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Author Topic: I have 12v at battery but only getting 2 to 5 volts at my panel.  (Read 2050 times)
jjchristian84
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« on: April 30, 2013, 01:55:31 PM »

I left my on switch on my 4104 and killed my batteries. I tried jumping it with van and the first time I cranked it it turned like it was trying to start, but didn't have enough juice. So I left it to charge for a little while. When I came back I flipped the on switch but didn't hear any of my relays click and no starting action going on. I pulled out my meter and it read about 5.5v at the panel. I checked the batteries and they are at 12.63v. Left it to charge for a little while longer hoping it would work it's self out. I came back and flipped the master switch and heard the relays click. But hit the starter switch and nothing happen. Checked the panel again and this time it is at about 2v. Any idea what is going on here?
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Frank @ TX
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« Reply #1 on: April 30, 2013, 03:40:14 PM »

Hi jjchristian84,
Someplace between the battery and the dash there is a loose connection.
Keep checking the voltage alone the way and you'll find it.
Look at both the pos and neg lines.
Good luck
Frank
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jjchristian84
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« Reply #2 on: April 30, 2013, 04:35:59 PM »

Thanks. I think my Master Diesel Relay is bad. I went to dinner and checked it again when I got back. It is now at 12 volts again, but I didn't try starting it again yet. Maybe some bad grounds causing the relay to overheat. Not sure. Just have to keep checking I guess.
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gus
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« Reply #3 on: April 30, 2013, 06:52:07 PM »

As I remember there are at least two relays necessary to start a 4104, probably more.

Your batts are probably just too weak and volts too low. You also may have one batt shorted, check each separately with a load tester after charging each separately. A shorted batt will kill the other, been there. 12.63v is not proof the batt is good, only a load tester will tell you for sure. $25 at WM.

Leaving the engine run switch on kept a couple of relays activated which drew down the batts.

How did you leave it on and shut down the engine? Or are you talking about the elect master switch?
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PD4107-152
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Jnbroadbent
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« Reply #4 on: April 30, 2013, 07:06:41 PM »

As I remember there are at least two relays necessary to start a 4104, probably more.

Your batts are probably just too weak and volts too low. You also may have one batt shorted, check each separately with a load tester after charging each separately. A shorted batt will kill the other, been there. 12.63v is not proof the batt is good, only a load tester will tell you for sure. $25 at WM.

Leaving the engine run switch on kept a couple of relays activated which drew down the batts.

How did you leave it on and shut down the engine? Or are you talking about the elect master switch?

You can get it load tested at a discount auto for free fwiw
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jjchristian84
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« Reply #5 on: May 01, 2013, 05:51:44 AM »

Yeah, I left the master switch on. So the batteries may be toast? I just bought new ones. That would be a disappointment.
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Jeremy
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« Reply #6 on: May 01, 2013, 08:48:25 AM »

Flattening the batteries will hurt them, but it shouldn't kill them, especially if they weren't left flat for very long. When they were flat, were they totally flat (ie., 0v)? If so that certainly isn't good and it can often be difficult to get batteries in that state to start to charge again - but it sounds like that wasn't a problem in your case, which may be a good sign.

As has been said, a load tester will determine whether your re-charged batteries actually still have a capacity. Failing that, simply measuring the voltage at the battery with your existing meter, but whilst trying to crank, will probably tell you what you need to know.

Jeremy


Edit: It occurs to me that I'm not clear on whether the 2v at the panel situation is happening all the time, or only when trying to crank. If it's only when trying to crank (and if measuring at the batteries gives the same voltage) then it's probably the batteries at fault. But if it's happening all the time then the problem has got to be in the bus (and presumably anything in the bus wiring which can cause such a large voltage drop when not trying to crank is potentially quite serious, not to say a big permanent drain on the batteries)

« Last Edit: May 01, 2013, 09:03:36 AM by Jeremy » Logged

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« Reply #7 on: May 01, 2013, 02:24:57 PM »

It takes a while to recharge batts that have been completely discharged, it needs to be done slowly.

A jump start will not work on a completely dead batt, even on a car.

