Thread: Dual Battery Setup TD5 Defender

Hi Scotty

I was at KLR (Windsor) on Friday asking the boys the same question. I need to shorty replace both batteries in my Td5 and am looking at installing dual batteries in my 300 Tdi project.

They recommended intimidator batteries which I had never heard of. They fit they to all the perenties. A quick search shows there’s plenty of intel on them but they are not cheap!

Maybe some other forum members have experience with them?

Cheers Simon

My old defer came with two full size batteries shoe horned under the seat, I found this to be a pain in the arse.

I relocated it to the cargo area.

Same with my current defer, I have a 110amp/hr AGM in the side storage compartment.

I haven’t used any of the smaller/compact ones you have mentioned.

I put the second battery under the back of the rear drawer. The drawer itself is the short version from Off Road Systems (ORS), leaving hidden space for a sealed AGM on its side.
Only having one battery under the seat left space for the Traxide DBS and a regulator for the solar panel on the roof.
The starting battery is wired through to the second battery in the back of the drawer with thick wiring and 60 amp fuses.
Works well. Set and forget.

I have just recently put 2 Exide Extreme's under passenger seat. 772 CCa 70 Ah

Redarc switch and a Projecta battery monitor.

Issue I think I'm having is with Smart alternator in the later model Defenders. Batteries dont seem to fully charge.


Defender 130 2006
Defender 110 2015
Disco 3
Disco 4

Hi alby, smart alternators are programmed to set voltages according to the state of charge of the cranking battery.

Because all other isolators are set to turn off when the voltage drops down to 12.7v or thereabouts, the cranking battery remains near fully charged.

As such, the alternator has no reason to run at a high voltage for more than a very short period of time, just long enough to replace the cranking battery energy used while starting the motor.

This is why your batteries never seem to charge properly.

Because my isolators allow the cranking battery to be discharged down to 12.0v or down to about 50% of their capacity, the alternator ( via the vehicle’s BMS ) sees the cranking battery is NOT fully charged and the alternator voltage stays high for a much longer period, charging both the cranking battery and the auxiliary battery at the same time.

NOTE, my isolators work well with all vehicles equipped with SMART alternators, not just in Land Rovers.