| Author |
Message |
DAVID HEAD (Chuck)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 12, 2005 - 9:13 pm: | |
I put two new batteries in the bus a few weeks ago and they seem to be loosing their power when I am not running the bus. The main switch is shut off but the bus is wired to have twelve volts when the batteries are shut off. The problem seemed to start right after I gutted the insides
and cut down all the lighting and sound system.any way to track down the problem the bus is a mc9 |
John that newguy
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 12, 2005 - 9:37 pm: | |
In my personal opinion.......
First thing to do, would be to see if there's any power being
used on that 12v tap. I removed mine, since the tap is more
of a problem than a benefit. Use a 24 to 12 converter instead.
That tap will keep the batteries from being properly charged
and will continually drain one battery more than the other.
When installing new batteries, it's best to fully charge each,
independently with a 12v charger initially. The 24v alternator/regulator
only cares if it sees 28v total and one battery can be undercharged
and never get fully charged. |
David Hartley (Drdave)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 12, 2005 - 11:09 pm: | |
I know that you said the main switch is off, But I was having the same problem with my MC9, Mostly with the switch on. Seems the bay lights were staying on " cus I had the doors open ".. However if it is a NJ MC9 and has the Vanner or equivalent 24 to 12 volt equalizer, The problem could be in that. It also stays tied to the 12 volt junction point even with the main switch off.
To test the theory of something on the 12 volt tap, Take the wire(s) off of it and put your handy dandy test light between the 12 volt battery terminal and the wire(s) that you took off. If you get a light then trace that down.
Good Luck... |
Craig (Ceieio)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 13, 2005 - 12:25 am: | |
David - here are a couple of posts I made on another board a while back. Sounds like the same situation. Hope this helps:
--------
First, it sounds from your description that your equalizer is
connected directly to the batteries? If so, I would move it to after
the battery cutoff switch. It is just good practice. While I am an
electrical engineer by education, I haven't looked at how one of these
things are designed, so I can't be authoritative on it. In general,
most active circuits are going to have parisitic draw and will pull
your batteries down over time. How much time depends on the batteries
and the devices.
Second, to furthur troubleshoot leakage current on things automotive
you can try this method. First, guess how big of current draw you are
dealing with so you know how big of amp guage to use. If it drains
down rather quickly, it would be a larger current.
If it is a small current, a "Radio Shack" multi-meter will work. For
a larger current (or if you just don't know) you can make a test meter
out of an truck/automotive amp guage from a boneyard or inexpensive
source.
Connect some reasonably heavy wire to each of the two terminals of the
amp guage and put some suitable sized alligator or battery clips on
the other end of the wire. Make sure the terminals on the back of the
gage are taped off or enclosed so that when the meter falls on the
body you do not create a mini arc-welder. It will fall on the body,
trust me.
Turn everything off in the bus and use the battery disconnect switch
to disconnect the batteries fromt he coach.
Next connect the amp meter in series with the batteries by removing
the positive lead from the coach to the battery bank. Connect one of
the meter clips to the battery cable and then wrap that up so that
when it falls on the body you don't make a mini arc-welder. It will
fall on the body, trust me. :-) Connect the other clip to the
battery post.
If all is right in the world, there should be no sparks or meter
deflections when you make this connection as (allegedly) everything is
off and disconnected from the battery. If the meter does move, then
there is a problem right away. It could be something connected
between the battery and the main disconnect, or something like a wire
with worn through insulation. Good luck crawling around looking for
that be at least the scope of the search has been narrowed some what.
Assuming the meter didn't move when initially connected, then it is
time for the next step.
Turn the battery disconnect switch back on. You should see the meter
deflect now since the everything is connected now.
Here comes the painstaking part. You need to isolate which circuit(s)
are drawing the current. On a car, I pull the fuses one by one until
the current draw drops. When this happens, you know which circuit the
problem lies in. You may have multiple curcuits causing problems so
you may have to repeat this.
