Jump Starting Question

[motorolanut]

My 813 has low batteries and don't wanna hold a charge. So prior to installing new ones.. Is it possible to use one of those portable battery jump starters to Help jump start a M800 series? and If so how do you hook it up? Or will the 12 vs 24 not work?

 

[cranetruck]

Relace the bad batteries.
Don't jump a 24 volt system with 12 volts, the minimum needed on your starting motor is 20 volts or you'll burn up the motor....

 

[motorolanut]

Okie Dokie...THX....

 

[Mike_Pop]

I've tried jump starting with a 12v system and sometimes it works but most of the time it doesn't. I've had better luck using another 24v vehicle and jumping from both batteries. I really need to get a slave cable adapter!

 

[mangus580]

The only time 12v jumping works... is on CUCV's really. Most the time with them, when your batts go dead, its the front batt only (leaving lights on or something stupid like that).

Now... if you had 2 jumper packs.... or a jumper pack, and a 12v vehicle... you could do it!

 

[Mike_Pop]

The only time 12v jumping works... is on CUCV's really. Most the time with them, when your batts go dead, its the front batt only (leaving lights on or something stupid like that). Now... if you had 2 jumper packs.... or a jumper pack, and a 12v vehicle... you could do it!

I've tried it with a vehicle and a jumper pack. If the batteries are really dead, it won't work. But you are correct, putting juice to the front battery does help and can get you started.

 

[ida34]

You have to have two of the jump starters. One for one battery and one for the other. I have done it before. I have seen some 24 volt jumpers but two 12 volt models hooked up right will have twice the capacity of the one 24 volt jumper. I assume you know how the batteries are set up. Two each batteries in series with the two sets connected in parallel. If you do not understand what I am saying then don't attempt it.

 

[Mackfire68]

If this is the dual battery settup, disconect the cable between the two batteries and charge them up individually with a 12 volt charger. Its hard to start a 24 volt system with 12 volts. This is what I do when my batteries get low until I buy a 24 volt charger. Check your batteries to make sur they hold a charge, it may be time to replace them. Also if they will be sitting for an extemded period of time , disconnect them.

 

[citizensoldier]

Kind of dumb question but I am just not sure? Is it bad or will you spike the alternator/generator if you jump a truck , leave it running and pull the batteries out? Or jump it with a 24volt jumper and there are no batteries even in the truck? I have been told that there is nowhere for the charge to go while running and it will fry things? Is this true? Must you have at least some old dead batteries hooked up for the power output from the alternator or generator to go? This would be on a deuce or 5 ton truck..

 

[ida34]

Yes. Keep the batteries in the truck. Even dead batteries.

 

[gimpyrobb]

For all practical purposes, Chuck is correct. Some trucks need the power switch to be on for the excite wire to work on the alt. If that is off, you should be OK. YMMV!

 

[citizensoldier]

Thanks guys. I just was unsure on this.. Many times you find a old truck with no batteries and want to try to start it.. I have a 21 HP jumper/charger that will start most jet planes... I just wondered what and if it would hurt anything. I no for example the M37 will run on its own once started and no batteries.. But a diesel firing off compression? Once started you only might need power for the fuel pump and even that is not a must once started.. I am learning guys.. Electrical is not my strong point on these trucks.. Wish we had a class for it! Bjorn you up for it?

 

[ida34]

The problem is not starting it or running the engine. The problem is blowing up the alt. I am not an expert but I do know that you have a great chance of damaging the alt if you run it without a battery. I know it is bad to check for charging by disconnecting the battery while running. I don't remember the exact technical reason but I am sure an electrical specialist will chime in on this one.

 

[cranetruck]

If the batteries are poorly charged and the alternator/generator is charging at a high rate, disconnecting the cable will create a so called "load dump", a high voltage spike, which lasts for several milliseconds (an eternety for electronic devices). This 50 to 150 volt spike can easily destroy most things hooked up, including the regulator itself.
Google "load dump" and find out for yourself.

Edit: The MX-7777 can absorb a load dump and should be used if you have radios on board.

 

[sinister]

Kinda off subject a little, I've had to jump off my duce with bubba's M1008 and I had to get creative on hooking jumper cables up to the jumper hook-up in the grille of the 1008. Is there a purpose made cable for this?

 

[kaiser2help]

What I have done is purchased 2 marine deep cyle, 12 volt batteries and I built a wooden box to carry them. I hook them up in the box in series with permanent leads. I then bought a cheap two wheel dolly and I carry the box with the batteries in them so now if the occasion arrives I can jump start my own or my friends with ease. Just make sure your leads are suitable for the correct ampere draw. This will start your truck in seconds.

 

[rosco]

In all the situations above, its best to have a meter, and check each batteries condition. Then go from there, so you know hat your doing. A fully charged 12 volt battery is 12.66 volts. The batteries can be checked, one at a time, even being hooked into the system - just run your meter leads between each batteries posts. That will check then, just that batteries volts. Often, there is one battery that is bad.

Lee in Alaska

 

[BEASTMASTER]

you redy for this ??? my buddie has two motorcycle batteries hooked together and has a slave cabel on it. he hooks it up to his 5 ton or deuce and every other 24 volt buggie he has and those little batteries fire off whatever he needs to jump. it amazes me and i laugh whenever he uses them..

 

[Recovry4x4]

Kinda off subject a little, I've had to jump off my duce with bubba's M1008 and I had to get creative on hooking jumper cables up to the jumper hook-up in the grille of the 1008. Is there a purpose made cable for this?

Sure is, you are looking for a slave cable.2 types exist, the NATO single pin style like on the CUCV and the older 2 pin design popular on deuces and the like. Very handy if you have more than one truck.

 

[emr]

Every year for a couple now i call all the charger manufactures looking for the ultimate charger, have found one , but a little over 500 bucks, so its on the wish list,The duel battery's in the above post is the way any of the battery charger people ive called for info say is the propper way to jump, and safest not a charger or another truck, useing 2 separate bats was strongly said to be the best by any tech ive ever ask ...good post... someday ill do it right...Randy