Dump truck batteries shot = bad news.
Dump truck will accept 8d's in bus = good news.
I have space in the rear corner of the engine compartment to put three g31's.
Three d31 or three g34? Going in o5 Eagle 8v71.
If you are only concerned about starting two group 31 will do the trick, That is what I have in the bus and my two dump trucks, one truck with a 8v-71 and the bus and other truck 8v-92. You will only new the 8D if you are running the two big blower in the bus, and the group 31 will also work for that but it will be hard on them, and make you charging system work harder. If I was using the big fans much and using in cold climate I would go with the 8D.
All that is removed. I have a dash heat/air unit only. Two would save a little money.
I have to size 31 Interstate batteries for starting (950cca each). If I need more I can activate the jumper solenoid to the deep cycle batteries and start it that way. I have started the engine on just the deep cycle batteries when the starting batteries were dead. Good Luck, TomC
Eric, I used to have two, it would crank but not fast enough. I bought another one and it made a big difference. I was afraid I would fry the starter, which as been done in the past. ::) And them suckers are heavy when your layin sideways! ;D
The faster the better, your DD will like it and so will you.
There is no substitute for lead. The bigger the battery, the more power when you need it.
Semi tractors use Group 31 batteries, but most semis run all day, every day, for weeks at a time. Of the others, most are run several days a week. They don't sit around and lose charge.
If you spend a lot of time parked, 8Ds will do a better job for you, over a wider range of conditions.
HOWEVER:
1) If you have a genset, you can light that off and top off Group 31s, if they have sat a while between starts. I would only plan for this if the genset has its own starter battery, which is automatically charged when the genset is running.
2) If you are running 24VDC for your house, you can flip a switch and parallel them with the starters, giving yourself more cold cranking amps than 8Ds have.
3) You can buy Group 31s pretty much anywhere, for half the cost of 8Ds -- which means that you will replace a sick battery before it strands you somewhere.
The bottom line: If replacing one 8D and the other one is less than two years old, I would put in another 8D (and in fact will be doing that this week). If replacing both, AND you have the genset or the parallel house batteries, I would go with Group 31.
Whatever you do, I suggest putting marine terminals on all batteries, preferably the brass ones, and use copper cable ends.
Also, using either paint or felt pen, draw a diagram on the floor of the battery tray, AND on the wall (or inside the door), showing placement of batteries, polarity of each terminal, cable routes, etc., because you may not be the next one who has to know what changes have been made -- and they may be in a snowstorm and in a hurry.
I replaced on 8D battery one time. The next time I replaced the entire set.
An old battery and a new battery will just cause you trouble when you don't need it.
The batteries should be done in "sets" and there was another thread that explained about connecting them correctly.
HTH
YMMV
Melbo
The truck parts place had a pallet of interstate blem 31's for $ 50.00 ea. I bought three. The 8d's are about three years old and even tough a little big for the battery boxes in the mack dump will work there. The cost was less than half that of the ones with the pretty plastic wrap on them. Same exact battery just a ding or scratch. I am going to build a battery box right inside the bumper. Frees up the entire compartment where the ac con. was. Lots of ideas!!!! BBQ GRILL, MANLY SIZE TOOL BOX, BIG COMPRESSOR, PRESSURE WASHER FOR THOSE LONG TRIPS WITH THE 8-71....etc.
Eric, Are you planning on around the mitre box area? I have seen that done on an 01 and it looks like a great spot. He built a frame out of angle and dropped them in, he had one square frame on top to secure them.
Pictures please when you build it, OK?
Paul
Thats correct. On the passenger side.
Eric, I saw those pictures at the Eagle site of your engine compartment.......you should post them here......its impressive! Nice looking!
Eric, i have 3 g31's on my Eagle with 8V92. they can be tied in with the house batteries, but my engine just requires a quick touch to fire up (when it's above 40). it came with 3, and the battery box seems to have been made that way. The bus is a model 15.
i think 3 should be plenty.