Inverter / Charger suggestion

dparker · January 16, 2008, 08:30:06 PM

Gentlemen,

I know that you guys all have a lot of experience with inverter/chargers for coach applications ... on my coach I mainly just utilize my generator, so I do not have much experience with inverters/chargers... I have been asked to help my local fire department with their fire truck, (whom like churches I like to support by donating services) they want to charge their on scene radios, infrared camera and laptops (<300 watts AC load) in the truck, the fire truck has 4 12 volt batteries in parallel (12 volt) for truck operation and engine starting a large alternator +250 amps, the truck came equipped with a 20 amp float charger, this charger is currently not working. When the unit is in the station they plug it in to provide 120 vac, when the unit is on scene they always leave it running -- i was thinking of a RV type inverter charger that would pass the 120 vac, float charge the batteries, then switch to battery when the 120 vac is disconnected to provide 120 vac in truck in route and on scene -- suggestions -- I found a tripp lite unit that will do 750 watts and provide 11/45 amps for battery charging and float ....

thanks in advance ....

david

JackConrad · January 17, 2008, 05:31:16 AM

David,
That should work. Since the batteries are never used to provide 120 volt without popwer being put back into them at the same time, you should not need a large capacity charger. Is this inverter/charger a modified sine wave (MSW) unit? If it is make sure all the chargers will operate off the MSW power supply. We had 12 volt chargers for our radios and laptops. I do not remember what the infrared camera charger operated from (this was in the BC's car). Jack

gumpy · January 17, 2008, 12:08:01 PM

I concur with Jack, but I'd recommend you go with sine wave, if you can afford the extra cost. Your small chargers might be ok on MSW, but they may acquire something in the future that isn't.

Stan · January 17, 2008, 12:43:55 PM

Almost all electronic devices that use rechargeable batteries can be charged directly off the 12 volt automotive battery with an optional charger that plugs into a cigarette lighter. On the fire engine, a permanent charging station cabled to the batteries would be simpler and more reliable than using an inverter.

gumpy · January 17, 2008, 01:30:14 PM

Quote from: Stan on January 17, 2008, 12:43:55 PM
Almost all electronic devices that use rechargeable batteries can be charged directly off the 12 volt automotive battery with an optional charger that plugs into a cigarette lighter. On the fire engine, a permanent charging station cabled to the batteries would be simpler and more reliable than using an inverter.

Maybe, if all the devices have 12v charging accessories available. Some do, some don't.

You would lose the capability to float the starting batteries when parked in the garage, though.

Another advantage of using the inverter is it will allow you to run power tools and flood/trouble lights if necessary.

Stan · January 17, 2008, 05:32:51 PM

Radio Shack sells universal chargers with selectable voltage and plugs to fit everything. I don't think it is common for fire engines to depend on inverters to power their emergency equipment. If they have AC powered equipment, they have a genset.

As 'Friends of the Fire Department' you need to discuss their needs with them efore you spend money on equipment that they may never use.

boogiethecat · January 17, 2008, 07:11:51 PM

You might want to look into "auragen" for them as a possibly better alternative to an inverter... a whole lot of fire trucks and other emergency vehicles use 'em. Basically it is a 5kw 120/240 volt pure sine system that is based on a big alternator-looking thing that bolts on to the engine, with a not-so-small control box that mounts somewhere else.
Instead of running on the 12 volt batteries, it uses the engine power directly to create 120/60 hz, no matter what speed the engine is running or idling at. Quite a nifty system, and there is an option that
will allow it to run on batteries only if the engine is stopped... They make installation kits for virtually every emergency type vehicle out there...

http://www.aurasystems.com/

DrivingMissLazy · January 17, 2008, 07:26:00 PM

Quote from: boogiethecat on January 17, 2008, 07:11:51 PM
You might want to look into "auragen" for them as a possibly better alternative to an inverter... a whole lot of fire trucks and other emergency vehicles use 'em. Basically it is a 5kw 120/240 volt pure sine system that is based on a big alternator-looking thing that bolts on to the engine, with a not-so-small control box that mounts somewhere else.
Instead of running on the 12 volt batteries, it uses the engine power directly to create 120/60 hz, no matter what speed the engine is running or idling at. Quite a nifty system, and there is an option that
will allow it to run on batteries only if the engine is stopped... They make installation kits for virtually every emergency type vehicle out there...

http://www.aurasystems.com/

My belief is that this is just a DC alternator driving a sine wave inverter except at a higher DC voltage. I believe it is in the 300 volt DC range to get a 6kw AC output.

A 24 volt alternator on the fire truck capable of furnishing 250 amps feeding a 6kw sine wave inverter will accomplish the same thing significantly less expensively. The not so small control box is actually the sine wave inverter.

I looked at these devices many years ago when I was manufacturing inverters for the luxury boat market and also visited their factory in Texas. We did not ever get together because their output power was too limited for my requirements.

Richard

dparker · January 18, 2008, 07:00:46 PM

Thanks guys -- i knew that you guys would think of aspects that i would miss ... the unit that I selected did indeed provide a true sine wave output -- good idea on the 12v dirrect charging and for the radios, but with the inverter unit if the firemen forgot to plug the truck in the inverter/charger will protect from discharge below a level that would prevent the batteries from cranking truck -- were the dirrect wire could drain the batteries in truck, espeically 12 chargers .... they also liked craig's idea about powering the search lights (120v) without having to power the generator -- we are going to do a 3 way switch for this function ..

thanks guys -- i appreciate the time you guys give to the board.

david