Help with Ambulance electrical system

[luthj]

FYI, Lead acid is AGM and vice versa. Flooded lead acid and AGM are the common variants.

 

[Bikersmurf]

With my Crestline I regularly see 14.8 v at the house batteries from the alternator even with a 200+ amp load.

 

[jesswrk88]

I'm looking for some advice on my ambulance electrical system.

My system is set up almost exactly like the attached diagram from the KKK-1822 specs. The only differences are I don't have an inverter, but I do have a charger. Also, the module disconnect switch is actually a module power solenoid.

I have one battery under the hood, and another two in the battery compartment in the patient module. They are all ganged together to make one large power source, as in the diagram. I'd like to have a separate deep cycle battery bank to run a fridge, lights, usb ports and a water pump. Ideally I'd be able to break of the module batteries for this purpose, but I'm not sure if only having one battery for starting is a good idea for my 7.3 L Powerstoke.

So now I'm thinking of adding another battery bank for the deep cycle purposes. I was thinking of changing the module power solenoid to a BlueSea automatic charging relay, and wiring in the new batteries just after that. I'm not exactly sure which model of ACR to get.

Later I'll add solar and wire the charge controller after the ACR as well. The idea would be to run all the module stuff off the deep cycles and those batteries would charge along with the starting batteries off the alternator or shore power, and off the solar power the rest of the time.

Am I correct in assuming I need the three existing batteries for starting purposes? Is placing the ACR in place of the solenoid the way to do it? Is there a better way to do it? Any other problems with or improvemnets on this plan?

Thanks in advance for any assistance!

Jon

View attachment 554494

Hi Jon,

Ive just bought an ambulance as well as a few lithium batteries and was about to swap those in as the power source as opposed to the starter bank just like you were mentioning. Similar to you I have two solenoids in my fuse box compartment that seem to be the switch allowing the lights etc to work only when the key is turned. I’m wondering how you ended up connecting your house batteries. Did you just take out the solenoids altogether and attach the batteries to the positive terminal on the fuse box? Or did you connect the batteries to the positive terminal on the solenoids and just remove the cable going to the starter batteries? There’s also a small wire that is labeled key power on each solenoid. Any advice from your experience would be great!

 

[Alloy]

With my Crestline I regularly see 14.8 v at the house batteries from the alternator even with a 200+ amp load.

Higher charge voltage = faster charging and a shorter battery life. Wouldn't surprise me if the batteries in an ambulance are replaced every 2-3 years.

 

[jhoyt]

Hi Jon,

Ive just bought an ambulance as well as a few lithium batteries and was about to swap those in as the power source as opposed to the starter bank just like you were mentioning. Similar to you I have two solenoids in my fuse box compartment that seem to be the switch allowing the lights etc to work only when the key is turned. I’m wondering how you ended up connecting your house batteries. Did you just take out the solenoids altogether and attach the batteries to the positive terminal on the fuse box? Or did you connect the batteries to the positive terminal on the solenoids and just remove the cable going to the starter batteries? There’s also a small wire that is labeled key power on each solenoid. Any advice from your experience would be great!

Hi Jess,

I ended up getting a Renogy DCC50S dc to dc converter with MPTT charge controller. I put it in place of the solenoid (I only had one). It has an input from the alternator, where I put the wire coming from the cutoff switch which used to go to the solenoid, an output to the loads (the out wire from the solenoid) and the house batteries, a ground and an input from the solar panels. I left the starting batteries alone. The DCC50S manages the charging of the house batteries from either the alternator, the charger when plugged in, or the solar panels. When the house batteries are full, it trickle charges the starting batteries. I'm far from an expert on these things, but this was a relatively easy way to get it all sorted.

 

[Cullitrel]

Iggi,

Thanks for the help!

Two batteries for starting and two for the module was what I'd planned on, but there's only one under the hood. I could break up the pair in the module, I suppose, but I thought I read somewhere that breaking them up was a bad idea? I figured it would be easier to add separate deep cycles and leave the 'extra' starting battery where it is, since I'll be buying them either way.

I'm afraid lithiums are way beyond my budget.

Jon

The 7.3 likes two starting batteries. All three of your batteries are probably AGM but not deep cycle. I have the three battery ambulance and wonder if I want to put in a separate solar system, which means buying another charger (I have a an extra inverter not in use) or alter my existing setup to incorporate the solar components.

 

[Cullitrel]

Hi Jess,

I ended up getting a Renogy DCC50S dc to dc converter with MPTT charge controller. I put it in place of the solenoid (I only had one). It has an input from the alternator, where I put the wire coming from the cutoff switch which used to go to the solenoid, an output to the loads (the out wire from the solenoid) and the house batteries, a ground and an input from the solar panels. I left the starting batteries alone. The DCC50S manages the charging of the house batteries from either the alternator, the charger when plugged in, or the solar panels. When the house batteries are full, it trickle charges the starting batteries. I'm far from an expert on these things, but this was a relatively easy way to get it all sorted.