Battery Question

[Booyah45828]

And yes, if you don't correctly remove door switches on a handicap lift bus, the bus will experience a no start. Some need jumpered, others need left open, there's a lot of safety interlocks involved.

[PhilipE]

Take a OHM meter. Unhook the wire that is draining the system on the ALT. With the meter hooked to a known good ground. See if you have a OHM reading to ground threw that terminal on the ALT.

From my testing over the years. I have found each OHM shown on the meter is equal to one amp of discharge back threw a ALT.

Chevy internal regulated ALT's are bad about the diode pack shorting to ground. It then discharges threw the ALT main charge terminal.

Your bus most likely has a Leech charging system on it. It still has a diode pack in it.

[Zork]

Originally Posted by Truthseeker4449

Generally speaking, particularly for cars, anything over half an amp is considered unacceptable after an hour or two of sitting. By that time all the modules in a car should have gone to into a very low power sleep state.

This past spring I ended up changing an instrument cluster in a Ford shuttle bus because it kept randomly powering itself on and killing the batteries. "Parasitic draw" really can be a pain to track down...

Buses are different than cars, and some components that are always powered down with the ignition in cars will stay energized in buses, such as part of the instrument panel. Other things to look for are navigation systems, anything USB, any appliances, etc. The OP ought to be able to track it down by individually pulling fuses while monitoring the amp meter.

[DoubleO7]

Originally Posted by Zork

The OP ought to be able to track it down by individually pulling fuses while monitoring the amp meter.

Yes, I did that on every fuse I could find.
Under drivers window with the outside door.
On the dash in the middle.others
Two more pigtail types right off the battery posts.
Do not know of any others

[DoubleO7]

Originally Posted by Booyah45828

And yes, if you don't correctly remove door switches on a handicap lift bus, the bus will experience a no start. Some need jumpered, others need left open, there's a lot of safety interlocks involved.

Would it crank/turn over but not start?

Or even sputter, etc.

I will look, the bus, until recently has been used as a storage unit. Packed to the ceiling and wall to wall. I will have move some stuff out of the way to get to the interior of the HC door.
The lift itself might have interlock switches as well. My father-in-law removed it on his own while I was away at work.
I am pretty sure I then had it running to make sure the related wiring then allowed it to run. But I will look it over again.
The lift got removed and is now mounted next to the deck on the house.
The wife has a high probability of ending up in a wheelchair some day far away. The lift will make it easier for her without adding a ramp to the house.

[Booyah45828]

Originally Posted by DoubleO7

Would it crank/turn over but not start?

Or even sputter, etc.

Eh, no, I don't think so. Won't crank is typically the issue.

Can't check either, as our wheelchair bus is non-existent, as they're now served by the county.

I've never had the experience, only second hand through a handful of people on here and facebook who have removed similar and disabled their bus as a result.

I believe it typically creates a no-crank condition, but you now have me wondering.

[DoubleO7]

Originally Posted by Booyah45828

Take a picture of your alternator. Is the red wire you refer to going to the b+ terminal on it? Yes
If so, you might have a faulty diode. Depending on the alternator, 22SI you might be able to get a new rectifier and repair it. I've never replaced an individual diode.

White wire is likely not a ground, but a sense wire. No, white wire is definitely a ground, in a picture you can see the tail end of GND raised letters in casting. Also, the lug is held with a bolt threaded into alt. casting there with no insulating rubber grommet in the casting like the red wire terminal has. That white ground wire is as big gauge as the red wire. The sense wire terminal is unused up near the red wire.
Very few alternators have a ground wire, as the case itself is grounded to the engine and chassis.

Does any part of the alternator feel warm to the touch? The last one vehicle I had parasitic draw on, I traced it to the alternator and you could feel the voltage regulator was warm to the touch with the vehicle off and cool, making the voltage regulator the obvious fault.
Do not know, will maybe be able to check tomorrow or friday. I do have a non contact thermometer gun tho.

