Something is draining my driving battery. It has been suggested it could be the alternator. Reading up on alternators it might be a rectifier diode if it is the alternator. How difficult would it be to change a rectifier diode on an alternator if it is that?
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You don't have all those .05 to 3 amp fuses hooked to battery?
Generally, hunting down of the drain first is better than guessing and swapping parts. A lot easier said than done. I may be facing the same sort of issue but with the new house batteries and inverter/charger just waiting for a bit until tuned up and settled in to see just what and how much is real drain verses batteries just not holding power.
Quote from: muldoonman on August 08, 2017, 05:42:55 PM
You don't have all those .05 to 3 amp fuses hooked to battery?
The house and driving circuits are totally separate. Everything I've added to the driving side (CB, reversing horn, camera, USB, cigarette lighter socket) is individually switched and fused and the switches are in the off position.
An old mechanic at work thinks it's the alternator. That was his first thought when I mentioned battery drain. I'm going to try to get somebody with an alternator tester to test it. Since his works with cars, it'll work with my bus as my bus is 12V.
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Using an alternator tester to see if it works (ie. charges the battery) will most likely tell you nothing at all about whether it might or might not also have a resistance which is draining the battery. As has been said, rather than guessing about possible causes you should actually try to find out where the drain is. The 'driving' circuit as you call it has many things connected to it (and many connections) and there are many possible causes for a drain on the battery, including the battery itself. Get yourself an ammeter and do some testing
Jeremy
Has the voltage been tested with the engine running and the engine off? Has the battery voltage been tested with the battery disconnected, and then 24 hours later to rule out the battery?
Just because everything you've added was done with switches and fuses, don't look past what someone may have added (or incorrectly removed) prior to you getting the bus.
I found a few bay lights which were removed years ago, but instead of properly capping the 12v leads they were just loosely taped. Years of dirt and moisture built up in the black gooey tape until they were carrying a small amount of current.
There were also a few items connected to our chassis battery which should have been wired to the house battery circuitry. An example would be our 12v water pump. Spent hours trouble shooting before I traced the wired to the chassis battery side and found the problem.
You have to be somewhat of a Sherlock Holmes to find all the things that a previous owner or mechanic may have done which is causing a problem.
Richard
Back years ago when I bought my Eagle I had the same problem. I tried everything to find the problem. When I bought a DC clamp amp meter only took a few min. and the problem was gone.
Jack
Has the voltage been tested with the engine running and the engine off? Has the battery voltage been tested with the battery disconnected, and then 24 hours later to rule out the battery?
Quote from: blue_goose on August 09, 2017, 04:21:41 AM
Back years ago when I bought my Eagle I had the same problem. I tried everything to find the problem. When I bought a DC clamp amp meter only took a few min. and the problem was gone.
Jack
I'm checking these out now. Seem to be the magic tool for very quickly finding which wire is carrying current when there is not supposed to be any. Any suggestions on what to look for? Fluke seems to go to brand but a bit pricey for a DIYer. HF works for some stuff; I don't trust them for quality electronics.
Be very careful, most clamp amp meters only check AC. You need to make sure it reads DC Amps. When I bought mine they were very costly. I gave my son one that I bought off Ebay and it works fine.
Jack
Quote from: blue_goose on August 09, 2017, 01:06:01 PM
Be very careful, most clamp amp meters only check AC. You need to make sure it reads DC Amps. When I bought mine they were very costly. I gave my son one that I bought off Ebay and it works fine.
Jack
I bought an inexpensive 800 amp DC and AC clamp-on meter recently - here's my reply no.30 in a previous post: http://www.busconversions.com/bbs/index.php?topic=32077.msg361797#msg361797 (http://www.busconversions.com/bbs/index.php?topic=32077.msg361797#msg361797) I think it will be fine for occasional non-critical use.
John
Quote from: Jeremy on August 09, 2017, 03:18:13 AM
Using an alternator tester to see if it works (ie. charges the battery) will most likely tell you nothing at all about whether it might or might not also have a resistance which is draining the battery. As has been said, rather than guessing about possible causes you should actually try to find out where the drain is. The 'driving' circuit as you call it has many things connected to it (and many connections) and there are many possible causes for a drain on the battery, including the battery itself. Get yourself an ammeter and do some testing
Jeremy
We can rule out the batteries as a problem because they're brand new and maintain their charge for months. I disconnect them every time park up, to be sure they don't get ruined by the voltage drain. Left connected, they'll be flat in two days.
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Most digital volt meters have an ammeter built in. The upside is you may already have one or can buy one cheap. The downside is that the meter has to be in series with the circuit. This means removing a wire from a terminal and connecting the meter leads in series. It's a lot more time consuming and not always easy to do but if you have a guess at where the problem is, you might be able to prove or rule it out without much investment. If you have questions about how to do it, feel free to PM me or post. (I troubleshoot electrical systems for a living!)
