Aloha! I don’t have an RV but I do have a 1972 VW bus converted to be a coffee bus and have a question. My first thought was an RV forum because it is similar to how RVs operate! I would like to be able to run my fridge and freezer off of an extra battery while in transit and parked (but not necessarily operating).Right now I run the fridge and freezer off of a 2000w generator while operating (I park in one spot only, and the bus plugs directly into generator and everything is powered by an inverter ). I also power an electric kettle and coffee grinder with the generator. When I’m not operating (in transit) the fridge and freezer remain unpowered. When the bus is parked at my house it is plugged in (power from the house plugs directly into the exterior of the bus (1972 VW) and everything is powered through the inverter). What I would like to be able to do is charge an extra battery while it is plugged in to the house so that it is possible to have the fridge and freezer running (off the extra battery) while I am parked/in transit for a little while. My husband could do it if I can get step by step instructions on what to do! Thank you so much for your help!

Need a total and complete list of refrigerator and freezer brand names and model numbers. Total hours of operation daily. Number of hours driven. It is a complex formula that can only be done by the numbers

If I understand your question correctly, you have three modes, parked, transit and operation.Parked is at your house and you have house power available. Transit is when you do not have power available. Operation is when you are powered with the generator.You require powering only the fridge and freezer with the battery during transit. You are not operating the kettle or blender with battery power. You can recharge the battery during Parked and Operation. How many hours a day are you in Transit mode?How many hours a day are you in Operation mode?

MEXICOWANDERER wrote:Need a total and complete list of refrigerator and freezer brand names and model numbers. If you do NOT start the discussion with this information it likely will just be a waste of time.....and maybe money too.Why ? Because the way you THINK things work may not be how it works at all.

Your engine alternator will be the only thing available to charge your batteries while driving unless you consider adding some solar power to the roof as well.A couple of good 6V golf cart batteries will likely keep your fridge and freezer going for 1/2 day if the doors are never opened and the battery if fully charged. The alternator will add some time to this formula and solar could make it pretty much unlimited depending upon the setup. Opening the doors puts a whole different twist to the story so what you have and how you plan to use it will make all of the difference in the World!

Given that you are in Maui, solar would be a good option You will have to do some calculations to figure out how much battery and solar you need. THIS IS A GREAT SITE to figure out your solar needs and explains it very well. I highly recommend you do your reading on this page and the linked pages, for some good education on how to use and manage a 12V system. You want to avoid repeatedly depleting the battery bank below about 50%--that is death to deep cycle batteries. They also need to be totally recharged often, don't keep running them at about 80%.

How to run fridge/freezer off extra battery | Good Sam Community

17 Replies

Dusty_R
Explorer
Mar 08, 2018
Maybe what your calling an inverter in a converter.
A converter changes 120 volts AC to 12 voltes DC.
An inverter changes 12 volt DC to 120 volts AC.
time2roll
Nomad
Mar 08, 2018
I don't follow if the generator or an inverter is powering these items? Or is this an inverter/generator like a Honda 2000?

Otherwise you need 2 to 4 batteries to really run a 2000 watt inverter. You also need a method to keep the battery charged. And you will need a transfer switch to integrate into the electric system... or you will be swapping plugs.
coolmom42
Explorer II
Mar 08, 2018
Given that you are in Maui, solar would be a good option

You will have to do some calculations to figure out how much battery and solar you need.

THIS IS A GREAT SITE to figure out your solar needs and explains it very well. I highly recommend you do your reading on this page and the linked pages, for some good education on how to use and manage a 12V system.

You want to avoid repeatedly depleting the battery bank below about 50%--that is death to deep cycle batteries. They also need to be totally recharged often, don't keep running them at about 80%.
Bill_Satellite
Explorer II
Mar 08, 2018
Your engine alternator will be the only thing available to charge your batteries while driving unless you consider adding some solar power to the roof as well.
A couple of good 6V golf cart batteries will likely keep your fridge and freezer going for 1/2 day if the doors are never opened and the battery if fully charged. The alternator will add some time to this formula and solar could make it pretty much unlimited depending upon the setup. Opening the doors puts a whole different twist to the story so what you have and how you plan to use it will make all of the difference in the World!
Sam_Spade
Explorer
Mar 08, 2018
MEXICOWANDERER wrote:
Need a total and complete list of refrigerator and freezer brand names and model numbers.

If you do NOT start the discussion with this information it likely will just be a waste of time.....and maybe money too.

Why ? Because the way you THINK things work may not be how it works at all.
2112
Explorer II
Mar 08, 2018
If I understand your question correctly, you have three modes, parked, transit and operation.
Parked is at your house and you have house power available.
Transit is when you do not have power available.
Operation is when you are powered with the generator.

You require powering only the fridge and freezer with the battery during transit. You are not operating the kettle or blender with battery power. You can recharge the battery during Parked and Operation.

How many hours a day are you in Transit mode?
How many hours a day are you in Operation mode?
MEXICOWANDERER
Explorer
Mar 08, 2018
Need a total and complete list of refrigerator and freezer brand names and model numbers. Total hours of operation daily. Number of hours driven. It is a complex formula that can only be done by the numbers

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How to run fridge/freezer off extra battery

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