RV Owner

looks like someone traced tractor circuit faults. with the way you do it bad grounds will also show up, neat suggestion thanks.'da ber

Bob,

The vehicle on board computers will light the test light and I am pretty sure it would not be a good idea to disconnect the computers on this R.V. Typical amp draw from the computers, (ecm, radio, clock,etc) is about one amp. Enough to light a test light. A good place to start, is with the battery it self. Disconnect the ground. Check voltage with meter and record voltage. Let battery sit for one to two hours disconnected, check voltage. A voltage reading below 12.5 indicates the battery is weak and should be replaced.

Next still with battery disconnected, check for voltage leakage. Place ground probe of meter on the ground of the battery, probe the top of the battery any where but on positive post of the battery. Any reading on the meter indicates voltage leakage with will cause the battery to go dead after one to 3 days of sitting. Clean the battery with baking soda water. If you still have a reading after cleaning battery, replace the battery. Often the battery is no good at the point of voltage leak anyway.

Next the battery having pasted the above two test, reconnect the battery and connect the probes of your meter to the battery. Crank the engine and note the voltage drop while craking the engine. If the voltage fell below 10.9 volts, replace the battery.

If you believe your alternator is the cause of your battery going dead a simple test you can do. With the battery connected, leave your r.v. sitting over night. The next morning, place your hand on the alternator. If the alternator is warm to touch this would indicate a failed diode in the alternator which will draw power from the battery when the engine is not running. Replace alternator. If your want a better test than that, take your r.v. to a local napa store or car quest or checkers or a dealer. A simple test can be done with the engine running to conclude the fault of the battery or alternator. Many parts suppliers will do this test for you for free.

Finally, R.V. charging systems are design to charge all of your batteries when the engine is running. A fault in that system will discharge your engine battery to when the unit is not running. In this case you will want to go to R.V. dealer who will track down the fault. Often it is a blown diode or a faulty charging equalizing system, some time a stuck relay. The living part of your R.V. has it's own electrical system until the above charging system fails.

Rules to protect your vehicle charging system:

Connect positive first, negative last when jump starting. Disconnect negative first when disconnecting jumper cables. (not following this rule can blow a diode in your alternator.) Remember that your R.V. is not protected in the like manor of a car. It has been modified for the R.V.

When replacing and alternator be sure to disconnect the battery negative first and positive last. When reconnecting battery, positive first, negative last.

Clean your battery every engine service to prevent a voltage leak. This adds more life time use to your battery.

I strongly - emphatically - disagree with the statement, "If the voltage fell below 10.9 volts, replace the battery." RV's tend to utilize larger engines than most cars. For car engines with displacements less than 3 or 4 liters (180 to 240 cubic inches), and in warm weather, the 10.9 cranking voltage figure might indicate a weak battery. But not for larger engines with displacements of 7 liters (420 cubic inches) or more. For such engines cranking voltages (read with a fast response digital voltmeter) often drop to 9 volts or less, for a brand new fully charged hefty battery (1,000 or more CCA = Cold Cranking Amps). In the winter, these voltages drop more. At 30 below zero fahrenheit, expect to see a cranking voltage of 6 volts or so - if the engine cranks at all. Note that cold cranking amps are measured at 1.2 volts per cell, or 7.2 cranking volts.

Having traced such problems many times, I agree with the others who suggest using a clamp on DC ammeter. It is by far the best tool for this job. MCM Electronics is a good source. http://www.mcmelectronics.com/search.aspx?C=3829457&K=Clamp%20meter

The vehicle on board computers will light the test light and I am pretty sure it would not be a good idea to disconnect the computers on this R.V. Typical amp draw from the computers, (ecm, radio, clock,etc) is about one amp. Enough to light a test light. A good place to start, is with the battery it self. Disconnect the ground.

You can't have it both ways.

Disconnecting the computer on this vehicle will only erase the memory of trouble codes, and some driving habits. There is also the problem of resetting the radio stations.

Yes the computer will cause the typical low powered test light to light up. What if there is a faulty capacitor in the computer itself? The test light will allow the op to see that. The relative brightness of the test light will show a small drain as a dim glow. And a blower relay causing a fan motor to run as a very bright glow. How about a thermal imaging camera? That should show the additional heat from the current flow.