If your batteries are stone dead, charge them up real slowly. You might have a chance at saving them doing it that way. If you fast charge, or jump the bus to get it started, you'll very likely kill them in my experience.

Pictures for your viewing pleasure.

[DoubleO7]

On second thought, I am betting the HC door switches are intact and fully functional. But being the lift was removed, there might be an electrical issue with it being gone.
I would think the lift could not be deployed unless the door was open. I don't remember if bus had to be off and brakes activated before door could be opened or not. Seems like it should have to be.
I would also think that both back end doors would have to be shut and fully latched before bus can be started and driven.

[DoubleO7]

Originally Posted by PhilipE

Take a OHM meter. Unhook the wire that is draining the system on the ALT. With the meter hooked to a known good ground. See if you have a OHM reading to ground threw that terminal on the ALT.

From my testing over the years. I have found each OHM shown on the meter is equal to one amp of discharge back threw a ALT.

Chevy internal regulated ALT's are bad about the diode pack shorting to ground. It then discharges threw the ALT main charge terminal.

Your bus most likely has a Leech charging system on it. It still has a diode pack in it.

Okay so I ohm tested the offensive wire/terminal (being the red to battery) with wire disconnected and meter on the 2000ohm range.
From that terminal to a good ground I get either 384 or 1849 depending on probes exchanged i.e. Red probe on red wires terminal and black probe on ground. Which makes no sense as flipped or flopped probe wise should be one value reading.
But I tried it three times and got the same reading.

But I managed to blow the 10 amp load test fuse and a new one is not in it yet. That event maybe messed up the meter? Or it needs the 10 amp fuse in there for it to do everything correctly?
I did work right on voltage measurements and the continuity buzzer worked.

[Dirtdoctor]

Change batteries as a set. One will only be as strong as the weakest battery. We always change in sets. Cheaper than burning up a starter.

[Booyah45828]

You have a Delco 22si and they're rebuildable

If you're getting any amperage through that red wire and into the alternator, something is leaking current internally, and it's most likely a diode in the rectifier.

If you're handy, you can likely find a replacement rectifier, disassemble the alternator, and swap it yourself.

As far as parasitic draw is concerned, there's only 2 real ways to measure it.

The first is with a test light in series to the positive battery terminal. It's not scientific that it doesn't give you an actual measured amount, but if the light is illuminated, it's likely too much current.

The second is with an amp function on a digital multimeter like you're doing. Have it in series as well, monitoring current as you disconnect loads and fuses on the circuit. Your fuse in the multimeter is there to protect it from overcurrent. You exceeded it's capacity in some way, either by running too many amps through it, or more often shorting the positive directly to ground.

FWIW, I occasionally will do the latter if go to check voltage after I've checked amps, and forget to move the terminal on the meter.

[DoubleO7]

Originally Posted by Booyah45828

You exceeded it's capacity in some way, either by running too many amps through it, or more often shorting the positive directly to ground.

FWIW, I occasionally will do the latter if go to check voltage after I've checked amps, and forget to move the terminal on the meter.

Exactly is what happened.

[Dirtdoctor]

It’s not impossible that a cell in one of the batteries has gone bad. A bad cell will “draw or short” the battery down.

[Booyah45828]

Originally Posted by DoubleO7

Exactly is what happened.

My meter takes standard agc fuses. I've got a pack of both 10 and .5 amp replacements in one of the case pockets. The 10's are blown typically by accidental shorts to ground, but the .5 amps are usually blown by opening the car door with the meter still inline. Your meter might not have/use the smaller fuses.

Originally Posted by Dirtdoctor

It’s not impossible that a cell in one of the batteries has gone bad. A bad cell will “draw or short” the battery down.

For sure, which is why you charge and test paired batteries individually. The battery with the shorted cell will only have 10.5 volts fully charged, which completely discharges a 12.6 volt battery when connected in parallel.