I bought a Craftsman 750 jump box. The manual says hook the pos to pos and the black to any unpainted metal surface. I understand that but my question is Is it safe to hook the black clamp to the neg post? ( like using jumper cables) And also the manual says on a pos ground sytem to hook the black cable to neg post and the red to any unpainted surface, I thought you always did pos to pos and neg to neg,no matter if its 12 or 6 volt to jump start and one last question is this unit to big to use on a 6 volt tractor battery. In my cub and Super A? Thanks
- Thread starter Cris
- Start date
old
Well-known Member
- Location
- Camdenton Missouri
Reason they say hook to a metal surface instead of right to the battery is to keep from having a spark at the battery. A spark at the battery can/will cause the battery to explode and that is a bad thing. As far as jumping a 6 volt system with it if its 12 volts the only way to do that is hook it right to the starter post NEVER so as to put the 12 volts across the 6 volt battery or you could blow the 6 volt battery up
Hobby farm
Hobby farm
John G. Hasler
Member
> ...is this unit to big to use on a 6 volt
> tractor battery.
Yes. You could destroy the battery unless the unit has a 6 volt setting (unlikely).
> tractor battery.
Yes. You could destroy the battery unless the unit has a 6 volt setting (unlikely).
Bob M
Well-known Member
Reason to make the last connection to a grounded member instead of directly to the battery negative post is so any sparking that might occur when the final connection is made happens a distance from the battery. This lessens the chance of a spark igniting H2 gas escaping from the battery and possibly causing it to explode.
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The manual's instructions for jumping a positive ground system ARE correct - you are still connecting pos to pos and neg to neg.
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Theoretically you CAN use a jump box to crank up a 6 volt tractor (I've done it...). But it's not recommended for a couple reasons:
- It may overload and ruin the jump box (I've done that TOO...!).
- If your Craftsman jump box is like my son's it has some internal logic that shuts it down if you try to connect it with the polarity reversed, or if you connect to 6 volt system. It simply won't work.
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The manual's instructions for jumping a positive ground system ARE correct - you are still connecting pos to pos and neg to neg.
----
Theoretically you CAN use a jump box to crank up a 6 volt tractor (I've done it...). But it's not recommended for a couple reasons:
- It may overload and ruin the jump box (I've done that TOO...!).
- If your Craftsman jump box is like my son's it has some internal logic that shuts it down if you try to connect it with the polarity reversed, or if you connect to 6 volt system. It simply won't work.
John G. Hasler
Member
> Reason they say hook to a metal surface instead
> of right to the battery is to keep from having a > spark at the battery.
No. You could get a spark at the positive terminal just as easily as at the negative, but the risk is negligible as there is only hydrogen present when charging and then not much. The reason for instructing you to connect the negative cable to "a metal surface" is to make reverse connection impossible (assuming negative ground). If you connect the black (negative) cable to the frame then the worst you can do with the positive is connect it to the negative battery terminal, shorting the jump charger. If you connect the black cable to what you think is the negative battery terminal and get it wrong when you hook up the positive you will have the two batteries connected in series and shorted. Messy.
> of right to the battery is to keep from having a > spark at the battery.
No. You could get a spark at the positive terminal just as easily as at the negative, but the risk is negligible as there is only hydrogen present when charging and then not much. The reason for instructing you to connect the negative cable to "a metal surface" is to make reverse connection impossible (assuming negative ground). If you connect the black (negative) cable to the frame then the worst you can do with the positive is connect it to the negative battery terminal, shorting the jump charger. If you connect the black cable to what you think is the negative battery terminal and get it wrong when you hook up the positive you will have the two batteries connected in series and shorted. Messy.
old
Well-known Member
- Location
- Camdenton Missouri
Sorry I do not and can not agree with you. You hook it up away from the battery so as not to have a spark at the battery which can in fact cause the battery to explode.
The exploding battery is the concern because of the gas. Probably have to be in a battery box to get the right hydrogen & oxygen mixture. Probably happened one out of a billion jump starts. I jump many a battery for years and years. Cell caps screwed on and taken off. Made plenty of sparks but never an explosion. Always on vehicles with the hood raised and open to the air.
Ron in Nebr
Member
For what it's worth, it doesn't have to be a battery in a box-type situation to to generate enough gasses to cause an explosion. Several years back my dad and I were starting our deisel-powered center pivot irrigation engine, and the batteries for it were lying right out in the open near the engine. Dad hooked up the jumper cables and one battery blew up right in his face. He was wearing sunglasses at the time but I still at about 9yrs old set a record time driving him home where he jumped in the shower to get all the acid washed off.
So, the point is, always assume a battery can and will blow up at any time, and make darn sure you're hooking it up right.
So, the point is, always assume a battery can and will blow up at any time, and make darn sure you're hooking it up right.
Nebraska Cowman
Well-known Member
'fraid not John. Listen to the other guys. They are right.
John G. Hasler
Member
Batteries explode due to the electrolyte boiling inside when they are shorted, not due to the ignition of the tiny amount of hydrogen present.
