How to run Multiple battery banks on Toggles

[JM923A2]

I am still new to M939 series trucks. With the weather turning cold starting (CCAs) seem to be low even if I run two battery banks in a jump start formation. I would like to know if anyone has run multiple battery banks to be activated by toggles on the dash. Thus if your single (summer bank) is not providing enough power you can switch via toggles to a second or even third bank to provide the CCAs needed for starting. I have tried to draw it out, in theory, but would like to get the opinions of more experienced members. In theory the benefit to this would be if you left your battery switch on and drained the main bank, by switching to the two others you can now start without jumping.

 

[tim292stro]

A single pair of Group 31's can deliver 1100CCA at 24V. If you are finding yourself needing more than that - something is probably very wrong with your truck...

If you want to do dual bank, use an isolator to charge both banks simultaneously from your single alternator, and use a Blue-Sea Systems 1/2/1+2 battery bank switch.

[EDIT:] It's also important to note that lead-acid batteries are a chemical process - when it's cold that chemical process doesn't work as fast. One hint is to use a battery warmer and a block heater. A warm engine has warm oil that circulates easier (the starter has to spin the oil pump too) and will make fire easier than an ice cold block. [/EDIT]

 

[wcuhillbilly]

I use 4 group 31s in my 816, I had the two slide out battery boxes, with the military batteries. 31s are what I have in everything else short of my wifes Yota... Thus 4 group 31 Dekas found their way in by welding the two boxes together in the middle and sawing out the middle wall. Next I pulled the spot welds of the bottom riser bars as I had top post batteries and would have just barely touched the step had I not done so... Wired up in series and all is well now..... And my truck is a bear to start now that its below 60*F Duel fuel, Turbo, and turned up fuel screw... (no block heater yet either)... Ether injection is on the way.. I have drained this set up once, while trying to prime the fuel line on an empty injection pump... Simple solution was to bring my Daily Driver over with its two 12v batteries and run a set of cables off each battery to a battery on the 816, then switch to the next bank of batteries.... so that each battery is recieving 12v (not each group, yes I had two sets of cables.)

 

[74M35A2]

You can run them like you are asking, but I don't understand the point of not having them connected if you are carrying them on board anyway.

Older twin engine boats have a "bridging" switch which is just a solenoid to connect the left and right battery banks if need be.

If you are referring to an A2 (8.3) like your handle suggests, it should fire quickly. I ditched the stock batteries and went with 2 x group 31's rated at 1000cca each, as I wanted equipment space under the pass seat. It starts just fine. Make sure engine is in a good state of tune. Clean filters, good connections, fresh tank to pump fuel lines, and it should take right off. 4 batteries were installed originally in case any trucks went to Alaska and sat, or so the conscious is anyway on that.

 

[emr]

It makes no sense ... sorry... In theory there should be no reason to have dead batts needing such a an additional wiring night mare.

 

[JM923A2]

Thank you all for your replies. To start I left the truck battery switch on and drained my batteries completely. I have been recharging them and they were under 15% charge at start. Due to my error in leaving the battery switch on and draining the batteries I figured why not try and build a backup system for emergency situations. My current batteries only deliver 600 CCA's. I have been saving up money to get some D31's and really don't want to drain those by accident.

I never thought about the bridging switch which is what I was looking for.

This is also because I am building a hunting rig and want backups on everything as Murphy seems to take a strong liking to me.

 

[tim292stro]

Oh, then get a Priority Start

 

[74M35A2]

Ah yes, digging deeper usually finds the treasures! A lot of people have done what you have, and when all you have is 12v around, you are stuck for at least a short while.

Or get a PortaCharger: http://www.portacharger.com. Ha ha! My product!

Yes, you can just use a high current solenoid with a momentary push butron switch, and a battery isolator to keep it charged.

How old are your batteries? If 5 years or more, then they are shot. They are only $100 each new to replace. But each time you drain them completely, it shaves a good chunk of capacity and life off of them.

 

[74M35A2]

I just started my 925A2 this morning to add a line to this thread for reference. Ambient temp was 28F at 7am this morning, and my truck cold started with just the usual "bump" of the starter switch, which is much less than even 0.5 seconds. Didn't touch the throttle, didn't use the ether. I could probably get away with even one group 31 battery if they were available in 24V.

Fired off on a few cylinders first, then all 6. I think I have an injector leaking down overnight, I have 6 brand new ones on order which have had the nozzle holes EDM'd out to 5 x 0.014" (stock is 0.011"). Going to get compression and leakdown data while the injectors are out. Engine could be 25 years old, so it may appreciate an in-frame kit. Several minutes of blue smoke during the cold misfire then clears up. Bought a turbo seal kit and valve seals also, but not sure I can get away with doing just those.

 

[tim292stro]

Blue smoke indicates oil in your combustion chamber (rings or valve seals), or bad turbo seals. Nip that in the butt before you end up with an oil fueled runaway diesel...

 

[74M35A2]

Yeah I know.