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Got a laugh today. Jumpping 24 volt system with 12 volts

O

old

Well-known Member
Location
Camdenton Missouri
Well a friend has a machine with a 24 volt system. 2-12 volt batteries in series. So he tried to jump start it with his 12 volt truck. He hooked it up + to + and - to - but he was hooking up a 12 volt battery to a series hooked up 24 volt system and he got lots of sparks. It took me a while to explain he can only hook up to 1 battery at a time and the fact one battery - hooks to the other battery + would not cause a problem. Of course he only has a 50/50 chance he jumps the battery that is the weakest
 

Simplest thing to do is attach one 12 V jumper vehicle to one battery(+ to + & - to -) and then attach(if available) another 12 V jumper vehicle (+ to + & - to -) to other battery and start engine. Saves ruining starter from too low amperage.
 
Ya you can do that if you have 2 12 volt batteries but that does not work if all you have is one truck that is 12 volts trying to jump start a 12 volt system
 
Ya that only works if you have 2 in this case he is alone and only one battery. Had a hard time explaining to him about 12 volts and 24 volts and how to hook things up to at least maybe work with only one 12 volt battery to jump with
 
(quoted from post at 16:34:55 01/20/14) Ya you can do that if you have 2 12 volt batteries but that does not work if all you have is one truck that is 12 volts trying to jump start a 12 volt system
Click to expand...

If only one jump vehicle is available then attach a 12 V battery charger with boost on the other battery
 
I have a JD 4020 with 24 volt starter. If I knew which battery was weak I could jump it with my 12 volt pickup. Did it many times just have to do it right.
 
Cant do that either the extension cord would have to be almost a mile long. The guy has an excavator that is parked way out in the middle of no where and takes 4X4 to get to and that is what is 24 volts
 
the simplest thing is to axe that split load system and convert to a normal 12v system, but as I was told by someone on here the reason I bad mouth it is because I am too stupid to understand it
 
What would be the best way to charge both batteries of 24 volt system with one charger? +to+ and - to - on one battery?
 
It is kind of like converting a 6 volt system to 12 volts. Lots of people will call you stupid for doing it. Do notice that Deere has kits for the 24 v to 12 volt. Wonder why they did that. Worked on a few of those 24 volt systems and they are a one of a kind. All the military vehicles I worked on were a straight 24 volt system so this insulated ground (or whatever you want to call it) that Deere used sure complicated things.
 
The problem with converting a 24 volt system down to 12 volts is that when you do so you double the amperage needed for every function. In other words if a function takes 500 amps on 24 volts it will take 1000 amps on 12 volts. As a result every wire on the machine will also need to "double" in size in order to carry the additional amperage. Not to mention on machine like an excavator, or pretty much any piece of construction equipment wired for 24 volt, there van also be a computer, solenoid valves, gauges, etc, etc that would also all have to be reengineered and changed to operate on 12 volt.

In the end changing voltages on an OLD piece of machinery might not be that big of an issue, but take anything from the 70"s on, and some even further back than that, and it"s just not something that you can economically do.
 
Hook the pick-up truck with the booster cables to one of the batteries on the excavator and turn on a work light or other 24 volt load on the excavator to complete the circuit.
With the 24 volt circuit completed the 12 volt charge from the pick-up will equalize between the two batteries.
Takes a while but it will get it going.
 
(quoted from post at 21:38:47 01/20/14) It is kind of like converting a 6 volt system to 12 volts. Lots of people will call you stupid for doing it. Do notice that Deere has kits for the 24 v to 12 volt. Wonder why they did that. Worked on a few of those 24 volt systems and they are a one of a kind. All the military vehicles I worked on were a straight 24 volt system so this insulated ground (or whatever you want to call it) that Deere used sure complicated things.
Click to expand...

Deere had to go with the goofy 12/24V system because Cat had Delco under exclusive contract for a straight 24V system.
 
Do you have any proof of that? How can you be
exclusive on rather basic electrical systems? I'm
sure other machines had 24 volt systems as well as
aircraft.
 
(quoted from post at 22:15:25 01/20/14) Hook the pick-up truck with the booster cables to one of the batteries on the excavator and turn on a work light or other 24 volt load on the excavator to complete the circuit.
With the 24 volt circuit completed the 12 volt charge from the pick-up will equalize between the two batteries.
Takes a while but it will get it going.
Click to expand...

Although I know nothing about an excavators 24 V electrical system I'd have to witness a 12 V alternator or charger that can charge both 12 V batteries in a 24 V system at THE SAME TIME.
 
