camping: long cord to car?

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raine137

camping: long cord to car?

Post by raine137 » Thu May 18, 2017 11:37 am

OK -- I've read a lot on here about deep cycle batteries and cases and battery tenders and have a bunch of stuff ready to pull the trigger in my Amazon cart when I called my dad, my go-to guy for all things electrical. He has a degree in electrical engineering and worked for HP for years. I wanted to make sure I had a good understanding of what I needed and used him as my sounding board.

I use a resmed elite ii, I never use the humidity, and I *think* my pressure is around 6 or 7. So based on an average of 8 amp hours per night (I'm guesstimating on the high end to be safe), a 35ah deep cycle battery should be plenty for 4 nights of camping. I have used my cpap machine for I think around 10 years now, and if it stops working, I wake up. I cannot go to sleep without it.

So he listened patiently, and when I was done, he asked why don't I just get/make a long extension cord and plug it into the car. He made me an excel spreadsheet to calculate the voltage drop for the gauges by length and amps and suggested I get 12g lamp or zip cord plus a regular 12v extension cord, and solder the 12v extension ends to the lamp/zip cord/wire rather than a splice job. 50 feet should be plenty. I don't understand any of the technicalities of that, but I can manage to go to a hardware store and get that cord, a 12v extension cord, and solder it together. Then I would click the keys in the ignition so the car battery is on but not running, plug the extension cord into the car and run it to the tent and power my cpap machine from the car's battery all night.

In the past, my old all in one jumper cable battery thingee died halfway through the night and I ended up sleeping in the car anyway (see above re: I wake up when the machine quits). The next night, I just set up my sleeping arrangement in the back of my sister's pickup truck, with my machine plugged into the car's cig lighter. Glad there was no rain

Is there a downside to this I'm not thinking of?

My dad assures me that running the car about an hour in the morning will bring it back up to charged, the amount of amps used will be fairly low.
This is a group camping trip, if the battery won't start the car in the morning, there will be another to get a jump from.
Also not in the middle of nowhere, a town will be fairly close by (30-60 min away).
Not super happy about leaving my keys in the car all night but it's probably fine.
I will make the cord and test it before the actual camping (although I'm running out of time, we leave next week).

Is there something I'm missing?

Much appreciation to CapnLoki for his very thorough and detailed thread about batteries -- what a life saver, thank you! (Ahem. Now, do I really need all of that? LOL)

-Amy

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Re: camping: long cord to car?

Post by Guest » Thu May 18, 2017 12:09 pm

raine137 wrote:In the past, my old all in one jumper cable battery thingee died halfway through the night
I'm gonna guess that it was an old battery which was not fully charged BEFORE use.

I would go with either a NEW Jump Start unit fully charged or the 35Ah unit you mentioned. Either can be used for power outages at home or for future trips. You make no mention of how old this car battery is but that could be a problem and you end up buying a new one.
raine137 wrote:if the battery won't start the car in the morning, there will be another to get a jump from.
This assumes that someone has cables to jump you.
raine137 wrote: town will be fairly close by (30-60 min away)
Is this walking?
raine137 wrote:(Ahem. Now, do I really need all of that? LOL)
Only if you want to sleep and have a stress free trip.

Consider that most of us also charge our cell phones (and other things) while we sleep too - you have plans for that? The 35Ah unit or the jump start can also handle that and either can be charged by your car running using jumper cables.

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Re: camping: long cord to car?

Post by Goofproof » Thu May 18, 2017 12:32 pm

I'm sure your dad is a great electrical wizard, but i'd trust CapnLoki, there are flaws in your dad's plan that he should know being a electrical wizard. 50 foot is a long way to run 12 volt, but 12 guage copper wire cable should handle it.

His plan has to weak spots, which a electrical wizard should already know. While rosin core solder makes a fine electrical connection, it also make a fine place for the wires to break off from vibration or bending at the point of the solder connection, properly used quality crimp connects are better. If you have to use a Cigar Lighter plug, get a quality one that hooks directly to the wires, a fused Plug!

The second weak spot, Automotive Batteries are made to provide a large burst of AMPs for a short period of time, they do not like to be ran low on charge, it shortens their lifespan. Also using the car generator to top the charge back up has a flaw, as a battery charger it takes longer to top it off as it charges. (it won't accept the charge at as high a rate) Car Alternators, have a set charge voltage (to keep the battery charged without over charging it) Batteries need a higher voltage to fast charge, than the car alt is designed for, so it's slower than you think. the last 10% is Slow to charge. That's what makes CapnLoki's methods best. The right parts to do the job, there are many ways to do every job, but their is only one better way, the one you can live with. Jim
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Re: camping: long cord to car?

Post by Goofproof » Thu May 18, 2017 12:40 pm

Guest wrote:
raine137 wrote:In the past, my old all in one jumper cable battery thingee died halfway through the night
I'm gonna guess that it was an old battery which was not fully charged BEFORE use.

I would go with either a NEW Jump Start unit fully charged or the 35Ah unit you mentioned. Either can be used for power outages at home or for future trips. You make no mention of how old this car battery is but that could be a problem and you end up buying a new one.
raine137 wrote:if the battery won't start the car in the morning, there will be another to get a jump from.
This assumes that someone has cables to jump you.
raine137 wrote: town will be fairly close by (30-60 min away)
Is this walking?
raine137 wrote:(Ahem. Now, do I really need all of that? LOL)
Only if you want to sleep and have a stress free trip.

Consider that most of us also charge our cell phones (and other things) while we sleep too - you have plans for that? The 35Ah unit or the jump start can also handle that and either can be charged by your car running using jumper cables.
My last car jumper did fine, lasted 5 years, had to replace it, bought a nice big one, it is a piece of junk, cost way too much, won't hold a charge, only used it once. gave my son the old one after he broke the compressor clip. It seems you can no longer buy products that are made correctly. Jim
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Re: camping: long cord to car?

