Hi Dave,
This will be my first time to keep the 5th wheel in storage. I have two questions, below. Mainly I am looking for a recommendation on a battery tender [maintainer]. I have two 12V batteries hooked up, as shown in the attached photo.
Q1: What battery tender do you recommend I purchase for my setup? It looks like the first battery is the one connected to the 5th wheel power. Second battery is tied to the first battery.
Q2: Is there a certain way I need to connect the tender to these batteries? I have seen conflicting info on Google. Some say connect only to one battery, some say connect to the negative on one and the positive on the other. —Cody, 2022 Rockwood Ultra Lite 5th Wheel 2893BS (Forest River)
Hi Cody,
You have two 12-volt deep cycle Flooded Lead Acid (FLA) batteries that are connected parallel, which is cabled positive to positive, negative to negative. That keeps the 12-volt bank but doubles your amp hours. And, as you indicated, there is a cable coming off the positive and negative cable on the upper battery to the ground and distribution center.
How the converter and inverter/charger work
Normally the converter or inverter/charger would provide a charge to these batteries when connected to shoreline power. In the past, I had recommended to just let the converter keep the batteries maintained. However, I have found too many times that the converter has boiled the batteries dry as it did not drop into maintenance mode.
When the batteries are low, the converter or inverter/charger is designed to give a higher voltage charge of 13.6 volts or even higher if your rig has a multi-stage charger. This type of charger puts out anywhere from 14 volts to 16 volts to break up sulfation that forms on the plates during normal usage. Then it is supposed to drop to an equalizing and float charge. A maintenance charge is 13.2 volts, at which voltage a typical FLA battery will not accept a charge and it just stays in a maintenance charge mode.
Here is a set of batteries that the charger did not come out of initial charge mode and boiled the batteries, rendering them useless. Notice the corrosion and swelling of the batteries!
RV trailer manufacturers don’t usually supply a battery
Typically the RV manufacturers of travel trailers and 5th wheels do not supply a battery. This is because there are so many choices as to how you will use the rig. The transport company uses a very inexpensive battery to deliver the unit, and the dealer installs whatever brand they carry. In your case, it was Interstate, which is common as they are inexpensive and easy to find all over the country. They are not the best battery, but they’re not the worst either. It depends on how well you maintain them.
Since you are asking about a low amp battery maintainer, I assume you will have 120-volt power available. As I stated earlier, I have found too many converter/chargers that have not dropped down to the maintenance mode. So I recommend shutting off the converter or inverter/charger at the distribution center or on the inverter so there is no charge voltage coming from that. I also assume your rig comes with a battery disconnect switch that would be good to activate, as well, to reduce the chance of something drawing from the batteries.
Notice I said “reduce,” as most of the LP leak detectors are wired direct. They will still draw about 1-2 amps and can drain a battery in a few weeks. This is where the low 1.25- to 3-amp battery maintainer comes into play. Most RVers use the Battery Tender, which is available almost everywhere and on Amazon here.
It is a good maintenance tool; however, your battery will still get sulfation during the storage months. Some people like to use a small solar panel to maintain the batteries. That does about the same thing and is a good option if you do not have 120-volt power.
BatteryMINDer is highly recommended
I like the BatteryMINDer® either in the small 120-volt model or the solar panel version. According to the technician I talked with several years ago, the BatteryMINDer uses a pulse technology to not only charge the battery but dissolve sulfation and double the life of the battery. You can find them on Amazon here.
Just a note: I have been telling readers and seminar attendees about BatteryMINDer for years and have used them myself. Everyone has been thrilled with the extended life of their batteries. However, I have also received a comment in one of my RVtravel.com posts that it is just snake oil and I have “drunk the cool aid”. I have used the product for years, given them to my father-in-law and friends, and have asked attendees in my seminars what they think of the product. All of the feedback has been positive. Plus, all the reviews on Amazon and other buying sites are 4.5-5 stars, so I am sticking to my recommendation.
How it should be connected
Typically your two 12-volt batteries that are connected parallel would have the positive cable coming from one battery and the negative coming from the other, rather than just the one battery. I would recommend switching your cables, then place the positive jumper clamp on one battery and the negative on the other.
You might also enjoy this from Dave
RV is plugged into 30 amp in a heated garage but engine batteries still die. Why?
Dear Dave,
My RV is plugged into a 30 amp that is located in a heated garage. Today and earlier this year the starter batteries were dead. I left the bay lights on for about 24 hours. I boosted the batteries with the house batteries, started the engine, and then shut the engine down. Then I connected a battery minder to the two starter batteries. After a couple of hours, the red light went out on the minder or tender. I was surprised that it went out so soon. —Denny, 2011 Monaco Camelot 43DFT
Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
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I’m confused on the “How to connect” paragraph.
Hi Dave I don’t understand your last statement ! “I would recommend switching your cables, then place the positive jumper clamp on one battery and the negative on the other.” Why or how can he do that as they are already hooked up like that! Of course its early, so I probally missed something.
Snoopy
I didn’t understand either.
I think Dave is referring to the connections from the battery bank to the RV. It is recommended the positive and negative be connected to opposing corners of a bank of batteries. From what I have read, if both are attached to only one battery in the bank it can cause an unbalance in current flows through the bank.
Ok after my second cup of coffee I went back & looked at Codys pic & sure enough it needs to be changed as Dave has said! It still needs some clarification on switching your cables!
Snoopy
When in storage with no AC available, I completely disconnect the battery from the RV so there is no parasitic use. And I use this solar panel. I also switched to AGM batteries rather than flooded to avoid dry cells during unattended storage. This solar charger has built-in circuitry to automatically switch between charge and float.
Rather than trying to charge both batteries I’d get 2minders and connect each battery individually. If any cell is bad the minder will attempt to charge it and boil the good cells. Cost me $1200 to find that out. Boiled and ruined my golf cart batteries . Best bet also is take the wires (only) off each negative post and put charger only on battery. Thereby eliminating any load like propane detector. If you just install minder it sees the propane detector as a load and will not shut off because thinks battery needs charge.
In my 40+ years of having to maintain equipment and batteries for everything from small lawn mowers to OTR trucks and D-9 Cats in a harsh winter environment where 20 below was not uncommon the only 2 brands of maintenance chargers that conditioned and protected batteries without overcharging are Schumacher and CTEC. Every other brand we tried ended with ruined batteries.
Battery Tender-failed. We tried them three different years on both AGM and flooded cell batteries.
Personally I have Schumacher’s trickle chargers permanently mounted in my truck and I use CTECK’s on the motorcycle’s , lawnmower and stored Nissan 300ZX.
CTECK’s are expensive but they have a reconditioning program.
I have used battery tenders for years with no problems. No FLA battery lasts forever…but I have gotten 10 years out of some of them using these chargers in the past. Have never used a battery minder so can’t say about those.