So I finally bought a fridge. I got the Alpicool C50. It was cheap ($339), had great storage, and dimensions that I thought would work for my existing rear storage. It didn’t. I didn’t account for the rake of the rear window, so the glass hit the fridge and would not allow the door to close. So, that has sparked a complete revamp of damn near everything. During this process, I am adding a dual battery and solar setup to the rear, where the spare tire used to sit. I’ve raised the floor about 3” to match with the lip of the rear opening.
For the dual battery and solar, I won’t have a whole heck of a lot of power consumption, the biggest being the fridge. But I have no interest in killing my main starting battery leaving my wife, my dog, and myself stranded in the middle of nowhere, hence the dual battery (as I’m sure is the reason most of us do so). To start, it will be a standalone system with just the battery and solar, not tied into the electrical system of the vehicle. Eventually, I would like to tie it in for added charging, but I’m not too terribly concerned with my low consumption needs.
My plan is to use a Renogy 30watt fixed mono panel with an MPPT charge controller. Battery I am looking at just using the Harbor Freight Thunderbolt 35aH battery. It seems to be a decent battery for the price ($70). My wife’s grandfather uses two in his toyhauler, and has had no issues for a few years now. I’m not 100% stuck on that battery, but pretty much any other deep cycle battery I’ve seen with a higher ah rating is twice the price. I’ve also considered a used deep cycle, but everything in my area right now is too tall (I have a tad over 9” to work with). I’m also hoping not to go too terribly wide on the battery, as I hope to eventually mount on board air in the same area.
Here is where I hope to tap into the wisdom of this site. By my math, using the little bit of data Alpicool provides as well as some reviews and reviews of similarly sized fridges, I will like use anywhere from 11 to 14 ah per 24 hour period. The discrepancy obviously has to do with quality (efficiency) of the compressor and insulation, ambient temp, capacity, and desired temperature. I’ve actually see some people see as low as 9ah, but since I went with an inexpensive option I want to plan for worst case scenario. So I am doing my math based on an inflated 15ah in a 24 hr period. Given that a 35ah battery will only do about half that, am I running it too close? Keep in mind, I will have solar. 15ah x 12 volts gives me 180 watt hours. 180wh divided by 24 hours gives me 7.5 watts. So theoretically, a 30 watt panel should more than account for that for 8 hours or so of the day. My thought is that the fridge will cycle on and off more during the day, but if you take out the hours for solar…
16 hours of straight battery is 2/3 of the day.
2/3 of the ah consumption is 10ah. I should only need 10ah out of the roughly 17ah the battery will give me. I can always run a jumper cable to the vehicle alternator if necessary.
I’m hoping this setup will get me by at least until next year. My thought is get a decent 30watt Renogy solar panel, a good MPPT solar charge controller, and an “okay” battery for now. Next step, in about 6 months or so, add in the dual battery wiring to charge off vehicle when driving. Then, add a second 30 watt panel, and eventually go to 2x 6v golf cart batteries. If I can get to 100ah of usable capacity, I will be thrilled. I just don’t have it in the cards to get two $100+ batteries right now. I am trying to get this all set up before an 8 day trip coming up in the middle of October. And I still need a few pieces of gear for camping, like some decent sleeping pads (currently using a 3” foam mattress topper sucked into a space bag for transport, but the space bags kinda suck, and so does the mattress pad, want some decent self inflating sleeping pads).
So what do you think of my math? Seem sound to you guys? If you have any suggestions, please feel free to send them my way. Especially if you have a decent battery suggestion.
Pic of my Subaru for reference.
Rebel
For the dual battery and solar, I won’t have a whole heck of a lot of power consumption, the biggest being the fridge. But I have no interest in killing my main starting battery leaving my wife, my dog, and myself stranded in the middle of nowhere, hence the dual battery (as I’m sure is the reason most of us do so). To start, it will be a standalone system with just the battery and solar, not tied into the electrical system of the vehicle. Eventually, I would like to tie it in for added charging, but I’m not too terribly concerned with my low consumption needs.
My plan is to use a Renogy 30watt fixed mono panel with an MPPT charge controller. Battery I am looking at just using the Harbor Freight Thunderbolt 35aH battery. It seems to be a decent battery for the price ($70). My wife’s grandfather uses two in his toyhauler, and has had no issues for a few years now. I’m not 100% stuck on that battery, but pretty much any other deep cycle battery I’ve seen with a higher ah rating is twice the price. I’ve also considered a used deep cycle, but everything in my area right now is too tall (I have a tad over 9” to work with). I’m also hoping not to go too terribly wide on the battery, as I hope to eventually mount on board air in the same area.
Here is where I hope to tap into the wisdom of this site. By my math, using the little bit of data Alpicool provides as well as some reviews and reviews of similarly sized fridges, I will like use anywhere from 11 to 14 ah per 24 hour period. The discrepancy obviously has to do with quality (efficiency) of the compressor and insulation, ambient temp, capacity, and desired temperature. I’ve actually see some people see as low as 9ah, but since I went with an inexpensive option I want to plan for worst case scenario. So I am doing my math based on an inflated 15ah in a 24 hr period. Given that a 35ah battery will only do about half that, am I running it too close? Keep in mind, I will have solar. 15ah x 12 volts gives me 180 watt hours. 180wh divided by 24 hours gives me 7.5 watts. So theoretically, a 30 watt panel should more than account for that for 8 hours or so of the day. My thought is that the fridge will cycle on and off more during the day, but if you take out the hours for solar…
16 hours of straight battery is 2/3 of the day.
2/3 of the ah consumption is 10ah. I should only need 10ah out of the roughly 17ah the battery will give me. I can always run a jumper cable to the vehicle alternator if necessary.
I’m hoping this setup will get me by at least until next year. My thought is get a decent 30watt Renogy solar panel, a good MPPT solar charge controller, and an “okay” battery for now. Next step, in about 6 months or so, add in the dual battery wiring to charge off vehicle when driving. Then, add a second 30 watt panel, and eventually go to 2x 6v golf cart batteries. If I can get to 100ah of usable capacity, I will be thrilled. I just don’t have it in the cards to get two $100+ batteries right now. I am trying to get this all set up before an 8 day trip coming up in the middle of October. And I still need a few pieces of gear for camping, like some decent sleeping pads (currently using a 3” foam mattress topper sucked into a space bag for transport, but the space bags kinda suck, and so does the mattress pad, want some decent self inflating sleeping pads).
So what do you think of my math? Seem sound to you guys? If you have any suggestions, please feel free to send them my way. Especially if you have a decent battery suggestion.
Pic of my Subaru for reference.
Rebel
