Community Forums

trode · 05-02-2013, 05:01 AM

Perhaps I need some advice on how the house and chassis batteries interact. I have my motorhome in storage without power, I put a "knife blade" disconnect on the chassis battery to keep it from being run down by parasitic devices. The disconnect is on the negative post (only place it fits) and still the batter is able to run down with the switch open. How can that be on an incomplete circuit to the battery, in other words the only post of the battery that is connected in any way is the positive post. Also, while here about this, I open the knife blade switch, turn off the house bank, and still the step activates when I open the door.

I have looked at the wiring diagram in the information folders, can not really follow them well and hope someone here will explain.

Shadowcatche · 05-02-2013, 05:24 AM

The problem is that lead acid batteries will self discharge over time at roughly a rate of 2% per month with an AGM to up to 10% or 30% per month (opinions vary widely) and no doubt dependent on battery condition and temperature. This is one of the major advantages to AGM batteries.

donhoward49 · 05-02-2013, 07:21 AM

I do believe the steps work off the chassis battery, but I have been wrong before. I wonder if your steps have been re-wired by someone? Try it again with the House battery disconnect off.. See what happens. I do not have a chassis disconnect, and store mine without power. I do run the generator every 4 weeks or just take the batteries out to charge at home. That gets me by without dead batteries

flaggship1 · 05-02-2013, 07:32 AM

^^^ what he said. When I use the chassis battery salesman switch the steps go off. Steps may just be the biggest battery drain when the switch isn't thrown and yours may have been routed to the house batteries. I have cutoffs at the battery bays too for longer down times.

trode · 05-02-2013, 08:05 AM

Quote:

Originally Posted by Shadowcatche

The problem is that lead acid batteries will self discharge over time at roughly a rate of 2% per month with an AGM to up to 10% or 30% per month (opinions vary widely) and no doubt dependent on battery condition and temperature. This is one of the major advantages to AGM batteries.

I would understand that, but my battery will go dead in a week! That is what is not making sense. House batteries hold up ok and I can use the dash switch to start with those, but do not understand my chassis battery draining. FYI the battery is about 8 mos old.

trode · 05-02-2013, 08:08 AM

Quote:

Originally Posted by donhoward49

I do believe the steps work off the chassis battery, but I have been wrong before. I wonder if your steps have been re-wired by someone? Try it again with the House battery disconnect off.. See what happens.

For clarification, my steps still operate with the house battery disconnect switch off and the knife blade switch on the chassis battery disconnected (open)!

As far as wiring being changed, there is not enough slack in any cables to route to wrong batteries.

sfrantz · 05-02-2013, 08:15 AM

Trode, if you disconnected the Negative lead, the only solution is that you have a bad battery. Contact the manufacturer.

Perhaps your knife switch isn't working? Try lifting BOTH leads and see if the battery dies.

alandbarbj · 05-02-2013, 09:13 AM

Do you have solar panels? On my 99 tradewinds, with ALL the batteries removed, my solar panels , which are hardwired into the system allow the steps to creep down, as well as feeding power to the Fantastic fan. I have actually started pulling wiring harness connectors from the fuse/relay panel to shut the flow from the panels off, as well as disconnecting the cables from the positive terminals of the batteries. It's a hassle but the batteries now maintain their charge when the coach is not in use.

YC1 · 05-02-2013, 09:43 AM

The knife switch is as simple and fool proof as possible. You have a bad battery.
Buy a new one, keep the receipt, charge it up and let it sit in the same situation for a week. If it is dead send me the receipt and I will buy the battery.

How's that for confidence. I have seen some amazing ways batteries die. Watched one you could literally set your watch by. Charged it up, turned the headlights on and in 20 minutes they went dim and the battery voltage was at 8 volts. Jump started a battery once and as soon as you put the vehicle in gear it would die and you had to jump start it again. The alternator was working fine. Tried it several times. Finally threw an old battery in place and off they went.

As far as dead, are you actually measuring the voltage across the terminals before you close the switch??
In any case, just replace it and your worries are over.

YC1 · 05-02-2013, 09:47 AM

Can't see well enough below the switch to see how it is mounted. To prove the switch is working just put your voltmeter across the switch while it is open and you should see full battery voltage. I am assuming there is enough parasitic draw to make the meter read when you do this. If you do not see the full battery voltage just turn your ignition key to the run position and measure again.

trode · 05-02-2013, 12:05 PM

Quote:

Originally Posted by YC1

The knife switch is as simple and fool proof as possible. You have a bad battery.
Buy a new one, keep the receipt, charge it up and let it sit in the same situation for a week. If it is dead send me the receipt and I will buy the battery.

As far as dead, are you actually measuring the voltage across the terminals before you close the switch??
In any case, just replace it and your worries are over.

That is why the battery was replaced. Prior owner told me about battery going dead while in storage, she replaced it week before I bought, when I brought home and let sit, had same issue so installed the knife switch, but what I still don't get is 2 things, what could drain battery with knife switch open, i.e. chassis battery disconnected, and house bank turned off, in that status what is powering the step? I know for example certain things, like the jacks are powered off the house bank, and will not operate with the house bank shut off, same with radio, steps have me stumped, because when the chassis battery is drained the steps DO NOT operate, yet operate when knife switch is open

. Maybe get some of my confusion now.

YC1 · 05-02-2013, 01:36 PM

I believe you may indeed be confused.

Your comment about house bank being turned off can be an issue. If you are flipping a switch the house bank may not be entirely cutoff.

If your steps are still working with the knife switch off they are tied to the other battery. You need to measure the voltge on the engine battery to see if the voltage really is going down with the switch opened. If it is the new battery is dead. I have seen may new batteries dead.

I would install a knife switch on the other battery too and your worries should be over except for getting them charged. If in storage be sure they are full before shutting things down.

Shadowcatche · 05-03-2013, 04:09 AM

A VOM/Multimeter is your friend and will find many/most electrical problems. Set on amps and disconnect one terminal and with every thing off check between battery and terminal and if you have a current drain, you have one. One of the neat little gadgets I bought from Harbor Freight, also available from Sears and Amazon is a fuse buddy (different names different stores). This plugs into the 12V panel replacing one of the fuses and lets you read amps directly. 30 Amp Automotive Fuse Circuit Tester I have one that stays with the trailer tool kit. If you have had the battery go flat it is already damaged and should be tested, after you find the problem and correct it.

GSGracie · 05-03-2013, 05:54 AM

I have an alarm that is connected to the positive terminal of the house batteries and then earthed to the chassis. That was a source of parasitic drain for me.
But I understand your concern, if there is NO connection to the negative post, there is no complete circuit and no current should flow. I can only think of cleaning the battery very carefully to make sure that there is no rust connection or any other way for the current to creep back to the negative post.
I will watch with interest to see what the problem turns out to be!