denviks Posted May 18, 2010 Share Posted May 18, 2010 hi all. i just want to get some idea if i am worrying over nothing. i have just fitted a spit charge system on to my discovery. both batteries are both known good and strong. anyway a long story short. i was only getting 13.4V coming into the batteries. so went straight to the main alti output and checked the output on the alti and i am getting the same 13.4V is that high enough? i dont know why but i have it in my head that it should be 14v any advice very welcome Quote Link to comment Share on other sites More sharing options...
Les Brock Posted May 18, 2010 Share Posted May 18, 2010 Generally charge voltage should be 2 volts over nominal battery voltage of 12.4 volts, so 14.4 v ideally but it does depend on the state of charge of the battery ! Quote Link to comment Share on other sites More sharing options...
denviks Posted May 18, 2010 Author Share Posted May 18, 2010 my battery at cold does sit at 12.4 ish so it looks like mine is charging at a lower rate by 1v. is that a sign of the alti on its way out ? i am a bit of a thicko when it comes to leccy Quote Link to comment Share on other sites More sharing options...
Les Brock Posted May 18, 2010 Share Posted May 18, 2010 Might just want a clear out is it full of mud etc, sticking brush maybe ? Quote Link to comment Share on other sites More sharing options...
Adam001 Posted May 18, 2010 Share Posted May 18, 2010 Hey, A split charge draws more than you might expect from the alternator, would alternator do you have? Once you draw enough current off the alternator it's voltage will drop. If you are using a standard 65amp, then 13.4V sounds about right but once they are charged the voltage should go back up assuming your other electrics are off. Also how big are your earths and how good are they? how is the aux battery earthed? this makes a huge difference. On mine I have around 5 additional earths to meet what I need as I run a slightly complex set-up Adam Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted May 18, 2010 Share Posted May 18, 2010 13.4v is correct for an older alternator, more modern ones are 14.4. Quote Link to comment Share on other sites More sharing options...
denviks Posted May 18, 2010 Author Share Posted May 18, 2010 thanks for the replies .....its given me something to go on now...... i can check a few bits now the alti i think is a 65amp one. its the standard one for a P reg discovery so i would asume 65amp. i have used it in anger offroad , but i did rinse it out after its last play some time ago , although it may need doing for longer. i have my aux battery earthed via 30amp cable. there is nothing connected to it at the moment as i want to make sure all is working fine before i start adding things. i may beef up the earth though as it does seem a little on the small side. i am glad that all seems to be working right, just read fridges reply ( thanks ) ....so maybe its all good and i should stop pannicing .... although is it worth going for a newer alti to supply more ommpph Quote Link to comment Share on other sites More sharing options...
Adam001 Posted May 18, 2010 Share Posted May 18, 2010 What are you using the battery for? 30amp cable is far to small really, go for a cable that can take double what you actually need. It's also important to note that if you dont earth back to the main battery you need to take into account how good the earth is from the aux battery to chassis and then again from chassis to engine Quote Link to comment Share on other sites More sharing options...
disco_al Posted May 18, 2010 Share Posted May 18, 2010 the flat belt disco alternators are rated at 100 amp according to my parts book, the earlier ones with a v belt are classed as 65amp. Quote Link to comment Share on other sites More sharing options...
denviks Posted May 18, 2010 Author Share Posted May 18, 2010 What are you using the battery for? 30amp cable is far to small really, go for a cable that can take double what you actually need. It's also important to note that if you dont earth back to the main battery you need to take into account how good the earth is from the aux battery to chassis and then again from chassis to engine at the moment nothing is connected to the battery. it will only be used to run 4 roof lights eventully and maybe a worklight. it will get an easy lift really. but who knows what next month may bring i will definatly give it a better earth i think for the advice given here. i am only guessing its a 65amp one to be honest. i would of said it would be as its a p reg and looks standard. Quote Link to comment Share on other sites More sharing options...
wizard Posted May 19, 2010 Share Posted May 19, 2010 I have two batteries in my 200 Tdi Disco with a manual selection switch so I can switch in or isolate the second battery. Each battery has a voltmeter across it. When the truck is off both batteries read 12.4 to 12.6 When running with just the main battery charging, it charges at 14.1v If i switch in both batteries the charge voltage drops to 13.5v regards wizard Quote Link to comment Share on other sites More sharing options...
denviks Posted May 19, 2010 Author Share Posted May 19, 2010 ah brilliant mate........ thanks all for your answers.... having not fitted a split charge before i started to worry like an old woman i think..... Quote Link to comment Share on other sites More sharing options...
Andy Posted May 19, 2010 Share Posted May 19, 2010 When I did twin batts on the disco I had i went to a scrappy & pulled the battery cables off a real mini. Nice thick several hundred amp cables about 8ft long, ideal for plumbing it all in. Quote Link to comment Share on other sites More sharing options...
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