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Author Topic: What Gage cable Battery to Starter  (Read 3535 times)
Sean
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« Reply #30 on: June 06, 2010, 10:53:36 AM »

I guess if a person felt the urge they could also wire a welder into the kitchen circuit, what I'm asking is, are the companies that manufacture buses all wiring them wrong by putting the disconnect switch where the factory put it, clearly somebody here is wrong, incidentally, my eagle also has the disconnect and it's factory installed.


Cody, the world is not that black and white, where someone has to be right and someone else has to be wrong in every instance.

What I said was that, for our purposes, where the coach builder put the switch may not be the "preferred" location, which does not make them "wrong."

Again, there are competing objectives.  For fleet vehicles such as seated coaches, I am sure there is a cost advantage to having the disconnects ahead of the alternator (and starter).  For example, service technicians can simply open the disconnects before working near these parts of the engine, whereas with them directly connected it will first be necessary to disconnect the battery ground before working near these items.

I was taught to always disconnect the battery ground before working around starters and alternators anyway, regardless of what switches may or may not be present.  And I would expect that for most of us here, the extra few minutes to properly disconnect and reconnect batteries before working on those items is probably not an undue burden.   For most of us, disconnect switches serve mostly to protect batteries from discharge due to phantom loads, and secondly to facilitate working on electrical components elsewhere in the coach -- how many times, really, are you swinging a wrench near the starter?

OTOH, for fleets, where mechanics may do this very thing dozens or hundreds of times in a week, saving the extra 2-3 minutes it takes to physically disconnect the batteries would be a good reason to wire it that way.

-Sean
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luvrbus
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« Reply #31 on: June 06, 2010, 10:58:17 AM »

I can not speak about any other bus on a Eagle it is like Len describes a cut off for each battery and the switches are rated for 1200 amps intermittent service and 300 amp continuous service for each switch maybe a overkill but I never saw one fail yet have seen a bunch of lost handles lol


good luck
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Sean
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« Reply #32 on: June 06, 2010, 11:07:15 AM »

Sounds like it would be a good idea to put a switch into the Vanner ground line, labeled "Disconnect FIRST, Connect LAST"
...
That means for long-term parking, it will need to be disconnected.  I'm thinking of a SPST for the ground and a DPST to cut the other two, so it would be:

1)  Cut Vanner ground
2)  Cut Vanner hots
3)  Main disconnect

Then the other way around when it's time to roll.


You know, we thought long and hard about this when we redid the bus, and decided to just hard-wire the Vanner.  So long as the batteries are already equalized, the idle current is so minimal as to be almost irrelevant.  If the batteries are unequal for any reason, you want the Vanner to be doing its job.  And, lastly, if you hook up any kind of trickle charger to top the batteries up during storage, you'll want the Vanner in the circuit.

If you store long enough, the batteries' self-discharge rate will cause you to have to top them up periodically anyway, whether that's by starting the bus, or using a charger.  The Vanner does not really decrease the period for this all that much.

JMO and FWIW.

If you do decide to use switches to disconnect the Vanner in storage, then, yes, that's the right way to do it, or, alternatively, you can get (for a price) sequentially broken/made multi-pole manual switches.  Just remember to use switches with the proper ratings -- some of those Vanners go up to 100 amps, which is a pretty big switch (one of the reasons we decided against it).

Quote
Looking at the MCI schematics, I have to sit corrected -- all Vanner connections are on the battery side of the main disconnect.


That makes more sense.  I was surprised when you said MCI had wired it the other way, because I know Vanner will not stand behind the units that way, and MCI was an OEM customer.

-Sean
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« Reply #33 on: June 06, 2010, 12:16:46 PM »

Sounds like it would be a good idea to put a switch into the Vanner ground line, labeled "Disconnect FIRST, Connect LAST"
...
That means for long-term parking, it will need to be disconnected.  I'm thinking of a SPST for the ground and a DPST to cut the other two, so it would be:

1)  Cut Vanner ground
2)  Cut Vanner hots
3)  Main disconnect

Then the other way around when it's time to roll.

You know, we thought long and hard about this when we redid the bus, and decided to just hard-wire the Vanner.  So long as the batteries are already equalized, the idle current is so minimal as to be almost irrelevant.  If the batteries are unequal for any reason, you want the Vanner to be doing its job.  And, lastly, if you hook up any kind of trickle charger to top the batteries up during storage, you'll want the Vanner in the circuit.

