Most ridiculous workaround ever, or a COOL idea? (Air conditioning)

[Keith_J]

I've got a MEP-026A that I will be converting to a C (electric start model) to do the same. It will be perfect for the M1031 SECM. It will ride on a receiver hitch platform.

108 amperes of 28 volt electricity.

 

[steelypip]

I have to say that it would not occur to me to try to cool a deuce/5 ton cab with an AC unit. No seals, canvas roof, no insulation...not going to work, at least not while the truck is running. I suppose you could put an MEP-002A and a tent AC in the bed and do it that way, but it wouldn't be quiet at all...

Now what you could do that would be very practical is a cool hat/cool vest setup (think NASCAR). Keeping a human happy in nearly any temperature really only requires the ability to get rid of about 2 kilocalories/hour of heat. That's 8 BTU/hour. No kidding. The NASCAR guys do it with icewater in a small box. Keep that, and then put a refrigeration coil in the icewater bath with a small vapor-compression cycle refrigerator hanging off the back - something like a wine cooler/dorm fridge would do the trick. A few hoses and quick connects and you can be cool and comfortable in any weather with your multifuel in front. And it'll keep your beverages cold as well.

 

[DrillerSurplus]

I have to say that it would not occur to me to try to cool a deuce/5 ton cab with an AC unit. No seals, canvas roof, no insulation...not going to work, at least not while the truck is running. I suppose you could put an MEP-002A and a tent AC in the bed and do it that way, but it wouldn't be quiet at all...

Now what you could do that would be very practical is a cool hat/cool vest setup (think NASCAR). Keeping a human happy in nearly any temperature really only requires the ability to get rid of about 2 kilocalories/hour of heat. That's 8 BTU/hour. No kidding. The NASCAR guys do it with icewater in a small box. Keep that, and then put a refrigeration coil in the icewater bath with a small vapor-compression cycle refrigerator hanging off the back - something like a wine cooler/dorm fridge would do the trick. A few hoses and quick connects and you can be cool and comfortable in any weather with your multifuel in front. And it'll keep your beverages cold as well.

I'm pretty sure I saw some sort of cooling vest for pilots a few months ago on GL, but didn't pay that much attention.

We occasionally had to work in full hazmat waterproof suits for environmental drilling- brutal if outside temp was over 80 degrees. We would just wear light cotton shorts & a t shirt under the suits and wet them down under the suits. The trick was to have a 1/4" airline with a quick connect and valve taped on outside of suit at belt line that went up to neckline and then down inside suit. We put a tee inside at belt line and a line down to each ankle. When you hooked up to the air supply and cracked the valve, the water evaporated off the damp cotton and the difference was amazing.

Not suggesting it's practical for MV use and it wouldn't work in humid climates, but it made a night & day difference in both comfort and the amount of work we could get done in a day. I might have to try a small auxiliary line off the truck air up into the cab though.

 

[ke5eua]

When in the 88 or in the M1 we would take the NBC hose in our nomex suit and turn on the NBC system. Sucked having to change filters but sure did knock a few degrees off in those fry an egg on the hull days.

 

[DrillerSurplus]

When in the 88 or in the M1 we would take the NBC hose in our nomex suit and turn on the NBC system. Sucked having to change filters but sure did knock a few degrees off in those fry an egg on the hull days.

That had to be brutal in especially considering you had plenty of hot machinery adding to the heat gain. When its really hot you have to do something or you are out of commission. I remember a couple of years ago 3 workers in the oil patch around Bakersfield CA died in a week when the first hot spell of the year warmed things up in just a couple of days.

 

[ke5eua]

That had to be brutal in especially considering you had plenty of hot machinery adding to the heat gain. When its really hot you have to do something or you are out of commission. I remember a couple of years ago 3 workers in the oil patch around Bakersfield CA died in a week when the first hot spell of the year warmed things up in just a couple of days.

Yeah, General Dynamics came up with this great idea of an air conditioner, only problem is it was ran off the hydraulics and was prone to leaks. We would have crew members put ice bags on the electronics in the summer to keep the electronics cool. It was then you found out if you really tightened stuff to spec or not, lol

 

[Tornadogt]

So to get back to the OP................ Price for BTU's Amps both DC/AC, Convenience and Versatility.. I have been looking around a few days and it seems that a 2000w or larger 24V to 110V Inverter that would draw from 20-28dc amps and a Home/Office Potable AC unit (8000-10000 BTU) that draws in the 8-12 AC amp range can be done for under $400-500.00 bucks. This setup allows the AC to run while the truck is running, while the truck is shut off (the inverters even have a low Volt cut off that will turn it off at 20volts to not drain the tucks batteries I am not sure how much time this will allow depending on the number of batteries and capacities), AND run on straight 110v power from a generator or outlet..... Also this seems to be the easiest install and removal or relocate to Tents or other Inclosures..

