Batteries

Jean-Marc Dugas

Jean-Marc Dugas

PCS Member
I plan on installing new batteries in my 54 XL when I go pick it up from storage in the spring. I seem to remember reading somewheres where they recommended installing a deep cycle battery as the second battery in a 2 battery system.

I have also always run the 54XL on the 2 batteries setting off the Cole Hersee switch, but when we had these setups in the van ambulances I used to work out of we always ran on battery number one and used battery #2 as a booster battery. What is the proper way to operate the Cole Hersee switch in the 2 batteries cars?

Thanks.
 
You should use the largest ampere hour battery that will fit into the battery tray, and both batteries should be identical in all ways including being replaced in pairs. We used to start on both batteries and then run the emergency call on only one battery leaving the other battery to "rest" should we need it for starting once we arrived at the hospital. It was policy to keep the ambulance running when we arrived on scene, because of the use of the emergency warning lights were on. When returning to the station (non-emergency) we would have both batteries in use so they both got fully charged on the ride back. There is no right or wrong, it is just the preference of the driver. We also always had jumper cables in the ambulance for those days when everything went wrong, and we could usually get a jump from one of the police cars.
 
Jean-Marc: Does your unit have an isolator in the system with the alternator and the batteries?

As Paul says there is no right or no wrong. We were always told to run on one or the other because the isolator would prevent the battery not selected from discharging. It could charge and therefore be ready, but not discharge until you select it.

We always shut both off in station so there was no discharge if someone left something on in back........
 
The Cole Hersee battery switch is just an interruption of the main battery cable going to the starter. Both batteries A & B connect to the switch on the rear and when you turn the selector dial, 12 o'clock is off, 3 o'clock is one battery and 9 o'clock is the other. 6 o'clock is when both batteries are connected to the starter circuit. That switch is also sold with a key switch in the middle so it cannot be turned without the key. It was originally designed for marine use and has been adapted to automotive use in the early 1960s or slightly before.
 
Bob Dyke said:
Jean-Marc: Does your unit have an isolator in the system with the alternator and the batteries?

As Paul says there is no right or no wrong. We were always told to run on one or the other because the isolator would prevent the battery not selected from discharging. It could charge and therefore be ready, but not discharge until you select it.

We always shut both off in station so there was no discharge if someone left something on in back........
Click to expand...
It does not have an isolator.
 
Th cole Hersie switch is a isolator. It will shut off either battery from the system. The isolator you are most likely refuting to is a solid state switch. Which you switch with a toggle on the dash. The other way the isolated battery is with salanoids. One on each positive wire of each battery.
The reason you need two battries with the same amp rating is if your using double the one with the higher amp rating would be the only one that would be operating. The only one taking a charge. Two 800 amp batteries in parallel do not give you 1600 amps only 800 with a lot of bottom. If your operating on one battery and you discharge that battery,then switch to the other the system will not charge the one you discharged. It has been isolated from the system. But if you turn them both on with one battery discharged with a 100 amp alternator you risk boiling that battery dry and burning it up. As the alternator will attempt to bring it up at once with all the power it can. To me you run both of them all the time. This will charge and discharge them both at the same rate at the same time. But that is me.
 
Ed is right about running both batteries at the same time. That was our common practice. In the early '80's Crestline (and no doubt other builders) started putting an isolator in. It is a big solid state box. Heavy. Big heat sinks. Once this unit was wired in both batteries would charge regardless of the Cole Hersee switch. However, only the selected battery would discharge. This way you had a charged unit set up and ready if you needed.

Demers upped the ante here on the prairies because Quebec law demands an ambulance battery system mirror the chassis battery system. So on a diesel with dual batteries, there had to be dual batteries on the ambulance side. Now we had 4 batteries running around. But by then computers had come into units and there could be no more shutting units completely off. QVM got involved and such. But these still had an isolator on the unit.

Most makers now put in a 'Conversion Master Power' switch which turned on the ambulance conversion only. Also, most added a momentary 'Emergency Boost' switch which tied everything together to get the unit started.
 
You could get the off battery to charge if you had a reverse diode in a charge wire but in the 70s such a animal was not a common run down to the store thing. That is how the solid state box worked
 
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