~Andy
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Quote from: Acausey on August 09, 2017, 04:37:14 PM
Most digital volt meters have an ammeter built in. The upside is you may already have one or can buy one cheap. The downside is that the meter has to be in series with the circuit. This means removing a wire from a terminal and connecting the meter leads in series. It's a lot more time consuming and not always easy to do but if you have a guess at where the problem is, you might be able to prove or rule it out without much investment. If you have questions about how to do it, feel free to PM me or post. (I troubleshoot electrical systems for a living!)
~Andy
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I think it's the alternator because it started after my first bit of electrical work which was to replace a 5A fuse marked fog lights and horn and a blown 30A fuse that should have been 20A that said brakes. I doubt either of those would cause battery drain.
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Quote from: Acausey on August 09, 2017, 04:37:14 PM
Most digital volt meters have an ammeter built in. The upside is you may already have one or can buy one cheap. The downside is that the meter has to be in series with the circuit. This means removing a wire from a terminal and connecting the meter leads in series. It's a lot more time consuming and not always easy to do but if you have a guess at where the problem is, you might be able to prove or rule it out without much investment. If you have questions about how to do it, feel free to PM me or post. (I troubleshoot electrical systems for a living!)
~Andy
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That's why I'm searching for a clamp on. I have a multimeter but it is a real hassle to put it in line for every circuit to test. It seems the clamp on will be a whole lot faster to find the shorting or draw then chase it down.
@John - why 800 amps? More is better? Unless one were testing battery cables during cranking, what else could possibly pull more than 800 amps? Is that some instant peak draw you are trying to capture? I was thinking a couple hundred would be more than enough.
If you think it's the alternator, just disconnect the alternator over night and see what the drain is. Or put a DVM in series with the power cable to the alternator. But I have never once seen an alternator that was working properly draw current beyond the reverse leakage of the diodes, which is usually around 5 mA when I have measured it. If a diode has failed that might change.
The voltage That feeds the alternator will have a diode in the line that should stop a battery drain. If it goes bad it will put a load on the battery. Be careful if you put your amp meter in line with the load. Most meters will only take about 10 amps. If your load is larger that that it will burn your meter up.
Jack
Quote from: windtrader on August 09, 2017, 08:48:20 PM
@John - why 800 amps? More is better? Unless one were testing battery cables during cranking, what else could possibly pull more than 800 amps? Is that some instant peak draw you are trying to capture? I was thinking a couple hundred would be more than enough.
That's exactly why! A starter like the 42MT draws more than 400 amps. My clamp-on meter still works for lower currents, but I like having the ability to also check the big 'uns if I want. Actually I bought it primarily for testing my PV system and house batteries, but then I realized I could have one that works for everything. It does have peak hold.
John
Both my meters have fuses inside on the amp terminals. PITA when you go to measure, and find the fuse is blown. FWIW any diode has a reverse current leakage in the .5 to 5 mA range, depending on different things. That level of current is usually considered negligible, the battery itself probably loses more than that. I have never had a standalone diode in the alternator cable on any of my vehicles, again FWIW. Not to say there isn't one inside an alternator over and above the 6 phase rectifier diodes.
Brian
Troubleshooting a power leak is a long process compounded by many years of owners hooking up wires in random locations with little understanding of the effects of their actions. Start by disconnecting a main battery lead - it doesn't matter if its the positive or negative but I prefer to use the negative side because its usually easier to get a clean disconnect. Then put a test light between the disconnected lead and the battery. You can use the ammeter on your VOM in place of the test light but most VOMs have a relatively low capacity ammeter so I find it best to start with the test light and transition to the ammeter once I get rid of the biggest leaks. If you don't do it that way be prepared to buy a lot of fuses for your VOM. Once you've got a test light in series with the battery lead start disconnecting circuits until your light dims or (ideally) goes out. Be warned though, you've likely got multiple paths so you will need to pull a lot of fuses before your light goes out. You'll probably end up pulling every fuse or disconnecting every circuit and then adding them back one at a time to see which ones turn the light on. Like I said, its a LONG process.
Bob, good summary of what I expect. The PO was very detailed, wires are labeled, and documented. Will make things quicker but still quite a project of its own.
I'm hoping the dc clamp meter still make it a lot faster to find the word with current
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How sensitive and accurate at low current are the DC clamp meters? Milli-amps or lower?
If your bus has a 12v disconnect ,just shut it off when you park the bus.I do this on my Prevost 'cause if I don't, over a period of time my batteries will drain down to the point of not starting the bus.Can't figure out why when CC converted my bus they did not provide charging to the bus batteries from the generator .
A couple of things.
If you have an electronic engine or transmission the power to those should still be on even if you turn the battery disconnect off.
Looks like a good deal on a clamp meter. Description Item # 03482369000P Model # 82369 Sears, they say 3% accruate.
$59.00
Google DC clamp meter it find it.
Jack