(quoted from post at 03:29:49 01/21/14) Do you have any proof of that? How can you be
exclusive on rather basic electrical systems? I'm
sure other machines had 24 volt systems as well as
aircraft.
Click to expand...

I have spoken to a retired JD engineer from that 12/24V era.
 
(quoted from post at 10:28:45 01/21/14) It is usually the right hand battery because the dust from the starter brushes discharges it .
Click to expand...

Are you sure the RH battery is the 1st to discharge on the machine this thread was initiated about??

The guy has an excavator that is parked way out in the middle of no where and takes 4X4 to get to and that is what is 24 volts
 
(quoted from post at 20:06:26 01/20/14) The problem with converting a 24 volt system down to 12 volts is that when you do so you double the amperage needed for every function. In other words if a function takes 500 amps on 24 volts it will take 1000 amps on 12 volts. As a result every wire on the machine will also need to "double" in size in order to carry the additional amperage. Not to mention on machine like an excavator, or pretty much any piece of construction equipment wired for 24 volt, there van also be a computer, solenoid valves, gauges, etc, etc that would also all have to be reengineered and changed to operate on 12 volt.

In the end changing voltages on an OLD piece of machinery might not be that big of an issue, but take anything from the 70"s on, and some even further back than that, and it"s just not something that you can economically do.
Click to expand...

Except that, only the STARTING system is 24V on these machines.

Everything else is 12V. All the computers and lighting... It's all 12V because that's the standard.

The starter is 24V because these machines are often parked out in the middle of nowhere in all sorts of nasty weather conditions and they need the power to crank the motor fast enough to get them started.

If you tried to do it with 12V you'd draw so many amps the windings in the starter would burn out unless it was really huge with extra-thick windings. On 24V they can use a much smaller much less expensive starter, relatively speaking.
 
(quoted from post at 10:56:50 01/21/14)

In the end changing voltages on an OLD piece of machinery might not be that big of an issue, but take anything from the 70"s on, and some even further back than that, and it"s just not something that you can economically do.
Click to expand...

Except that, only the STARTING system is 24V on these machines.

Everything else is 12V. All the computers and lighting... It's all 12V because that's the standard.

The starter is 24V because these machines are often parked out in the middle of nowhere in all sorts of nasty weather conditions and they need the power to crank the motor fast enough to get them started.

If you tried to do it with 12V you'd draw so many amps the windings in the starter would burn out unless it was really huge with extra-thick windings. On 24V they can use a much smaller much less expensive starter, relatively speaking.[/quote]

What makes an industrial machine require 24 V starter to start when an ag tractor will start in sub zero temperature with a 12 volt starter??
 
What makes an industrial machine require 24 V starter to start when an ag tractor will start in sub zero temperature with a 12 volt starter??
Click to expand...

Tractors don't start all that well in sub zero temperatures, and often need a jump or some other form of help to get running, such as a block heater having been plugged in for several hours, even if they are well-maintained.

Construction equipment is usually left out in the middle of nowhere with no access to electricity, so they usually have to start cold with no help. The boss isn't going to pay someone to sit there for three hours with a generator while the engines warm up ahead of time, and if they wait until starting time, it's three hours of work lost. It needs to start, without help, when the workday starts.

Tractors aren't immune to the problem. There have been more than several threads on this site about problems starting tractors that have been left in remote locations during the cold weather.

The reason you don't see 24V on tractors is twofold:
1. The whole Deere 24V issue from the 1960's gave it a bad reputation with farmers.
2. Tractor manufacturers figure since farmers don't earn an hourly wage they can afford to dink around in the cold trying to get their 12V tractors running.
 
Yes and this machine is a farmer owned Kamoshu (sp) excavator that is about wore out The guy who owns it loves to buy stuff with out knowing any thing about what e is buying then I get the fun of helping him keep things running
 
(quoted from post at 12:53:11 01/21/14)
The reason you don't see 24V on tractors is twofold:
1. The whole Deere 24V issue from the 1960's gave it a bad reputation with farmers.
2. Tractor manufacturers figure since farmers don't earn an hourly wage they can afford to dink around in the cold trying to get their 12V tractors running.
Click to expand...

I'm very familiar with the JD 24 volt system. When farmers need their tractors to start it's just as important to the farmer that it starts as an industrial machine owner. What % of industrial machines are 24 volt systems?
 
Can not give % but a large number of them are in fact 24 volt systems. Plus a good many of the Military stuff is also 24 volt. Told my friend he should start up the 6X6 truck he has and use it to jump start his excavator since both are 24 volt systems
 
CIH Steiger 350. Starts on 24v, everything else is 12v. Has an
electronic "battery equalizer" to charge the second battery.
 
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