car auxhilliary heater

[charles]

so it was quite easy to add things in. Haynes even gave the numbers of the individual cables.

[Capitol]

If you do a search on google.com, quite a lot of servicing information is available for the BMW units.

[Capitol]

In the US, Autozone frequently have that information on their website for US models.

[charles]

1. I don't have a BMW

1. I was doing my own maintenance in the 1960s and 1970s - long before Google was invented.

[Capitol]

I predate you!

[sm_jamieson]

I think it pumps the coolant water into an insulated tank between runs. Simon.

[Johny B Good]

My apologies. I didn't realise such handwarmers even existed. I'm familiar with the principle of supercooled water where it takes just a gentle tap on the bottle to initiate rapid crystalisation (where no mention of heat emission was made, probably on account the endpoint temperature was still below 0 deg C).

It would seem that considerable development has taken place since August 2007:

[Johny B Good]

I wasn't aware that such supercooling based re-usable heating pads had been developed until you pointed them out. :-(

I notice the 100 or more heating cycles limit which is fine for an inexpensive heat pad but does seem unsuited for use as a heat store in a car without the extra complication of a 100 cycles swap out maintenance routine involving some form of cartridge exchange system.

The main issue with such a system is designing it for rapid heat release of the stored energy. It's one thing to use a simple gel filled heat pad where the 45 minutes release time is a bonus but another thing when that heat energy needs to be transferred to the engine block in just a few minutes. It's this latter issue which seems to have been a major stumbling block for such pre-heating use according to one paper on the subject.

Of course, there may well have been further R&D in the 14 years since that thesis was published. If a workable pre-heat store based on supercooling of salts can or has been developed, it does offer the attraction of reduced insulation costs and, as you mentioned, 'indefinite heat storage'.

[Johny B Good]

The "Reusable 1000's of times." claim seems overly optimistic considering the S&A Magic Gel Handwarmers features list includes the phrase. "With proper care, these hand warmers can be recharged over

100 times"

I wonder what the truth of the matter is?

[Peter Crosland]

Cloth the child properly. For example a blanket wrapped around them as well as normal clothing. Make sure you they don't overheat.

[fred]

Surely you mean " sehr gut "

[Thomas Prufer]

The physical principle will work indefinitely -- it's a supercooled liquid, and the little metal clicker provides a crystallization point when activated.

However, it's plastic bag you boil and knead and sit on and carry in a pocket with keys, so its lifetime is limited...

Thomas Prufer

[Windmill]

Ground (well, outside window sill) temp a couple of days ago went down to -10C here in Edinburgh and a few days before that it was 2C and damp inside and out when I rented a City Car Club Leaf (they had a special price, and I can see why!).

I had to use the battery-powered heater to be able to see through the windows, and the first few miles of driving with heater on used up 10% of the range, according to the dashboard display.

The car, however, was great.

I suggested later when I filled out their survey that a propane or butane heater would be a useful option for those who aren't religious about the matter.