77 W200 charging question

[Don Williams]

I replaced the ammeter on my 77 W200 with a volt meter. The voltage level at full charge is higher than the "industry standard" of 13.8 volts. That may not be the exact number but it is the one I am familiar with. My truck will charge as high as 15 to 15.5 volts. Voltage regulator and alternator have been replaced. Wiring and connections checked (grounds too). Volt meter accuracy verified.

I have owned a few of these trucks and this is the first with a volt meter. I'm wondering if this is the normal charge level for these trucks. I don't know what the other trucks were doing because I never put a volt meter on one of them. Just wondering if anyone else with one of these trucks is running a volt meter and what your numbers are. The higher voltage doesn't seem to be hurting anything except my inverter does not like it. At peak voltage my inverter will shut down due to over voltage.

[rxinhed]

You have a problem. Perhaps the voltage regulator is malfunctioning, though replaced recently. The voltage being high will also damage your battery.

[The Other Ross]

There are two different voltage regulators for these trucks.They appear identical except the HD one is thicker.

[n1265]

I ran a 100 amp alt / Mopar external regulator with a marine grade volt meter for about 4 years. It also ran around 15 volts. Not sure why it did that but it never caused me any problems.

I recently converted to a GM 130 amp one wire alt with an internal regulator. All the other wiering and volt gauge were the same that I was running with the 100 amp / external regulator, but now I am running a constant 14 Volts.


I cant say that you would never have any problems, But I never did.

[76WAGON200]

Ideal charging voltage is 13.8 volts. The highest you should ever see is 14.7 volts. Any higher than that and you are going to cook something. Are you reading this voltage on the new volt gauge or on a meter across the battery? is it an accurate meter? Are you reading at idle or higher? If this is a true reading of what your alternator is putting out then first step is to go through the alternator, battery, firewall and regulator connections and grounds to make sure they are clean and tight. Poor grounds or loose connections are the cause of 95% of all charging system issues. If that looks good and voltage is still high, try a new regulator. If that doesn't work, try a smaller pulley or a lower output alternator. Your battery can even be the culprit. Try swapping it with another one if you have a spare.

[76WAGON200]

Larger pulley....I meant to say. In order to slow it down.