Voltage Problem, reverse problem
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So there is one battery in the engine compartment and 2 in a slide out tray on the side of the ambulance. Those two on the side are wired in series and I'm not sure where they connect to. I do know there are no special switches or anything, so all 3 batteries charge off the alternator without any human input.
Lead Driver
Joined: Oct 2003
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From: Madison, WI
The two in series makes, effectively, one 24V battery. Those must be for the rescue equipment in the box of the ambulance. So either that alternator has to be a 24V alternator with a step-down in-line somewhere between it and the engine battery in order to charge it, or there's a step-up somewhere between the alternator and the equipment batteries. TBH, I don't know what the voltage reading at the alternator output should be with such a configuration.
This also implies that the truck is being started by a single battery. There are supposedly some high-end AGM batteries capable of starting our engines single-handedly; it'd be interesting to know the chemistry and CCA capacity of that battery.
It would also be interesting to measure the voltage of the two equipment batteries together, that is, from the positive of the "first" battery in the series to the negative of the "second". Again, wait 'til after the glow plugs have cycled off.
This also implies that the truck is being started by a single battery. There are supposedly some high-end AGM batteries capable of starting our engines single-handedly; it'd be interesting to know the chemistry and CCA capacity of that battery.
It would also be interesting to measure the voltage of the two equipment batteries together, that is, from the positive of the "first" battery in the series to the negative of the "second". Again, wait 'til after the glow plugs have cycled off.
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check voltage at the wires going into the gauge.
i bet you will find the gauge is bad.
my mack gauge shows 16.2 volts but is only receiving 14.2volts. i just never get around to changing it.
i bet you will find the gauge is bad.
my mack gauge shows 16.2 volts but is only receiving 14.2volts. i just never get around to changing it.
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