Community Forums

donhoward49 · 11-14-2013, 04:46 PM

Need ideas. Class A, starting battery, 6 months old. Unattended for 3 or 4 weeks. And dead. I charged it and its holding a good charge for several days. but what could drain it so quick? Ignition off, steps off. I am looking at a knife blade switch but would prefer to find another way.

dabrooks · 11-14-2013, 05:01 PM

On our previous motorhome the chassis battery would only stay charged 2 to 3 weeks. I put the knife blade disconnect on the negative post and had no more problems. It was easier than looking for what was draining the battery. I am thinking of doing the same thing to the new one.

Rocky Larson · 11-14-2013, 05:19 PM

Look for items that are front end / dash related. CB radio on but turned down, dash radio display on, under the hood light left on, anything plugged into power sockets?

BFlinn181 · 11-14-2013, 07:01 PM

Your radio memory and clock, engine ECU all take energy from the battery. In addition, you might have other circuits on 'standby' that might use energy. You're taking it out and not putting it back in. Install an isolating switch or put a solar battery charger on the roof if leaving it unattended more than 2-3 weeks.

chuckftboy · 11-14-2013, 07:55 PM

If you are parked outside, you could just put a 5 watt solar panel on the dash and plug it into the cigar lighter

Fred and Bonnie · 11-14-2013, 08:01 PM

Quote:

Originally Posted by chuckftboy

If you are parked outside, you could just put a 5 watt solar panel on the dash and plug it into the cigar lighter

X2, I use an additional 10W panel to keep the house batteries charged.

fred

donhoward49 · 11-14-2013, 09:57 PM

Thanks all. no CB radio, dash radio is on house batteries, MH is undercover so cannt do solar... Still thinking I will do the knife blade to isolate the battery. As DABrooks said, it will be easier than finding the problem.

2 Stroker · 11-14-2013, 11:21 PM

We got our coach in January and it had new batteries but it took about 3 weeks for my 8D starting battery to go dead. After checking my Xantrex Echo Charger
Xantrex Echo Charge went bad so I replaced it with a Magnum Combiner. Now I have 13.5v all the time when pluged in.
Magnum Me SBC Smart Battery Combiner | eBay
Some coaches do not charge the starting batteries when plug in to power.
2 stroker

TVforMyRV · 11-15-2013, 08:22 AM

Indeed, many coaches do not charge the chassis batteries when plugged in.

As mentioned before, there are a lot of parisitic current drains on a motorhome even with everything turned off. For instance, the power step control unit, the engine and transmission ECUs, and many more.

The Ultra Trickle Start is a good and economical way to keep the chassis batteries topped off when you are charging the house batteries. It is very easy to install and requires no maintenance or looking after.

If you are not plugged in and are storing under a cover, the portable solar panels ( 5 watt or 10 watt )work great too. Just hook them up to your chassis batteries and lay the panel out in the sun. A 10-watt solar panel will not produce enough current to "overcharge" your chassis batteries.

Don

donhoward49 · 11-15-2013, 08:28 AM

TV4MYRV, thats an idea to just lay a solar charger on the ground.. I am in a storage lot but its secure and has cameras... Do you think I could put a cable lock on the charger, maybe drill a hole close to the edge..

garbonz · 11-15-2013, 08:39 AM

Quote:

Originally Posted by donhoward49

Thanks all. no CB radio, dash radio is on house batteries, MH is undercover so cannt do solar... Still thinking I will do the knife blade to isolate the battery. As DABrooks said, it will be easier than finding the problem.

Get a disconnect.. If you need convincing get or borrow a fluke meter and see what your parasitic draw is.

Put simply a .25 amp draw (pretty typical) is 6 amps per day, which, in a 100amp starting battery gets you 14 days before dead and maybe less than that is you want to use it to start the coach. There probably is nor problem just normal draw

Cheapest and easiest way is a disconnect. Solar option would work also.

TVforMyRV · 11-15-2013, 08:55 AM

One reason that I try not to use the knife switch is that many newer engine and transmission controllers "learn" and "adapt" shift pressures etc, based on driving experience. So when you dis-connect the batteries, the ECUs and TCUs are going through it's learning process every time you start out.

The portable solar chagers that I linked to in the previous post have grommets installed in the corners. I'm sure you could thread a cable through there to provide a "locking" function. However, a determined thief could cut around the grommet. Actually a determined thief can get around almost anything.....

garbonz · 11-15-2013, 09:01 AM

Quote:

Originally Posted by TVforMyRV

One reason that I try not to use the knife switch is that many newer engine and transmission controllers "learn" and "adapt" shift pressures etc, based on driving experience. So when you dis-connect the batteries, the ECUs and TCUs are going through it's learning process every time you start out.

The portable solar chagers that I linked to in the previous post have grommets installed in the corners. I'm sure you could thread a cable through there to provide a "locking" function. However, a determined thief could cut around the grommet. Actually a determined thief can get around almost anything.....

Good point, although many have some non volatile hard memory that stores the important information and reloads it on start or power up. It is a pain to reprogram the stereo tho...