Battery Off/On Switch

[Joe Cannarozzi]

I have a couple of questions.

Does it matter if you put a disconnect switch on the pos. or neg.?

What and where exactly is this parasitic draw that can take the bus bats. down even if you switch them off?

[hhoppe]

Joe: I'm no expert on this but when towing my Tahoe the manual said to pull certain fuses out of it before towing. I tried that, only to have a dead battery after towing. I next put a battery switch to disconnect the negative side of the battery. At the end of the trip, I had a dead battery. I changed the battery disconnect switch to the positive side and no dead battery after towing. I don't know what happens, but I like the results. I'm sure Jon or one of the electrical experts will solve this one.

[Omnitech]

The parasitic draw is from a keep-alive for the engine and transmission electronic control units. While the draw is not much, it is enough to deplete the chassis batteries over time if they are left unattended. The chassis batteries are designed for cranking amps, and do not have the long-term amp hour capacity that is usually associated with battery types used for house loads.

The cut-out switches are put on the "hot" and not the ground. If you were to put the cutout on the ground circuit and found yourself touching a battery negative post and chassis ground at the same time (as in leaning over the batteries to get to something during maintenance or troubleshooting) you could find your body as part of the ground circuit.

[Joe Cannarozzi]

O/K so it is the pos. side for the disconnects. I have an all mechanical, no computer bus so I should not experiance this particular draw problem if disconnected

[garyde]

Hi Joe. What's becoming more and more prevalent on the newer Conversions is more and more electronics with computers. All of these need to have UPS(un-interrupted power supply) to retain memory. Therefore, they are connected before any disconnects. It is hard chasing them all down depending on the individual Convertors wiring methods.

[Jon Wehrenberg]

Mastr teknishn,

Before everybody goes a little crazy relative to your comments about parasitic draw on the Prevost batteries I think your statement should be amended to reflect "on some coaches".

I have had two Liberties. I rarely turned the master chassis switches off on either coach. I never had the batteries drawn down.

Specifically, I parked the coach on May 15, and it was not shut off. The switches remained on and there was no trickle or maintenance charger providing power to the bus batteries. On Aug 15 I started the bus for the trip I am on right now. It fired right up.

I did find on the first Liberty a home made attachment a previous owner added to the chassis batteries (I forget what it was for) and it drew the batteries down in one week. I removed the load and from that point on I never had to worry about shutting off the bus chassis.

I do not think my experiences are unique.

[Joe Cannarozzi]

Here is a easy solution to needing power outside with only a short extension available

My Bus 303.jpg

Deb came home and said, are you sure you know what you are doing? I said, you better hope so

Installing lower, outer access door/louvers for a propane fridge that originally did not exzist. Show and tell to come later.