Dear Dave,
Should I install a 30-amp service and keep the trailer plugged in when not in use? The trailer is under cover and I monitor the battery charge and run a heavy-duty cord at least once a month for a long weekend to charge the batteries. Adding a 30-amp circuit would mean trenching 75-ish feet. I’m very capable of this. Thank you. Enjoy your articles. —John, 2016 Arctic Fox travel trailer, 30-amp, with two 12-volt batteries
Dear John,
Battery charging profiles have changed considerably in that past few years, especially with the different types of batteries and converter/chargers. For years I was a believer in either having the rig plugged in so the converter/charger could keep the batteries charged. However, I have updated my ideas, as they say.
Storage solution depends…
The best storage solution depends on the type of battery and the area of the country you are in. If storing your rig in cold temperatures, you want to make sure you keep a Flooded Lead Acid (FLA) and Absorbed Glass Mat (AGM) from freezing, which can be done by applying a charge.
A battery at 100% State Of Charge (SOC) will not freeze down to -90 degrees F; however, at 50% SOC it will freeze at 5 degrees, and at 20% it will freeze at 20 degrees.
Lithium batteries do not have electrolyte and will not freeze; however, they can be damaged if charged below freezing. Therefore, they either need a heater or no charge.
I just had a similar situation with a Winnebago View stored in a facility behind my office. A new set of storage stalls were installed and one was rented out to the owner of the View. By code, any new enclosed storage facility requires a GFCI-protected outlet with either 50- or 30-amp service. The View is over 10 years old and, with nothing on in the unit, kept tripping the breaker.
We got an electrician in and found that the converter/charger was leaking voltage back through the neutral. They are so sensitive, it would not hold! Campgrounds with outside outlets only require a GFCI outlet on the 20-amp outlet, not the 30- or 50-amp. So that is why there is typically not an issue.
Options
So I did some research to figure out what options we had. This brought up another good topic of discussion. If you are just plugging in the unit to charge or condition the batteries, why do you need 30 amps? I got this question from Winnebago Industries, Expion 360, Battleborn, and others.
When you are plugged into a 30-amp outlet through the shoreline cord, the converter will always be running, providing at least 13.2 volts of maintenance charge. if it is not a multi-stage charger, it is not conditioning FLA or AGM batteries and they will become sulfated.
Also, you run the risk of the battery having a bad cell, or a charger not recognizing the SOC and providing a full charge of 13.6 volts or higher if it is a multi-stage charger. Plus, an FLA battery would need a fluid check every few weeks.
More options
Since you do not have any electricity currently, there are a few options.
1. Just keep doing what you are doing but get a trickle charge conditioner like this one and leave it plugged in. You can find it on Amazon here.
2. Have a certified electrician run a 20-amp outlet to the storage facility and plug in the same charger.
3. Use a smaller solar panel on the roof of the storage facility like this Renogy model, which is a 3-stage charger. It is available on Amazon here.
4. Remove the batteries and put them inside your garage and use the trickle charger.
If you have lithium batteries, most companies that I talked to suggested just removing the negative cables and let them sit. They will not drop more than 10% SOC for more than six months!
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Storing RV engine and house batteries in winter
Dear Dave,
My question is about RV batteries, both engine and deep cycle, while my coach is stored for longer periods during colder months. I have been shutting off power to batteries while in storage between trips. But, in longer winter storage periods, should I practice the same process? I’m not able to remove the batteries and place them on trickle charge like some people have recommended. I keep the coach in covered storage with power. Still learning more and loving it! Thanks for your input. —Karen, 2008 Safari Simba 36PCT
Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
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Thank you for expanding my knowledge of RV electricity, Dave! Have a great day and safe travels! 🙂
I prefer the #4 option.
It is worth noting that AGM batterIes self-discharge at a much slower rate than flooded lead acid batteries. I find that I still have 75% SOC after 6-8 weeks in storage at which time I use a Battery Minder to recharge
I have a LiTime lithium battery in my camper. The manufacturer states it has to be stored above 14 degrees F, so I had to remove it for the winter. When I had my AGM I kept a solar battery maintainer on it as you suggested. It kept the battery fully charged all winter, ready for spring.