peltier fridges

[rockcrawler31]

i just got a waeco cooler/heater for the old man that uses a peltier effect type element. (couldn't afford to get him a compressor type)

what is the best way to get the best efficiency out of it.?

how much do these units struggle when the day gets really warm?

it draws a nominal 48 watts, so i have advised him to run a dedicated 4mm fused cable direct from the batter instead of using the cigarette socket, until he can get a second battery setup (who knows when ), the original socket and cigarette plug uses fairly small cable so i told him to shorten this as much as practical and then plug straight into the heavy dedicated line, and only use it for an hour or two when the car isn't running.

i also asked mum to sew up a cover that has sandwiched layers of reflective foil and neoprene

any other tips to get the best out of it? maybe keep deep frozen blocks in it as well

cheers
MILO

[festy]

Best efficiency is to use it in a cool climate They will cool to x degrees below ambient, so the cooler the ambient temperature, the cooler the inside of the fridge.
They really need to be well ventilated - it will have a fan that moves air across the back of the peltier, make sure it's not obstructed. Having the air conditioner on in the car makes a difference, as it lowers the ambient temperature and helps draw heat off the back of the peltier.
Think of it as an assisted esky, rather than a fridge. An ice brick or two will go a long way. Like all fridges and eskies, they work best when full.
And don't switch straight between cooling and heating, let it sit for a few minutes turned off before changing over.

[murcod]

Yes, you'll find a big aluminium heatsink assembly somewhere externally on it with a fan blowing air on it. The cooler that heatsink is kept the colder the fridge will be inside.

I got hold of a broken peltier fridge a few years back. I replaced the dead peltier device and mounted a big mother of a heatsink onto it, plus a huge fan. It worked very well after that!

One thing I did discover when researching is the peltier should be cycled on/off quickly to control the temp via an electronic circuit. Cheap fridges don't have such circuitry and simply have some sort of thermal switch that controls the power to the peltier. Apparently they don't like that sort of treatment due to thermal shock and won't last as long.