If, for example, you pull a fuse for windshield wipers and the current
draw drops, then you can start checking out the wiring, switches, and
wiper motors for the problem. You can also plug all of the rest of
the fuses but the wiper one back in and see what else is connected to
that wiper circuit by finding the things that no longer work. Many
times there are multiple things tacked on to a single circut either by
design or do-it-yourself projects.
Repeat as necessary until the current draw is minimal. It may never
go to zero if there are things that have an electronic memory like a
clock or radio connected. These items draw little power so the drain
won't be much on the batteries, but you can still detect the drain.
I don't know enough about the MC9 to know how you go about breaking
circuits, but the idea holds the same. There are a gaggle of curcuit
breakers, fuses, and you may have to resort to taking a wire or two
loose in the panel.
Please notice that you should not try to start the bus or any other
really high current draw item as your test rig can't handle that load.
If you do try to start the engine or turn on the coach blowers, you
will probably find a molten lump of plastic where your cheapie auto
amp guage was formerly located. If it melts really good, you may even
have a wire fall against the body and create a mini arc-welder.
One other thought unrelated to the above rant:
One thing that can really drain a battery in a couple of weeks is an
automotive alarm system. If you have one connected to the coach
batteries, you are going to have to find a way to get a trickle
charger on them.
Best of Luck,
Craig MCI 7
--------
Message 2:
Generally equalizers have three connections on the input side, 24V,
12V, and ground. Move the 24V connection from the battery to the
other side of the disconnect switch. For the 12 volt connection, add
a high current switch (like drag racers use or a knife switch) to
switch the 12 volt center tap. Mount it next to the 24V cutoff
switch. This way you can disconnect the whole shooting match when the
bus sits for a while or when you need to do electrical maintenance.
Or you can leave it like it is. :-)
Craig MCI 7 |
Pat Bartlett (Muddog16)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 13, 2005 - 5:03 am: | |
Chuck, a digital amp meter(gun type) clamps around the conductor, most amp guns are ac/dc capable, to read current you must be in series with the circuit being tested! Digital meters regardless of the type give excellant resolution (read smaller values more accurately) the best thing about a amp gun is you don't have to break into the circuit to read it! Most of us carry those new digital multimeters they are very inexpensive these days, a digital ac/dc ampgun has many uses in a bus! They can save many headaches and a lot of time! Good luck! |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 13, 2005 - 7:33 am: | |
The Vanner equalizers, that I have used, must be connected directly to the batteries. There is a warning label giving the correct order to connect and disconnect the wires. |
Jim Ashworth (Jimnh)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 13, 2005 - 7:59 am: | |
Prevost issued a service bulletin about their Vanner installations that were switched at the main disconnect. It said to hook the equalizer directly and not on the switched side of the disconnect. Guess they had problems with it.
If you aren't using the bus or the 12 volt very much, then just disconnect the equalizer or put a trickle charger on it.
Jim |
Sojourner (Jjimage)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 13, 2005 - 12:00 pm: | |
All above is helpful but added clarification and my life tools to deal with current drainage & shorts.
Reason battery drain overnight, week or months;
1) Something left power-on
2) Dirty or acid coated out side of battery…clean w/mix baking-soda & water with battery’s cap on (stronger the faster)
3) Alternator’s diode is leaking
4) No master-cut-off switch between battery to whatever for in case of appliances is left on.
5) Isolator’s diode is leaking
6) Equalizer (drainage??) is on
7) Normal with master-cut-off “IN ON POSITION” due to any electric appliance with timer or clock or 24hr stand-by such as remote control TV and w/converter or alarm system
Highest draw = Diesel’s starter when bearing is worn or shorted.
Lowest draw = Electronic clock or timer either stand alone or appliance w/clock build-in or idle-remote-control appliance.
Low-cost & simple trouble-shooting unwanted current draining and shorts, IF it high enough to power low power flasher unit.
