Discussion in 'Mech Tech' started by AndyC, Apr 9, 2015.
So the T in the diagram is a step down transformer from mains (is that US mains or UK?) to 12v?
Yeh. Drops 110v to 12v
I take it there are diodes missing from the circuit?
I guess the 240v (110v) circuit should be able to be disconnected simply because you can't drive about plugged in to the mains!
I assume that's what the selector switch does.
Although I don't have one.
The circuit on my 220V version doesn't have any diodes. There's no need to rectify to DC for this as it's only running a heating element. AC is fine. However if the circuitry is also part of a battery charging system (mine isn't) you would need to consider this.
Yeah, that's correct. ^^^
The bit under the bed was a step down transformer/charger which I replaced with one of these power supplies when we got the bus back to the UK in 2008. It worked perfectly on 230v hook up, using the OG Westy control panel. The reason there is a timer on the control panel is so the older single function chargers didn't boil the battery if left on charge for extended periods.
However, I'd go for a 10 amp CTEK now as they are a bit more sophisticated and kinder to batteries, and just use it on the continuous output function when hooked up. As I said earlier, you "may" struggle to keep up with replacing the lost amps to the fridge with anything less than a 7 amp charger so to be on the safe side, go with 10 if using the original Westy fridge. Oh, and replace the wiring and connectors if you can with newer rated cable and fuses. Best to be safe when heating an element in the space where you sleep...
Just thought, @AndyC , if you've got one of these panels, carry a spare 10 amp glass fuse of the type that sits in the holder bottom centre. Yours should be OK as you have DC to the multi plug, but.....??
I wasn't thinking of using them to rectify the AC - more as protection in the charging circuit you describe to be honest
In the event that the fridge is kaput, is there a modern model that'll fit in its place?
i have a waeco coolmatic cb 40, but i think it may be a bit bigger than yours. there is an option to buy a compressor and cold plate unit and fit that into your current coolbox part of the fridge. again @theBusmonkey is the man for that
Also i bet your fridge will be fine if you leave it upside down for a few days and then leave it plugged in for a few days also. guys on the samba have fixed their fridges this way for ages.
a big benifit of changing it though is the massive reduction in the current a compressor fridge draws. mine runs at about .64 A per hour when it isnt being asked to cool too much
That last bit is another thing I'm thinking.
I am probably on the limits of what my leisure battery charger can do.
what leisure battery charger do you have?
CTEK MXS 5.0
ah right yeah you may be starting to pushing it. mxs 7 is a bit beefier
Ooh, i ike the idea of fitting a modern cooler plate etc. @theBusmonkey do you have info?
something like this: http://www.marinemegastore.com/product.asp?pf_id=MAR_4G080BA100013&jump=0&cat_id=CABREF004
Cor, that's expensive aint it?!
They certainly aren't cheap but then you do get what you pay for...
This is the next step for us and it's based on the Danfoss compressor. Most high end compressor fridges use this kit as the cooling system and style around it. Remember, you'll be paying 500-600 quid plus for a good quality Waeco or Shoreline fridge so the price is comparable.
There are companies, such as Tek Tanks who will build a custom sized insulated box or you can have a go at DIY. I remember @vanorak had some good advice on the best insulation materials for DIY cooling.
In any case, a custom box allows you to turn a locker (or the old Westy fridge cabinet) into a more modern and useable refrigeration unit.
I've not worked it out yet but I suspect the compressor would need additional help with cooling in very high (Continental summer) temperatures in a tight bus install, but this should easily be achieved with a 12v computer fan. Food for thought....
BTW, we still reckon on factoring in 3 to 5 amps/hours average with a compressor fridge and that's from the experience of living with both 12v DC Waeco fridge and freezers 24/7....
Yeah my cb40 was even more!!
the danfoss could be mounted under the bus...they're pretty bullet proof...they can heat up a bit, so maybe you could make use of that somehow....
these guys will be able to advise but something like Tarecpur board would be ideal for lining a custom box...normal Kingspan would do also....When I looked into it, I settled on the idea of a stainless steel liner, rather than a plastic one, as it could be fabbed up quite easily...
Separate names with a comma.