Strange battery cable connection results

[East Tenness]

I was in the process of changing out may chassies batteries on my 2004 newmar essex. I taged every connection (wire/cable end) as I disconnected the batteries. When I went to replace the new batteries and started replacing the cables ( neg frist ). When I went to connect the Pos side the horn and the windshield washer pump came on. I disconnected everything fooled around with for several hours and as it stands now, when I connect just the main Pos. & Neg. the headlights come on even without any other wires/cables connected. Any suggestions??? THANKS

[Arch Hoagland]

Have you checked the voltage with a voltmeter?

[wirelessenab]

I don't have any insight towards what is happening but, I always disconnect the negative cable first then the positive. I reconnect all the positives and then reconnect the negative.

Reason is that if while you are tightening the positive with a wrench and hit the frame or some other metal piece, nothing happens if the negative is not connected. When you tighten up the negative it doesn't really matter if you hit the metal frame with your wrench.

If you connect the negative first and then while connecting the positive your wrench hits some metal on the frame, you end up with a big spark and maybe even smoke etc.

Jim

[autofish]

Much safer to hook pos. cables up first... then last hook up the neg. cables this may be the problem.

[Dunner]

Sounds like the positive is finding a ground through the other devices and lights.
If you hook up the negative first, then the positive does it do weird things?

[mr300ce]

Yes, safer to hook positive side up LAST. Wrench touching metal while tightening Positive terminal last is why a tech in shop has NO ring finger, as his gold wedding band melted to the bone.

As for the other issue, it may be that 1 or more relays are energized as soon as you hook the battery back up.

[AFChap]

I replaced my two chassis batteries last month. When I reconnected them, positive first, when I touched the negative cable to the post, the horn honked. As soon as it was firmly on the post, the horn stopped...no idea if anything else activated. It startled me, but all seemed to be normal after.

[wa8yxm]

Why did you connect the negative first? Standard practice for negative ground vehicles is to connect it LAST.

Depending on the coach. Some of the systems you describe may be computer controlled and the computer may have "Falsed" due to lack of power.

Restoring power then cycling the appropriate switches may fix it.

[Roadking]

Same results as AFCHAP. Connect positive first and then negative. When negative is first touch to battery the Horn honked momentarily and then stopped.

On negative ground systems I've always been told to hook Positive up first and then negative. The reason is if while connecting the positive you accidentally touch your metal wrench to ground, then you will NOT short out the battery as there is no complete circuit yet as the ground has not been connected. Clearly when connecting the negative it doesn't matter if the wrench touches ground as it is already ground. Safety is the reason for positive first. When disconnecting follow the inverse... disconnect negative and then the positive.

[Cat320]

Quote:

Originally Posted by Roadking Same results as AFCHAP. Connect positive first and then negative. When negative is first touch to battery the Horn honked momentarily and then stopped. On negative ground systems I've always been told to hook Positive up first and then negative. The reason is if while connecting the positive you accidentally touch your metal wrench to ground, then you will NOT short out the battery as there is no complete circuit yet as the ground has not been connected. Clearly when connecting the negative it doesn't matter if the wrench touches ground as it is already ground. Safety is the reason for positive first. When disconnecting follow the inverse... disconnect negative and then the positive.

Agree, negative first off, last on.

[mr300ce]

Quoting myself: "Yes, safer to hook positive side up LAST."
In case you didn't get the real meaning....that action cost the technician his finger. Be careful with battery terminals.

I was standing 10 ft away when a trainee had charged a battery with the terminals still hooked onto battery. He forgot to turn OFF the charger, and when he removed the clamp there was a spark.....BOOM !

Battery blew up in his face. There is always a heavy vapor on the surface while charging from the 'boiling' of the water.

They rushed him to E-room. He was OK later, and lucky he didn't go blind, but they "scrubbed' his skin down 2-3 layers to get the acid out. He looked as white as this background. We called him 'whitey' for about a month.

Some lesson are hard learned, and should be done so by others.