Dual Battery setup

Just wondering if anybody has some recommendations on a dual battery isolator for my 96 suburban. I have visited a few web sites and some sites say I need a special isolator to work with my stock alternator and other
sites say the regular one will work just fine. Anybody done this and which one did they use? Looking in my Haynes(piece of crap) manual, the diesel version came with 2 batteries but there is no mention of an isolator from the factory or were they just both hooked together which would be stupid because they would both be drained if you left the lights on. Main reason is for when it's -40 deg and just the assurance of having an extra battery just in case. Any thoughts would be much appreciated.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Not only does this cat make a fine isolator he also has a slightly modified '79 K-10 http://www.hellroaring.com /
--
Mad-Dog
'79 Chevy K-10
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Helroaring's products looks good.
I planning on doing the same modifcation, however, I've having a tough time find a good location to mount the second battery.
Do you have any thoughts on this? Where are you mounting the 2nd battery? I have a Chev Sub 97, 454.
Let me know if you have any insights.
Thanks! Jon

is
just
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

sites
which
from
reason
The best way is with a heavy duty relay. They are available many places, like golf cart shops. They look like a Ford starter relay but they are different internally. If you need help with the circuit, let me know.
The Diesel batteries are hard wired together. If you leave the lights on they both die. On the newer trucks the computer shuts the lights off if you forget them on:)
Al
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Big Al wrote:

We have a 100 car fleat at work with dual batteries. one under the hood, and one in the truck for the radio and computer equipment. (can not start the car with the second battery) They are set up with a heavy duty relay. and since the cars are run 24/7 on and off all day and night, the relays wear out ofter a while. the manufacturer changed the relay contacts from silver to some other metal. Just by not having the silver contacts, the relays last half as long as the older ones. so make sure and get a top end relay of you go that route.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Sorry Al-- the best way is NOT to use just the relay.
If you go that route and lose the alternator, you kil both batteries. Plus, over time, they will fight each other and damage the cells.

other
diesel
stupid
battery
you
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
burntkat wrote:

After running dual battery cars at work in a 24 hour operation, the batteries have laster over six years, both in the trunck and under the hood with a relay setup. I really dont think we have anything special, just a deep cycle battery in the trunk for the Radio and computer.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
agreed
you should wire a setup that disconnects the unused battery. i used to wire them for friends using ford solenoids to switch off and on to the battery i wanted to use/charge.
john

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Go to Pep Boys and get an isolator rated at the amperage your alternator puts out, or higher.
Wire as indicated.
Get a Ford starter solenoid <the kind that mounts to the fender> and wire the positives of both batteries so that each mains terminal goes to one of the batteries.
This gives you ultimate flexibilty. If you need a jump start, just activate the solenoid via a switch you installed in the cab, and you're able to jumpstart yourself!!
Have done it on every truck I've owned and several folks in the Jeep club's vehicles. Works like a champ, for about $100 of materials including cable <use 0 gauge welding lead>.

is
just
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

activate
club's
Battery isolators are just large diodes. The forward voltage drop changes with current. A relay is better any way you look at it. Years ago I did this for a living, we used RBM 375 relays. RBM is now owned by Gould if someone didn't buy them out. The 375 could handle a lot of current and was dead reliable. It's easy to wire in, just one wire from the ACC terminal of the ignition switch, easily found in the fuse box, and some wire and it's done. No need to cut or splice any of the original wiring. If you think an isolator is better, tell me why.
Al
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
my 96 k2500 w/5.7 has dual batteries and they are wired together. I would get the second tray from a junkyard or dealer and a new positive cable from NAPA. The ground is just a ten gauge wire screwed into the drivers side fender. There is no isolator from the factory and my truck fires up fine in the winter (Indiana)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.