Don't like the adverts?  Click here to remove them

Dual Battery System

Sparra

New Member
Joined
Jan 16, 2022
Messages
3
Country Flag
australia
I have just acquired a 2006 4.2TD with 2 battery cranking system...To connect a dual battery system can I just connect my isolator to one of the main batteries?

Cheers...
 
The two batteries in the 100 series with the 1HDT-FTE engine are connected in parallell and work as one unit. It's just that it was easier for the designers to find room for two 100 Ah units than one 200 Ah unit. There is a good size cable connecting the positive terminals running over the radiator, while the negatives are connected to the body and/or block on both sides. The problem with separating them is that there are consumers connected to both. Not too hard to redo tho', so they can be separated with a bit of effort.
Most people who want a dual battery system find a place for a third battery, at least in cold areas or if they have a winch. The engine will start nicely on only one 90-100 Ah battery without any problem, especially if the temperature is not too far below freezing. Just make sure the CCA is high on the starter battery, like >800 A.
 
Where are you planning to locate your third battery Sparra?

I reworked the standard dual-battery setup so that the left one became the leisure battery, and the right one did the normal car duties. This worked ok, but one battery for starting can be marginal in my experience, so I would like to return to the standard dual battery and find somewhere for a third, ideally not in the cab. Would be interested to hear what you have in mind.

sim
 
You can fit a size 31 in each under bonnet battery compartment - look at what’s available in that size, it’s a hell of a lot of battery. EG 1000cca is common - more available, or a shade under with a higher Ah rating. I’m running a single 1000cca as my starter - admittedly I’m in Australia but I’ve removed my heater screen and it starts instantly and effortlessly at -3*C (the coldest I’ve faced). I can’t believe a single 1000cca battery would struggle in the uk. This then frees up the other slot for another high spec 31 if you need - or a regular size 27
 
Ah, that is interesting to know, about the potential for a larger size. I'll look into that!

Mine does struggle a bit in cold weather ( < 5C) especially if it has been left a few days. I would like a bit more in reserve!

I have been looking underneath for potential mounting points for a third battery... There are a couple of potential locations but nothing that looks very easy or open.
 
Yeah the 31s are quite a bit of battery… and they only just fit - you have to cut and shut the plastic wafer battery surround, then they only just squeeze in.

I don’t think you’ll find anywhere good for a 3rd battery underneath or in the engine bay. In the boot is about the only spot - so you’ll want a lithium or sealed AGM. Then it’s so far from the alternator you’ll need a smart DCDC charger as the voltage drop due to distance will make using a traditional VSR unsatisfactory.
 
Don't like the adverts?  Click here to remove them
Yeah the 31s are quite a bit of battery… and they only just fit - you have to cut and shut the plastic wafer battery surround, then they only just squeeze in.

I don’t think you’ll find anywhere good for a 3rd battery underneath or in the engine bay. In the boot is about the only spot - so you’ll want a lithium or sealed AGM. Then it’s so far from the alternator you’ll need a smart DCDC charger as the voltage drop due to distance will make using a traditional VSR unsatisfactory.
 
Back
Top