trouble with battery power

Hello everybody,
I'm a long haul truck driver. I use a remstar CPAP plugged into a cigarette lighter port. It usually works fine, but every once in a while when plugged into the truck the machine will stop and show "ER-40" on the screen. If it does it once, it will do it over and over all night. If I start the truck and let it idle it doesn't do that. It's not at all consistant either. I will go for months at a time without having it happen, then out of the blue it will act up. I have had 2 differant machines and 4 differant trucks in the past 4 years and it has happened with all of them. What the heck is going on? With diesel fuel costing over $4 a gallon I sure don't want to idle the truck if the weather allows me to shut it off.
Why does it do this and how can I make it quit?
Thanks,
Jeff

You didn't specify which model of machine you have. I looked through a number of manuals I have for various models and couldn't find an error code "E-40" that would pertain to DC voltage problems. Although, I did find one referencing AC voltage being too low.

Possibly obtaining a battery pack from CPAP.COM that could be plugged into your lighter outlet and then plugging your CPAP into that......???

Maybe something like this one:

https://www.cpap.com/productpage/respir ... -pack.html


Den

jeff0520 wrote:Hello everybody,
I'm a long haul truck driver. I use a remstar CPAP plugged into a cigarette lighter port. It usually works fine, but every once in a while when plugged into the truck the machine will stop and show "ER-40" on the screen. If it does it once, it will do it over and over all night. If I start the truck and let it idle it doesn't do that. It's not at all consistant either. I will go for months at a time without having it happen, then out of the blue it will act up. I have had 2 differant machines and 4 differant trucks in the past 4 years and it has happened with all of them. What the heck is going on? With diesel fuel costing over $4 a gallon I sure don't want to idle the truck if the weather allows me to shut it off.
Why does it do this and how can I make it quit?
Thanks,
Jeff

Jeff, my guess is that your truck battery voltage may be a bit too low for the cpap machine. It may still be more than adequate for starting the truck, but cpap machine probably expects 12v or so. If you use a separate battery pack, which is charged up thru the cigarette lighter while you are driving, might be a solution. If you have the space, another small 12v motor cycle or car battery may be your cheapest solution. Unplug the new car battery from the cigarette lighter before you stop the truck.

jeff0520 wrote:Hello everybody,
I'm a long haul truck driver. I use a remstar CPAP plugged into a cigarette lighter port. It usually works fine, but every once in a while when plugged into the truck the machine will stop and show "ER-40" on the screen. If it does it once, it will do it over and over all night. If I start the truck and let it idle it doesn't do that. It's not at all consistant either. I will go for months at a time without having it happen, then out of the blue it will act up. I have had 2 differant machines and 4 differant trucks in the past 4 years and it has happened with all of them. What the heck is going on? With diesel fuel costing over $4 a gallon I sure don't want to idle the truck if the weather allows me to shut it off.
Why does it do this and how can I make it quit?
Thanks,
Jeff

It is a DC motor inside the machine, just like the heater motor in your truck the lower the voltage gets the slower the blower spins. You cannot have that happen with a machine controlling your breathing, so when your battery level gets below a certain voltage the machine will shut OFF from low voltage and display an error.

Note: Under low voltage condition, the machine won't simply run slower it will shut off.

That is what you are looking at. I suggest:
Installing a round digital volt meter in your sleeper so you can easily monitor the voltage in your truck. Do you leave your running lights on while you sleep? Remember a fully charged battery is 13.7 volts and a dead one is like 10.2 volts. At what voltage does the machine stop functioning? I haven't seen that but I highly suspect that is your problem, low voltage.

Maybe time to get a hydrometer out and check for a dead cell in one of your batteries. It is probably the one that is the hardest to get to.

Optionally, you could install and set up a separate automotive lead acid battery on your truck with a RV style battery isolator, that way any lights, fans etc. from the truck draining the batteries doesn't put your CPAP machine out of commission. With the battery isolator, the CPAP battery would automatically recharge when you run your truck. You should have a 100+ AMP alternator on your truck, check your voltage next time it runs, you probably have a air starter so you may not know of the low voltage condition.

Thanks for the info. I suppose low voltage makes more sense than anything else. My truck carries a rack of 4 BIG 12 volt batteries though and the only things running at night are my CPAP and my cell phone charger. The only thing that comes to mind is that Internationals have automatic fuel tank heaters. They kick on in cold weather and prevent the fuel from gelling up. They aren't supposed to come on unless it's cold outside though. I suppose it's possible that the thermostat has gone out.
I have noticed though that I'm getting 2 different error codes. I don't notice any pattern as to which code shows up when. They are 36 and 40. Does that shed any more light on the question? It's a RemStar plus model 1005960.
On the positive side, if low voltage is the problem, I already have the solution. I have a really big deep cycle battery that runs my CPAP with no problem on 3 day camping trips. With a little wiring a can connect it to a switched power supply in the truck so when the engine is running it charges, and like the heater blower motor, when the key is off it's disconnected from the batteries.
Thanks again,
Jeff

Oh yeah, I forgot to mention, my truck does not have an air starter. It's just like the starter on a car, just supersized. I've never had trouble getting the truck to start. A time or two I have even forgotten a dome light on when I went home for the weekend and it cranks right up. The batteries in the rack are the BIG industrial batteries.

Most truckers run their marker lights while parked for safety, that will draw the top voltage off your batteries quickly, another solution would be a A/C Inverter, to run the XPAP off 110 Volt. it might manage the voltage drop better. A engine at idle is costly, in fuel and wear. Jim

There are 2 points of view on the issue of marker lights while parked. One side says it makes the truck more visible so people don't hit it. The other side says it's too easy for an inattentive, sleepy, or drunk driver to try to "follow the truck" in the dark without realizing the truck is stopped and plow into the back end.
I'm a believer in the second point of view. The truck has more than enough reflectors and retro-reflective tape on it to be seen and when all my lights are off there's no doubt that I'm parked.
I also don't park on the side of the road unless I'm just falling down tired and there's no place else. The roadside is not a good nights sleep because of the traffic noise and it is dangerous no matter what precautions you take.
One of my favorite dodges for a good place to sleep when there's no truck stop spot available is to find a shopping center, pull around back, and back into the dock. If they are closed when I get there, and they don't open till 9 or 10 they will never know I was there and any cops or security won't bother me because I look like I belong there.