Unless the batts are pretty old I agree with Jeremy that they probably are ok, it just takes patience or renewing their life. However, complete discharge will often kill an old batt.
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jjchristian84
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« Reply #8 on: May 01, 2013, 06:14:15 PM »

They are both new batteries. But I have been forgetful lately and have drained them a couple of times down to 0v. Here is how the voltage problem goes: If I went out right now and measured the batteries they read 12volts +/-. Turn on the master switch, the relays click, and the panel shows 12volts +/-. Hit the starter switch and it gets half a turn before dying out. The battery gauge reads very low, almost negative and now the panel reads 2 to 5 volts. Now, turn the master switch off and back on and the relays do not click and the panel is still at low voltage. Batteries still reading 12 volts though. If I wait five or ten minutes I can go back out there. Flick the master switch, relays click, and do that whole process over again. Never resulting in more than half of a turn on the motor. This still happened while I had two running vehicles hooked up to it with jumper cables.
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Sam 4106
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« Reply #9 on: May 01, 2013, 06:37:48 PM »

Is your 4104 still positive ground? If it is, and you are jumping the batteries from a negative ground vehicle, with the positive jumper cable hooked to the negative bus battery post, you are charging the bus batteries backward. With a completely discharged battery, it can be charged backward and have very little power. I know this is a long shot, but I've seen some really strange things happen. If you have charged the bus batteries backward, they will have to be completely discharged again to try to charge them correctly. If your 4104 has been switched to negative ground, the above doesn't apply.

Good luck, Sam
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« Reply #10 on: May 01, 2013, 07:46:54 PM »

Put the charger on them and leave them for 2 or 3 days before trying to start it,...they might come back if you are lucky. Since you drained them a couple of times, even though they are fairly new, I would start thinking about buying new ones. Take them in and have them load tested before you buy any just to be sure they are shot.
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jjchristian84
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« Reply #11 on: May 02, 2013, 07:08:41 AM »

I can't say I am familiar with the positive/negative ground idea. It had old batteries when I bought it and I was able to jump start it them. So...It has been changed over? I got one new battery yesterday. I'll get the other one in a couple of days. Here's to being hopeful. The limits of my 'handyman'-ness is getting stretched to it's limits!
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Ed Hackenbruch
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« Reply #12 on: May 02, 2013, 09:48:03 AM »

Follow your battery cable from the starter back to the batteries. If it attaches to a + post, you have a negative ground, if it attaches to a - post, you have a positive ground.
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« Reply #13 on: May 02, 2013, 10:19:04 AM »

Check all the connections you can from the battery to the starter.  Check the grounds also.  It could even be in the cable connectors.
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jjchristian84
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« Reply #14 on: May 02, 2013, 11:52:43 AM »

Thanks! I'll do that.
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gus
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« Reply #15 on: May 02, 2013, 03:52:52 PM »

Ed,

Both batt cables on a 4104 connect to bulkhead bolts in the batt compartment, it is kind of difficult to figure out how they properly connect.

It does sound as if he has two cables connected in reverse due to the low voltage after trying to crank.

jj,

Please check very carefully that you don't have your batts connect in reverse, it sounds that way to me. the huge drop in voltage makes me think this. This is easy to do in a 4104 because all those cables look like a spider's nest and the two bulkhead connectors are easy to mix up.

If you're charging the batts separately then connecting them this is probably what is happening. However, if you're charging them while connected in parallel that may not be the problem. I'm not sure what would happen if you charge two together connected in series??

Another thing that could cause that huge drop in voltage is a stuck starter but I can't explain why it works a while later. A stuck starter will draw huge amps and voltage and won't crank the engine.

Corroded connections could cause some voltage drop but I don't think that much. I once cleaned all my cable connections from the batt to the starter and it did help quite a bit, those cables are pretty long and old.

Another thing to check is the starter relay in the rear right hand elect comp but that wouldn't explain the huge voltage drop. A bad relay will keep the starter from cranking but won't drop the voltage because the circuit isn't activated.

One other thought and I'll stop guessing, it could be a cable that is so frayed only a few strands are left and when you try to crank they get really hot and increase resistance. A badly corroded connection will do the same thing. Then after it cools it will once pass current for a short time. A wild guess but possible!
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Dave5Cs
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« Reply #16 on: May 02, 2013, 04:23:31 PM »

You said after charging they showed 12volts.If that is true that battery is toast. Fully charged it should show 12.6 to 14.
Maybe the problem.

