Battery and Refrigerator fan

dougrainer wrote:

You need to clarify what a LOT of power means.

Fridge in LP mode can draw 7-10 AH per 24 hours. 15 AH is not unheard of. This is more than a small fan would draw, especially if the fan is small and cycling. Compared to 40 AH usable capacity of 27 Group battery, this is a lot too.

What I'm trying to say here, is that the OP should measure or check his fan specs. And consider his frig draw. Thinking that the fan is the only item that is drawing the current when everything seems to be "off" would be a mistake. Parasitic loads may also include radio on standby, detectors etc.

The small (4cf?) frig in my TT draws only .5 amps in LP mode. I installed two "3-speed" computer fans behind my frig and they each draw anywhere from .3 to .6 amps depending on speed (.6 to 1.2 amps total). I run them 24/7. Addition to this, my TT also has a parasitic draw of .13 amps (everything turned off).

With only the frig turned on in LP mode, plus the two frig fans set to low, my total 12 vdc current drain is 1.23 amps (including parasitic). I'm guessing a 27 series battery (approx. 85-95ah) would power my TT in this mode for about 55-70 hours if I completely discharged the battery (0%). Of course, discharging less than 50% is not recommended, but at least this gives you a general idea of a 27 series battery's maximum capability.

Almot wrote:
Most RV fridges draw a lot of 12V power when in LP mode. Can be 5-7 times more than that fan. Older propane fridges require no 12V power when on propane, but those newer than 10 years usually do.

You need to clarify what a LOT of power means. The refers draw very small 12 volt power when on LP. A LOT less than any 12 volt fan. Less than 1 amp. The Fan should be connected to a tstat to prevent operation when the refer does NOT cool and has reached the preset temp. Remember, refers do NOT run on LP all the time. They will cycle off and on as the tstat opens and closes. As to your statement on older refers 10 years? Well those refers are MORE than 30 years old. Refers built since about 1983/85 have electronic ignition. The amp draw listed below is for the LARGEST RV refer, a Norcold 1200 with 2 fans and EXTRA heater systems. Most 2 doors will not have the Moisture reduction and 2 fans but 1 fan. Pay close attension to the gas valve draw. THAT is usually the ONLY draw on a 2 door. Doug
DC amp draws (at nominal 12 Vdc)
Automatic ignition-------------------------------------------------------------------------------------------------------------------0.50 A
Moisture reduction heater and divider heater--------------------------------------------------------------------------------0.70 A
Fresh food compartment lamp--------------------------------------------------------------------------------------------------0.46 A
Gas valve----------------------------------------------------------------------------------------------------------------------------0.146 A
Fans (2)-------------------------------------------------------------------------------------------------------------------0.30 A (per fan)

ours has two fans small like in a computer, they run all the time ,I have two batteries in my rv ,its never run the batteries down, they pull very little. AND I disagree with the post that say a frig pulls alot of 12V . with the electronic boards and etc they use very little 12v.

Most RV fridges draw a lot of 12V power when in LP mode. Can be 5-7 times more than that fan. Older propane fridges require no 12V power when on propane, but those newer than 10 years usually do.

Hard to say with any accuracy since we don't know the draw or duty cycle of this fan. Fans specs should indicate how much power (watts of amps) is consumed and does it run all the time or only at certain temps which would help determine duty cycle.

Since the fan is more than likely a very small draw, battery will behave about the same as before the install with slightly less performance, overall the change won't be extremely noticeable. Hopefully we are only talking about a few days, to expect more from a single battery is asking a lot.