simonr Posted January 11, 2010 Share Posted January 11, 2010 In a series connected system i'm not sure there will be any issues, in a parallel system it can cause the batteries to discharge each other. Errr.....If the current draw is very small, say to run a radio or charge your mobile, that is true. However it will cause problems if the current is higher. Batteries are damaged if you charge them at too high a voltage (typically 14.7v max for Gel / AGM batteries). If your alternator is designed to charge at a maximum of 29.4v (for a 24v system) - what happens if one battery is discharged more than the other? The 29.4v is split proportionally to the internal resistances of the batteries, which are in turn proportional to their state of charge. If there was say a 10% imbalance - the lower charge battery would only see 13.3v and the higher charge 16.1v. This means that the battery you are not discharging is being charged at too high a voltage and the other one is not being fully charged. Both suffer harm, but for different reasons. The technical way this is solved in most strings of batteries (such as in electric vehicles) is to use a shunt regulator. This prevents the battery voltage getting higher than 14.7 by shorting it out with a resistor. Once the higher battery has reached full charge, it will stop charging and the shunt will allow the lower battery to continue until fully charged. An example of such a regulator is here: Volt Blochers. The simplest and lowest cost solution is just to use a number of cheap CB power supplies as used in trucks to give you the 12v (13.8v) and minimise what you run on 12v. 20A is easily achievable. I used to have a LR with 24v electrics - but I put in a 12v engine. I used a 12 to 24v converter to run the heater motor, dash instruments and converted everything else to 12v. Worked pretty well - so long as you remember to connect things to the right supply! Si Quote Link to comment Share on other sites More sharing options...
istruggle2gate11 Posted January 11, 2010 Author Share Posted January 11, 2010 Simon, thank you for the detailed response, begining to understand the electrickery a little more now. Back to plan A now, onto the voltage droppers, with the knowledge of being able to run off the 12v battery for emergency breakdowns. BBC - will call you soon! (work gwtting in the way!) Quote Link to comment Share on other sites More sharing options...
Soren Frimodt Posted February 16, 2010 Share Posted February 16, 2010 So Rog, how's it going with this project? I'm dying to hear more about it, did you decide to EDIS your Mog? Quote Link to comment Share on other sites More sharing options...
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