%th Wheel Batteries

Digital Multimeter..

HERE for $7..

Set to 20V DC on the meter.

Plug red lead into meter socket marked "V" (the middle one)and the black lead into the bottom meter socket.

Turn meter on.

Place red lead on POSITIVE battery post and black lead on NEGATIVE battery post.

Battery resting voltage hen fully charged with no load and charger/converter is turned off should be 12.8V or a bit better..

With converter turned on you should have 13.4V-13.6V minimum voltage.

If converter is turned on and you have less than 13.4V-13.6V you have an issue with converter (blown fuse, dead converter, no power to converter).. Which will require additional troubleshooting..

Battery resting voltage below 12.8V-11V with converter turned off will mean partially or fully discharged battery or failed battery..

Battery resting voltage below 10V with converter turned off means deeply discharged battery or completely shot battery..

Do you disconnect a battery cable to isolate the fully charged battery while in storage? Otherwise the battery will most likely overly discharge, sulfate, and lose capacity.

The 12 Volt Side of Life

While in storage, the disconnect switch is set to "off". Once a month, I recharge by running Honda generators for about six hours. That's not scientific (I don't know how much time is required for a full recharge), but it seems to work. It has the added benefit of exercising the generators.

RoyF wrote:
While in storage, the disconnect switch is set to "off". Once a month, I recharge by running Honda generators for about six hours. That's not scientific (I don't know how much time is required for a full recharge), but it seems to work. It has the added benefit of exercising the generators.

Not "everyone" has a "disconnect switch" on their RVs, on most trailers it is not even an option. If owner wants one, they must install it.

To me, disconnect switch just adds an additional point of failure and more resistance..

But, yes, IF it is not possible to have shore power connected 24/7 while in storage it IS highly recommended to disconnect the battery(ies) from the trailer electrical system..

No switch, no problem, just locate the negative terminal of the battery and remove the wire(s) from the negative of the battery.

No need to remove both pos and neg.

Also, MARK THE WIRES CLEARLY WITH GOOD LABELS!!!!

Spring time always brings tons of posts with questions about which wire goes where.. Labeling the wires before disconnecting them from battery will go a long way towards not having to ask that question.

A fully charged battery in fair condition can sit for 3-6 months without needing to be recharged as long as it is disconnected without hurting the battery..

If shore power is available 24/7, then you can leave plugged in 24/7 as long as the converter is a modern multistage version which has a storage mode.. Basically any RV manufactured yr 2000 and newer should be fine.. Older than yr 2000 models you should consult the power center for the model number and research to see what converter you have.

“Once a month, I recharge by running Honda generators for about six hours.”

While regularly running your generator under load is a good idea, six hours isn’t necessary and if you have shore power to charge your batteries it is wasteful.

RoyF wrote:
While in storage, the disconnect switch is set to "off". Once a month, I recharge by running Honda generators for about six hours. That's not scientific (I don't know how much time is required for a full recharge), but it seems to work. It has the added benefit of exercising the generators.

This is good. To really know what is going on you would need to measure voltage before charging to see if they are getting too low. 12.2 is about as low as you should let them be in storage.

The hard part is getting a full charge from many converters as they just charge at 13.6 volts and it is really slow. For a good charge you are looking for 14.2 to 14.6 volts about 30 minutes into the charging session.

Measure first but you might be better with a portable battery charger if you have one.

Or everything might be fine and the battery is just worn out.

Gdetrailer wrote:
With converter turned on you should have 13.4V-13.6V minimum voltage.

You should be getting about the same (or a bit higher) when your truck is running. Wait until it has been running for at least 5 minutes.

rockcandymountain wrote:
How can I check to see if my electrical system in my 5th wheel is charging the batteries?

My unit is a 2016 and after being in storage all winter and plugged into shore power, when it is not plugged in and I go to use the electrical leveling jacks, I get a low voltage error.

If the batteries are bad, I will replace them, I just don't want to do that if they are good. I keep the water level topped off. But I suspect the batteries are just worn out.

Tools needed Digital multi meter.

Optional pencil or pen and paper

Procedure

Hook up but leave tow vehicle OFF
Hook meter to batteries in trailer NOTE voltage (12.6 eggcelent)

Start Tow vehicle
Wait 2 minutes
Re-check meter anything higher than it was means charging.

Great answers all around. One other question that I forgot to post. If I wanted to trickle charge the batteries, not knowing if the 5th wheel is doing in when on shore power. Could I charge both at the same time by leaving the common jumpers that each battery shares but disconnect the batteries from the 5th wheel?

wa8yxm, I really like your answer! quick and simple. but I will explore all remedies before I drop a few hundred on new batteries

If you have incandescent bulbs, turn one on. Then start the vehicle. If it gets brighter--then the tow vehicle is sending energy to the RV.