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Battery Booster And Air Compressor

P

pbaker2225

Junior Ranger
Donating Member
Can anyone recommend a portable battery booster with air compressor? On my upcoming trip I will have the refrigerator in the back of the car and want some insurance that I will be able to start my car if the fridge drains the battery. Thanks
 
Hi Pat,
Letting your automotive battery drain down to the point where it would need a booster to get your vehicle started is really hard on the battery, and will do irreversible damage to the battery's reserve, and charging capacity with each such event.

If you want to use your TV battery to run your refrigerator you might want to consider something that would prevent the battery from being discharged enough to require a jump like this Amazon.com: Battery Protector (T4): Automotive or Blue Sea m-LVD Low Voltage Disconnect or a few more options Automatic Low Voltage Disconnect Switches | Waytek Wire
I don't have experience with any of them, so can't make a recommendation, but I do have experience with having to replace batteries that have been allowed to carry a load to the point of depleting the charge to below engine cranking capacity.
A dedicated deep cycle battery and solar/car charger might be another option for your continuous use appliances.

Just my 2 cents worth.

Dustin
 
pbaker2225 said:
Can anyone recommend a portable battery booster with air compressor? On my upcoming trip I will have the refrigerator in the back of the car and want some insurance that I will be able to start my car if the fridge drains the battery. Thanks
Click to expand...
I'm really surprised to have found this thread :) What I am looking for. There is the solar eclipse Amazon.com: Solar Eclipse SE_JUMP_AIR 1,700 Peak Amp Jump Starter with Air Compressor (425 Cranking Amps, Portable Battery Booster), 1 Pack: Automotive air compressor and battery booster and also jump starter. Battery indicator, built-in AC charger o_O
 
I agree with points made by dustinp. The problem with running the refrigerator in the tow vehicle is that it is a large draw on the battery. There is no simple, practical way of solving that problem.

Check out the website for Battery Tender. They make a battery monitor that can alert you via Bluetooth if the battery voltage drops below a set point. But a Dometic will drop the voltage low enough that it might get set off a lot.
 
Randy, Thanks, I'll look up the Booster and you reminded me that my Mom may have one of those little compressors in the shop. I'm sure if she was still here she would know exactly where. I think I will look for it.
That battery protector looks like a good idea. I was hoping to never run the battery so low it is damaged but want the insurance that I can start my car in an emergency. I thought our fridge has a protector on it to prevent complete discharge of the battery. Does that only work with the camper battery? Looks like I have a lot of work to do. I sure don't want to be constantly worried about my battery when I stop to see sights. I'm going to be traveling in hot weather so the fridge will probably shut down in the Galley.

Thank you everyone. This will be my first long haul trip so I need all the help I can get.
 
You are correct Pat. I just read through the owners manual for the Dometic CF35, and here is what it says:

Using the battery monitor
The device is equipped with a multi-level battery monitor that
protects your vehicle battery against excessive discharging when
the device is connected to the on-board 12/24 V supply.
If the cooler is operated when the vehicle ignition is switched off,
the cooler switches off automatically as soon as the supply voltage
falls below a set level. The cooler will switch back on once the
battery has been recharged to the restart voltage level.
a
Caution – Danger of damage!
When switched off by the battery monitor, the battery will no longer
be fully charged. Avoid starting repeatedly or operating current
consumers without longer charging phases. Ensure that the battery
is recharged.
This is how to select the battery monitor mode:
CF-25, CF-35, CF-40, CF-50, CF-60
➤ Switch on the cooler.
➤ Press the "SET" button (Fig. 4 4, page 4) three times.
➤ Use the "UP +" (Fig. 4 6, page 4) and "DOWN -" (Fig. 4 7,
page 4) buttons to select the battery monitor mode.
✓ The selected mode then appears in the display for a few sec-
onds. The display flashes several times before it returns to the
current temperature.
I
Note
When the cooler is supplied by the starter battery, select the battery
monitor mode "HIGH". If the cooler is connected to a supply battery,
the battery monitor mode "LOW" will suffice.
If you wish to operate the cooler from the AC mains, set the battery
monitor to the "LOW" position.

