Split charge relay for Peltier fridge box supply socket?

davidpbo

davidpbo

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In this hot weather we are struggling keeping our cool box remotely cool using freezer blocks. It is an Aldi/Waeco cool box with a Peltier effect lid. Could I use this relay to automatically switch it on when the outboard engine is running? I want a voltage sensitive relay that ideally is adjustable.

www.towsure.com/towbar-split-charge-relay-wiring-kit

Sadly I can't download much info on this one using my phone.
 
If you only want to power it when the outboard is running you could simply fit a power socket to the "ignition" connections on the boat, so that the socket powers up when you turn the ignition on and goes off when you switch it off.

Fitting a VSR will have the same effect, as soon as you start the engine the VSR will close, as it will sense the alternator output.
 
davidpbo said:
VSR is the simpler option as all the outboard control and ignition wiring is in the cockpit. Cool box resides in the cabin close to the switch panel.
Click to expand...

Oki doki. This seems to be the same relay, without the kit https://www.towsure.com/self-switching-smart-split-charge-relay-for-towbar-electrics

The "kit" only appears to be some wire and a fuse. If you were looking to charge a domestic battery, i'd suggest something different. As you only want to run the coolbox, according to the blurb on the website it should be OK. For a tenner, i'd probably take a punt.
 
davidpbo said:
In this hot weather we are struggling keeping our cool box remotely cool using freezer blocks. It is an Aldi/Waeco cool box with a Peltier effect lid.
Click to expand...
A GOOD cool box opened 2 or 3 times a day with as much frozen in it as possible should still be cold at 3 days. The trouble is these Peltier boxes seem to have pathetic insulation and seals.

In addition to what you are doing, I'd consider:

- Adding extra insulation
- Using wine coolers on top like a cool blanket like these cut it so that it is a rectangle rather than a cylinder. Ideally, you want three of these (or 3 parts of one) so that you don't have remove all the cooling at one when you get the milk out.
- Add extra frozen stuff. If you have drinks etc - freeze it.
- Adding a fan to bring cold air from the bilges over the heat sink. The Peltier drops ~15C below the temp on the warm side. If the air on the warm side if its in locker etc will be even warmer than the crazy heat we have currently. So it could be 35C, meaning the cool side gets a shivering 20C.
- If there is room - add a fan to move the cold air from the inside of the Peltier. Switch it so the lid being open switches it off.
- Add extra external insulation.
- Make sure the internal seal is 100% air tight
- If power was no limit - I'd add a second Peltier to cool the heatsink on the one on the box. If that was the case and everything was efficient - you can get the temp down to 0C with air temp 30C, but I wouldn't do it from a battery!
- I'd probably then add a thermostat because on 'cool days' it will turn into a freezer!

Then I'd give up and buy a proper fridge ;-)
 
These are not the greatest cool box. They can achieve a difference over ambient. When ambient is high then their internal temperature will reflect that.

50 years ago peltier diodes were part if my physics practical.
Cool is the best you can hope for and cold is an ambition
 
The box is like a simple ice/ice block cool box with a Peltier effect lid. We use it with ice blocks and sometimes ice. I tend to use the electric cooling part when we are going to or from the boat or travelling elsewhere. It can also be powered off 230V without an external PSU.

I do wonder whether I would be better with either a better icebox or the metal lined Peltier effect boxes which I have steered clear of because I don't think they can be used with ice or can cope with much water inside.

I have a small version of the above which was quite effective at keeping drinks and sandwiches cool last week at work.

Using a VSR in line with the socket powering the box is a bit of a play.
 
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