Alternator, Battery Troubleshooting

[katcatkmc]

2019 Jayco Melbourne 26L Class C
2017 Sprinter Chassis
13,207 miles

I posted here about my overheated battery/leakage and am now troubleshooting with the battery replaced by Napa. They suggested checking my alternator because the battery may have been overcharged. So I checked some voltages and posting below. All seem normal?

Battery without engine running: 12.61
Battery with master switch plugged in: 12.53
Battery with engine running plus lights, AC, Radio, Rear Cam: 14.07. Not much diff with just engine and no additional power
Battery after revving up to 2K: 14.05 (Couldn't maintain revving by myself - Is measuring while revving important?)
Battery after revving with lights, AC, radio, rear cam: 14.07

I've read where people replaced the Y-Cable or voltage regulator cable and some replaced the alternator.

I don't have the additional(optional?) battery installed under the hood. Would this help? Not sure what it's purpose is.

Any thoughts?

Thanks, Kathleen

 

[pconroy]

I don't have a Sprinter chassis, I'm on a Ford platform. I'm also not sure which battery you were measuring, as I have two: one for the engine under the hood and the other for the "house" back in the RV.

But, I'm not sure it matters. To me, those voltages look OK.

Battery without engine running: 12.61
Battery with master switch plugged in: 12.53
Battery with engine running plus lights, AC, Radio, Rear Cam: 14.07. Not much diff with just engine and no additional power
Battery after revving up to 2K: 14.05 (Couldn't maintain revving by myself - Is measuring while revving important?)
Battery after revving with lights, AC, radio, rear cam: 14.07

12.5, 12.6V on a battery is just-about fully charged.
Revving the engine shouldn't make a large difference. If it did, I'd be concerned about the alternator.

I think I pull a smidge more than you do off the alternator. I think I'm 14.2, 14.3V. But to me that's an insignificant difference. I don't think you have an "over charging" alternator.


--
You've got me wondering why the NAPA guys didn't check this stuff out when you were there? Were they busy? Did they just try to "send you on your way?"


If this is how they treated you, I'm not super thrilled with that.....

 

[JimD]

Voltages look good. You may want to install an easy to see constant voltage display to keep an eye on it. Also, you should check the voltage from the rig's converter. Should look much the same, maybe a tad higher for the boost voltage. The attached picture is what my converter is suppose to put out. I monitor it and indeed it is correct.

 

[Vicr]

You've got me wondering why the NAPA guys didn't check this stuff out when you were there? Were they busy? Did they just try to "send you on your way?"

"Napa guys" sell parts, they are not mechanics and are not qualified to troubleshoot automotive electrical systems.