Technical domain
  Lebanon land Rover Union publications


            Double Battery System
by Nadim Samara

 Most of us want to have a nice camping trip next to our Land Rover, listen to the radio, have some
lights on, or run a cooler off the car's battery, but are scared to drain all the juices out of our battery.
Enter another battery…

Land Rovers come prepared to accept 2 batteries (Discovery, Range Rovers, Defenders, at
east), due to the design to simply jump from left hand steering, to right hand steering. Now if you
want to have 2 batteries in your car, you have these choices:

A) simply "add" one by wiring the new one in parallel. This will keep your voltage at 12. If you wire
them in series, the you double the voltage…not recommended at ALL, since you will fry your
electrics. The benefits from automatic charging are numerous, but the one heavy drawback is that
you can’t "spare" one batteries for the engine’s starter when you want to leave the camp for home

B) get an "isolation switch" to isolate each battery for specific use. They come either automatic, i.e. it
alternates between one and the other, depending on what you have on each, or manual, where you
put your control over the electrical output of you car. I opted for the manual one…I like to get my
hands dirty!

So say you want to winch hard, you use both (while the engine is still running)...or you stalled in a
river and need to winch yourself out, you use one to save the other for the cranking. The benefits are
many. Moreover, you can switch off all the electricity if you turn the switch to "off", in case a fire
starts, or for security reasons, but then your alarm would not work! .

Wiring is simple, and a diagram should be sent with the switch. The tough part is finding the space for
the second battery, and finding the appropriate switch in Lebanon. I found mine at a marine store,
and they sell for around 50-60 US dollars. Make sure to buy the best you can afford…electricity is
dangerous.  Not only did I add another battery, but I got a higher ampere alternator (dynamo), to
help charge both batteries evenly and easily…it is also preferable to get identical batteries and at the
same time.

With two new Watta 70 amp. batteries, the switch, the alternator, and all the necessary hardware, I
was $US200 behind, but now I can deliver almost as much electricity as a house!

After some time with these two batteries, it was clear that they were not up to the job. The reason is
I believe that they drain too fast, and charge too slow, when I needed electricity the most. Therefore
I purchased an OPTIMA Yellow top deep cycle battery, and will hopefully mate it to another one
when the winch arrives. I do have to notify you that the OPTIMA costs as much as $US250 if you
do not shop around!

If you have any questions, do not hesitate to contact me at:

p.s. 2 batteries = 2 fire extinguishers!