Jump starter pack

G'day Odog.

You don't mention a brand name, but the mini jump starter I have (they say) can easily start a 6 cylinder diesel engine, this is yet to be proven, but it too is a lithium battery unit.
Sadly it can't handle the high ambient temperatures in the Pilbara, I've had it replaced once already because the plastic case housing the lithium battery swelled up enough to look like a Volkswagen Beetle, the replacement one is looking very much VW'ish already, I use it purely for camera and phone charging and for this it's faultless.

Safe travels : Joe Fury

Hi Odog
If you divide your wattage by the voltage you will get the amperage that the solar panel will generate.
Usually solar panels are between 15v to 20v which is then regulated down to your nominal 12v.
So your 8 watt panel will generate around 0.5 amps per hour and that's only when the sun is shining.
So if your battery is dead flat it will take around 40 hours of good sunshine to recharge it.

Cheers Craig

This is the one I bought....a bit exxy but at least I know it has the capacity to start a prime mover, so should handle my 6.6 litre Duramax without too much hassle:
https://www.partsales.com/details/autoelec/new-noco-genius-12-volt-4000-amp-gb-150-portable-lithium-jump-starter-booster-b95770?gclid=CjwKEAjwjPXIBRDhwICRg-DbgHISJADP6QXprb6dnWyNBBuHW8FzflS4Is5pEkQxuuQq8Oi55nRVkBoC9RLw_wcB

https://www.youtube.com/watch?v=nsOvksbZLBE

Hi Odog,
Agree with previous reply about 8 Watt panel - gives under 0.5Amps so about 40 hours to charge your 20Ah pack - that's several summer days in a row. Short answer = not good!
Cpap machines draw 15-35Ah over an 8 hour stint, depending on make, and with humidifier off. (more detail see: http://12voltblog.com.au/how-much-power-does-12volt-stuff-use/). So the 20Ah pack is not really enough - risky.
Cheers,
AJC

I recently assisted a fellow camper whose Cpap machine had cut out after 6 hours or so, even though he had a second 50AH battery.
It turned out his machine used 6.5 amps without dehumidifier and this had completely drained the battery, which was also running an Engel fridge.
Make sure the Cpap rating amp is at 12volts as another poster noted that some are at 24 volts, and in the campers case was watts at 240 volts.
Even so at 2.5 amps you will be pushing it with a 20AH unit.

The camper's solution was another battery pack which he already owned, but I don't think he realized that he would have to drive for about 6-8 hours every day to charge them, or would need very large solar panels.

as you have already found out ..... timely charging of the 20Ah pack from an 8 watt panel is not going to happen.

As for running your Cpap ....... I've done the maths for a fellow on a number of Cpaps ...... yeh you will need a bigger battery than you think to get an 8 hour run from your machine.

Get your facts straight about the energy demand of the Cpap ...... I can tell you right now it does not draw 2.5 Amp Hours ...... it might draw 2.5 amps ...... but is this from a 240V supply or from a 12 volt supply.

Is this actual measured draw or what is written on the power pack for the unit.

I'll tell you right now ..... you will need 100Ah absolute minimum .... and at that you will hammer the battery to death pretty fast ....... 200Ah or 2 x N70 batteries ...... AND the ability to recharge them.

AND that will be with a well selected machine that is efficient and low current drain.

Cpap machines my not seem to be high demand ..... but they draw continuous current the entire time they are running.

you must get your facts right for the specific machine and do the math ....... and being optomistic is no help at all.

cheers