Adding Solar Panel to dual battery system....

[Iva]

Hello Guys,
Already running dual battery system with optima batteries and blue sea acr ml 7622. I’m satisfied with it but when I’m parked on one place for a camping my fridge runs outmy aux battery in around 24 hours so thinking to get 100w solar panel and controler to have my aux battery charged when im parked for a camping couple days.
My question is: where to connect wires from solar controller, to start or to aux battery?
aslo while driving when my car alternator will charge my batteries and same time solar will charge them is it a problem or not?
I don't want to burn my car ))))
P.S. photo shows my current setup!

 

[86scotty]

You want to connect your solar to your auxiliary battery. Your solar controller limits the amount of charge from the solar panel depending on need. While your car is running and the solar controller feels that juice coming from the alternator it will not allow solar charge as well, at least in every setup I've installed or owned. You won't burn your car if wiring is properly sized and wired. This should work in reverse with your isolator as well. If parked in the sun charging auxiliary battery via solar eventually your isolator will charge that battery and divert some current to your vehicle battery to keep it topped up.

I would recommend you consider a solar suitcase (portable) panel setup. This will allow you to park in the shade when possible and put your panel out in the sun. Personally I use both a fixed and a suitcase but just going with a portable setup allows you to not need to drill holes in your roof for the panel wiring.

I actually do not have a solar suitcase but a flat/flexible 100w panel with a long cable that I keep stored under the bed. I can drag it out wherever and whenever. I can magnet it to my roof, cover the windshield with it or drag it out in the sun and anchor it to flat ground. Works great.

 

[RDinNHand AZ]

Good advice ^^^^. I’d also look at what that refrigerator is drawing. I had a Norcold 3 cu ft wall refrigerator (NR751) and have since gone to a 35 liter chest (Alpicool CF35) as It is so much more efficient. It should run for about 4 days on those aux batteries. If your current fridg. runs them down in one day a 100 watt panel will probably not give enough power to keep you going. My new fridg. could run on a 50 watt panel!

 

[Iva]

Good advice ^^^^. I’d also look at what that refrigerator is drawing. I had a Norcold 3 cu ft wall refrigerator (NR751) and have since gone to a 35 liter chest (Alpicool CF35) as It is so much more efficient. It should run for about 4 days on those aux batteries. If your current fridg. runs them down in one day a 100 watt panel will probably not give enough power to keep you going. My new fridg. could run on a 50 watt panel!

I have alpicool t50 with freezer and it consumes 60w so it runs out optima yellowtop battery in one night to to 10.0v sometimes.

 

[Iva]

You want to connect your solar to your auxiliary battery. Your solar controller limits the amount of charge from the solar panel depending on need. While your car is running and the solar controller feels that juice coming from the alternator it will not allow solar charge as well, at least in every setup I've installed or owned. You won't burn your car if wiring is properly sized and wired. This should work in reverse with your isolator as well. If parked in the sun charging auxiliary battery via solar eventually your isolator will charge that battery and divert some current to your vehicle battery to keep it topped up.

I would recommend you consider a solar suitcase (portable) panel setup. This will allow you to park in the shade when possible and put your panel out in the sun. Personally I use both a fixed and a suitcase but just going with a portable setup allows you to not need to drill holes in your roof for the panel wiring.

I actually do not have a solar suitcase but a flat/flexible 100w panel with a long cable that I keep stored under the bed. I can drag it out wherever and whenever. I can magnet it to my roof, cover the windshield with it or drag it out in the sun and anchor it to flat ground. Works great.

Thank you for your advice! My wiring is correct as it comes with all wires like a kit.
I will not drill anything solar panel has a holes and will ziptipe on roof rack. For the first panel will use it and try to buy not fixed one also !
One more question do i need to put fuse? An where ?

 

[86scotty]

LInk the kit you are considering. It may come with a breaker or inline fuse. Someone here will have experience with it.

I understand you are attaching to a roof rack but you still have two 10 gauge wires (not exactly thin) to the solar controller and then on to the battery. For most rigs that requires a hole in the roof somewhere. It's possible you could through the corner of your rear hatch but not as clean or durable that way.

 

[Iva]

LInk the kit you are considering. It may come with a breaker or inline fuse. Someone here will have experience with it.

I understand you are attaching to a roof rack but you still have two 10 gauge wires (not exactly thin) to the solar controller and then on to the battery. For most rigs that requires a hole in the roof somewhere. It's possible you could through the corner of your rear hatch but not as clean or durable that way.

This is kit i take.
I have already thought how i will wire it. On one side of windshiled i have already hiden wire from my led and awning light so on other side i will hide solar wires and it will go than to hood, controller and battery.

 

[VanWaLife]

You might also want to add a low voltage disconnect for the dual battery system...actually thought most fridges would turn off before hitting 10V. But I've burned through two yellow tops pretty quickly running them down that low.

 

[Iva]

You might also want to add a low voltage disconnect for the dual battery system...actually thought most fridges would turn off before hitting 10V. But I've burned through two yellow tops pretty quickly running them down that low.

So you think for yellow top going to 10.0v is too low ? Mine working still perfect even sometimes i use it till 9v

 

[VanWaLife]

So you think for yellow top going to 10.0v is too low ? Mine working still perfect even sometimes i use it till 9v

I know I've burned up two running them down that low in probably fewer than 50 cycles, took them back to the battery shop and they confirmed dead cells, while my starting yellow top is I don't really know how old and never gives me problems. Different charging between cycles could account for our different experiences. Taking a second to read up, apparently letting them sit for long periods of time in a discharged state is them big problem, which is exactly happened to mine before adding the low voltage cutoff.

 

[86scotty]

I would never run any battery down that low. My threshold is 12.0v

Most modern fridges have a low voltage cutoff built in and they are the biggest power hog for most of us in overland vehicles.

Iva, I would run a good quality DC breaker (20 amp) between your panel and your controller but I would not recommend a cheap controller like that one. I have heard of those cheap PWM controllers overheating and failing. If you can afford a decent MPPT controller you'll never have to replace it, even if you add panels, and it will also pull more juice from your panels and charge your batteries more efficiently.