Outer Limits 4x4 Board

All of a sudden my MQ 24v Diesel is going flat. I took it to the auto electrician who told me batteries wired up in series (ie 24v) only last 2 - 3 years. Is this correct or is he trying to sell me 2 new expensive batteries? They r both marked 2003.

It did this a few months ago for a week and has been ok since then until now Alternator is showing 24 - 28v when running???

Any ideas thanks

Your auto sparky is right - in this instance. I recently saw an MQ wiring diagram, and their 12V stuff is tapped off one battery. VERY BAD!!!

It's not 100% accurate, but in rough terms, whatever charge flows out of a battery during discharge must be pumped back in during recharge.

The battery which is connected to ground (call it "bottom") has more charge drawn from it than the other battery (call it "top") but both are recharged with the same current. They are discharged at different rates, but recharged at the same rate. Before long the top battery is being overcharged while the bottom battery struggles to charge properly. Result? Short battery life, for one battery at least.

Three choices:

Cheapest option: Regularly swap your batteries over.

Simplest option: Do nothing and wear it.

Best option: Install a converter to generate 12V (13.8, actually) from the 24V supply (usually closer to 28V while running) and connect all your 12V accessories (i.e. radios) to that.

I was a little stunned to see the diagram, but I suppose it was the cheapest option for Nissan - the batteries wouldn't die under warranty, so it never becomes their problem.

Cheers,

Scott

Yes, that set up is very bad!

I'd be buying a 12v convertor from Jaycar / Dick Smith. Then got out and buy the cheapest batteries you can that have got a 3 year warranty- at least you're guaranteed of getting 3 yrs out of them.

I am surprised to hear it's wired that way too, so I agree with the 12V convertor idea. I had assumed there was a 12V convertor built in for the radio etc like there is in the 24V GQs.

With the batteries, though, they are stuffed now so you have to get new ones either way. The question is just whether you do the wiring improvement at the same time.

If you don't do the upgrade, I would suggest swapping the batteries back and forth every few months.

Remember you want two identical batteries.

Jason

They are both identical batteries, but i will try swapping them now n then and c how it goes. Thanks guys