Battery drain

Zephod · August 08, 2017, 05:29:01 PM

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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muldoonman · August 08, 2017, 05:42:55 PM

You don't have all those .05 to 3 amp fuses hooked to battery?

windtrader · August 08, 2017, 10:05:00 PM

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.

Zephod · August 09, 2017, 01:48:59 AM

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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Jeremy · 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

Jon · August 09, 2017, 03:42:49 AM

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?

richard5933 · August 09, 2017, 04:14:02 AM

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

blue_goose · 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

Jon · August 09, 2017, 04:37:37 AM

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?

windtrader · August 09, 2017, 12:10:51 PM

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.

blue_goose · 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

Iceni John · August 09, 2017, 01:38:25 PM

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 I think it will be fine for occasional non-critical use.

John

Zephod · August 09, 2017, 02:13:53 PM

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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Acausey · 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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Zephod · August 09, 2017, 05:17:40 PM

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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