Can anyone point me to a good reference site about these? I need to be able to explain to my Saudi Arabian medical director what it is, how it works, and why we need to incorporate a quality one on our new ambulance specifications.

Currently, the vehicles that we have incorporate a system where we can plug into a shoreline cord for charging in station. Unfortunately, the Chinese inverter that we have is located in the patient care module away from the cab. The shoreline needs to be unplugged first, and then you have to walk around the vehicle to open a compartment inside the patient care module to turn the inverter on to run everything in the back. When the engine is turned off, the inverter begins to whine, and drain the battery. If the inverter is left turned on while the shoreline is plugged in, and the ambulance is off, it still pulls enough to drain the ambulance batteries.

I need to be able to explain to everyone that we must have one installed that only requires turning on a switch in the cab to power on the equipment, and outlets in the back.

Any help would be greatly appreciated.

 

You could wire so that its only on with the key on or put a switch on the dash for it. You will need one that can handle the amp load of the inverter. This explains how they work. Relays

 

There is a module disconnect switch up front already. Apparently though, these things were wired the wrong way. Why else would the switch turn off all the power to the module, but not do anything to the inverter, which has to be turned on/off separately?

I don't know electronics, so I can't really say. And I wouldn't want to do anything myself. Having said that, I don't think I would really trust anyone here to do anything.

The link will help, though. Thanks.

 

What are you running with this inverter? How many amps does it use, and is it a motor load? Inverters take gobs of power if you are running a large load. If you want to run something large without the vehicle engine running, it will take many large batteries for it to keep up and be able to use it for a period of time. But it all depends on what you are trying to power with it.

If you are trying to power something large, there are other solutions like generators that mount in the engine compartment.

 

We're not running a lot of stuff off the inverter. It is only used when the ambulance is running. Otherwise, we are connected to a 220 shoreline cord.

The problem is the way the inverter is set up/wired in our ambulances. When you go to start the ambulance, you disconnect the shoreline cord. Then, start the engine. If it has a module disconnect switch, the Saudis usually remember about now to turn that on.

The inverter is in the patient care module in the back (the "box"). You need to get out of the cab, and walk around to the curbside door, open it, and reach in and open another compartment to turn the switch on the inverter to power all the accessories in the module of the ambulance. The accessories consisting of the wall outlets, and the small drug fridge.

When you shut the engine down, you need to repeat the process, and walk around to the side door, and manually turn off the inverter. Otherwise, it begins to emit a nice, ear-shattering whine.

On my US ambulances, you got in, turned on the module disconnect switch, and started the engine. That was all that was needed to be done. I believe the inverter came on with the disconnect switch. When finished, turn off the engine, and plug into the shoreline cord. Done.

 

Ok, I understand now. The other poster was correct, you need a large relay. This does not usually come with the invertor, but is wired in by the guys who are putting the ambulance body on the frame/truck. It's going to need to be a big one, depending on the rating of the inverter. Here's an example of one.
Cole Hersee 24143 - 12V Continuous Duty Solenoid 200 amp

This will control the power to the inverter, and they can install a small switch up front to control it.

 

Links:
Vanner LifeStar ambulance inverter/charger

Tripp Lite PowerVerter® 1250W Ambulance/EMS Inverter/Charger with 2 Outlets (EMS1250UL)

12 VDC Single Phase Quasi-sine Wave DC to AC Power Inverter Specifications for Emergency Vehicles

Lithium Solutions from Clayton Power

 

I got a 1999 ford e350 diesel. If the shoreline cord is not connected on my vehicle the batteries are drained as well. I tried using the switches behind the drivers seat to disconnect the battery but still the batteries drain. I think it is built this way so that there is no human judgement error in forgetting to connect the inverted when an emergency arises. The problem I have is. How do I disconnect the inverter? Is there a fuse for it?

 

Find the inverter in your vehicle. It should have some very large wires going to the batteries. Follow these wires along and see if you run across a large relay. If you don't, then you need to add one to disconnect it.

 

What model box do you have ? Most inverters now don't have a relay, just like a 150 amp fuse and a module or pair of smaller wires to a switch. Do you have the large bat disconnect sw on the drivers seat base ? 99 was the last year ford let the builders do that. Before then the bat sw killed everything engine and box. just had a few smaller wires to bat side for pcm and abs and radio memory.

 

Texas Industrial Electric offers quite a few super high current relays, solenoids and contractors that would meet your needs. If you look at a starter solenoid, you'll get the idea and how they're wired. The only difference is that TIE's products just add a ground terminal for universal usage, while a starter solenoid is self-grounded.

To put their products in perspective, a Mazda RX7 automatic starter is rated for 2.0kw, or ~2.7hp (1hp= 745 watts). Since it runs at 12 volts, we can apply Watt's law (Watts=Volts x Amps) to calculate that it draws 166.67A. TIE's products are made to handle such loads continuously, instead of intermittently like a RX7 starter solenoid.

But yeah, redo that hack job wiring ASAP. Pretty sure that TIE offers SPDT options for simple, easy switching between shoreline cord and onboard 12v power too.