Battery life - newbie query

[The Wibbler]

One the first trips in our new van will be a long weekend without EHU.

My question is twofold. I have to use a CPAP machine at night and without hookup, i will need to find a suitable car charger to run it. So question part one - does the cigarette lighter power come from the main or leisure battery? Question part 2 - would a car charger significantly drain the battery if used for two nights, assuming fridge use and limited internal lighting? For reference the charger spec is 11V-25V Max 10A.

Sorry if this is covered elsewhere.

Chhers for now

 

[Qnapper]

Using a continuous positive airway pressure (CPAP) (most commonly prescribed device for treating sleep apnea disorders) for those that don't know will draw as you state up to 10amps. Without knowing what your current battery is the question you ask is to opened ended.

Example: A 100amp hour AGM will ONLY give you 50amps before it starts to die (discharge it to many times, and it will fail and not hold a charge) So you might get 5hrs of running the CPAP device providing nothing else is drawing amps. The cigarettte lighter socket will blow the fuse very quickly drawing 10amps as most are only disgined for 8amps. In your case it would be best to fit a socket direct to the battery (leisure) with a fuse in line. Do not use cigarettte lighter in cab are as you will/may not be able to start van in the morning.
If I was you I would buy a portable generator with a portable solar panel that will drive your CPAP during the night without problem and then charge during the day via solar panel or 12volt cigarettte lighter (as they only drawmax of 8amps)
Link: https://www.amazon.co.uk/EF-ECOFLOW-Portable-Flashlight-Generator/dp/B091Y9ZT3Z

or better still if you can afford it:
Link: https://www.amazon.co.uk/dp/B091YLDBZS

Hope that helps you.

 

[The Wibbler]

Using a continuous positive airway pressure (CPAP) (most commonly prescribed device for treating sleep apnea disorders) for those that don't know will draw as you state up to 10amps. Without knowing what your current battery is the question you ask is to opened ended.

Example: A 100amp hour AGM will ONLY give you 50amps before it starts to die (discharge it to many times, and it will fail and not hold a charge) So you might get 5hrs of running the CPAP device providing nothing else is drawing amps. The cigarettte lighter socket will blow the fuse very quickly drawing 10amps as most are only disgined for 8amps. In your case it would be best to fit a socket direct to the battery (leisure) with a fuse in line. Do not use cigarettte lighter in cab are as you will/may not be able to start van in the morning.
If I was you I would buy a portable generator with a portable solar panel that will drive your CPAP during the night without problem and then charge during the day via solar panel or 12volt cigarettte lighter (as they only drawmax of 8amps)
Link: https://www.amazon.co.uk/EF-ECOFLOW-Portable-Flashlight-Generator/dp/B091Y9ZT3Z

or better still if you can afford it:
Link: https://www.amazon.co.uk/dp/B091YLDBZS

Hope that helps you.

Hi John, that is really helpful. Wouldnt I have the same problem with the leisure battery?

Cheers Richard aka The Wibbler

 

[Dellmassive]

Good advice above ...

You can also run a stand alone power box.

SOLAR GENERATORS - LifePo4 Battery Boxes -- How I done It --

SOLAR GENERATOR -- How I done It -- OFF The back of these two threads i thought i was time do a dedicated thread. https://www.t6forum.com/threads/awesome-3-in-1-battery-bank-how-i-done-it.18674/ . https://www.t6forum.com/threads/jackery-power-stations.27586/ . The Lithium battery...

www.t6forum.com

.

 

[Qnapper]

Richard, without knowing your battery size and how long you have been using it for I cannot answer your question. Dellmassive has provided link above which is well worth a read and will give you a better understanding.

 

[t0mb0]

One the first trips in our new van will be a long weekend without EHU.

My question is twofold. I have to use a CPAP machine at night and without hookup, i will need to find a suitable car charger to run it. So question part one - does the cigarette lighter power come from the main or leisure battery? Question part 2 - would a car charger significantly drain the battery if used for two nights, assuming fridge use and limited internal lighting? For reference the charger spec is 11V-25V Max 10A.

Sorry if this is covered elsewhere.

Chhers for now

You probably need more details here on the actual power draw of the CPAP device. You refer to the “charger spec” - does this mean the CPAP has its own battery which you can then charge with a car charger? If so, what is the battery life of it and ideally what is the capacity of the battery? If you have a link to it, we can probably puzzle it out.

 

[The Wibbler]

You probably need more details here on the actual power draw of the CPAP device. You refer to the “charger spec” - does this mean the CPAP has its own battery which you can then charge with a car charger? If so, what is the battery life of it and ideally what is the capacity of the battery? If you have a link to it, we can probably puzzle it out.

Hi, This seems to be turning into a minor minefield, but hey ho!