I believe that all of the possibilities you suggested would have been revealed with the method I suggested. How long do you think it will take to find an interior light with a blackened bulb that is still in the "on " position. There might still be one more unscrupulous mechanic that would not be able to resist selling the op a new alternator, or battery combiner.

selanoid is the problem common ford crap problem

this will fix it

The most common problem associated with battery drain is the alternator. If a diode goes out the alternator will slowly drain the battery over a day or two. It will charge as normal, but will allow current through it when it is not operating. If you take a screwdriver and touch it to the alternator shaft, and the shaft is magnetized it means that a diode has gone bad.

Will charge as normal? No, it won't and it can be checked at any Auto Zone or other parts store where they do the "we'll check your .... for free" deal. If you've got a blown diode it will show up instantly.

What bob said. plus I would take it to a auto electric repair shop because Ford can have several at one time I found that out the hard way thinking I had it fixed only to die on me on I-95 with kids late at night in the heat of summer.

I had the same problem in my 1987 Winnebago. No faults found.

The problem turned out to be parasitic loads imposed by all the RV accesories and status indicators. During a certain era, all lindicators were LED. In addition you have tank level circuits, a 2 or 3 way fridge that uses 12V 120VAC or propane. Each fuel source is selected by a solenoid one of which is always energized it seems.

In my galley I had a central panel that showed potable water, grey water tank, and black water tank levels.Full status would light up all four LED for every sensor. this was easily 1/4 amp per sensor circuit.

My dash had an indoor /outdoor thermometer with nice big 1/2" LED numbers. Each dash sensor pulled some current and the LED display drew some more current. If you use propane for cooking the propane tank may also have a level sensor.

I also had radios with remote control. If you have a TV/VCR with remote control or worse a satellite TV receiver these also uses curent in OFF or standby mode. If you have a big power inverter, be aware that some of these inverter will eat an amp or more idling current even in stand-by mode. Invoking "power save" mode will drop the parasitic current but not to zero.

My parasitic loads would kill a pair of fully charged Group 31 batteries in about 8 - 9 days. If I forgot to disconnect the start battery from the house bank, the starter would also go south. The power center would only charge the start battery if the combiner switch was closed. So it was normal to leave the combiner switch closed when plugged in. But if the power center was not plugged in. No joy!

Good luck!

I have had the same type problem happen before. Turned out to be the vehicle alarm system. You need to hook up an inline meter which detects any amount of voltage being drawn from the battery. Could be several different things, but isolating the source using this method worked for me. Have seen batteries getting pulled down from something as simple as a radar detector which only had the red LED indicator on. Hope this helps.
Tim Da Toolman

Certain loads like clocks, are expected to be continuously energized. You are looking for a load, or group of loads that total about 1.0 amp. As previously suggested, I would hook an ammeter in series with the battery and make a note of the quiescent current drain. Then go to your fuse panel and one by one, pull and replace each fuse making note of the change in current drain. Using this method, you should quickly be able to determine which circuit(s) are causing the problem. If the offending circuit is not a critical one, you can leave the fuse out until repairs are made. If the problem circuit is critical, you can leave the battery cable disconnected until repairs are made, or install a master battery disconnect device and disconnect the battery when the vehicle is not in use. If the battery drain is less than about 0.2 amps, and the problem persists, then I'd replace the battery.

You are talking about the engine-starting battery, right? Don't you have a house battery bank in addition, or is this a small RV that uses the same battery for both? Engine battery and starting battery should only be connected together when the engine is running. A bus conversion I had did this with a solenoid relay triggered by an oil pressure sensor on the engine. Others are right that there will always be SOME load from the house systems. If you have an inverter, it will draw perhaps as much as an amp when turned on, even if no 120 VAC loads are turned on. Of course, if you have any instant-on electronics like TVs and steros, they draw current when turned off--they must be unplugged (or 120 VAC removed) to be fully off. A great device for monitoring battery banks is a shunt-based monitor like like Trimetric TM2020 from http://www.bogartengineering.com/ I just bought another of these for my new coach--show's digital read out of amps flowing into or out of the battery bank, and % charged/discharged. I wouldn't be without one in an RV.

