E350 Ambulance Wiring... Batteries and Alternator

[Bikersmurf]

Until the interior is useable, I'm not using it much at all. It'll run 4-5 hours off the batteries no problem and when I get home, I can plug it in. I've found the alternator will put out 14.5+ for hours, so the batteries get a steady 14v.

 

[Bikersmurf]

Well the time came... Got a Blue Sea 7610 ACR for $107 shipped to my door.

Something odd. After running for a minute all is normal. About 14.6-14.7 v to both banks minimum.

Wired ting is when its started cold. Voltage hits about 15.2 v and amps are limited to about 20-25 amps. Rev it up a bit and no change. A couple minutes later there's an audible click from under the hood (or dash) area... Voltage drops to about 14.5-14.6 and amp output jumps up to 100-125 amps.

Thoughts... wouldn't be a big deal, but 15.1 v triggers the over voltage safety on the inverter and shuts it off for a few minutes. Thoughts?

 

[Bikersmurf]

Turns out the VR gets it's input from the starting batteries. Meaning that at startup the VR isn't able to monitor the alternators output so the alternator puts out 15.2 V until the ACR connects the two banks together. Once connected, the VR senses the Alternators output and Voltage drops to 14.5-14.6 V.

After Switching the Alternator to the house bank, the problem is solved.

 

[guidolyons]

Is the click you hear the glowplug relay switching off? When cold, glow plugs/glowplug relay suck a bunch of power right at start up, takes a few before back up to 14 volts after start up.

 

[Bikersmurf]

The click was the Automatic Charge Relay connecting. I was initially seeing 15.2 right at startup because the Glowplugs were only connected to the Batteries and the Voltage Regulator wasn't getting Alternator input (Best guess is that the Alternator has a limp mode which puts out about 15.2 V and 20 Amps till the VR gets Alternator input).

Now the load of the Glow plugs keeps the voltage down for 20-30 seconds and then the voltage goes up to 14+ V.