I am not an electrician or a HVAC export, Please let me know if my Amps to Volts conversions and BTU Capacities seems out of reason....

Thanks

 

[ke5eua]

So to get back to the OP................ Price for BTU's Amps both DC/AC, Convenience and Versatility.. I have been looking around a few days and it seems that a 2000w or larger 24V to 110V Inverter that would draw from 20-28dc amps and a Home/Office Potable AC unit (8000-10000 BTU) that draws in the 8-12 AC amp range can be done for under $400-500.00 bucks. This setup allows the AC to run while the truck is running, while the truck is shut off (the inverters even have a low Volt cut off that will turn it off at 20volts to not drain the tucks batteries I am not sure how much time this will allow depending on the number of batteries and capacities), AND run on straight 110v power from a generator or outlet..... Also this seems to be the easiest install and removal or relocate to Tents or other Inclosures..

I am not an electrician or a HVAC export, Please let me know if my Amps to Volts conversions and BTU Capacities seems out of reason....

Thanks

Even a modest ac unit that draws up to 8 amps will NOT draw 28 amps from a 24v source.

Good way to figure out your ampere draw on a 12v inverter. Multiply the amperage by the voltage, 8x110=880 then drop the zero, so your amperage draw of the inverter should be in the 88 amps range. Now a 24 volt inverter should be half that.

So on a good day the startup is 12 amps.

12x110=1320. Now let's drop the zero, 130. Ok that leaves us with 130 amps, now let's divide it in half, 66. Now you might be thinking this is ok, it's only 66 amps, my stock alternator is 60 I should be fine.

Factor in your alternator draw no morally before the inverter then add that to your inverter draw and you will see that you will discharge your batteries before the alternator can recharge them.

As far as the low voltage shut down, can your truck still start at 20v? Yes it has 20v available, but how much amperage is still available in the batteries to start the truck?

This is done to prevent over discharge and destroying the battery.

Side note, the 20-28 should be the operating voltage range.

 

[Skinny]

I'm just thinking that any 120v 15amp window shaker unit would have a hard time keeping a cab cool, especially one that is not thermally well sealed. That is pretty much any old truck.

I think your best way is to use a vest or a traditional AC system driven off the engine. If not, do what Keith did and run the compressor with an electric motor.

 

[Keith_J]

Yes, you need at least 1 ton of cooling capacity. 12,000 BTU per hour. That is roughly 3500 Watts of cooling. If the system has a coefficient of performance of 2, that means for every watt of power used, it transports 2 watts of heat out of the cab, you are still looking at 1750 watts of power needed. That is 72 amperes at 24 volts.

But CUCVs have a 100 amp charging system, right? That is surge capacity, the steady state current is closer to 65 amperes. Because you also need to supply power to the injection pump shut off solenoid, the lights, wiper and blowers.

 

[steelypip]

But CUCVs have a 100 amp charging system, right? That is surge capacity, the steady state current is closer to 65 amperes. Because you also need to supply power to the injection pump shut off solenoid, the lights, wiper and blowers.

On top of that, it needs to have power to charge all the batteries, too. After starting the 6.2 and probably running the glow plugs, you've got to put those amp-hours back in the starting batteries, plus you need to top up the deep cycle you've got hooked to the inverter running the cab AC unit. Standard lighting/blower/charging consumption on a non-AC passenger vehicle are in the 500 Watt range.

The other problem is that the loads don't go away when the engine is idling. So you need at least 18 amps at idle to break even before you turn the AC on. You've got about 25 available most of the time. Run the AC too long at idle and you'll suck the batteries dry.

Conversion efficiency on a claw pole alternator is usually around 70%. Let's assume the inverter is 90% efficient. And the motor turning the compressor is 95% efficient. Congratulations, your AC drive system is 60% efficient compared to the 90-95% of a V-belt drive on an engine mount compressor.

My parents dealt with this exact same problem on their antique motor home. It didn't come with on the go AC originally, and they wanted to be able to drive through places like Monument Valley in the summer without suffering unduly. Dad considered an engine-driven system, but packaging requirements were pretty ugly. He decided that replacing the roof-mount camper AC unit with a newer, more efficient one and putting a small generator on a baggage trailer behind the coach to run the AC would solve the problem. It did. But the coach is white, has insulation in the walls, and is rear engined - there are no drivetrain heat sources forward of the rear axle. The roof-mount unit is rated for something like 12,000 BTU. The 2KW OHV Generac on the trailer has soldiered on for over a decade, and has also served as emergency power for their house when an ice storm hits.