SINGLE OR DUAL ALTERNATOR SYSTEM?

[chrisbaffico]

Hi all,

Over the past year, the battery light on the dash has been coming on intermittently. I bought a battery/alternator monitor that plugs into the cigarette lighter. Even when the red battery light on the dash is on/flickering -the tester never wavers and indicates everything is good. I checked the battery terminals on both batteries (7.3 Diesel) and everything looks good. The batteries are only about three years old from Costco. I maintain then regularly by adding distilled water and cleaning the posts. I have not checked the wiring at the alternator. I brought it to Autozone to have the charging system checked. The first time, they told me the batteries were testing 85% and the alternator was bad. Yesterday, I brought it back and they tested the system again, batteries were at 65% and two low to finish the test. I checked into a new alternator but they asked me if it was a single alternator system 130 Amp or a dual alternator system 110 Amp. Anyone know how to determine which system I have? Any other suggestions?

Thanks in advance for you help. -Chris

[Bellpilot]

I do not think you would have a dual system, believe this was an ambulance option. Easy to check to make sure by raising the hood and see if you have two alternators. I had the same issue just a few weeks ago with the flkering light. Took it to the dealer and turned out to be a bad alternator which had taken out my batteries.

[carringb]

Dual alternators was an option on non-ambulance vans as well. Should be pretty easy to see both if you have them. Basically one up top one tucked in near the bottom. The belt routing sticker shows where it would be if you had the 2nd alt.

[chrisbaffico]

Thank you,

I never thought to look for two alternators. I did see the serpentine belt routing label and confirmed only one. I appreciate the help.

-Chris

[daveb]

Originally Posted by chrisbaffico

Thank you,

I never thought to look for two alternators. I did see the serpentine belt routing label and confirmed only one. I appreciate the help.

-Chris

I'd sure drop each battery, charge them up and have a load test done on each (one at a time) before replacing the alternator.
I would hope they did a voltage AND amp check to determine the alternator is failing. Sometimes a short can cause the alternator to fail. A single shorted battery can trick some shops in thinking the alternator is going out.
A battery load test is a good idea anyway after an alternator fails.

[jage]

A plug in volt meter will not diagnose alternator problems- it has to be taken out and bench tested.

I only hope the 7.3 is a lot easier in the vans than the 6.0L!