Are both batteries needed on a 2500hd with the 8.1? I read somewhere that the second battery is for a camper or other use. If its not hooked to the starting circuit I would like to remove it. Whats the downside of removing it?

I've not actually seen one, but based on my last gasser and the option list as I understand it, here goes.


2nd batteries on the 8.1's are for the camper package and should not even be wired into the electrical system except for charging.


It's probably got a pair of like 10 guage wires running from it?


If so, then it is just camper power with a solenoid/diode in the charging system feed for it. That allows the engine's alternator to charge the battery when it's low, but isolates it if the camper runs it down.


Just make sure you do something appropriate with the leads to that battery.


Only downside I can think of is that there were a couple of occasions when I used the second battery in my gasser to jump the chassis battery since I'd run it dead...http://www.dieselplace.com/forum/smileys/Confused.gif


Maybe MaxPower or some of the other members with more electrical system experience will chime in with some more exact answers if you need them.

I thought they were wired in parallel so you can't really easily remove the 2nd one. Not true?

I thought they were wired in parallel so you can't really easily remove the 2nd one. Not true?


The key to his question is that he's got an 8.1 which is a gas engine and doesn't require two batteries like the Dmax.


The Dmax trucks require two batteries and yes they are wired in parallel.

On my 95 350 gas Both battery are parallel

I'd have to look to see how it is wired but I won't have that information in front of me until Monday. Any way you look at it, it would be ok to remove it. You just have to figure out a way to remove the wiring or isolate it some other way. Make sure it can't short out! I'll look into it when I get back and let you know. (Hopefully I remember)

I know of several that have removed the battery on a DMAX so I know it's not a problem.

if it does have the small wires why not remove them and run heavy cable from the positve(aux batt) to the cranking battery (positive)and ground to the chassis some were and then you will have two for starting.If you think you are going to save weight and gain milage on that 8.1 then don't bother you will not notice it!

I remove mine every time I replace the fuel filter.

I always start it up and check for leaks before reinstalling and it seems to work fine on the single main battery - just make sure you insulate the positive cable as I believe it is live from the main battery!!!

Thanks for the input everyone. I just got done removing it. It does have small wires, the black goes to the frame and the red goes to a 30 amp mega - fuse in a small plastic box and then to a relay.I disconnected the red cable from the fuse and stashed it away along with the battery.

For what it is worth, I installed dual batteries on a 2000 K3500 5.7 and factory hardware/diagrams had them in full parallel with 4 gage cabling. On my 89 burb they were seperated by a contactor that could be engaged to strap them together for starting on demand (also factory setup)

On the diesels two batteries are needed due to the high compression, but it sounds like some of you are able to get the engine to crank over ok for now. I believe over time you will wear the battery down befor its time.


While starting your engine everything is turned off like your lights, radio, etc... to use all available power.


I am not sure what the compressoin is on the 8.1's but I think it is around 9.

On the diesels two batteries are needed due to the high compression, but it sounds like some of you are able to get the engine to crank over ok for now. I believe over time you will wear the battery down befor its time.





Well if they go anyplace cold in the winter with only one battery on a Dmax, they will just have to wait until spring for it to start again...http://www.dieselplace.com/forum/smileys/HiHi.gif Edited by: Zeeb

On the diesels two batteries are needed due to the high compression, but it sounds like some of you are able to get the engine to crank over ok for now. I believe over time you will wear the battery down befor its time.





Well if they go anyplace cold in the winter with only one battery on a Dmax, they will just have to wait until spring for it to start again...http://www.dieselplace.com/forum/smileys/HiHi.gif





That's entirely possible, remember the General has to build a truck that will work from AZ to AK. Down south one Optima works fine. BTW those with the stock Batts. Warning it's not if they will leak, but when. Do yourself a favor, can them before you remove a lot of paint with battery acidhttp://www.dieselplace.com/forum/smileys/Cry.gif

On the diesels two batteries are needed due to the high compression, but it sounds like some of you are able to get the engine to crank over ok for now. I believe over time you will wear the battery down befor its time.





Well if they go anyplace cold in the winter with only one battery on a Dmax, they will just have to wait until spring for it to start again...<IMG id=chkImg1 onmouseover="this.style.cursor='hand'" onmouseout="this.style.cursor=''" alt="Click on image to open in new window" src="smileys/HiHi.gif" name=chkImg2>





That's entirely possible, remember the General has to build a truck that will work from AZ to AK. Down south one Optima works fine. BTW those with the stock Batts. Warning it's not if they will leak, but when. Do yourself a favor, can them before you remove a lot of paint with battery acidhttp://www.dieselplace.com/forum/smileys/Cry.gif

It is more than possible. It is a sure thing as you have the load from preheat (around 100 amps or so) and the very high draw of the starter in cold weather to (much higher than a gasser) It would be straining one battery in mild weather and shorten its life too. Also, if 15 years of dual batteries, I have yet to have first one leak. If they do start to leak, it is a sign of a charging problem (to high a voltage) not because they are destined to leak.

If I want to hard-wire an inverter to one of my batteries, which one should I draw from? Since they're run in parallel, does it even matter?


Also, (I'm an electrical newbie), I'm planning to get a bluetooth car kit for my cell phone. I'm sure the installer will charge me more than he should and not position the mic/speaker in a custom-looking spot, so I'd like to do it myself. Assuming the kit comes with instructions, how difficult a job do y'all think this is?


Anyone local (to San Jose, CA) that could offer some assistance in exchange for a fat porterhouse and a bunch of beer? I love to learn mechanical things; unfortunately, I don't really have anyone to teach me.


~Terel