i need a new 8d batt for my bus, while looking i found a 4 d that looks like the 8 d, anybody know what the difference would be??
Frank Allen
4106
A little shorter, lighter and less AMP Hrs. HTH
Figure on having about 4 less D's than an 8D. ;D
Jay
87 SaftLiner
Frank,
This is a very good time to get rid of those heavy monsters and change to Group 31. Three 31s will fit in the same space as one 8D.
I did this with my 4104 and it is one of the smartest things I have done. You just don't need that size battery in a conversion. They were made to run those huge fan motors that conversions don't need.
I'm too old to be moving those monster D series things!
Ditto on that. Unless you keep the bus air, there is no reason to keep the 8D's
my 4D's have 200 amp hours, and the 8D of the same manfacturer had 250 amp hours. I agree with the earlier posts on not needing the bigger batteries if you are getting rid of the bus air.
This post is good timing because my 8Ds need replacing. What are the dimensions of the 31s? Do I need two or three 31s? I am removing the bus a/c but I was going to keep the bus heat even though at this time I am not sure how much I will use it. What are the dimensions of the 4Ds? Are they an acceptable replacement? I checked with the vender that supplies batteries for my employer and AC/Delco 8Ds are $138, and AC/Delco 31s are $68.
Laryn
I have two group 31's in our Eagle. They measure 13" L x 7" W x 9" T. They work great, Interstate Battery is the brand. Don't remember the cost though.
Hope this helps.
Paul
Amp hours is applicable to a deep cycle battery. What you want in a cranking battery is Cold Cranking Amps, or CCA rated at zero degrees. Typically an 8D will have about 1200 - 1350 CCA. I have two Interstate 31's that are rated at 950 CCA each and turn over my 8V-71 just fine. If in cold weather, I can turn on the jumper solenoid to my two AGM 8D batteries for them to help out. Have been pleased with the 31's for starting especially since they weigh about a third of what the 8D's weigh. Good Luck, TomC
ok group 31, question, how many?? should i keep my remaining 8 d tell it goes bad?? how many 31 s do i need to replace them both?? ive always just replaced what GM put in there but i can see the advantage of smaller lighter and cheaper batteries, thanks to all
Frank Allen
4106
I had two 8 D's, replace them with two group 31's. That was over a year ago, I have not experienced any problems at all, at least so far anyway.
Paul
I think a simple rule of thumb is- If you live in mild temperatures-like in the south- then two 31's will work just fine, even if you live in the north it will work if you have a jumper solenoid to tie into your deep cycles to assist in cranking on cold days. If you don't have a jumper solenoid to your deep cycles and live in cold weather, then you should have at least 3-31's if you have a 12v system or use 4-31's if you have a 24v system. All sleeper trucks from Freightliner use 4-31's but mainly for extra capacity for running lights, TV, reefer overnight. The sleeper trucks also have a 12.3 volt electronic cutout that turns off the accessaries, but can still run down the batteries if you leave the lights on all night. Personally- if I were buying a new inverter, I'd make sure the inverter had an automatic generator start up that was set at no lower than 12.0 volts (50% discharge). Then you'd be assured that your batteries are always up. I know some truck drivers with the new stand by small generators or APU's (auxiliary power unit) have that feature and sometimes park for a couple days while at home and leave the reefer running since the automatic low volt start on the generator will keep the batteries up. Size 31 batteries are what all trucks and most buses are running now. Good Luck, TomC
Like TomC mentions, I have the jumper solenoid. Not only does it serve to jump (or combine) both the house and start batteries, it allows the start batteries to charge from the alternator when the engine is running. It will also serve the same purpose as the 8D's did with regards to the OTR heat and A/C. Although I've not used the 31's to start the bus in cold weather, they've done fine in the summer.
On another note, when I was buying new 8D's a couple of years ago, I called one of the chain auto parts stores. I asked them if they had "... 8D batteries, the big ones". They assured me that they had many. When I went to get a pair, they pointed me to the display rack at the register with A's, C's, D's, and 9-volt batteries. The guy was correct; there were two whole spaces full of D-cells! :D
David