Post by LSAT » Thu May 18, 2017 12:49 pm

I know nothing about electricity, but, if you are depending on this 10 year old CPAP, I would be worried about any fluctuating voltage
damaging an already borderline machine. Be prepared to buy a new CPAP....even without this trip you are on the verge of needing an upgrade.

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Re: camping: long cord to car?

Post by CapnLoki » Thu May 18, 2017 5:26 pm

raine137 wrote:...
Much appreciation to CapnLoki for his very thorough and detailed thread about batteries -- what a life saver, thank you! (Ahem. Now, do I really need all of that? LOL)
You're welcome!
raine137 wrote:Is there something I'm missing?
You should always listen to your father. He's completely right in his analysis.

Except ...
You already have to get the 12V converter (I'm not sure what model your elite uses). Now you're adding 50 feet of cord plus the fittings, etc. And when the trip is over you just have a pile of wire that won't be used again. If you buy a battery/charger you have backup system that will get you through power outages and jump start cars and recharge cell phones. The BatteryTender is inexpensive but its a "last a lifetime" item. If the 35 Amp-hour battery seems like overkill, you can get a 20 AH for about the cost of the lamp cord! (But then you should charge it in the car every day.)

And this doesn't get into the issues of possibly killing the car's battery. Is a 5% risk acceptable? 10%? Will you have jump starters? And 50 feet might seem like plenty, but when you add the length of the car and the size of the tent, it sounds like you're camping right next to the car. What if you want to go just a bit further? And what happens when someone trips over the wire and yanks the mask off you?

I guess my thinking is that in the name of simplicity, your father is making it more complex! As someone who lives on battery power several months of the year, more batteries = goodness!

Also, off the top of my head, a 100 foot run (50 feet each way) of 12 gauge is about a 3% voltage drop. This should be OK, but its not overkill.

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Re: camping: long cord to car?

Post by rohdej » Fri May 19, 2017 7:56 am

What will you do if the calculations are not correct and drain the car battery in the first night? If you drain the car battery to the point that the Cpap shuts down it definitely won't have the juice to start the car. You may have to go without the cpap the second night waiting for a jump.

Use a separate battery.

Most motor homes use 2 batteries for this very reason. One for the engine and one for the coach. Coach battery at minimum connected through a diode to keep it charged when driving but unable to drain the engine battery.

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Re: camping: long cord to car?

Post by chunkyfrog » Fri May 19, 2017 10:01 am

I would seriously consider a machine that will run directly off 12VDC, like a Respironics or a DeVillBiss, like my reserve machine.
I can actually plug my Intellipap Autoadjust into the lighter outlet if we need to stop at a rest stop for an hour nap.
This type of receptacle is common in direct battery solutions.

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Re: camping: long cord to car?

Post by CapnLoki » Fri May 19, 2017 2:43 pm

raine137 wrote: Is there something I'm missing?
In going over this again I noticed that the power draw of the Elite II is actually rather high, as much as an amp or 8 Amp-hours for a night. For four nights thats 32 AH, which doesn't leave much margin of safety with a 35AH battery. For this reason you should consider some way to charge the battery at least once, either with a simple plug into the cigarette light and driving around a bit. or maybe with finding an AC outlet somewhere. Or you could use a larger or second battery. This doesn't change my thinking about using a "long cord," actually it makes the cord approach worse.

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Re: camping: long cord to car?

Post by CapnLoki » Fri May 19, 2017 3:05 pm

xxyzx wrote:you need the deep cycle battery next to your RAD
OP says she has an Elite II, not a "RAD" which implies a BiLevel or SV pap.
xxyzx wrote:then charge it from the car while it is running or carry a generator with you to do it
do that every morning
A generator would certainly do the trick, at the risk of alienating the campsite. But a larger or second battery would be a lot more cost effective.

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Re: camping: long cord to car?

Post by silversleeper » Fri May 19, 2017 4:20 pm

check out this link http://www.resmed.com/us/dam/documents/ ... lo_eng.pdf it willanswer all of your questions. The elite is a ways down on the list. By the way think that Resmed is 24 volts so you need a converter

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Re: camping: long cord to car?

Post by Goofproof » Fri May 19, 2017 7:44 pm

xxyzx wrote:
CapnLoki wrote:
xxyzx wrote:you need the deep cycle battery next to your RAD

OP says she has an Elite II, not a "RAD" which implies a BiLevel or SV pap.
xxyzx wrote:then charge it from the car while it is running or carry a generator with you to do it
do that every morning

A generator would certainly do the trick, at the risk of alienating the campsite. But a larger or second battery would be a lot more cost effective.

=================

RAD = respiratory assist device which covers all of the various machines


Can't you spell XPAP, you have been breathing too many fumes from your Radiator, I'd open a window. With a little help you could learn the terms, if you thought more and typed less! Jim
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Re: camping: long cord to car?

Post by CapnLoki » Fri May 19, 2017 8:13 pm

xxyzx wrote:
CapnLoki wrote:
xxyzx wrote:you need the deep cycle battery next to your RAD
OP says she has an Elite II, not a "RAD" which implies a BiLevel or SV pap.
=================

RAD = respiratory assist device which covers all of the various machines
Nope. RAD implies BiPAP and ASV. CPAP often implies both CPAP and APAP. A simple search will find numerous references, such as:
"a prescription is required for a continuous positive airway pressure (CPAP) or respiratory assist device (RAD)"
http://www.itamar-medical.com/wp-conten ... -Guide.pdf

The long standing convention in this forum is that XPAP includes all of the relevant devices.

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