cookie64 Posted January 5, 2011 Share Posted January 5, 2011 Hi all I have an urgent need to fit a 24v supply into my defender before the 11th February Does any body know the best way to do this? Also cheapest I was wondering about either a 24v alternator or a 12 to 24 inverter but all the inverters seem to be naff power output and expensive Please advise Tom Quote Link to comment Share on other sites More sharing options...
Puffernutter Posted January 5, 2011 Share Posted January 5, 2011 Can you tell me what the supply is for and what the expected current draw is and for how long? Cheers Peter Quote Link to comment Share on other sites More sharing options...
cookie64 Posted January 6, 2011 Author Share Posted January 6, 2011 A water heater for cooking rations Army issue 15amps continuous hopefully Otherwise 30minutes 3 times aday for 2 weeks Tom Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 6, 2011 Share Posted January 6, 2011 Would seem much easier to use a camping stove or one of those plug-in 12v water heaters or kettles you can buy for a few quid. Failing that, the easiest way is to find a 12->24v DC-DC converter, otherwise you're into fitting a 2nd 24v alternator somewhere. Quote Link to comment Share on other sites More sharing options...
nickwilliams Posted January 6, 2011 Share Posted January 6, 2011 Your simplest solution is to fit a split charge system and a second battery, and wire in switches, fuses and other gubbins so you can connect the secondary battery and the vehicle battery in series for a short time while you cook your rations. Nick. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 6, 2011 Share Posted January 6, 2011 If it's just got to cook rations, buy a 12v jump-start pack and when needed connect it in series with the main battery, rest of the time leave it charging from the 12v supply. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted January 6, 2011 Share Posted January 6, 2011 Step-ups get very expensive, very quickly: http://cgi.ebay.co.u...=item4cf41e90db That would do it, but personally I would fit a very small 24V alternator, and a small 24V battery and run a second charging circuit. That or use a gas stove and a pan of water. Quote Link to comment Share on other sites More sharing options...
Puffernutter Posted January 7, 2011 Share Posted January 7, 2011 I have a Defender with a 24v Eberspacher (they are cheaper than the 12v versions!) I have two batteries in the seat box, but for the last 2 years I have just taken the second battery out at regular intervals and charged it off the mains. This won't work for you (obviously!) I also have a circuit design that allows you to take 24v off the two batteries, but via a single switch and a relay, manually swap the 12v charging between the batteries. One of these days I'll get around to fitting it. It would mean that I would leave charging on the main battery for about 30 minutes after starting, then switch across for 30 minutes and then back etc. It will require reasonable length journeys to make sure both are charged. Otherwise as some have suggested, its a 24v alternator, but then you run into difficulties of making sure both are charged as with a 24v charge and two batteries, one tends to charge in preference over the other. Not sure if that helps or not! Cheers Peter Quote Link to comment Share on other sites More sharing options...
cackshifter Posted January 7, 2011 Share Posted January 7, 2011 Or ... (suggesting this as no-one else has) an inverter and transformer. 24v / 15A into a nice resistive load is only 360w. You'd probably get away with a 500w inverter feeding a 240/24v transformer, but probably 1000w would be better. Ideally you'd have a 12-24v inverter but I suspect that's expensive ( see for example linky, and inverters are normally quite efficient. The only thing is it's probably going to draw around 40a while it's running, so you'd need a) good thick leads from battery to inverter, and b) to leave the engine running. I think the second battery & switchover is most practical - I think that's how David Bowyer's 24v turbo winch device works. Nigel Quote Link to comment Share on other sites More sharing options...
pete3000 Posted January 7, 2011 Share Posted January 7, 2011 Hi all I have an urgent need to fit a 24v supply into my defender before the 11th February Does any body know the best way to do this? Also cheapest I was wondering about either a 24v alternator or a 12 to 24 inverter but all the inverters seem to be naff power output and expensive Please advise Tom how about one of these, http://www.nkrecovery.co.uk/mod.html £90 cheaper than another battery and 24v alternator. 3rd down on left. Pete Quote Link to comment Share on other sites More sharing options...
fozsug Posted January 7, 2011 Share Posted January 7, 2011 We use this range, good quality and reasonable price http://www.alfatronix.eu/1482-dd-ddi-series-voltage-converters.php HTH Tony Quote Link to comment Share on other sites More sharing options...
pete3000 Posted January 7, 2011 Share Posted January 7, 2011 We use this range, good quality and reasonable price http://www.alfatronix.eu/1482-dd-ddi-series-voltage-converters.php HTH Tony Can't see one that will do above 10A though, especially for 30 mins? the rations would probably get warmer on the inverter Quote Link to comment Share on other sites More sharing options...
cackshifter Posted January 7, 2011 Share Posted January 7, 2011 - I think that's how David Bowyer's 24v turbo winch device works. Nigel Further to this there's a thread about this on the workshop forum linky Giving the pt no of a Bosch parallel start relay - switches batteries parallel for charging/series for starting and can presumably handle heavy currents, if you decide to go the 2 batteries route. Quote Link to comment Share on other sites More sharing options...
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