altenator

[backhoemike]

My MH has VDO gauge, it is reading just a little over 11 volt while running , today i started my coach and the battery read 11.7 volts, once i started the engine it dropped to 11.4 , i started the generator and it slowly started creeping up to 12 volts, but the gauge on the dash never moved, curious if my genny is charging the chassis batteries along with the coach? i drove it at night about 500 miles but had the generator running the whole time and was worried any minute my lights would go out. just confused as i cant tell if the altenator is working correctly.

[mgrovesjai]

Always check the alternator output AT THE ALTERNATOR and not just at the chassis battery. I say this because the problem I have is that my alternator is overcharging by 1.5 Volts (about 15.5 or more), while at the battery the charge shown is 14.5 (which is still over what the alternator is rated - 14.2).

This burned up a rebuilt alternator within 4000 miles. The shop which just rebuilt the alternator again detected the overcharging condition and did a wire patch to limit the output of the alternator to 14.2 so as not to burn it up again. I am guessing that there is some resistance within the circuit to the batteries but have yet to trace it through to find out what is causing the "request" to generator such a voltage from the alternator. The alternator tested out at the spec 14.2 voltage on the test bench before they put it into the C-12 Beaver Marquis engine. Bottom line, always test the alternator output at the alternator - shouldn't be more than 14.2 for a Leece Neville 160amp that I have.

[backhoemike]

THANKS ALL , I GOT A VOLT METER AND CAN FIGURE IT OUT JUST NEEDED SOME OF WHAT I GOT BELOW BUT ALWAYS CAN COUNT ON YOU ALL FOR HELP INSTEAD OF TALKING TO MYSELF.

[ccxnola]

Aw, com'on - play nice in the Sandbox!

[Dog_Trainer]

xctraveler wrote:
Looks to me like Dog Trainer hijacked OPs thread. This needs to be two threads.

No Hijack Here I simply explained how mine works in order to help the OP with his question Maybe you should learn to read or get your glasses on

[wolfe10]

While a jumper wire between battery positive post will work electrically, it is QUITE DANGEROUS.

If either end jumps/vibrates off while driving, you will have a dead short to ground (any metal) with full battery amperage applied. Welding and fires can happen.

Safer to hard wire a jumper or combine wires on the battery combine solenoid as I outlined above.

[wa8yxm]

You could run a jumper wire (Automotive jump start grade) between house and chassis to charge but...

Some motorhomes come with a bi-directional isolator relay, This is controlled by a device we call a BIRD (BIdirectional Relay Delay).. what it does is connect house and chassis together once the voltage on EITHER side is high enough to indicate charging.

Some (many in fact) do not, so there is a device called a Trick-l-start or by another more expaensive company, echo-charger, this is a simple 3 wire device (House positive, Chassis positive, Ground) device that offers the reverse path, you connect it at your isolator solenoid since all 3 points exist there.

IF you have old fashion V-Belts.. Check them for tension (Long story 5 different cars (2 of 'em mine) re-tensioning the belt made a big difference).

If you have a serpentine belt.. Make sure you actually HAVE a serpentine belt.. Short story ... There is another thread on one of the forums I visit where ... It was missing.

[xctraveler]

Coming back two weeks later I have no idea what I was complaining about. Would delete this entirely if possible.

[ccxnola]

Please read my post about a similar problem - here:
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/27754651.cfm
It Was NOT the Alternator!!

[rgatijnet1]

I have an OBDII gauge and monitor my charging voltage continuously while on the road. When my alternator is charging properly, the output is just over 14 volts. On my coach there is an electronic circuit that directs the alternator charging current to the house or chassis batteries as needed.

[wolfe10]

All coaches charge both chassis and house batteries from the alternator (if working of course).

Many do NOT charge the chassis battery from the converter, charger or inverter charger (powered by either generator or shore power).

While plugged in or on generator, use a digital voltmeter to check voltage at each battery bank. That will tell you instantly how yours is wired.

Now, if yours is not set up to charge the chassis battery, a safe "workaround" is to:

1. If you have a constant duty solenoid/switch that can remain on for "battery combine"/"battery boost", leave it on.

2. If it is not a constant duty solenoid/momentary switch, locate the boost solenoid. Label (tape, zip ties, etc) all the wires on one large lug. Move them to the other large lug. Electrically, everything will work with generator powering the converter, converter charging the house bank and the "rewired" solenoid charging the chassis battery. Be sure to return the wires to their original position when you reach your destination.

[Gjac]

The simple way to test the alternator is to check the voltage at the chassis battery with the engine running and it should be about 14 volts. Do you have a multi meter?

[nomad297]

It sounds like you need to replace your alternator. Do as little night driving as possible until you get it replaced. While driving, turn off as many accessories as possible.

Bruce

[Dog_Trainer]

My Genny does not charge my Battery It does power the charger and inverter that powers the house and inverter batteries. I carry a charger and plug it into a socket that is located near the engine batteries then the power from the Genny can be used to run the charger. I would also be worried at 11.4 volts.