbs is a strain for me in my late seventies. I thought about using a lithium battery due to its lightweight and had read that my current charger/converter can take them to 80%. I know that my solar unit supports lithium and should take the battery to 100%.

Have a blessed day and thanks for the insight. I know now that when on shore power here at the house, I need to leave the battery cut-off switch in the on position so the converter/charger can do it's job.

**powerscol** · 03-17-2024, 12:02 PM

Originally Posted by terryriddle

Thanks, Rob for the clarification. That I did not know, and before solar, I took the battery out of the RV after each trip and kept it in the garage on a trickle charger. But lifting 57 lbs is a strain for me in my late seventies. I thought about using a lithium battery due to its lightweight and had read that my current charger/converter can take them to 80%. I know that my solar unit supports lithium and should take the battery to 100%.

Have a blessed day and thanks for the insight. I know now that when on shore power here at the house, I need to leave the battery cut-off switch in the on position so the converter/charger can do it's job.

Terry
I see no reason to ever turn the disconnect switch off. Just always leave it on. If you want the power off during storage or to do electrical repairs disconnect the positive battery cable. That way you know there are no live 12v wires. If you ever have any welding done to the frame, remove the battery positive cable and disconnect the solar panels (disconnect the solar panels first.)

BTW - do you have a disconnect between the solar panels and your solar controller? If not you should put one is as many of the controllers have issues of getting solar power when disconnected from a battery. The proper sequence for operating the panels and when disconnecting the battery is disconnect solar power from controller and then disconnect the battery. To power back up, connect the battery first then turn on the panels. I use 12v circuit breakers in my set up - also protect against panel shorts from reaching the controller. Size a little higher than your max panel output

**terryriddle** · 03-18-2024, 06:32 AM

Originally Posted by powerscol

Terry
I see no reason to ever turn the disconnect switch off. Just always leave it on. If you want the power off during storage or to do electrical repairs disconnect the positive battery cable. That way you know there are no live 12v wires. If you ever have any welding done to the frame, remove the battery positive cable and disconnect the solar panels (disconnect the solar panels first.)

BTW - do you have a disconnect between the solar panels and your solar controller? If not you should put one is as many of the controllers have issues of getting solar power when disconnected from a battery. The proper sequence for operating the panels and when disconnecting the battery is disconnect solar power from controller and then disconnect the battery. To power back up, connect the battery first then turn on the panels. I use 12v circuit breakers in my set up - also protect against panel shorts from reaching the controller. Size a little higher than your max panel output

Yes, on the line from the solar coming down into the front storage area, I have a mini-breaker before the control unit to protect it when the battery is disconnected or taken out.