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PeterH-350LE · 09-06-2002, 04:37 PM

On my recent trip to Alaska, I spend some time with Curtis trying to figure out the motor battery drain on his 1979 MH.
Facts:
disconnected + from generator, no help
replaced bad battery isolator
replaced bad headlight switch (low beam would randomly turn off)
its not the step switch, since it is vacuum operated.
the radio is wired to the coach batteries
Besides bad diodes in the alternator, what else could cause a constant drain and sometimes a dramatic overnight complete discharge. The battery is new.

Inland RV Center, In · 09-06-2002, 07:49 PM

Peter.
I would get an ammeter and start looking. It's the only way you can positively identify any mysterious drain.
But, don't assume that brand new batteries don't do crazy things, because they do.
Therefore you could chase a drain for hours, only to find perhaps a battery that's bad.l

Andy
inlandrv.com
airstreamparts.com

53flyingcloud · 09-06-2002, 10:15 PM

PeterH,
Not sure if this is related to your situation but, last year when I finis my tour out with the A/S..I parked in a local parking lot overnight and, the next morning when I went to start up my Burb..the batteries were dead from just sitting overnight..Left the power cord hooked up overnight and, the refrig, being a 3way unit must've switched to 12volt during the night..Drained it completely..Just my two cents worth..
I know were talking TT AND MH here but....
ciao

ALANSD · 09-07-2002, 06:05 AM

You know the problems i was having, were all related to the wiring going from that small terminal box to the starter solenoid.
The wires looked fine until you looked closer and saw that they were basicallly burning through from heat. The color of the insulated jacket was even normal looking, but the wire inside was down to just a few usable threads. May not be Curtis' problem, but it sure took meawhile to find it on my rig. Cured all my electrical difficulties, and probable was what made my battery isolater look bad. I will bet the isolater (long thrown away) was ok.

PeterH-350LE · 09-07-2002, 06:09 AM

Andy, according to Curtis, the battery was new and bad. This 'new' one is a replacement. But who knows...
towner7, we ran the refer on gas and electric only.
I use a little indicator light for the 12V functions of these old refers. Wired to the 12V out terminal of the small relay will tell you when you are on 12V.

Larry Brown · 09-07-2002, 08:34 AM

I just started to have the same problem, My batteries (coach) both just died they were dyehard golds 7 years old .So I thought ok they served thare time so I purchased 2 new exide automotive type batts as were the others auto type (non deep cycle) over the time of less than a month they both died. They will charge up but do not hold a charge. I wonder how something could develop a short or a drain just sitting there as this is what happened .I now just flip the dissconect switches from the batteries when I hook up to power or I'm not going to use it for a while. What should I check for?

74Argosy24MH · 09-07-2002, 09:37 AM

As Andy said the only way is with an ammeter. You can pull fuses and see if it stops, but there is a lot of wiring that does not go through the fuse block, or it could be shorted before the block. It is time consuming, but really is the only solution.

John

Curtis-79MH · 09-07-2002, 10:56 AM

Hi,
First of all, thanks for your time and effort.

I was just casually reading these posts when I noticed LARRY mentioned Exide batteries....both the new battery that went dead (and needed a replacement, under warranty) and the current battery that goes dead after a few days are both Exide batteries....

Peter and I tried to figure the battery problem out using a voltmeter and prior experience (mostly Peter's!). At one point we thought we had been successful only to be disappointed with a dead battery a day or two later.

Both Andy and John mention using an ammeter to run down this electrical problem. Any ideas how, and where, to begin using the ammeter? I read that I should check the fuse box. I guess that means the P-30 fuse box, correct?

ALANSD mentioned the "small terminal" box to the starter. Where is the small terminal box? Do you mean the one mounted near the engine? I replaced that, but did not investigate the wiring in depth....I will.

What about the alternator diodes? Peter mentioned that someone had a problem with the alternator leeching from the battery and the culprit were the diodes in the alternator.......

I'll stop this lengthy inquiry while wishing you all charged batteries, and your only shorts in life are the ones you have to launder.

