Alternator is Border Line Charging

[Outbound]

I recently questioned if I was charging correctly, my gauge reads a little over 13 volts but when I checked voltage at batteries I was getting 14.2 volts, seems I have a one volt drop between batteries and gauge.

[twinboat]

Do you have a belt routing guide.

Yours may be wrong.

It may go this way.

[srh]

Originally Posted by Outbound

I recently questioned if I was charging correctly, my gauge reads a little over 13 volts but when I checked voltage at batteries I was getting 14.2 volts, seems I have a one volt drop between batteries and gauge.

Good point!

I'm planning on approaching it as RobRoy suggested. I have ordered the battery tester. It could be the problem you had. Hopefully, I will find out. I want to thank everyone for sharing their know how and experiences!

Regards

[srh]

Originally Posted by twinboat

Do you have a belt routing guide.

Yours may be wrong.

It may go this way.
Attachment 209603

No, I do not have one. I didn't realize the belt would fit another way! There are plenty of 08 ISX 600HP around. Hopefully, someone will chime in if they see a difference.
Thanks

[srh]

Originally Posted by twinboat

Do you have a belt routing guide.

Yours may be wrong.

It may go this way.
Attachment 209603

I found a picture of the ISX engine in my Owner's Manual, and it shows it like the picture I posted. Thanks

[BFlinn181]

Originally Posted by srh

Good point!

I'm planning on approaching it as RobRoy suggested. I have ordered the battery tester. It could be the problem you had. Hopefully, I will find out. I want to thank everyone for sharing their know how and experiences!

Regards

I'd think an alternative way to test the alternator in place would be to hook up a bad or discharged battery to the chassis cables and see if the alternator kicks in to charge the weak battery.

[nehog]

Originally Posted by srh

Bob and Skip426:
Thank you very much for the pointers - I very much appreciate it!

One other question, I keep my MH plugged it to shore power. After disconnecting the ground wires for the chassis batteries, can I leave it plugged in to keep my house batteries charged as checking the alternator may take a few days?

Regards,

Don't plug in... The charger will attempt to charge the disconnected batteries along with the house batteries, and if you've accidentally shorted something it won't be nice...

Also resist the temptation to use the disconnect switch--it doesn't disconnect the alternator (or starter).

[srh]

Originally Posted by BFlinn181

I'd think an alternative way to test the alternator in place would be to hook up a bad or discharged battery to the chassis cables and see if the alternator kicks in to charge the weak battery.

A neat idea! Although at the moment I do not have another battery on hand, but this is good to keep in mind!

IF I need to take the alternator out, any tricks on taking a 30+ lb alternator out?

[srh]

Originally Posted by nehog

Don't plug in... The charger will attempt to charge the disconnected batteries along with the house batteries, and if you've accidentally shorted something it won't be nice...

Also resist the temptation to use the disconnect switch--it doesn't disconnect the alternator (or starter).

Great info. Thank you very much!

[BigLar368]

Originally Posted by srh

Great info. Thank you very much!

Just be careful. The 12V large wire to the back of the alt. is usually still hot even if you shut off the batteries with the disconnect. I just disconnected the chassis batteries so there was no chance of shorting things out. Take your time. Take a pic of your belt routing. Might come in handy when going back together. Label all wires if you have any others or take a pic. From the pic you posted looks like a straight shot in there. Other than being a little bulky/heavy should not be to difficult. Best of luck to ya.

[srh]

BigLar368: Thank you very much for the pointers. I'm still waiting for the tester I have ordered. While waiting for that, I will try to clean the battery terminals. Have a great day!

[CJScepter]

There sure is a lot of wishful thinking when we ponder buying an alternator, really, the 2 coaches I have replaced the alternator on looked as though they were charging,,, a little bit. Truth is if you don't get 14+ volts it's bad(at battery), the dash gauge doesn't help much. Check out AJ-elec.com. They sell new alternators, probably around $250.00, and he will throw on the pulley if you ask,,,as he needs it on to test the alternator anyway.
Good luck,
John G.

[RobRoy]

Originally Posted by CJScepter

There sure is a lot of wishful thinking when we ponder buying an alternator, really, the 2 coaches I have replaced the alternator on looked as though they were charging,,, a little bit. Truth is if you don't get 14+ volts it's bad(at battery), the dash gauge doesn't help much. Check out AJ-elec.com. They sell new alternators, probably around $250.00, and he will throw on the pulley if you ask,,,as he needs it on to test the alternator anyway.
Good luck,
John G.

While I agree that In most cases your theory would be correct. Typically you can check open circuit voltage at the battery while it is not running and then fire it up and the when alternator comes on line charging expect to see a min of 1vdc increase relative to battery temperature and testing and readings are taken at the battery.

That being said a sulfated battery can skew those numbers and pull the charging volts low and fool you into thinking the alternator is the issue when it is not........ and if you're hooked up to the good tester you will also see that the charging amps stay high and don't come down and again the charge volts will be very low and make you wonder if it's charging.

Ive seen many sulfated batteries still start vehicles.

Another quick check for sulfated battery... disable the engine from starting and then crank the engine for 30 seconds ....then start the vehicle and watch the charging volts and charging amps, in short order you should see the amps start to decrease and the voltage rise to above 1vdc over open circuit readings typically 13.6 or higher with a good battery and also if there are no other loads are on the vehicle.

The purpose of my post is for the OP to avoid a wrong guess and throw good money after bad.

But yes there sure seems to be many posts regarding alternator failures on these coaches.

Happy Trails.

[slemnah]

SRH, just hook up a digital volt meter to the batteries when the engine is running at high idle and see what voltage the batteries are charging at, the gauges in these motorhomes are a suggestion only, don't rely on them. Learn how to use a volt meter and hook it up to the batteries positive and negative posts and see if there is really a problem before you do a lot of expensive work. You can also disconnect each battery one at a time and check the voltage. A six volt battery should have 6.3v minimum and a 12v battery should have 12.6v (2.1v per cell). Just make sure that you reconnect everything correctly- TAKE LOTS OF PICTURES!