Hello All
How could two new batteries drain down when the main switch is off? Everytime I go to start the bus my batteries are drained just enough to not start the bus. When I hook up the jumper cables to my truck and the bus starts great, The funny thing is I always turn off the main power and the end of the day.
You'd want to get an clamp style amp meter and see if you notice any draw.
Maybe infant mortality on the new battery? Make sure they get a good charge after being drained.
By chance do you have an equalizer? Maybe that is malfunctioning and drawing current?
If you have an equalizer that could very well be your problem !
Double check to nothing is connected to the unswitched side of the main disconnect. We found that the shore power charger and a couple of circuits were on the wrong side of the switch, causing them to never disconnect.
It would be nice to know what year and model of bus we are having the problem with ,without the info it's a WAG some buses will not kill all the power drain even with the master switch turned off.If it's a MCI with the center tap for 12v you will find it on the 12v side,my MCI is electronic transmission and engine there no way to stop the drain even with the master switch off.You will find some baggage bay lights are hot with the switch turn off lol I discovered that at night time
Quoteget an clamp style amp meter
Ditto that! Once I got a good multi-meter with a clamp for current readings, life is much much better. So much less guessing. Disconnect the starts from house or any other batteries. Quickly just put the clamp over the positive sides of the different banks looking for draw. If nothing then connect the main start battery. Check again. If you get no reading here then your start side is not pulling any current.
On the house bank, look for current draw. Then start looking for which circuit is drawing. For example, check something like a 24v to 12v equalizer for current.
It won't take much time to discover the source. Good luck
Charge batteries, then fully disconnect them and check batteries in a couple days-just to make sure the batteries are OK. Good Luck, TomC
Like TomC said you don't need any meters to tell if you have a drain,disconnect the cables when you connect those back up you see a small spark if you have a drain lol it's easier for me to see when it is later in evening and turning dark
The PA amp is a notorious parasite on the older coaches.
Inside the electric compartment under the driver's mirror.
Follow the microphone leads, pull the power plug. Ghost gone?
Happy coaching!
Buswarrior
I have a MCI 102c3 that I am converting. I haven't gotten to the stage where I am wiring so the bus is still stock as far as the wiring is concerned.
Quote from: luvrbus on September 23, 2018, 05:40:07 AM
It would be nice to know what year and model of bus we are having the problem with ,without the info it's a WAG some buses will not kill all the power drain even with the master switch turned off.If it's a MCI with the center tap for 12v you will find it on the 12v side,my MCI is electronic transmission and engine there no way to stop the drain even with the master switch off.You will find some baggage bay lights are hot with the switch turn off lol I discovered that at night time
So this past week I went to start the bus and the battery was dead. Not both batteries, just one. I thought that was strange because if they were tied together wouldn't they drain together? I unhooked the two batteries and with a voltmeter tested each one. 12 volts on the left battery and 0 volts on the right. The batteries were purchased at Batteries + in February. So I brought the battery in and in order to receive a new battery they needed to try to charge it overnight. So two days later I called them and they said they would give me a new one, however they said that the "defective" batter had reversed polarity. I asked them how that could have happened and they said that I must have charged the battery in reverse. How can that happen? When I charge the batteries I always disconnect the cable that links the two and charge them separately with a 12 volt charger. So my question is how can one of the batteries go dead when the main switch is off and the batteries are connected together? I want to figure this out before I put the new batter in because they specifically said they won't warrantee the new battery.
What testing did you do before replacing the batteries?
Rather than all of us make the same suggestions over again, could you tell us what you found the last time around and what steps you took before installing the new batteries? It would really help us help you.
Which battery? The one closest to ground, or the one closest to the battery cut-off switch?
Sounds suspiciously like something on a center tap.
happy coaching!
buswarrior
I have a 1989 MCI 102c3. The first thing I did was disconnect the batteries from each other. Tested both and charged them independently from one another. They both tested at 12 + volts. Then I connected them back up and tested each. Both 12 volt and 24 volt when combined. I then checked to see if the main shut off switch was actually working correctly, it was as far as I could tell with the volt meter. At this point I was able to start the engine. I then checked to see if any of the circuits in the electrical panel under the drivers window was hot while the main switch was off. I could not find a circuit that was live when the main switch was off. I then let the bus sit for a few days. After a few days I came back and checked the batteries again. The left side battery that was under the Vanner box was at 12 volts. The right side batter closest to the main disconnect was less than 12 volts.
I have gutted the PA system and I don't have bay lights. I guess I don't know what else to check in regards to a current draw when the disconnect is off. Perhaps I am missing something.
I waited a couple more days and tested again. This time the right battery showed no volts. So I disconnected it from the other battery and attempted to charge with a 12 volt charger. It would not take a charge of any kind. That is when I brought it in and the tech at Batteries + said the battery had it's polarity reversed. They said it could have happened by charging the battery backwards. However, I am positive (pardon the pun) that I charged them correctly.
