alternator and charging help

[wijnendael]

can anyone help, my boat is fitted with two batteries and just found out that the alternator is not charging them (no output) the alternator is a Nissan LR160 and the + out goes to the split charger which has the name Talamex. This unit has 5 terminals which are three big ones marked battery 1 - Generator - battery 2 and are connected correctly. The other é connections are D+ & D-, the D- goes to the negative on the batteries which are linked together and the D+ goes to one of the terminals on the alternator I am still trying to follow the other cable from the alternator to find out where it goes but i think it goes to the negative. The boat was bought secondhand and not sure if the wiring is correct and cannot find any info on the charge splitter which is a large heatsink with the terminals as above, is this a diode splitter ?. I wish to purchase a new alternator but would like to know the correct connections before installing it if anyone can help.

 

[Sneds]

Try a local auto electrician, good luck.

 

[Kawasaki]

That unit is fiitted in lots of Nissans and some Madas too.
Why not carefully label the terminals and wires so You know where to put them back.
Presuming they are right as You mention.
Take the unit to the Local Alternator man.
Ask for a recon or fix or diagnosis.
I had the same snag last Year with a Paris Rhone alt.
Bit more complicated tha Your set up with 4 batts.
Took 3 goes to the alt man till He sussed the prob.
£40 in the end + a lot of of and on with it and travelling!
Least if You have a working unit, when You re install if the wires are right it will work.
If it doesn't the wires are wrong.
Know ist a faff about but I tried Auto Electricians Marine Elecrticians to no avail.
Got more help off here!
Cos boats are more "individual" than cars, ie lots of one offs and mods etc.
Sometimes a good auto leccy gets a bit baffled.
How did You check the output by the way?

 

[paulm299]

You do not mention a positive going to the battery ? Surely the alternator should connect to generator on the splitter and D+ to the positive ?

 

[mont]

Take Alternator to auto electrician for testing and re-condition if its needed.
Suggest to get rid of diode and install VSR voltage sensing relay unit as per instructions. Diodes loose at least 1 volt onto system.Easily available with net search / mail order.
Methodical listing of existing system before dis connection most important - draw a plan.

 

[Wiggo]

OK, so the wiring sounds about right. The unit you describe with the heatsink is a diode splitter and will lose about 0.7V, so to get 13.8V to charge the batteries you need 14.5V from the alternator etc etc.

The D+ terminal on it sounds like a battery sense lead for the alternator (rather than machine sensing). This is how the alternator voltage is regulated, and should compensate for the voltage drop in the splitter - the alternator is reading the voltage at the battery rather than at the splitter, so everything should be OK.

I would leave all that alone for now and just get the alternator to an electrical specialist like the others said. Once you have a working alternator, then you can decide if you want to change the rest.

 

[wijnendael]

Thanks for all the replies, i have now had a thorough look at the wiring from alternator to splitter and ignition and batteries and everything seems to be correct for the equipment installed. As i was not sure if the green light that comes on with the ignition key was correct i followed all the wires and this light was wired correct to go off if the alternator is charging. I have also today taken the alternator for testing and it is indeed faulty so rather than the repair i decided on a new one ( not fitted yet as i came back with the wrong mounting holes and had to take it back, now Tuesday when i receive the correct one) The wiring on our boat is a real mess with lots of plastic terminal connectors so i am rewiring this part first ready for the new alternator. The old one i will refurbish myself at a later stage and keep as a spare. Now hopefully everything will be ok next week. The new wiring circuit will go through the ignition/charge light and will have no connections to the splitter except the generator in and batteries out.