Battery Requirement and configurations

[flhtc01]

So, do I really need two batteries? If so. I only have one altenator and only one wire running from one battery to the altenator, how does the second battery get charged? Will one altenator charge both and if so, do I need another cable running back to the altenator post from the second battery? Seems like there should be some sort of switch or something somewhere. Could I get a littel enlightening?

 

[Will L.]

Yeah, need the power of two. Fast crank speed is crucial for starting. The battery cable that goes from one battery to the other will carry the current between the batteries as needed. It is important to have clean connections between them and at grounding locations. The alternator will have no problem charging them both, it will do them at the same time and level. This is why when it is new battery time put in 2 new at the same time or the one old one will kill the new one.

If this didn't cover it for you, ask anything else.

 

[flhtc01]

Yeah, need the power of two. Fast crank speed is crucial for starting. The battery cable that goes from one battery to the other will carry the current between the batteries as needed. It is important to have clean connections between them and at grounding locations. The alternator will have no problem charging them both, it will do them at the same time and level. This is why when it is new battery time put in 2 new at the same time or the one old one will kill the new one.

If this didn't cover it for you, ask anything else.

Ok. Remember this is a sabotage CUCV converted to 12V. How should the batteries be wired? Positive to positive and negative to negative. Can I use the terminal strips on the fire wall and run all positives to the same point and then run the altenator wire there too? I am just stupid backyard mechanic. :hihi:

 

[WarWagon]

You converted to 12v. Forget 24v stuff. You still need the power of two batteries. It is the same energy at 24v with half the amps as it is 12v with double the amps to crank the engine.

Positive runs to positive then the starter all the same thick wire gauge. Or run both positive wires to the starter if a double connection at the battery is hard to build. Grounds good and clean to the engine from both batteries.

Terminal strips are too small and will smoke when the starter kicks in - so you must have the positive posts wired together with heavy wire. One wire from the alternator to the battery - current will get to the other battery by the heavy cable connecting the positive posts together.

If you want to use the sense wire on the alternator you run the alternator to the main power distribution point and the charge wire then goes to a battery. The sense wire would go to the main junction and detect voltage drop from the alt to the main junction and correct output voltage to be correct at the main junction.

Always disconnect the grounds on both batteries before doing any work. Grounds because if you drop the wrench it is not likely to spark and burn in half because the frame is also ground. You don't have to insulate a loose positive cable from any metal ground by pulling the ground cables... Disconnect one cable and the other battery keeps the positive wire 'hot'. So disconnect the grounds first.

I trust you have removed the second alternator. If not do so as they will fight each other at 12v unless you do some heavy duty changes including pulley size changes to make a lead-lag setup.

 

[flhtc01]

You converted to 12v. Forget 24v stuff. You still need the power of two batteries. It is the same energy at 24v with half the amps as it is 12v with double the amps to crank the engine.

Positive runs to positive then the starter all the same thick wire gauge. Or run both positive wires to the starter if a double connection at the battery is hard to build. Grounds good and clean to the engine from both batteries.

Terminal strips are too small and will smoke when the starter kicks in - so you must have the positive posts wired together with heavy wire. One wire from the alternator to the battery - current will get to the other battery by the heavy cable connecting the positive posts together.

If you want to use the sense wire on the alternator you run the alternator to the main power distribution point and the charge wire then goes to a battery. The sense wire would go to the main junction and detect voltage drop from the alt to the main junction and correct output voltage to be correct at the main junction.

Always disconnect the grounds on both batteries before doing any work. Grounds because if you drop the wrench it is not likely to spark and burn in half because the frame is also ground. You don't have to insulate a loose positive cable from any metal ground by pulling the ground cables... Disconnect one cable and the other battery keeps the positive wire 'hot'. So disconnect the grounds first.

I trust you have removed the second alternator. If not do so as they will fight each other at 12v unless you do some heavy duty changes including pulley size changes to make a lead-lag setup.