It's just weird that one battery would drain when connected to the other battery. Logic would tell me that if there was a draw it would draw equally from both batteries, correct?
Quote from: richard5933 on October 31, 2018, 04:31:07 PM
What testing did you do before replacing the batteries?
Rather than all of us make the same suggestions over again, could you tell us what you found the last time around and what steps you took before installing the new batteries? It would really help us help you.
If nothing in the drivers electrical panel showed current when the battery switch was off, the next step would be to confirm the same at the electrical panel in the rear of the bus. I'm not sure where it is on your bus, but don't MCI buses have a panel in the rear near the engine somewhere?
You can also just check on the master switch itself. With both batteries connected and the master switch off, there should be no current at all on the load side of the switch. You said that you confirmed the switch is working properly, so then I'd check to see if something is connected incorrectly and is tapping into the battery side of the switch.
Sounds like you're still running the Vanner to get 12v from the 24v battery bank. This is where my attention would go. If it's failed or not hooked up correctly you could get the same results as not having an equalizer at all - one battery fully charged and one dead.
What it sounds like to me is that even with the master disconnect in the 'off' position, you've got something drawing power from the center tap - either directly or through the Vanner.
Can you post either photos of how this battery bank is connected or a drawing showing the wiring?
If that battery was bad from the store...
If the Vanner battery equalizer is properly deployed...
The Vanner will valiantly try to equalize... as it should...
All this foolishness over a bad battery...
What other wires are attached to the batteries?
If you leave a hose connected, there's going to be a leak...
At this point, a reset of the mind is required, and start over.
happy coaching!
buswarrior
edit - my Vanner stays directly connected inside the cut-off switch all winter, with no ill effects.
Disconnect it, wires off in correct order, temporarily, to get this battery set to behave, once behaving, add it back in and be sure it is not the culprit.
If you suspect the battery is at fault, swap the batteries around and see if the problem follows the battery. I realize that you already replaced it, but something to consider if it happens again.
I replaced my 8D start batteries back in May, and in July one went dead (shorted cell). So it is very possible for a mb ew battery to fail. Has happened to me a few times over the years. The 8D seems to fail more frequently in my experience. Doesn't make much sense to me but whatever.
Here are some pics. That might help.
Quote from: richard5933 on November 01, 2018, 03:47:21 AM
If nothing in the drivers electrical panel showed current when the battery switch was off, the next step would be to confirm the same at the electrical panel in the rear of the bus. I'm not sure where it is on your bus, but don't MCI buses have a panel in the rear near the engine somewhere?
You can also just check on the master switch itself. With both batteries connected and the master switch off, there should be no current at all on the load side of the switch. You said that you confirmed the switch is working properly, so then I'd check to see if something is connected incorrectly and is tapping into the battery side of the switch.
Sounds like you're still running the Vanner to get 12v from the 24v battery bank. This is where my attention would go. If it's failed or not hooked up correctly you could get the same results as not having an equalizer at all - one battery fully charged and one dead.
What it sounds like to me is that even with the master disconnect in the 'off' position, you've got something drawing power from the center tap - either directly or through the Vanner.
Can you post either photos of how this battery bank is connected or a drawing showing the wiring?
Here are a couple more pics.
I will check the rear electrical panel and if I find nothing drawing power I will disconnect the Vanner and install the new battery. I will make sure all the voltage is correct on both batteries when connected and wait a couple days. Then if all is good I will add the Vanner into the mix and see if the batteries go down. Does that sound like the correct plans?
Quote from: buswarrior on November 01, 2018, 06:22:34 AM
If that battery was bad from the store...
If the Vanner battery equalizer is properly deployed...
The Vanner will valiantly try to equalize... as it should...
All this foolishness over a bad battery...
What other wires are attached to the batteries?
If you leave a hose connected, there's going to be a leak...
At this point, a reset of the mind is required, and start over.
happy coaching!
buswarrior
edit - my Vanner stays directly connected inside the cut-off switch all winter, with no ill effects.
Disconnect it, wires off in correct order, temporarily, to get this battery set to behave, once behaving, add it back in and be sure it is not the culprit.
Quote from: Jcparmley on November 01, 2018, 10:18:42 AM
I will check the rear electrical panel and if I find nothing drawing power I will disconnect the Vanner and install the new battery. I will make sure all the voltage is correct on both batteries when connected and wait a couple days. Then if all is good I will add the Vanner into the mix and see if the batteries go down. Does that sound like the correct plans?
Sounds like it would help to determine if the problem is in the bus's 24v system or something feeding from the Vanner.
Quote from: Jcparmley on November 01, 2018, 10:14:23 AM
Here are some pics. That might help.
Not seeing any photos.