If you store long enough, the batteries' self-discharge rate will cause you to have to top them up periodically anyway, whether that's by starting the bus, or using a charger.  The Vanner does not really decrease the period for this all that much.

What is the idle current on the Vanner?  Any more than half an amp can cause long-term problems on a coach which isn't run much.

Quote
If you do decide to use switches to disconnect the Vanner in storage, then, yes, that's the right way to do it, or, alternatively, you can get (for a price) sequentially broken/made multi-pole manual switches.  Just remember to use switches with the proper ratings -- some of those Vanners go up to 100 amps, which is a pretty big switch (one of the reasons we decided against it).

If you check around, you can find manually-operable circuit breakers up to 140 amps in the $25 range, and I've bought them by the boxful from wrecking yards for a couple of bucks each (go where they put the rice rockets and other too-damn-loud-stereo cars).

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cody
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« Reply #34 on: June 06, 2010, 12:45:04 PM »

I don't recall saying 'they" were wrong.  I believe that was another poster other than me.  My fear would be that somebody unfamilier with coach wiring or wiring in general would take the gospel and look and find out that their coach appeared to be wired differently and not knowing that the gospel may in fact be wrong proceed to rewire their factory coach to the new schematic and get hurt or damage their equipment, it doesn't matter who the gospel is according too.  My point being that there are thousands of coaches on the road from several different companies and I still cannot believe they are all wired wrong because one individual has declared that to be the case.  Many far more experienced engineers would have picked up on the mistake long ago if it had been in fact an error.  I do agree that some people change their wiring aftermarket and that could be wrong but when factory schematics agree with how the switch is wired in, I'll take that as my gospel.
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luvrbus
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« Reply #35 on: June 06, 2010, 12:49:34 PM »

Guys we were a big help to Art he knows how to wire everything except his Eagle LOL
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Sean
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« Reply #36 on: June 06, 2010, 04:04:24 PM »

What is the idle current on the Vanner?  Any more than half an amp can cause long-term problems on a coach which isn't run much.


17 milliamps (0.017 amp)

-Sean
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« Reply #37 on: June 06, 2010, 04:27:01 PM »

What is the idle current on the Vanner? 

17 milliamps (0.017 amp)


Yeah, that's pretty much equivalent to built-in voltage loss.

Speaking of which, I'm looking for a used Vanner . . .
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Lee Bradley
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« Reply #38 on: June 08, 2010, 09:59:41 AM »

As Sean said most Neoplans, mine is a Colorado built Neoplan. I am installing my leveling system with 24 volt air valves and needed 24 volts to check their operation and the easiest 24 volt source is the start batteries. Because of this discussion, I checked my disconnect switch. The starter and alternator are connected to the switched post with the batteries on the other post. The disconnect also has a small spring loaded switch to power the regulator, it is spring loaded to power so a failure will be no power to the regulator. Something to remember if the charging system stops charging. The Vanner is hard wired to the batteries.
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Sean
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« Reply #39 on: June 08, 2010, 11:56:06 AM »

I probably should have mentioned it in my first post on the subject, and of course Brian pointed it out in relation to race cars, but this is the other "safe" way to implement a disconnect switch between the batteries and the alternator.

Disconnect switches, such as the one Lee has, are available with a second set of contacts to control the alternator, and these switches have a sequential break/make sequence.  The alternator contacts are broken first and made last, so that the alternator is never running when the batteries are disconnected.

The alternator contacts can either be in the field wiring (between regulator and alternator) or in the regulator power (between "ignition" and the regulator).  The latter is preferred, when possible, to keep the regulator from working at exciting an alternator that is no longer in the circuit.

Of course, none of that is applicable if you have a "one-wire" type alternator, in which case, once again, my recommendation is to stick with wiring the alternator on the battery side of the switch.  Fortunately, most of us have externally regulated alternators.

That said, few manufacturers likely go to the extra expense of the fancy switch with the extra contacts like Lee has.  I'd be curious to know if any of the Prevost or MCI folks have such a switch installed from the factory?

-Sean
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muddog16
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« Reply #40 on: June 09, 2010, 05:03:11 PM »

I love these threads!  LOL........more is learned in threads like these than any other!
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Pat

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