Assuming you have check the normal stuff like the brake light switch, the switch under the hood, the dome light, etc. I would guess that the diode inside the voltage regulator has gone bad. Most of the engines from the mid 80's and newer have the regulator built into the altenator. When the diode inside the regulator goes bad, the altenator will still charge, but it will discharge by trying to turn the altenator into a motor. When they use to use generators, prior to 1965, you just took off the fan belt and the generator would spin if the contacts inside the regulator went bad. Those contacts were replaced with diodes. Try unplugging the altenator over night. If it still discharges this is not the problem. If it is not that, good luck! It is a tedious job with a good multimeter.

PS The guy that said it's the solenoid is probably wrong. When those stick, the starter will hang up. The old Fords use to make a peculiar noise when they started to go bad. It is very easy to find that problem.

For the the people that suggested Amp meters, and volt meters, they are correct. they will give you more information during this process. But an amp-meter will allow the wires that you may have to disconnect to still be "live". Not always good. The voltmeter will keep the wires safe, But it may not be in your tool box. If you have none of the above, the test light is the cheapest.

All of the suggestions are good possible causes of your drain. In my personal experience The factories have to warranty these trucks for many years. The RV people are converting what Ford gave them to their use. The aftermarket people are more likely to have quality control problems with their laborers than the factory. Don't forget that some of your accessories on the RV may have been installed at the delivery dealer, or possibly a previous oner of the RV if it is not new.

Does this RV have separate batteries for the start function or not. If your RV has separate batteries, your job will be easier. Good luck.

Do you mean as to a safety issue? I tend to agree... the monitor system I suggested uses a shunt in line with the battery, which can handle up to 500 amps. It consists of some special metal that produces a precise voltage drop across it to enable measurement of current flow. I tend to agree with you--just sticking an ammeter inline is problematic unless you know for sure how much current is flowing and can size the wires and the ammeter appropriately. I just used this monitor to track down every amp in my huge and complex coach, and I do have about 1 amp drain I can't find.

We've been talking detection, but in terms of solution, one great approach is to get some solar panels for the RV. I had two 100 watt panels on my old coach and they always generated plenty to keep the batteries up if most everything were turned off, and even with some things left on. It enabled me to leave the coach parked for a long time without worrying about the batteries. This was for the house bank. I found that if I disconnected the starter batteries, they didn't drain much on their own, or if I had wanted to get fancy I could have switched the solar to charge both house and starting banks.

Another Problem with Ford Alternators is the connection wire bundle going to the alternator. This has been a problem for years. The connections from the wire bundle into the main wire harness corrode and short out. Unfortunately this most commonly damages the components in the alternator. Ford Alternators normally include, or suggest replacing this section of the harness when a faulty alternator is replaced.

Follow steps as in response #1. I had the same problem and it could have been coming from anywhere. It was a ford, and turned out to be the horn relay switch. As soon as I pulled it off the fender well my drain on the meter went to "0". Could be anyone of these items. Good Luck.

I think it's just a JOKE...

Voltage doesn't leak...

Current leaks.... Hence the use on an Amp-meter (current is amps)
Most people have ignored/missunderstood this.
It's a bit pedantic and doesn't really make any difference to the excellent replies you have received.

Del

Post #1 is fully correct, but do use a tiny (watts wise) 12 volt bulb, it will light much better than a high wattage one.....solder a couple of long leads to it (or use a holder) and a couple of crocodile clips, so that you can see it from wherever you are working when you disconnect wires or pull fuses.....make life easy for yourself.

Always place it in the negative line, its safer and does not affect the way it works.

The fault could be more than one bad wire or unit, so when the lamp finally goes out, place an ammeter across the negative to earth instead of the bulb. Use the (usually) 10 amp range first before switching to ma (after making sure that no reading is shown under amps!!). Find all losses till you see 0 ma....

I had a similar problem in my 97 tahoe 5th wheel

I used an amp clamp and traced it down to a ground in the inverter panel

just check one circuit at a time and the one that shows current is where the juice is flowing

Gee I wish you guys would have been around when I had this very same problem with my 98 Chevy Pickup truck.

I ate up 4 batteries in a year and no one, including the 2 different Chevy dealer service depts., could seem to figure out why. When I say ate up, it destroyed at least one cell in each new battery I used.