There was a table on what the voltages are for the different modes, but I couldn't get it to print. If you are interested in looking at it, or any of the rest of the manual, here is a link to the online version: Using The Battery Monitor - Dometic CoolFreeze CF-35 Instruction Manual [Page 17]

So, as long as that is the case, your original idea of the booster as some added insurance may not be a bad one, as long as the Dometic does it's job of shutting down before discharging to the point where damage to the TV battery is done. Sounds like you need to make sure you charge it long enough after a low voltage shut down to make sure it gets fully recharged in order to prevent battery damage.

Good luck, and let us know how your choice works out!
 
Most brief sightseeing stops shouldn't be an issue (that really depends upon when the compressor chooses to cycle on - it could cycle on while you are driving, or choose to wait until the ignition is turned off). It is the longer overnight storage that is the main challenge.

There is indeed a built in battery monitor in the Dometic. Without regurgitating a lot of past posts, I think you will need to see for yourself how the three settings work out. We had a three week old camper battery last spring (before it started warming up), and with the Dometic on Med and temp set at 39 it would not last the night without shutting off repeatedly. Perhaps it can do that and things will still be fine - we were never willing to risk a full load of food to know for certain. You would need to check the manual, but on Med I believe that when the compressor cycled on it drew the battery voltage below something like 11.4v, causing it to shut down. So in our view how well you will do with any setting other than Lo is a big question mark. We have our Dometic in our van throughout the day, but we put it in the camper at night. In our uneducated view, that balances the stress on both batteries, so that neither takes all the deep draw downs when the compressor cycles. But we can appreciate that not everyone would want to lug it back and forth.

But there are endless variables. For instance, we normally drive just a few hours per day and relatively short distances. I suspect most owners drive farther and thus the alternator does more charging.

I'm sorry we can't offer any concrete advice. The folks with sophisticated battery monitors would be better able to do that, but I don't recall any of them storing the Dometic in their tow vehicle.
 
I would recommend testing this in your driveway, measuring the battery accordingly. I follow off road overlanding groups that use Dometic in the back of their Jeeps, 4Runners, FJ's, etc with no issue for multiple day/week trip. I use a fairly large Snomaster CL60 fridge that's direct connected to the battery 24/7 and have had no issues including on a recent 2 week trip. An empty fridge will work harder/cycle more on/off than a full fridge, so even if you put in jugs of water, test it full as as close to how you'd expect to use it as possible. Full is best. Make sure your battery isn't near the end of it's life either. Good luck!
 
Thank you everyone for all the information. I should have looked at my fridge instructions. I think I need to double check and see if I have it set properly. I also wondered about putting a frozen jar of ice in there is case the fridge shut down. I think you are right that I need to test it in the driveway and check the battery to see how old it is. Maybe if it is aging I should buy a new one and have it ready to install in an emergency.
Also am thinking about solar. Will locate the connection that came with my trailer. My daughter has two 15 watt Goal Zero panels that she has never used but no controller. She will let me take them on this trip to see how they work. I don't suppose 30 watts is enough though.
 
I don't know what your tow vehicle is, but if you are towing a 560 it is likely to have a fairly heavy duty battery. And how any auto battery compares to the camper's AGM battery is a total mystery to me. I suspect the larger the tow vehicle, the more substantial the battery's capacity as compare to the AGM. There are just way too many variables.

30 watts would generally be about 1/3 of what you need to keep the AGM battery fully charged while running the Dometic. But if you are primitive camping and had the Dometic in the camper, it would help take some of the load off the battery.

Putting the frozen block of ice in the Dometic will considerably reduce the load on it. While Dometic doesn't recommend it, when we fried our camper battery a couple of years ago we put a bag of ice in it to keep our stuff cool (we needed to be very vigilant against leakage).
 
Terri has done several off-road weekly trips in her Jeep with our Dometic CF35 in the back. Keep in mind, she is traveling 4-6 hrs a day minimum. She has never had a problem with the Dometic pulling the Jeep's battery down, nor the Dometic staying cold enough. She does precool the Dometic before venturing out. We keep several water bottles in the bottom of the cooler and move them to the top when necessary. We keep the temp set at 29 which will freeze the water in the bottum of the cooler. Since we don't use a small fan inside the cooler, the temp will vary from the top to bottom of the cooler.
 
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