Genius question of the day. Identify positive and negative battery cables for jump-starting.

[TOBASH]

Pulled the old 100lb batteries without first taking a picture. That was months ago.

So how does this genius now identify 24v positive and negative for purposes of checking electrics and possibly jump starting.

Can I even do that?

 

[kendelrio]

Pulled the old 100lb batteries without first taking a picture. That was months ago.

So how does this genius now identify 24v positive and negative for purposes of checking electrics and possibly jump starting.

Can I even do that?

Use a digital multimeter on DC voltage. If your batteries are already connected in series, place one lead on the "first" post and one on the "last" post. If you read 24vdc, your red lead is on the positive post. If it reads -24vdc, your red lead is on the negative post.

Use a red paint marker and mark the "hot" (+) cable appropriately to assist in future battery swaps.

 

[Ronmar]

Follow the wires… there is a diagram on the inside of the battery box lid. That shows placement and interconnection, but the only way to be sure you have the right cables connected to the right place is to follow them.

there are three 24v cables.
one to the starter solenoid large terminal
one to the polarity protection device 24v batt terminal(shares that terminal with the 24v alt cable)
one goes to the nato plug center post.

there is one 12v cable that goes to the PPD 12v batt terminal(also shared with the 12v alt cable).

There are two ground cables
one goes to the front of the starter motor casing(via a shunt near the PPD on an A0 truck)
the second ground cable goes to the nato plug outer conductor.

consult the lid diagram for where these cables connect…

good luck!

 

[TOBASH]

If the battery box cover has it, my vehicle did not come with the battery box cover and I needed to purchase one aftermarket that I do not believe has the markings.

can someone take a picture of their battery box cover diagrams for me? I would really really appreciate it. Please take a high def picture.

 

[Ronmar]

Search this forum for battery wiring or dropping to 2 batteries, you will find one…

 

[Guyfang]

Its in the TM, if I remember right.

 

[kendelrio]

Found this online. Hope it helps.

 

[GeneralDisorder]

You have a NATO receptacle? The center is +24v and the outside is ground. That's two of the three..... ought to be obvious which one is the final +12v cable.

You still have the polarity protection? You can continuity test the cables from the 12v batt and 24v batt studs and once again the last of the three kinda has to be ground eh?

Then it's just a matter of configuring the batteries into a 24v bank and a 12v bank. LOTS of pictures all over this site and the wider internet on how to do that. Definitely not lost knowledge.

Would be a good idea to make up a diagram, laminate it, and glue it to the inside of your battery box.

 

[Ronmar]

@kendelrio that drawing is missing stuff, with the nato plug, there are three 24v leads. Nato, PPD batt and Start solenoid and two grounds nato and start motor…

The battery layout is correct . When standing beside the truck facing the battery tray. The closesest terminals are neg/ground. The center 4 terminals that are tied together where the outer and inner batteries meet are 12v, and the innermost + terminals near the chassis frame are the 24V terminals…

 

[Guyfang]

This fit your truck?

 

[TOBASH]

You’re all awesome

 

[TOBASH]

Any pictures of batteries installed and wired?