Curtis-79MH

ALANSD · 09-07-2002, 04:21 PM

yes you have the right terminal box. My wires to the starter solenoid looked ok at a casual inspection, but they were fried fron heat, and got worse as time went on to the point of having not enough strands connected. First my tv/vcr did not work right.
The tv played but vcr would not come on. Weeks later- the horn and lights died. Then the volt meter started going progressively down from 14+ to 11, stayed there a while then went to zero.
All the while my battery got weaker and weaker. I checked alternator output, battery isolator outputs, and so on. The wires at that point did not look bad to me. Eventually, after replacing the alternator and the isolator- (a technicians not very good advice)- my rig just would not start.
Left me in the dump area of a state park. I got underneath and the starter wires were burnt down to one strand holding on to the solenoid terminal. I jumped the starter, got it home, and the whole solenoid cover and terminals came apart in my hands.
Sorry for the long tale...but this all happened over a 4-6 week period, during most of which I was on the road a long way from home.

74Argosy24MH · 09-07-2002, 06:12 PM

Before you start I would definitely take the battery and have it load tested. You have had a bad one already, it is quick and easy compared to what you have to do.

Everything must be turned off, but don't make any valiant efforts to do so. If a switch is sticky, it could be the problem. Just make sure all switches are off as normal.

A clamp on ammeter is the only way to go. An inline meter requires you to unhook and hook each wire you check. A chassis schematic is nice to chase circuits but not necessary.

Start checking at the battery hot. It will hook to the solenoid and several wires should feed from it. You should have a current flow at the battery, keep following it down through the smaller wires. This is where the schematic is nice, but if you don''t have one follow the loom until you can get at the wire again. At each junction follow the wire with current flow.

There may also be a terminal block on the upper alternator bracket. Check it and any other large red wire you see, it will eventually feed several circuits. The light and ignition switches are also major feeds. Don't forget the circuits added by POs, fog lights, cb's, other accessories.

John

john hd · 09-07-2002, 07:19 PM

Quote:

Originally posted by 74Argosy24MH
Before you start I would definitely take the battery and have it load tested. You have had a bad one already, it is quick and easy compared to what you have to do.

Everything must be turned off, but don't make any valiant efforts to do so. If a switch is sticky, it could be the problem. Just make sure all switches are off as normal.

A clamp on ammeter is the only way to go. An inline meter requires you to unhook and hook each wire you check. A chassis schematic is nice to chase circuits but not necessary.

Start checking at the battery hot. It will hook to the solenoid and several wires should feed from it. You should have a current flow at the battery, keep following it down through the smaller wires. This is where the schematic is nice, but if you don''t have one follow the loom until you can get at the wire again. At each junction follow the wire with current flow.

There may also be a terminal block on the upper alternator bracket. Check it and any other large red wire you see, it will eventually feed several circuits. The light and ignition switches are also major feeds. Don't forget the circuits added by POs, fog lights, cb's, other accessories.

John

a clamp on ammeter will only work on ac circuits, you will need a series connected meter on dc

john

shelocta · 09-07-2002, 09:52 PM

Hi everyone;
I've I thought I would give my thoughts on this problem. I'm going to make some assumptions and they may not be correct. If anybody knows differently please inform the forum because the documentation I have is a little bit sketchy on some of the finer points on the Univolt system. The assumptions that I'm going to make is that the battery is good, the isolator is functioning properly and that the charge lead from the Univolt is not interacting with the chassis electrical system. Since we don't have an ampmeter available will have to take a little bit different approach to this. First take your volt meter and make a quick rating on what the battery voltage is, we are going to assume it's between 11 and 12 volts. Now disconnect the negative lead from the battery and measure between the battery terminal and the cable clamp. If there's a significant current drain that voltage should be the same as the voltage measured across the battery terminals. If you are reading at a much lower voltage it means that the resistance of volt meter is actually pulling down the voltage so there were to be enough current drain to use the lightbulb method to troubleshoot this. The next step is to take a automotive 12 volt lightbulb and connected between the negative battery terminal and the negative cable and hopefully there's enough current flowing that the filament will glow. If you have this condition the next thing to do is get a helper to pull out the fuses on the chassis fuse panel one at a time and see if the lamp ever does out. This will identified the circuit where the leakage is. And once we know that then we can make some guesses about what we should do next. If you don't have a helper you can put the cable back on the battery and wire up your lamp with a couple wires and as you pull out a fuse place the lamp in the circuit where the fuse was and if there is current flowing in that circuit then it should glow as brightly as it did when it was connected to the battery terminal. If going through this procedure and the light remained on then we got to start looking at the unfused portions of the circuit. This would be the leads to the alternator, the starter, or perhaps even the vehicle side of the isolator. This is where are I have a shortage of knowledge so if anybody knows how we can isolate the unfused portion of the circuit please chime in. We may have two problems because as I understand it sometimes the battery discharges slowly and other times there is a rapid discharge and we may only fix one problem and then will have to address the other.
Hope this helps.
Bill

74Argosy24MH · 09-08-2002, 04:46 AM

A clamp meter with a hall effect transducer will measure dc current. AC only use transformer input.

