Samakand
New Member
I want to run a plug in fridge only while the engine is running. What is the easiest way, the ignition or the alternator or some where else?. Engine 3ym20. Thanks.
12v source while engine running
- Thread starter Samakand
- Start date
john_morris_uk
Well-Known Member
Hello Sam,
Welcome to the forums. I am not familiar with a sencer 33 - except when I Googled the design I see that its a very attractive 33 foot GRP sloop.
Most sailboats have at least two batteries. One is usually reserved for starting the engine and one is used for running lights etc when the engine is running. Reading behind your question I assume that you want to only run the fridge when the engine is running to avoid running your domestic battery down.
If you want an automatic system, the easiest way would be to wire a voltage sensitive relay to detect when the alternator cuts in. An alternative would be to hard wire a relay from the ignition switch. Some of the latest boat fridge systems can also automatically detect when the batteries are being charged and freeze down a 'holding plate' before going to 'economy mode' when the batteries are'n't being charged.
Take your pick of any of the above.
I wouldn't wire to the alternator - the positive is wired straight to the batteries anyway (usually via a switch 1-2-off-both, or a charge splitter, or a voltage sensitive relay. There are advantages and disadvantages with each of these, but I'm drifting away from your question...)
Welcome to the forums. I am not familiar with a sencer 33 - except when I Googled the design I see that its a very attractive 33 foot GRP sloop.
Most sailboats have at least two batteries. One is usually reserved for starting the engine and one is used for running lights etc when the engine is running. Reading behind your question I assume that you want to only run the fridge when the engine is running to avoid running your domestic battery down.
If you want an automatic system, the easiest way would be to wire a voltage sensitive relay to detect when the alternator cuts in. An alternative would be to hard wire a relay from the ignition switch. Some of the latest boat fridge systems can also automatically detect when the batteries are being charged and freeze down a 'holding plate' before going to 'economy mode' when the batteries are'n't being charged.
Take your pick of any of the above.
I wouldn't wire to the alternator - the positive is wired straight to the batteries anyway (usually via a switch 1-2-off-both, or a charge splitter, or a voltage sensitive relay. There are advantages and disadvantages with each of these, but I'm drifting away from your question...)
oldharry
Well-Known Member
Most caravans have a similar system, with a relay that connects a sensing wire to the alternator warning light circuit. This only allows the fridge (connected to the vehicle charging circuit usually at the battery) to operate when the engine is actually running.
Cheap and easy to install.
Cheap and easy to install.
maxi77
Well-Known Member
Such relays are quite common now and some boat fridge manufacturers supply them as do some of the marine power management companies. For a cheap simple solution though the type supplied for caravans (actually fitted in the car to prevent the car battery being discharged) would seem to be best. They sense the voltage and when it is up at that supplied by an alternator they make and allow current to flow, and switch off again when the voltage falls, also as they are equally designed to power absortion and battery charging fridges (normal for caravans) they should be able to cope with a normal boat fridge.
davel
Well-Known Member
You want a Fridge Mate.
Eygthene
Well-Known Member
On my Yanmar diesel engine, the "ignition" switch controls a supply which is only live whilst the "ignition" is on. I use this supply to feed some instrument circuits. If you were to run the fridge (suitably fused) from this supply, there may be a question whether it can supply enough current without overloading the "ignition" switch contacts.
However, if you employ a simple relay, energised by this supply, to switch the fridge, with its own (suitably fused) supply from the main power bus, that would be a satisfactory solution. You can get a suitable relay from a car accessory shop - they are used to switch power to the headlights.
However, if you employ a simple relay, energised by this supply, to switch the fridge, with its own (suitably fused) supply from the main power bus, that would be a satisfactory solution. You can get a suitable relay from a car accessory shop - they are used to switch power to the headlights.
maxi
Well-Known Member
Another vote for FridgeMate, splendid bit of kit that you can fit and forget.
The fridge runs when the voltage is high and cuts out as soon as it drops below 12.8v (I think thats the figure). And you don't have to rememeber or do a thing.
It also has a button whereby you can opereate the fridge without the engine, for a timed 60 minutes - again you don't need to remember to turn it off.
The fridge runs when the voltage is high and cuts out as soon as it drops below 12.8v (I think thats the figure). And you don't have to rememeber or do a thing.
It also has a button whereby you can opereate the fridge without the engine, for a timed 60 minutes - again you don't need to remember to turn it off.
gianenrico
Well-Known Member
Gentlemen, isn't it that nowadays boat frifges (i.e. compressor) have such a feature already on theur circuitry? I recall installing in 1990 and later replacing IndelB compressors whose electronics boards had that same feature. /forums/images/graemlins/smirk.gif
Samakand
New Member
Thanks. This is what I was considering. Thanks to other replyers also. Very helpful responses.
hightech
Well-Known Member
Relay on the live feed out of your ignition switch will do the trick, so when the switch is on the relay pulls in and the fridge goes live.
All indel fridges have a voltage cut-out to save batteries as well.
All indel fridges have a voltage cut-out to save batteries as well.