I am looking at getting a pair of battery packs - the sort and size that can be used to jump start a bike. Are there any characteristics that I should be avoiding or looking out for?

I will have to have a suitable power supply set up for them so will be fitting a “car” lighter socket.

Hi, is it only as a starting backup? Because for cars you can carry this small jump start lithium packs, should definetely have enough oomph for bikes.

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2011 Overland from Amsterdam to Nepal and back
2018 Overland from Amsterdam to Tokyo via Central Asia and Mongolia

It is for both jump starting the bike - so any of the car one should be overkill to be honest - and using it to charge up my phone, camera, iPad etc. Part of me - the part that likes to drink tea with fresh milk rather than UHT / dried milk - is looking for some sort of cooling system to make the milk last a little longer than a day.

As I am planning on making my own panniers for a couple of longer trips to hotter climes than the UK I am wondering whether to build the panniers so that one is part fridge / part normal pannier - this would require a few batteries / solar panels to supply 30W when not riding. The fall back position is to have one pannier that is double walled (aluminium outer and plastic inner walls with a polystyrene sandwich between) and so it is well insulated pannier with positions for ice to be added every other day to keep the temperature low. The nerd in me wants the fridge though!

We just took a small coolbox (5L I think) with us for our US road trip. Worth its weight in gold in the hotter areas. Plugged into the bike on the road and into power sockets in campsites and hotels. Having it as it came was ok for us but if you were going to build it into a pannier I suppose you could strip one down and use the working parts.

Battery packs for phone / camera etc charging work very well and I've got three or four of them now. Only one with jump leads though and when we needed it to start a flat battery car a couple of weeks ago it failed miserably. No idea why as it was fully charged but they're obviously not all equal.

It is a relief that it is not just me thinking that a fridge would be useful then.

I hadn’t thought about stripping one down to get to the essentials - that could mean that a recycled caravan fridge (they tend to operate on 12V, 230V and off gas) could be the basis for a pannier - dumping the 230V and gas side completely. Hmm. This could be fun. The one downside is that the smallest caravan fridge I have seen is 42 litres so far which may be a little too large - dropping the size may be the hardest thing without damaging the gas carrying tubes. The compressor and other electrical components etc would have to be out of the way of water from the road - to at least waterproofed which may require some thought as they would need to be in circulating air to keep them coolish.

I have plumped for a battery pack off eBay rated, apparently, at 68800 mAh. I shall see how good it really is by having it run a sidelight bulb - it should be capable of running it for 9 days if it is fully charged....Should being the operative word.

I don't really know much about how cool boxes actually turn electrical power into 'coldness' (though I'm sure others here will) but I'm pretty sure it can't be compressors and all the other stuff I see round the back of my fridge. Some years ago a friend was given a crash helmet as part of a sponsorship deal that had a reversible cold / heat mechanism built into it so whatever system it used can be made pretty small (it did work and you could feel cold(er) air coming out of it after a while). Unless you're taking temp sensitive medicines or similar with you that need a specific temperature (we didn't), 15C or thereabouts colder than ambient felt pretty good and that's about what our box would deliver. No ice cubes but cold enough , the milk would last long enough to use it, meat would keep etc.

Re battery packs, 68 Ah is a biggie. My largest is 20Ah and bought because I read that was the largest you take on aircraft without it being classified as dangerous goods (or something like that) and having to declare it. For us its been about the perfect size - not too big itself but with enough power to keep all our stuff charged. Last 'major' trip we took ridiculous amounts of battery powered stuff - 5 cameras, 4 phones, 2 intercoms, 2 tent lights, iPad, air bed pump etc. Often there weren't enough power sockets in hotel rooms never mind campsites when the whole lot went flat at the same time.

I hadn't realised that there was a limit on the battery size for aircraft - but then again I wasn't looking for any information on that subject.

Now I just have to find an old caravan fridge to play with - I am fully expecting to kill off a couple before getting it right - and that is before I even start trying to fit it into a pannier design.

A lithium jump starter back is basically a big battery pack to charge your tablet and phones, but then with high amp output on 12v to help start bikes and cars.
Just buy the smallest one you can find. When you come with a big diesel car it won't do, but that is not important for you. More amps is better though, because in the cold you get less amps.

I once met a Belgian couple, and they had the bottom of one pannier cooled for the insulin one of them needed. Only cooled while driving, but had some isolation.

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2011 Overland from Amsterdam to Nepal and back
2018 Overland from Amsterdam to Tokyo via Central Asia and Mongolia