Jump Starter Help Please

I can't offer any suggestion other than the fact if you get one of the original type large jump pack like these, they generally contain another lead acid battery which will die the death if left flat for prolonged periods and you'd be back to square one & need jumps leads & something to jump from.  

The newer power bank jump starters seem to get a good press & are small enough to be tucked away somewhere in the motorhome charging while you drive ... and can be used to charge phones etc like this

NB I just picked 2 chargers at random & not endorsing any one  

I watched a video last year from a full time van dweller He had a small Rugged Geek RG1000 inteliboost jump starter and power supply device that he was using to power lighting and to charge phones etc. It was the size of the old video cassette. I was amazed that he was able to use it when 80% charged to cold start a 5.4 litre V8 Petrol engine van.

However maybe start here for ideas and then read some reviews https://kit.honestjohn.co.uk/top-tens/top-10-jump-starters/

Indeed. In the 15 years I have had the X-Trail the warning, 'you have left your headlights on' buzzer has failed to operate twice. You can test it as often as you like and it always works 

The first time we had met up with friends for a Sunday walk and lunch on a very cold winter's morning. Back to the car 3 hours later. The break down took almost an hour to arrive as a lot of calls. We were sat in the pub with a large cafetiere of free coffee. 

Second time meeting OH's sister and B in Law just before Christmas.. 4 hours over coffee and then lunch at a garden centre. An employee of the centre came out with his Renault Clio and jump leads. He had to run it for 20 mins to put enough into the X-Trail battery for me to start. No way would the car start off his little battery otherwise. Before we next go away I shall replace the battery. The little device that I mentioned previously was 90 dollars US. If I had one I would want something bigger so that I could power the motormover for 80 metre or more or more.

All solar panels are not equal. Like most things, you get what you pay for. A high quality solar panel will perform much better in poor light conditions than a low efficiency panel. 

There are two aspects, prevention (of battery discharge) and cure.

There is a view that jump starting a flat battery is dangerous to the health of the donor battery and the flat battery and also potentially to the alternator on the donee car. Rescue organisations use a jump start pack these days but any type of jump start risks the battery because of the load imposed on a flat battery by the vehicle alternator. So the safest solution is to remove the battery,  charge it at home and then refit it.

As regards prevention a solar panel may be helpful but it depends on a number of factors including the size of the panel and quality of installation amount of sun and ambient draw for example by an alarm. 

So my advice is essentially NOT to use jump leads except in an emergency. Rescue companies are there to rescue you and if your battery fails later its not their problem (but it may be their opportunity if they sell you a new one). 

I was thinking of getting one of those small lithium jump starters for emergencies but was interested that all the ones I looked at had very short leads.  I was told that you should never put the negative lead on to the negative terminal of the battery but  with the jump starters I was looking at you had no choice.

Not a problem as you connect before making a circuit and then switch the lithium device to charge.. If charging from another car using jump leads the last connection that you make will likely cause a spark and hence the advice to avoid sparks above the battery with possible hydrogen gas being emitted.