Dave5Cs from Galaxy S III
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gus
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« Reply #17 on: May 02, 2013, 06:22:05 PM »

At some point I think he said 12.6v but I kind of lost track of the thread along the line!
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Dave5Cs
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« Reply #18 on: May 02, 2013, 08:12:14 PM »

Gus I know what ya mean. Cheesy

Dave5Cs
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jjchristian84
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« Reply #19 on: May 02, 2013, 10:41:51 PM »

The batteries are at 12.6v or above. I did have a problem with switching the pos and neg cable connections once upon a time, but I think I have that figured out. I am worried about the bad connections thing. I extended the wiring harness' and moved the panel to behind the driver's seat for easier access. I used solid wire. A friend of mine who is an electrical engineer told me after the fact that that may have been a bad idea as stranded and solid wire sometimes don't mix well. I know the 4104 has a lot of redundancies and protection circuits, but I am guessing there is not a lot of actual 'electronics' that go into the operation of the motor and drive system itself. Pretty much mechanical in 53' right? So, I may have to wire directly into the starter and engine electronics to bypass the panel. Because at this point, I have no idea where the bad connection might be. A good portion of the wire is dry-rotted and corroded . And I have no access to the tunnel running down the middle and cannot trace wires through there. A little depressing, but I knew I was in for a challenge when I bought a 60 year old bus with millions of miles on it.
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« Reply #20 on: May 03, 2013, 02:27:05 AM »

This is all standard 4104 stuff/problems.  Get a good smart charger and your bats will live longer.  Buy batteries with a guarantee and you may save enough to fix other stuff,  Poor grounds have not been mentioned but you need to start there.  Until you KNOW your electrical system is fully functional, do not leave the batteries connected while away from the vehicle as a short can cause a fire and you need to br around to put it out.  Speaking of which make sure you have a fairly large fire extinguisher in/on/near the bus.  For trouble shooting wiring I use a couple of extension cords and alligator clips to make sure circuits are getting the volts they need. When I use the original wiring I always isolate it and check it for continuity and then for voltage drop to make sure it is usable.  Finally one group 31 bat will start your engine, so keep it simple for now as having the 2 bats connected just hides problems and can lead to a bad bat killing the other bat. 
BTW master switch and starting relays MS relay almost definitely need to be serviced/replaced, especially if the are original, I use a lot of cube relays on my bus as the huge old relays, while still functional, are very inefficient and leak a lot of voltage even after PM/adjusting.
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jjchristian84
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« Reply #21 on: May 03, 2013, 12:14:47 PM »

Okay. I don't understand all the weird voltage stuff that was happening. But it appears it was just a case of a ruined battery. It's running again! Grin Thankfully it was under warranty. I think I need to go trade the other one in too.
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gus
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« Reply #22 on: May 03, 2013, 09:56:31 PM »

jj,

You probably connected the two pos to neg and ruined one, lucky you didn't get both. Knowing the 4104 as I do I assure you this is not hard to do. I've had a few batts ruined when a mate shorted out.

You will continually have elect problems from corroded wires, especially at the terminal ends at the panel stud connectors. I cleaned those terminals, replaced the nuts with brass, replaced a bunch of the terminals and things got better. You will find that those old steel nuts and posts really caused the brass terminals and copper wires to corrode - too many different kinds of metal in contact for too many years. I cut about an inch off every wire when I replaced the terminals, went back to fresh clean wire.

You may not be a mechanic now but you will be after you own it a few years, it is a good project for training in many skills.

There is nothing electronic in a 4104 except maybe you could consider the selenium rectifiers electronic but that is a stretch! All that I could see they were used for was to isolate alarms so the circuits could be multi-purpose.

Zub is right, just use a single Gp31 or 29 batt for now so you won't have this problem anymore until you get it on the road.
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jjchristian84
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« Reply #23 on: May 04, 2013, 04:52:28 AM »

Thanks for all the help!
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siberyd
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« Reply #24 on: May 05, 2013, 10:32:35 AM »

How about that, 2 - PD 4104's across the country from each other having similar battery problems - no start on vehicle/bad or dead batteries.

Similar answers, chuck the second battery. Get a group 29 or 31 battery and use a battery disconnect when parked.

Thanks a million guys, I am learning a lot about my bus here. Its a longprocess making the move from driver to driver/mechanic/bottlewasher.

Siberyd
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« Reply #25 on: May 05, 2013, 02:58:30 PM »

These things happen. Just yesterday I remove both my 4D starts for their two year cleaning and refilling. I found one 2/0 ground cable completely corroded off, it was solid green. It was broken but snug up against the lug so the break wasn't obvious-you never know! Luckily the PO had tied the two batt ground posts together so the batt was still in the circuit. Otherwise I would have been operating on one batt and not have known it.

I may stick with 4Ds after all since the posts are on the end like the 8D. With my 4107 batt box design side posts would be a pain to access. It would also require changing to longer cables-I may be too lazy to do all that!
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