big-gags avatar image
big-gags asked

Solar Setup for ARB Elements Fridge

Hey guys - I'm new to this forum and looking for a bit of advice in setting up a solar panel and MPPT regulator for my Ranger.

Car has a 60 litre ARB Elements fridge fitted and a 55 Ah Optima yellow top battery. Also has a Redarc BCDC1220 fitted which unfortunately does not provide regulation for a solar input. The aux battery is located under the rear seat and it has a short lead with an Anderson Plug on it that the previous owner apparently used to attach solar to.

I don't have detailed specs of the fridge but the label on the back of it lists a "nominal current" of 6.5 Amps. I also found a US website that claims it uses 0.89 Ah per hour and an AU video on youtube that measured about 0.65 Ah per hour (at about 25 deg C ambient).

My thoughts are to go with a Victron 175W fixed monocrystalline solar panel and a Victron MPPT 75/15 regulator as a short-term solution and in the long term I will most likely also upgrade to a LiFePo battery.

Question - if I go with this setup, should I connect the Load output of the MPPT 75/15 directly to the fridge or should I connect the fridge directly to the battery??

Assuming that the "nominal current" of 6.5 Amps on the fridge label represents the maximum current when the compressor and fan are both running then theoretically it should be OK to connect directly to the Load output and this would also prevent my Optima battery from over-discharging.

Would appreciate any advice from those in the know.



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2 Answers
Mike Dorsett avatar image
Mike Dorsett answered ·

First would be to use a clamp meter to measure the fridge current. If this is <15A at startup, things should be fine, according to the data, the load output is short circuit proof, so it would be ok to try. If the start up current is very high, then you can use a 12v relay driven by the load output to disconnect the fridge.

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kevgermany avatar image
kevgermany answered ·

Usually compressor fridges have a much higher startup current than the nominal one. It may or may not work on the load terminals. See section 3.6 of the manual. If it doesn't, just switch the wiring direct to the battery.

Solar output from the panel will depend on the amount of light you get. Very heavily affected by weather conditions as well as season and location. On the surface it looks as if the panel is big enough, but...

Would be a good idea to design it so that a second identical panel can be added if needed and you have space. I'm getting 0-10% of theoretical panel output at the moment, coupled with short winter days it means that with everything off, I can just about keep the batteries topped up on solar.

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