Thread: FFRR - Alternator or battery failure?

Originally Posted by rar110

The charger finished its recondition process. It's now sitting at 13.3v.

I'm now doing the other battery.

stick a 25A load on the battery and time how long it takes to get to 10.5V. that many minutes should equal your RC rating.

then charge it again.

this is the most important factor for the situation you're in.

if you can do that 3 times in short order and the time stays within about 10% of the batteries nominated RC then the battery is OK.
20% is workable
50% is as good as cactus but will provide some use as a backup battery/light duty battery

temp will effect your results you want to do the test at 25 degrees

Now for some basics.

If you can, leave the battery charger connected to your cranking battery till you are about to start the motor.

While you have the charger connected, turn everything off in your RR, like interior lights, A/C, entertainment system.

From memory, turning off the entertainment system will also turn Bluetooth off. If Bluetooth remains on, check your manual and turn it off, it is power hungry.

Have your RR packed and ready to go while the charger is still connected.

Just before you start your motor, remove the charger, start your motor and go.

BEST OF LUCK!

Thanks again. I'm not sure how I would put a 25 amp load on the battery. I will read up about shutting off the Bluetooth.

How do I get the cig lighter out, does it just lever out from the top. My preference is to use the cig lighter in the centre console or ash tray.

The battery is currently sitting steady at 12.3v with the motor running.

My plan is to put the other battery in the cargo area and connect it to the end point of the heavy +ve lead behind the panel and an earth point to support the main battery. I will use some very heavy jumper leads I had made up with insulated alligator clamps.

I suggest that you disable the air suspension to prevent it lowering when the voltage gets too low and will also save some battery draw. Remove the 20A suspension fuse and there should also be 2 x 5A suspension system fuses so remove those to stop annoying 50 kph warning messages. Only the 5A ignition feed fuse for the suspension ecu needs to be removed but no harm removing both as the 2nd one only protects the compressor relay sense wire in the event of it shorting to earth somewhere.

I replaced my alternator a few months ago at about 90 000km as a preventive measure. They are known to fail at about that mileage. It is not a 15 minute excercise to replace, lots of stuff to remove from the engine bay including draining engine coolant, etc.

I found an easy access point to under the two cig lighter sockets at the rear of the centre console. The panel below the sockets pulls away to reveal the + & - wires. The plugs and spade for the + & - are also different to help ensure the correct wire is fitted to the correct terminal.

I'll fit the multimeter to these wires to monitor the voltage.

the 25A load thing is for when you get back and test the battery not something to do before you go....

if the battery comes up ok then you know you're looking for a vehicle related fault.

I expect Drivesafe's suggestion was to get a voltmeter that plugs into the lighter socket, not to replace the socket. They're readily available.

EG http://www.ebay.com.au/itm/2-In-1-Ca...item3ce7e029db