While reading the current thread "HJ60 starter system issue" I started thinking about dual batteries in a 12 volt system. This is something I've wondered about before, but never could get any definitive answers for. My question is this: which can be stronger/better, dual 12V batteries wired up in parallel to stay as a 12V system? Or dual 6V batteries wired up in series to make for a 12V system? (I think I've got those two terms correct) I realize that the outcome can vary, depending on what batteries you start with. My big question is which set up will be better for the long life of the batteries, and work better for the starting system.
My application is not Toyota, but I think this information could benefit many Landcruiser owners. I have a 1994 Chevy K2500 with the 6.5 diesel motor. Specs call for two group 78 batteries (10.3" long X 7.1" wide X 7.3" high) of at least 770 CCA capacity. The 6.5 is a power hog when it comes to starting, and this may be true for Toyota diesels, although I think most are single battery for the 12V systems (have never owned a Toyota diesel). First, the glow plugs take a big draw (comparable to a starter), then once the glows are done you use the starter. The two together make for a huge draw on a good pair of batteries, and if your batteries are old and marginal, you may have trouble getting the motor to crank over fast enough for a diesel to start easily.
I currently have two Interstate Megatron group 78 800 CCA side post batteries (one also has top posts for easy hookup for jumpers or winch) which are about 4 years old. At this age they are probably close to the end of their life for this motor, and I want to be prepared with good information when I need to replace them. I also replaced the battery cables with larger size welding cables for better currant capacity. I do realize that welding cables are not as good as automotive cables because of oil resistance for the insulation, but they do have some real good currant carrying capacity.
I have rebuilt one battery tray to be able to hold a larger battery (Ford, group 65, 12.1" long X 7.5" wide X 7.6" high), and although not done yet I have most of the parts to do the other battery tray.
The two group 78 batteries i have add up to 1600 CCA, when new. Two of the better group 65 batteries can add up to 1700 to 1900 CCA. But, these are some real expensive batteries, up to $335 each. For that kind of money can I get two 6V heavy duty (industrial?) batteries that will give me more/better/stronger life than two 12V batteries? Or, am I better off to stay with 12V batteries?
Opinions and speculation are fine, but real life experiences will be much better.
Thank you, Don
My application is not Toyota, but I think this information could benefit many Landcruiser owners. I have a 1994 Chevy K2500 with the 6.5 diesel motor. Specs call for two group 78 batteries (10.3" long X 7.1" wide X 7.3" high) of at least 770 CCA capacity. The 6.5 is a power hog when it comes to starting, and this may be true for Toyota diesels, although I think most are single battery for the 12V systems (have never owned a Toyota diesel). First, the glow plugs take a big draw (comparable to a starter), then once the glows are done you use the starter. The two together make for a huge draw on a good pair of batteries, and if your batteries are old and marginal, you may have trouble getting the motor to crank over fast enough for a diesel to start easily.
I currently have two Interstate Megatron group 78 800 CCA side post batteries (one also has top posts for easy hookup for jumpers or winch) which are about 4 years old. At this age they are probably close to the end of their life for this motor, and I want to be prepared with good information when I need to replace them. I also replaced the battery cables with larger size welding cables for better currant capacity. I do realize that welding cables are not as good as automotive cables because of oil resistance for the insulation, but they do have some real good currant carrying capacity.
I have rebuilt one battery tray to be able to hold a larger battery (Ford, group 65, 12.1" long X 7.5" wide X 7.6" high), and although not done yet I have most of the parts to do the other battery tray.
The two group 78 batteries i have add up to 1600 CCA, when new. Two of the better group 65 batteries can add up to 1700 to 1900 CCA. But, these are some real expensive batteries, up to $335 each. For that kind of money can I get two 6V heavy duty (industrial?) batteries that will give me more/better/stronger life than two 12V batteries? Or, am I better off to stay with 12V batteries?
Opinions and speculation are fine, but real life experiences will be much better.
Thank you, Don