Bill- If you pull the battery cable and place the meter between the cable and battery post the meter will become part of the circuit. If it is set for volts it will blow the meter fuse or the meter movement. The test light will work, once you have pulled the fuses, I would look on the alternator bracket for a terminal block and follow any large red wires which should feed several circuits. Don't forget the accessories added by previous owners.

John

john hd · 09-08-2002, 08:25 AM

Quote:

Originally posted by 74Argosy24MH
A clamp meter with a hall effect transducer will measure dc current. AC only use transformer input.

Bill- If you pull the battery cable and place the meter between the cable and battery post the meter will become part of the circuit. If it is set for volts it will blow the meter fuse or the meter movement. The test light will work, once you have pulled the fuses, I would look on the alternator bracket for a terminal block and follow any large red wires which should feed several circuits. Don't forget the accessories added by previous owners.

John

correct!

john

shelocta · 09-08-2002, 09:09 PM

No harm should come to the volt meter because of it's high internal resistance. Most of your garden verity meters have a 20,000 Ohm per volt impendence. If you are on a 20 volt scale you would only draw about 30 microvolts. The reason to make the voltage check first is to see if any of those pesky electrons have made it back to the battery with all the circuits open.....Bill

Larry Brown · 10-02-2002, 07:20 PM

Hello everybody ,Just got back from Anacortas Washington on a bike rally .before we left I pugged In the univolt for 2 days to get the batteries charged up. as you may recall I was having a draining problem with my new exide batteries. Anyhow as cleaning the exterior of the rig I could smell hydrogen gas coming from the battery box so I opened it and one of the new batterys was puffed up and ready to explode (hot as hell) ok I said to myself here is the problem (dead short in the new battery) So I went and got a a new battery everything was fine on the trip and when we got home everything checked out ok.We where hooked up to shore power the 3 days of the trip.When we got home I dissconected the coach batteries via switch and pluged in the univolt to run interior lights after one day I could smell electrical like a burnt armature in an electric motor so I unplug the univolt I'm sure its toast. So what I'm getting at I think the load from the bad batt blew up my univolt .How much How Hard And were do I get one ??/ PLease Help

thenewkid64 · 10-02-2002, 07:57 PM

You can go to yopur local Airstream dealer or to Andy at Inland RV.

Univolt
Here is a link to the picture of the new model. It goes for 265.00 US from Andy. R&R should not be all that hard as I think yours is on the floor behind or under the pass seat. I hope mine never fails as I would need to take yoga up prior to R&R mine, it is under the bathroom counter accessable thru a closet.

PeterH-350LE · 10-02-2002, 08:15 PM

I have been very happy with the Intelli Power 9100
It is very quiet with the occasional cooling fan kicking in:
http://www.campingworld.com/browse/s...5&skunum=17299
In the 79 the univolt is located to the right of the passenger seat under the box, which is fastened with a few screws to the side and the floor.
drawback: AC indicator light will not work as wired.

Larry Brown · 10-02-2002, 08:32 PM

Thanx for the reply I panic everytime something go's wrong as everytime I think I'm getting all the bugs out of this thing something else happens (probably why the old dude sold it in the first place) I think its becoming a challange just like many of the cars I had as a kid. Although as I get older I find it harder to take when things aren't perfect.Lets see besides the battery problem the passenger heater core blew (I need one of those also) The furnace also was not working this year.Last year I replaced the brain and the year before it was the relay so this year I took it in to the shop and they went through it for 30 bones and it worked perfectly the whole trip.Anyhow one thing at a time as I can afford them and maybe before I'm to old of a dude everything will be in working order.

ALANSD · 10-03-2002, 07:24 AM

Larry- many of us are in the same boat, where just when you think you have caught up in your maintenance and repairs, you are faced with some new one.
While this can be a big frustration, and I know it has seemed so to me at times this past year, if you back up, take a deep breath and move forward slowly it usually will be solved at less expense and with less panic.
I have had so many little and again not so little things to attend to, each one coming soon after another was completed. Some of that is the "fun" and challenge of owning a classic machine with so many systems that have to work together to make it a complete operating unit.
Hope you don't get too frustrated where the enjoyment is outweighed by the pains in the.....well you know.
Just some support from another who understands where you are coming from.