When I was with Sarns (a manufacturer of medical life-support equipment now part of 3M) one of the products I designed the electronics for was a "UPS" for hospital operating rooms: four truck batteries and a solid-state 110VAC inverter in a stainless-steel case on wheels. Because the product was for hospital use we had to investigate every possible failure mode, including hydrogen explosions. We found, through both calculation and experiment, that it was impossible to accumulate an explosive mixture even inside the closed case with the charging circuit jiggered to overcharge. The amount of gas is too small and it diffuses away too fast. There can be an explosive mixture present in the headspace inside a cell, but you'd have to get a spark in there and even then the amount of energy released would barely pop the cap.
Batteries explode when people short them and the results are much more spectacular than the little pop you'd get from a bit of H2.
When I was with Sarns (a manufacturer of medical life-support equipment now part of 3M) one of the products I designed the electronics for was a "UPS" for hospital operating rooms: four truck batteries and a solid-state 110VAC inverter in a stainless-steel case on wheels. Because the product was for hospital use we had to investigate every possible failure mode, including hydrogen explosions. We found, through both calculation and experiment, that it was impossible to accumulate an explosive mixture even inside the closed case with the charging circuit jiggered to overcharge. The amount of gas is too small and it diffuses away too fast. There can be an explosive mixture present in the headspace inside a cell, but you'd have to get a spark in there and even then the amount of energy released would barely pop the cap.
Batteries explode when people short them and the results are much more spectacular than the little pop you'd get from a bit of H2.
teddy52food
Well-known Member
What kind of batteries were you working with. Lead acid batteries will blow the case apart not just pop a cap. BTDT
Like others have said, positive to positive, negative to negative, regardless of which terminal is connected to the chassis.
Assuming you're talking about one of these little portable jump starters, it's unlikely that the gel cell battery in the jump box could supply enough current to damage a 6 volt battery, but still better to not take the chance.
Keith
Assuming you're talking about one of these little portable jump starters, it's unlikely that the gel cell battery in the jump box could supply enough current to damage a 6 volt battery, but still better to not take the chance.
Keith
I wonder if heat and the sun could make a difference. Softens up the case enough to make it easy to explode?
I twisted the post loose on one on a 100 degree day after driving down the interstate. Went to remove the terminal and top was soft enough the post was moving around and broke while removing a cable.
I twisted the post loose on one on a 100 degree day after driving down the interstate. Went to remove the terminal and top was soft enough the post was moving around and broke while removing a cable.
Bob M
Well-known Member
"For what it's worth, it doesn't have to be a battery in a box-type situation to to generate enough gasses to cause an explosion."
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You got THAT right Ron!
This is the battery on my Minnie Mo U after it exploded a couple weekends ago. Engine had been idling/warming up at about half throttle for about 5 minutes when it let go - it was NOT being jumped, etc.
Battery top was separated from the case around the entire perimeter, one end was blown out and acid was sprayed all around. The cell caps were never located (lost somewhere in the snow). Fortunately the tractor was warming up unattended so no one was nearby when it burst.
Consensus opinion is the cause was an internal defect - a sudden short in one cell. (The battery is only about 1 year old...)
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You got THAT right Ron!
This is the battery on my Minnie Mo U after it exploded a couple weekends ago. Engine had been idling/warming up at about half throttle for about 5 minutes when it let go - it was NOT being jumped, etc.
Battery top was separated from the case around the entire perimeter, one end was blown out and acid was sprayed all around. The cell caps were never located (lost somewhere in the snow). Fortunately the tractor was warming up unattended so no one was nearby when it burst.
Consensus opinion is the cause was an internal defect - a sudden short in one cell. (The battery is only about 1 year old...)
old
Well-known Member
- Location
- Camdenton Missouri
You better read up more on this. Even the company that sells jumper cable say to hook up the ground away from the battery and the jump boxes do also because of the fact a battery can explode. I have seen it happen and its not a good thing. Even the navy teaches you to hook up away from the battery. Being an EX navy E.T. I understand zap you trons very well
Now I guess I have to worry about a ticking time bomb down their between my legs. Guess I'll have to get one of those plastic marine battery boxes from Walmart to hold the battery and contain the acid from an explosion.
I guess it can't hurt to have the battery covered to keep the snow and ice off of it. Lately I just keep the battery in the barn on the charger so it is ready when I need it.
Bob, I wonder if the snow and ice on yours contributed to the explosion? Looks like the snow and ice could cause a dead short between the terminals.
I guess it can't hurt to have the battery covered to keep the snow and ice off of it. Lately I just keep the battery in the barn on the charger so it is ready when I need it.
Bob, I wonder if the snow and ice on yours contributed to the explosion? Looks like the snow and ice could cause a dead short between the terminals.
Bob M
Well-known Member
Probably not. There were 2 other tractors (a Super H and JD A) parked overnite with the Minnie. All had uncovered batteries (the Super H battery a twin to one that blew up). All were fast idling to warm up when the Minnie battery let go.