1) Need low power 12v two-tab flasher unit.
2) Remove battery + terminal from battery’s post
3) Connect jumper from battery’s post to + tab of flasher
4) Connect jumper from battery’s terminal to other flasher’s tab
5) Need hand-held battery AM radio (.25 cent garage-sale item will do)
6) Set radio to about 1300 kHz range and tune without broadcasting on
7) Listen to “Flasher” current pulse anywhere between
shorted or draining source points
8) If you wear Hearing-aid (I have two, one for each ears), flip switch control to telephone pick-up and repeat #7. Another word I am equipping with current detectors whenever hear-aid on.
If drainage current is lower than flasher power requirement, connect standard DC or multimeter between battery’s post & battery’s terminal. Do like what others had posted, remove fuse one by one or all to read zero voltage then reinstalled one at time until meter read voltage. Point .5 voltage max (fair diode drainage) is consider normal with alternator equip. If all fuses are removed and still voltage, remove alternator hot terminal……..if no change, then you have to go thru process of wire limitation which take more time.
CAUTION about purchasing “Clamp” (amprobe) meter to record DC ampere. BE SURE IT DC AMP clamp version as well AC amp combine.
CAUTION if battery’s drainage is .1 (point 1) amp or greater than DC amprobe can be helpful but multi-meter will do for must less $$$$ and more active tool for weak drainage.
That DC capable version costing $100 or so more than AC amp clamp only version.
I have Fluke 336 and love it. Capable to read up to 600 ampere either in AC or DC as well true AC RMS volt and ohm digital.
http://www.heavydutytools.net/Scripts/prodList.asp?idCategory=81 for $240
Or w/discount business name at http://www.grainger.com/Grainger/wwg/start.shtml
Type in “Fluke 336” in search box.
Here one for less $$ without true AC RMS volt meter;
http://shop.store.yahoo.com/brandsplace/0246-sr-cm600.html
There are others good buys but be sure it able to read at least 400amps or higher and better yet equip with true AC RMS volt meter equip to measure converter output voltage.
Remember only true AC RMS equip meter can read actual voltage from all type of converters.
What is true RMS?
http://www.bcae1.com/voltages.htm
Must have favorite freebie;
Everything (almost?) under the sun about electric complied by William Darden;
http://www.uuhome.de/william.darden/index.htm
Be sure to click on “Battery Information (or Reference) Links List”
FWIW
Sojourn for Christ, Jerry |
Buswarrior (Buswarrior)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 13, 2005 - 1:06 pm: | |
Hello David.
I have a vanner equalizer connected directly to my batteries, ahead of the main disconnect in my MC8.
With the battery switch turned off for 6-7 weeks this past winter, following my return to the frozen north from Arcadia, the voltage was up and when I plugged in the SW4024 to charge the batteries, it only went to 3 amps on bulk charge!
Yes, I know I am an uncaring heathen for leaving the coach unloved for that long.
So, a vanner equalizer doesn't do much draining.
A popular culprit for power consumption in these old buses is the PA amplifier, and any radio wiring that was added by someone else.
A bus in commercial service sits at most for a few days between runs. As a converted coach, a parasitic loss that was well within the tolerances of that commercial duty cycle may be a battery killler.
I always leave the batteries turned off when the coach is being "stored", and I turn off the start batteries to avoid dumb mistakes when at rallies and camping.
You will find many older coach drivers do the same when they are out on a multi-day charter, especially in the winter at the ski slopes. For a generation that doesn't attend church, the younger ones seem to have an amazing faith in the coach to keep a charge!
At the moment, all of my 24 volts is tied together so the coach alternator may charge everything while driving and while "in storage" the inverter/charger may be used to charge everything at once by running out the shore cord to the house.
The more convoluted maintenance practices become, the more likely you'll find something "better" to do with your time?
happy coaching!
buswarrior |
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