So the military junction blocks on the firewall are not heavy enough. Correct?

What size battery cables should be used for this?

Thanks for the replies.

 

[WarWagon]

Just to bridge the batteries positive you need battery cable to do so directly or bridge off the starter terminal. Any thick battery cable will do the job with some preferring to use welding cable. A vendor on here sells battery hookup kits. All other wiring can use the junction blocks - just not the positive to positive battery connection.

 

[flhtc01]

Just to bridge the batteries positive you need battery cable to do so directly or bridge off the starter terminal. Any thick battery cable will do the job with some preferring to use welding cable. A vendor on here sells battery hookup kits. All other wiring can use the junction blocks - just not the positive to positive battery connection.

So, I have my single battery hot wire which is 2/0 going to the junction block with the hot wire from the starter. This is no good correct? I cannot run another 2/0 connection to the same point. Correct? I need to run a battery cable from positive to positive and then directly to the starter correct?

 

[WarWagon]

Sounds like an aftermarket conversion with a large lug then. Not 100% on what the Military used. Used to small wires and lugs on the civilian stuff. I would not put a connection between the starter and the battery - simply a lot of current for any connection to handle. It would work, just better more reliable ways to do it. Anytime you eliminate a connection you gain reliability. We are talking a 10+HP starter taking 1100 CCA or more...

So run positive to starter. 2nd bat positive to starter.
Or
Run positive to positive then to starter.

 

[JayTheCPA]

Here is what folks over at Steel Solderis point to when converting the CUCV to 12v.
http://www.roscommonequipmentcenter.com/news_notes/nn10.pdf

Seeing as it looks like the rig is already down the 12v conversion road, try to reverse engineer back to the document.

In case you also join SS, try to hide that you are running 12v from the SS folks as they are somewhat of the 'purist' nature and any requests for help (even if it is not related to the 12v systems) will draw comments to take the rig back to OE. Here on TDP , folks will help no matter what. Just say-in, not pick-in.

And by the way . . . :welcome2:

 

[flhtc01]

Here is what folks over at Steel Solderis point to when converting the CUCV to 12v.
http://www.roscommonequipmentcenter.com/news_notes/nn10.pdf

Seeing as it looks like the rig is already down the 12v conversion road, try to reverse engineer back to the document.

In case you also join SS, try to hide that you are running 12v from the SS folks as they are somewhat of the 'purist' nature and any requests for help (even if it is not related to the 12v systems) will draw comments to take the rig back to OE. Here on TDP, folks will help no matter what. Just say-in, not pick-in.

And by the way . . . :welcome2:

Great document. Thanks.

 

[JayTheCPA]

Great document. Thanks.

You are welcome.

And am surprised that I did not draw fire from others about not having my mind in the right place (caffeine had not kicked in yet). Here on TTS, folks will help out no matter what.

Ahem...Jay...



:hihi:

 

[WarWagon]

Here is what folks over at Steel Solderis point to when converting the CUCV to 12v.
http://www.roscommonequipmentcenter.com/news_notes/nn10.pdf

Seeing as it looks like the rig is already down the 12v conversion road, try to reverse engineer back to the document.

In case you also join SS, try to hide that you are running 12v from the SS folks as they are somewhat of the 'purist' nature and any requests for help (even if it is not related to the 12v systems) will draw comments to take the rig back to OE. Here on TDP , folks will help no matter what. Just say-in, not pick-in.

And by the way . . . :welcome2:

:suicide: A purist would take one look at my stuff with the SS 6.2 heart wrapped up in 6.5 stuff and a Dodge purposed spool valve and their head would just explode. And if that doesn't do it: Vehicle the 6.2 came out of was used as target practice on a bombing range. Yeah, nothing even remotely to do with stock...

Purist here, No! Certifiable 6.5 NUTS, well not exactly proven... Welcome to the funny farm of old diesels. :hihi: