Solar for dual battery setup?

[4Roamer]

Hey all,
I'm going to be getting a second car and my overland vehicle, and current DD, will get solar to charge the dual battery setup while it waits for the cool trips. I want to get something that can handle more than just "maintenance" charging while on trips. I already have a Blue Sea ACR already so I don't want to rebuy something to replace that unless I have to. I only know the big names for "good" controllers and I don't mind buying a decent one. I found the Zamp unit that can do dual batteries but that seems to be a PWM charger. The other names that I know don't seem to have dual bank setups. Does anyone have something like this that they would recommend in an MPPT flavor?

Thanks!

 

[DiploStrat]

You don't need a dual bank charger. Simply attach the solar panels/controller to the battery of your choice - typically the camper battery, and the Blue Sea ACR will combine when the battery exceeds the target voltage, thus charging both batteries.

Scholars can debate MPPT vs. PWM. For me, the important consideration, if you have lead acid batteries, is that the charger have a full absorb stage. (Some do not and this will lead to partial charging.)

Automatic Charging Relay (ACR) Explained - Blue Sea Systems

Engineering high quality marine electrical components for safety, reliability and performance

www.bluesea.com

 

[4Roamer]

With your BlueSeas ACR, you wont need a dual battery charger.

Thank you both for the quick reply. Does the "start isolation" not require that the vehicle key be in the run position?

 

[DiploStrat]

You don't need "start isolation." Just let it work.

 

[4Roamer]

I found this on the Blue Sea website. I'll give it a whirl and see what happens. Thanks for the fast feedback.

"An ACR will work with all charge sources, including an alternator, AC charger, or solar panel. However, low current charge sources might not produce the voltage rise required to force the ACR to combine."

 

[DiploStrat]

"Start isolation" is almost never required except on boats. Used a home brew intelligent charger on a camper for years with no form of start isolation.

As a practical matter, most of the time the ACR will disconnect as soon as you turn the key because the demand of the starter on the starting battery will drop it below the disconnect voltage of 12.7v.

Thousands of electrons die terrible deaths on this form as people keep trying to overthink these beasts. If you are using lead acid for both starter and camper battery, then the voltages selected by Blue Sea are perfect and, unless you have some sophisticated navigation devices on the camper side of your vehicle, start isolation is simply not needed.

N.B. If your camper battery is lithium iron, then the ACR is NOT a good choice as the resting voltage of most lithium banks is higher than the combine voltage of the ACR and it will effectively never disconnect, leaving your starter battery as a constant drain on your camper battery. In this case, a battery-to-battery charger is usually a better option. With a B2B, assuring a maintenance charge from the camper battery to the starter battery is a bit more challenging.

Soooooo, if both of your batteries are lead acid, then plug in the solar charger of your choice and let the ACR do its job.

 

[PSea]

i suggest going w a renogy dcdc charger w built in mppt. can charge batteries fr alternator or solar panel or both. i got the allpower 200w folding panel. works great.