Wiring under front seat of Leader E350 Ambulance. *Not for the weak of heart!*

[Ambolorian]

The following post may cause heart palpitations and/or nightmares. Read on at your own risk.



Here is my 2002 E350 Super Duty with Leader Ambulance package.
This rig comes with 2 starter batteries and 2 "spare" batteries that I will be replacing with a 300ah bank of Renogy AGMs.
My current project is to create two separate battery banks that are independently charged by the dual alternators up front.
I was able to get a bunch of schematics from Leader (no easy feat!) and some pics from another user on the forum that unfortunately is no longer active.

Here is what I have under the driver's side seat:





Here is breakdown of what each component does:
A: This solenoid is controlled by the Module On/Off switch above the driver.
B: This is the Manual ON/OFF switch mounted on the side of the front seat
C: This is a timer that shuts off rear power 5 minutes after the ignition key is removed.
D: This is a Battery Isolator that takes power from the positive post (which is connected to the alternators and starter batteries) and sends it to the "spare" bank.
E. This solenoid is for Emergency Start and combines all batteries to start the diesel in very cold weather.


Here is the power schematic that Leader sent me:


A closer look at D (Battery Isolator)


A closer look at the TImer:




Wiring at this level is a little daunting to me.. I'm hoping someone gifted with an electrical engineering background can chime in and answer some of my questions.
Here is my plan:

1. I'd like to remove C (Timer) and D (Isolator) and effectively have an independent "house" bank of batteries that runs the camper conversion led lights and sockets in the back.
2. I want to replace the current isolator with a Blue Seas ACR 7620 but I'm not clear on how to wire it into the system.
3. How can I bypass the timer?

Has anyone else worked on a rig like this before or have some suggestions for me?

Thanks!

 

[Bikersmurf]

When I ditched my isolator for a Blue Sea's ARC, I connected the alternator output lead to the starting battery lead, and house battery lead to the other pin on the ARC.

I originally wanted to charge the house batteries directly and then connect the starting, but the Alternator's regulator wasn't wired to work that way. I'd get a voltage spike until they connected, and then the regulator would correctly read the charging voltage. Rather than rewire how the alternator worked, I hooked it up as Ford designed it and now it works as it should.

It now looks like your isolator is connected as a diode to protect one set of batteries from draining the others (to take a stab at it. If I had more time I could study the wiring diagram, but I don't at the moment.

 

[Ambolorian]

Thanks for the reply Bikesmurf.
You are correct.. thats how its currently set up.

Was this how you had it wired initially?

 

[Ambolorian]

Oops, scratch that middle wire going from the Junction to the House lead.

 

[Bikersmurf]

Thanks for the reply Bikesmurf.
You are correct.. thats how its currently set up.

Was this how you had it wired initially?
View attachment 790347

Initially I essentially had it wired like that less the wire from the junction point to the starting batteries.

In my case I have a single 215 amp Mitsubishi alternator. I’ve read that this 32 pound beast can put out up to 300 amps cold, and the 215 amps 24/7. The big catch is that it’s $950 CDN from Ford, and when I was told that price there was no stock showing in North America.

I found with the initial setup the alternator’s VR read the starting batteries voltage and peaked at +/- 16.5 v for a. split second until the ACR connected the house batteries to the starting batteries. Once combined, the output was reduced to 14.4v. Although the 16.5 likely wouldn’t harm anything for a momentary peak, the Inverter I was running registered over voltage and shut everything off for 20 seconds until it reset and registered the 14.4 v which was below its 15v max limit.

Now it’s connected as shown (less the wire from the junction point to the house batteries. The small (inconsequential) difference is that junction for the alternator to ACR is at the ACR rather than the starter battery terminal. However in the real world, the circuit is the same, and I’d recommend sticking close to how the ambulance up fitters set it up and not making it hard on yourself.

 

[Ambolorian]

Copy that.
I wasn't sure if it was better to begin at the Starter batteries and have the ACR switch to the House or visa versa.
And I think you're right, why re-invent the wheel when Leader already did a solid job with their build.

Thanks a lot for helping me work thru this.. I really appreciate your input.

 

[iggi]

A couple suggestions based on where I'm at with my own ambo build.
I've removed all connections from the starter batteries to the aux power.

My auxiliary / camper panel will be fully independent except for:

a) a DC to DC charger so I my auxiliary lithium battery bank can charge from the alternator. (for AGM the ACR is fine)

b) a 20 amp battery charger connected full time to my starting batteries that is powered either from my inverter or from shore power.
I considered trying to retain the super start relays but it added a lot of complexity and with the size of my aux battery bank I can fully charge the starting batteries if I ever have to, plus I can trickle charge the starting batteries from excess solar.

I'm curious why you're going with AGM instead of a lithium iron phosphate.