I finally ended up buying a battery from a Chevy dealer and suddenly the problem when away. Now I wonder if that particular service guy knew something no one else did and fixed it. The only reason I doubt this is because I wasn't charged for any parts or labor other than the new battery cost. Now my truck sits for weeks at a time and it fires up without a hitch.

Now if I could only get the A/C to actually cool the truck I'd be in heaven. Its been looked at more times than I can count and again no one seems to know why the truck cab never cools off. Every one says everything is working correctly but it never get cool in the cab using the A/C. Most like to blame it on the new refrigerant that was just started to be used in 98 for the reason it never cools down. I've given up on using the A/C in the truck. Any suggestions?

Evidently that service guy knew the trick with the dielectric sheeting.

I have seen some of that series trucks collect dust, lint and other crap over the a\c evaporator. When the air is sucked up from the cab it drags some crap with it. Try removing the right lower kick panel. That should allow you to get to see or feel the front of the evaporator. If it is covered with crap, it will cut down on air flow. Service people have no good test for air flow. Try to suck it off with a vacuum cleaner or blow it off with shop air.

If that is not the problem, try putting dielectric sheeting under the truck for 2 to 3 days.......

You could do what I did on a '57 chevy once. I installed a battery kill switch. Every time you get out of the car you just reach under the seat and disconnect the battery. No more battery leaks to ground. It would probably be a pretty good theft deterrent for most theives as well. The only problem would be if you have electronics you wanted to keep "alive" which that '57 didn't. That could be taken care of as well though with a small battery seperated from the main system with a diode.

I had the same problem . the way to solve the dead battery problem is to install a cut off swich near the batterys the cut off switch is the same as they use on boats they have a key and cost about $5.00

To Kenn, and Keywalker .

I have to disagree with both of you. Starting any vehicle is the largest load on any vehicle electrical system. Do not make it worse by adding four additional connections (at least) to the starter circuit, and, a sliding switch. Currently the best practice is to never interrupt the starter current. If a cutout switch is needed, use it on the other wires leading away from the battery pack. There is now argument on interrupting the current from the charging system as well.

Do it right the first time, and save the band-aids for your fingers. Take the time to chase the drain as so many people have tyred to guide you through. You will be happier in the end. How many cut out switches will it take to correct a battery case that has a leak?

I agree it would be better to fix the problem than put a "bandaid" on it. The kill switch that I installed on the '57 was while I was working for an auto shop called "Performance Plus." I was instructed to do this by the owner of the company because this was what the customer wanted. The contacts were all very heavy duty copper and the wire was something like double zero (very big stuff and not easy to work with) so the current needed to start the car was always available as long as the switch was on. The switch was never switched under load so there was no concern of a build up from arcing the switch. All were very solid and reliable contacts. I just threw this in because I thought of it as an alternative solution when all else failed. Sorry if it was a dumb idea.

Not a dumb idea at all. It is just that a large engine that has sat for 5 min. while refueling has all that it can do to restart when things are working well. If he is going to add four more connections and a switch, he might not get it started till it cools or he gets a jump from an additional battery. Substituting one problem for another problem does not make sense.

The wire you described, and the length of wire needed for a trunk location would probably cost more than buying an additional battery and short cables to add to the original battery on the RV.

Rear mounted battery disconnects are a common requirement in some forms of motor racing. Regulations are there to keep all vehicles the same for use by emergency personnel during an accident.

I did not make myself clear, what i was suggesting is that you put the cut off switch on the neg battery cable just as it was leaving the battery box

kenn

It sure would be nice if Mr. Guest would bother to check back in and report on his success or lack thereof in following the advice provided so far.

I have a battery cut off switch at the battery on my truck but during the winter I don't use it. When I needed my truck the most, after a heavy snow & ice storm I couldn't get the hood open due to the ice freezing it shut. Thus couldn't drive my truck to work.
And don't tell me to pay attention to the weather forecast. The meteorologist around the St. Louis area get 1 out of every 100 forecast close. The storm I mentioned above was supposed to be a light dusting and we ended up with 1 inch of ice under 4 inches of snow.
But since I've installed the battery that I bought from the dealer I haven't had a problem. I know there are only so many battery manufacturers in the world and they just stick different names on them. But the batteries I've bought from Autozone (?), Midas (Interstate Bat.), Advance Auto (?), Sears (?). Don't seem to hold a candle to the battery I got at the dealer.