Land Cruiser 80 series power upgrade Group 31 install and Optima content


Expedition Leader
I have been running dual Optima Blue tops wire together for the last ~7 years. I know there is lot of hate on Optima's but I have abused my Optima's and they have performed excellent and there time in service speaks loudly. Only one of my blue top died the other is still going but because my batteries are wired together and never separate both need to be replaced. One would think after such great results I would just replace the Optima's and hope for another 7 years of stellar performance but nooooo.

I ended up going with a Duracell Ultra AGM group 31 in the factory location and replacing the Blue Top Optima AGM in the rear. The combination wired together in parallel gives my ~160AH of power or ~80AH at 50%. I went with the Duracell Group 31 for more available power, because it was the same cost as the Optima Blue with 2 times the available power and a slightly longer warranty.

Fitting the group 31 in the factory location with all my wiring was ultra tight. In order to fit I needed to trim the bottom drivers side back corner of the battery box. Not a big deal and feel I will see no issues down the road. It would not be possible to use the factory style hold down with this group 31 but not a problem because I never liked the factory hold down and changed to a front to back hold down years back. Front to back has always worked great me and the battery super secure. The fit is so tight I had to change the winded nut to a bolt on the negative side because it was hitting the hood.

Because I was just replacing the rear Blue top with another it would be quick and easy. Yes and no the rear battery is super tight and surrounded by lots of metal creating a situation were you need to be very careful not to ground out and cause big problems. By taking my time it worked out and its in and like the front it will never more a mm.

In the end I now have 1800A cranking power and 160AH of available power for around $450 not bad if the new set up last 7 years like the last.

Some pics of the action



Could you explain your dual battery set up? What gauge wire is running from the battery in the rear? What is the rear positive and ground attached to also?


Expedition Leader
Could you explain your dual battery set up? What gauge wire is running from the battery in the rear? What is the rear positive and ground attached to also?
My set up is both batteries are wire together in parallel and do not separate unless I manually do it. I run #4cu from battery to battery with a 100a breaker in line. The rear battery feeds the Puma air compressor, solar tie in, and 12volt outlets.

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