The CPAP doesn't have a battery, but i can obtain one (which would only good for 1 night i think). The CPAP unit draws 3.75 A and has a variable power draw due to the air pressure it is providing at any one time. The average would appear to be circa 1.0A when its humidifier function is off and 2.3 A when in use. The leisure battery on the van is quoted as 70A and the Dometic fridge would draw 3.45 A (per hour?) I tend to average out at about 6.5 hours/night with the CPAP. I am thinking of having a direct connection fitted to the leisure battery to allow the use of a car charger lead to the CPAP, but remain concerned that two nights use without EHU will essentially drain the battery.

At this point, I will have to run up the white flag as my knowledge of electrics is exhausted! Does the above help at all?

 

[oldiebut goodie]

Have you considered adding another ( larger ) leisure battery that can be dedicated solely to the machine? That is what I would do personally, the fridge can go flat then but you can still breathe.

 

[The Wibbler]

Or (light bulb moment?) I run the fridge on gas overnight and top up the battery with a solar panel the next day?

 

[CAB]

Or (light bulb moment?) I run the fridge on gas overnight and top up the battery with a solar panel the next day?

If it is a three-way fridge, it will have to run on gas when off-grid in any case.

12v should only be for when the engine is running, it would flatten a leisure battery. If wired as per normal, it shouldn't be capable of running off your leisure battery.

 

[oldiebut goodie]

When I had a 3 way fridge in my old van I always ran it on gas even whilst travelling only switching it off and back on at fuel stations. Never once used it on battery power.

 

[CAB]

Hi, This seems to be turning into a minor minefield, but hey ho!

The CPAP doesn't have a battery, but i can obtain one (which would only good for 1 night i think). The CPAP unit draws 3.75 A and has a variable power draw due to the air pressure it is providing at any one time. The average would appear to be circa 1.0A when its humidifier function is off and 2.3 A when in use. The leisure battery on the van is quoted as 70A and the Dometic fridge would draw 3.45 A (per hour?) I tend to average out at about 6.5 hours/night with the CPAP. I am thinking of having a direct connection fitted to the leisure battery to allow the use of a car charger lead to the CPAP, but remain concerned that two nights use without EHU will essentially drain the battery.

At this point, I will have to run up the white flag as my knowledge of electrics is exhausted! Does the above help at all?

If that 1-2.3 A is at 12v, then 7 hours gives you a maximum of about 16Ah (Amp-hours).

Your leisure battery is 70Ah, but you shouldn't use more then half of that regularly, so 35Ah available (if it is a normal leisure battery).

If it is fully charged when you leave home (via EHU preferably, the van may only provide up to 80% charge if it is a Split Relay charger) then that should be enough for two nights with no other significant use (LED lights are very low power) and any solar top-up is a bonus.

That just leaves you with the CPAP 12v and the solar connection to sort!

Please note I am no expert - I just remember a lot of what I have read. It would be worrth having a decent battery monitor.

Battery Monitoring -- How I Done It --

Battery Monitoring -- How I Done It -- Part #1 Battery monitoring is a very important part of your 12v system . . . . whether its just the vans starter battery or your leisure setup keeping an eye on the power in your battery bank will keep you from breaking down and make sure your weekends...

www.t6forum.com

@Dellmassive's 'how I done it' threads are always very informative:

Dellmassive’s "How I Done It" blogs.

-- Dellmassive`s -- "How I Done It" -- thread -- ************************************************** Dellmassive`s -- "how I Done It" -- Thread ************************************************** Kit List And Stuff -- How I Done It & What I Use --...

www.t6forum.com

 

[Qnapper]

The Wibbler​

The best thing to do for your health and peace of mind is to go see these guys below.

Eco Tree Lithium | The Lithium Battery Specialists

At Eco Tree Lithium we develop tailored battery solutions for each market sector.

ecotreelithium.co.uk

They will replace your current battery for a lithium battery and advise you what you need to run your CPAP device off grid. What you are asking for is not going to be cheap, but the long term benefits far outweigh the cost. Good Luck.

 

[The Wibbler]

The Wibbler​

The best thing to do for your health and peace of mind is to go see these guys below.

Eco Tree Lithium | The Lithium Battery Specialists

At Eco Tree Lithium we develop tailored battery solutions for each market sector.

ecotreelithium.co.uk

They will replace your current battery for a lithium battery and advise you what you need to run your CPAP device off grid. What you are asking for is not going to be cheap, but the long term benefits far outweigh the cost. Good Luck.

Gulp!

 

[The Wibbler]

If it is a three-way fridge, it will have to run on gas when off-grid in any case.

12v should only be for when the engine is running, it would flatten a leisure battery. If wired as per normal, it shouldn't be capable of running off your leisure battery.

As I noted, I'm new to all this and thought three way meant using the leisure battery. I now know better!