Its your Vanner. I found if I leave the vanner all hooked up while the bus is sitting awhile it will reduce the charge over time in one start battery if bus is not plugged in. If I disconnect the ground while it is parked no problems. Just a thought that I found works. The Vanner take a small amount of charge to run. HTH :)
I had the same issue with my 1981 MCI MC9 when I purchased it over a year ago.
I bought it from a friend who sold it to me with the "parasitic drain", and we always just disconnected the batteries when not running the engine.
Ultimately, to solve the problem, I took a volt meter to the main junction box on the exterior driver's side.
With the batteries connected but the Main Power Switch in off position, I checked each connection to see where power might be pulled from.
In the end, it turned out power was being drained from the batteries through several wires that previous owners had just left disconnected inside the cabin walls.
By disconnecting the unused wires from their solenoids in the junction, I eliminated the drain on the batteries.
I don't understand why it only drained one of your batteries, though.
Also, another obvious (but not so obvious) issue could be the "step light and chimes" switch.
Don't know if yours has one of these. But of course if you need it switched "on" to start your bus, then I guess you had probably also remembered to turn it off :D
Well there's the problem...
Where does that rats nest of wiring go?
No point shutting off the master switch with all that CRAP connected on there.
How many of those circuits are unprotected/not fused? Where do they all go?
You have 12 volt centre tap and 24 volt coming out of there.
If you get all that trash out of the battery box, put the 24 volt all together on a buss, and then create a 12 volt buss, with shut off between the centre tap and that, you have half a chance to get the draw to zero.
Be careful to label everything, as to where you take it off, way too easy to hook something up wrong.
The goal is a simple battery box, all the clutter needs to be elsewhere, so that it doesn't get disturbed or screwed up when working on the batteries, and also away from the battery gases and corrosion..
So, in there, big main battery cables, Vanner Equalizer, and then feeds to two main disconnects, 12 and 24. Everything else moved to newly created buss bars out of the way.
And protected from setting the coach on fire by a short circuit.
happy coaching!
buswarrior
Pics are in post 17 and 18.
Quote from: richard5933 on November 01, 2018, 10:59:35 AM
Sounds like it would help to determine if the problem is in the bus's 24v system or something feeding from the Vanner.
Not seeing any photos.
I haven't wired anything in the bus yet so everything in the battery bay is as it was when I bought the bus. So I'm assuming that the white wire and the small black are not normally there, is that correct? I am trying to determine what is "crap" and what is required.
Quote from: buswarrior on November 01, 2018, 12:51:56 PM
Well there's the problem...
Where does that rats nest of wiring go?
No point shutting off the master switch with all that CRAP connected on there.
How many of those circuits are unprotected/not fused? Where do they all go?
You have 12 volt centre tap and 24 volt coming out of there.
If you get all that trash out of the battery box, put the 24 volt all together on a buss, and then create a 12 volt buss, with shut off between the centre tap and that, you have half a chance to get the draw to zero.
Be careful to label everything, as to where you take it off, way too easy to hook something up wrong.
The goal is a simple battery box, all the clutter needs to be elsewhere, so that it doesn't get disturbed or screwed up when working on the batteries, and also away from the battery gases and corrosion..
So, in there, big main battery cables, Vanner Equalizer, and then feeds to two main disconnects, 12 and 24. Everything else moved to newly created buss bars out of the way.
And protected from setting the coach on fire by a short circuit.
happy coaching!
buswarrior
Just to raise another point (and maybe start trouble, IDK) if the battery voltage was zero, how could they ever have determined that the polarity was reversed? Doesn't that presuppose that you have a 12v positive voltage on the negative terminal? And doen't a zero voltage summarily indicate no voltage of any polarity on either terminal? I don't think any sort of a residual voltage would count here, a lead/acid battery either produces about 2v per cell or it produces nothing. It can loose all it's current capacity and still give you that 2v, it just can't handle any load. So if he comes back with any kind of crap about there being anything less than 12v of reversed voltage it's nothing more than attempt to shift the responsibility for the bad battery off on the customer, you. Like getting you to accept a replacement battery without the warranty. Sounds to me like you got a bad battery, and now you have a bad battery dealer.
Jim
That's exactly what I told them. They gave me the new battery but said that the warrantee dosen't begin new, so I only have a few months left on both batteries. I thought that was a very week policy. Perhaps I should call the corporate. The company is Batteries + Bulbs.
Trial and error is shooting in the dark IMHO. Use a clamping meter that measures current draw. You will find the source in no time. Also, get the batteries tested. Good/bad - done.
When a battery fails with ,say, a 3 year warranty, after so many free replacement months, the rest of the time could be prorated like tires. You pay some money for the new replacement battery. In any case, if it is free replacement and no prorating for so many months use, they don't extend your warranty. It is the original warranty time even with a new battery.
Btw, here: https://www.batterystuff.com/blog/battery-myth-can-a-battery-reverse-polarity.html