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It's getting quite hot!

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I just experimented with a 12V, 140mA (1.7 watt) PC fan. Although it's not 30C here, I believe that if it were placed to blow over the bed it would be more than enough. I tried it on 5V, and that was also encouraging (less air, very quiet). It would be enough for one bed - need another fan for a second bed.

If you're only consuming 1.7W, then for overnight you need only 1 or 2 AH. I would recharge it with an ordinary wall transformer, about 150 mA, 13-14V.
 
I note from 'HugoC's original post:


1) Power Supply
Mains power is available but the supply is intermittant.
In Ghana the mains electricity supply is 230V 50Hz.

2) Food preservation
Fridge type not given above but assuming that the fridge is a small european style **broken link removed*** then the fridge will draw about 120W while running.
The fridge will be conected to a wall outlet using either the UK **broken link removed** plugs or the older UK **broken link removed** plugs that are both used in Ghana.

3) Ventilation
The type of fan being used has not been stated.
A floor standing pedestal fan or a ceiling fan will draw up to about 60W
A ceiling fan may have a permanent connection to the lighting circuit so a seperate fan will likely be required. These should be available locally (?)

Inverter
A 500W 230V 50Hz power invertor* would be required. (As motors draw more starting current the inverter must be rated higher rather than the nominal 200W).

Switching between the supply from mains and inverter
The simplest way would be to change plugs manually from the mains outlet to the inverter. An automatic switch could be used.

Battery Size
200Ah* for 12 hours (200/12 x 12) or
135Ah for 8 hours (200/12 x 8)
-This is a conservative estimate as the fridge will be an intermittant load due to it not running continuously. The inverter will not be 100% efficient. A 24V inverter would be more efficient then 12V.


From the original post it looks like the locals use a car radiator fan running off batteries which are charged from a car alternator which is run from a motor connected to the mains whenever mains power is available. Presumably the alternator and car fan have been salvaged from a car. No doubt the mains motor was also salvaged from somewhere.
This is a workable means of charging the batteries and would save the need for a charger unit. This also suggests that batteries are available locally though this should be looked into - the batteries may be salvaged car batteries so they may be of uncertain quality and capacity.

The sort of batteries to use are would what we in the UK call leisure batteries and which are designed for deep discharge. They are available from camping or marine supply shops which will also have inverters, chargers and changeover switches.


The **broken link removed*** (aka "Elextrolux fridge" in the UK) can work off 12V battery, 230V mains or bottled gas. The disadvantages are that they are small, expensive and less efficient than a conventional compressor fridge.
The absorption fridge has no moving parts so has nothing to wear out though they can ocasionally stop working. (if this does happen, the solution is to turn off the fridge off and after its cooled down to invert the fridge and leave it upside down untill all the bubbling and gurgling has stopped. It will then start working normally after being returned to its normal way up and relit. (I did have one that went into 'reverse' where the inside was getting hot while the external coils were covered in ice). The 30 litre model shown above gives consumption as: 12V 75W. gas 12g/24h (about a year from 5kg gas bottle)

The local availability of bottled gas should be checked. When I was in East africa bottled gas was not easy to find. Kerosene was much more readily available and could even be bought from street sellers (bring your own bottle!). (I loved the trusty **broken link removed*** **broken link removed*** even though they took some, easy to learn, practice to light)


The idea of lifting a weight sounds interesting. This could be done using a hand crank or even an electric motor. some means or governing the speed would be needed. Perhaps looking at a centrigal governor from an old rotary phone dial might give some ideas ?

Digging a hole - Do the locals do this? Potential problems: flooding, insects, vegetation. How would it go down with neighbours (this is in a large town not some out of the way hamlet)


Are there any other ex pats around ? What do they do ?




*For illustration only - this is not a reccommendation
 
Last edited:
CheapSlider said:
(As motors draw more starting current the inverter must be rated higher rather than the nominal 200W).
Some inverters are rated to double the nominal power for short periods. My advice is to check the inverter's surge capability and the maximum size motor it can power.

Also consider a purse sine wave inverter as it will be kinder to the compressor motor and run it more efficiently.
 
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