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Discussion Starter #1 (Edited)
Does anyone know anything about using solar trickle chargers (https://www.amazon.com/dp/B071ZZ2Z6X/ref=psdc_13638740011_t4_B01MYVUSRH) with the volt?

To be clear this is *not* about charging the high voltage batteries with a dinky panel. This is about keeping low power accessories from excessively draining the 12v battery with parasitic draw.

I have a evextend inverter installed in a 2013 and i'm not sure how to integrate one of these chargers so that it is safe and always keeping the battery topped. I want to run low power draw through the OBD-II port (couple hundred mA max draw) so having the 12v battery not die because of that would be amazing. Trickle charger seems to fulfill that. Could I just fit the connectors between the inverter leads or would that mess the inverter?

Ideally I want the solar to be fed to the battery with the inverter connected and be able to use everything normally without any extra maintenance. Also two panels for the front and rear windows would be really cool to cover all bases.

Any info would be appreciated!!
 

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You could probably just leave the negative lead of the trickle charger connected to the 12 volt battery negative, and connect the positive lead of the trickle charger to the positive terminal via a normally "closed" solid-state relay. When the car is on a signal of some type keeps the SSR dis-engaged and the trickle charger disconnected from the battery and when the car turns off the SSR engages and connects them, maybe with some hysteresis/a short delay on the relay release after the car shuts down to prevent rapid cycling.

The other thing to be careful of in any 12V switching arrangement is load dump spikes, the voltage on a car's battery terminals can instantaneously spike very high when loads like the AC compressor are disconnected while the alternator is running. I don't know how often this occurs in the Volt as it doesn't have a traditional alternator as far as I know but it's a common thing that needs to be protected against in automotive 12V system design. Some types of automotive-grade relays designed for switching the power bus may have a protection network built in already, and there are off-the-shelf modules that can be connected in line as well

Looks like the trickle charger comes with a blocking diode built in to prevent the battery from discharging back thru the panel when it's not illuminated. Remember that in some jurisdictions it's illegal to drive with any obstructions covering either the front or rear windows
 

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Discussion Starter #3
You could probably just leave the negative lead of the trickle charger connected to the 12 volt battery negative, and connect the positive lead of the trickle charger to the positive terminal via a normally "closed" solid-state relay. When the car is on a signal of some type keeps the SSR dis-engaged and the trickle charger disconnected from the battery and when the car turns off the SSR engages and connects them, maybe with some hysteresis/a short delay on the relay release after the car shuts down to prevent rapid cycling.

The other thing to be careful of in any 12V switching arrangement is load dump spikes, the voltage on a car's battery terminals can instantaneously spike very high when loads like the AC compressor are disconnected while the alternator is running. I don't know how often this occurs in the Volt as it doesn't have a traditional alternator as far as I know but it's a common thing that needs to be protected against in automotive 12V system design. Some types of automotive-grade relays designed for switching the power bus may have a protection network built in already, and there are off-the-shelf modules that can be connected in line as well
Woah that's a lot of technical info, thanks. Sounds like I need a specific type of relay that has load dump protection huh? I don't really know how to find or build something like that, so it probably isn't worth the effort/risk unless I had help.

Remember that in some jurisdictions it's illegal to drive with any obstructions covering either the front or rear windows
That's alright; the car would be charging it appropriately. I can remember to remove them before driving, and eventually it'll just be parked all it's life anyway.
 

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I have a 100 watt solar panel on my truck. Right now I use it to charge the auxiliary battery on my truck. This battery is charged by the truck alternator when running and by solar when stopped. Nothing special was done for the solar, the solar charge controller is connected directly to the battery. No attempt was made to switch from one charging system to the other because the solar charge controller already does this. When the motor is not running the solar charge controller maintains 13.6 volts at the battery. When the battery is fully charged it backs off to a lower float voltage. When the motor is running the alternator sends about 14.2 volts to the battery, when the solar charge controller sees this voltage it backs off to its float condition.

If your solar trickle charger works the same way, that is, revert to float voltage from charge voltage when the battery is charged from another source, you should be OK.
 
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