alternator advice please

[stevew]

The split charge relay is simply connected to the charge indicator light such that as soon as the alternator is up to speed it connects the two batteries in parallel. If the aux battery is really flat (mine often is since it's buggered!) then it will draw current from the main battery as the alternator cannot bring the volts up in the two seconds or so after starting.
If you take into acount the internal resistance of the battery and the cables and everything else you realise that this dangerous situation can never exist for more than, say, 5 seconds but in the worst case it could leave you unable to start.
An easy solution would be to fit a voltage sensing split charge relay but even these are approaching the price of a second alternator
You're right about the redundancy thing! Perhaps I should carry a motorbike in the back at all times
The main point for me is that if you fit a sealed lead acid or an AGM battery or some other exotic high capacity battery you can optimise its charging voltage to get the longest life from it.
Steve

[madvanman]

You could change your split charge system from the relay type you have to a split charge diode type then your aux battery will never pull power from your start battery.

[stevew]

Yes, I could do that. Another advantage is that there realy is nothing go wrong with diode splitters. A disadvantage is that you always get a volt drop across the diodes so can never setup your charging exactly right. Also you can't ever start from both batteries is your start does go flat for any reason.
I guess I just fancy having two alternators!
Steve

[MrMPuk]

Yes, I could do that. Another advantage is that there realy is nothing go wrong with diode splitters. A disadvantage is that you always get a volt drop across the diodes so can never setup your charging exactly right. Also you can't ever start from both batteries is your start does go flat for any reason.
I guess I just fancy having two alternators!
Steve

Diodes do go wrong believe me! Most split chargers with diodes do have a bypass so you can start off either battery!

[Gunslinger]

hehehehehehe .... on the subject of redundency, would you like a smaller moter mounted in the back just to drive the second alternator ... just incase your split charge system fails and you cant start your main motor to drive the 2 alternators .... perhaps something like a small mower motor with a pull cord type start


just kidding with you