We're thinking the battery was charging normally (and bubbling H2 a bit...) when a sudden internal short developed in the end cell. The short then ignited the hydrogen.
ANYWAY for my peace of mind the new battery is gonna be living in a marine poly battery box. This is the 2nd unconfined battery explosion I've experienced in my 40+ years of tractoring - that's enough for me. I figure a $15 battery box is cheap insurance(!)
John G. Hasler
Member
> Even the company that sells jumper cable say to
> hook up the ground away from the battery and
> the jump boxes do also because of the fact a
> battery can explode.
Lawyers write the warnings. There is a hazard but it is of a steam explosion resulting from a short.
> I have seen it happen and its not a good thing.
I have seen a battery explode due to being shorted. Nasty! I have never seen nor read nor heard a credible report of a vehicle battery exploding due to hydrogen ignition.
> Even the navy teaches you to hook up away from
> the battery.
A good idea: makes it hard to get it backwards and keeps you away from the battery if you manage to screw it up anyway.
> Being an EX navy E.T. I understand zap you
> trons very well
Being an electrical engineer with 30+ years experience I understand electrons very, very well.
> hook up the ground away from the battery and
> the jump boxes do also because of the fact a
> battery can explode.
Lawyers write the warnings. There is a hazard but it is of a steam explosion resulting from a short.
> I have seen it happen and its not a good thing.
I have seen a battery explode due to being shorted. Nasty! I have never seen nor read nor heard a credible report of a vehicle battery exploding due to hydrogen ignition.
> Even the navy teaches you to hook up away from
> the battery.
A good idea: makes it hard to get it backwards and keeps you away from the battery if you manage to screw it up anyway.
> Being an EX navy E.T. I understand zap you
> trons very well
Being an electrical engineer with 30+ years experience I understand electrons very, very well.
John G. Hasler
Member
> What kind of batteries were you working with.
Heavy-duty lead-acid truck batteries.
> Lead acid batteries will blow the case apart not
> just pop a cap.
If you short them, yes. Estimating the headspace inside a cell at .5in x1in x4in and using references on hand such my Handbook of Chemistry and Physics I calculate that detonating a stoichiometric mixture of H2 and O2 in that space would release about .2btu. What do you come up with?
You certainly can create a hydrogen explosion hazard with lead-acid batteries, but it takes something like a forklift battery charging station or the battery room in a telephone switching center to do it. The stuff just won't stick around in sufficient quantity under the hood of a vehicle.
Again, the real hazard is of a steam explosion due to short-circuiting, and the real hazard when jump-starting is of connecting the two batteries in series and shorting them by mixing up plus and minus on one battery. Connecting frame to frame makes that impossible (unless one vehicle is positve ground). You can still short one battery that way if you get confused as to which terminal is positive but the jumper cable resistance will limit the current so all you'll get is some dramatic sparking.
Heavy-duty lead-acid truck batteries.
> Lead acid batteries will blow the case apart not
> just pop a cap.
If you short them, yes. Estimating the headspace inside a cell at .5in x1in x4in and using references on hand such my Handbook of Chemistry and Physics I calculate that detonating a stoichiometric mixture of H2 and O2 in that space would release about .2btu. What do you come up with?
You certainly can create a hydrogen explosion hazard with lead-acid batteries, but it takes something like a forklift battery charging station or the battery room in a telephone switching center to do it. The stuff just won't stick around in sufficient quantity under the hood of a vehicle.
Again, the real hazard is of a steam explosion due to short-circuiting, and the real hazard when jump-starting is of connecting the two batteries in series and shorting them by mixing up plus and minus on one battery. Connecting frame to frame makes that impossible (unless one vehicle is positve ground). You can still short one battery that way if you get confused as to which terminal is positive but the jumper cable resistance will limit the current so all you'll get is some dramatic sparking.
johnlpleasantview
New User
As a 15 year old growing up on the farm I had watched my dad several times check the battery charge by "wiping" a flat wrench across the two posts of the battery and seeing how much it arced. I did it once and it blew the whole top of the battery out and up on me.
These modern times I use a meter to do the check.
These modern times I use a meter to do the check.
johnlpleasantview
New User
As a 15 year old growing up on the farm I had watched my dad several times check the battery charge by "wiping" a flat wrench across the two posts of the battery and seeing how much it arced. I did it once and it blew the whole top of the battery out and up on me.
These modern times I use a meter to do the check.
These modern times I use a meter to do the check.
old
Well-known Member
- Location
- Camdenton Missouri
Ok so you also know a lot then why in the world would you tell some one its ok to do something when in fact if there is any chance at all it can hurt a person to do it. Me I tell people the very safest way to do something figuring they know nothing about what there doing so they will not be likely to get hurt. Thats like you can in fact jump a 6 volt system with a 12 volt system and most of the time get by with it but there is always that chance that the 6 volt battery will in fact blow up so why put others in harms way if you can keep from doing so.
teddy52food
Well-known Member
Most batteries get blown up when they are arcing and sparking at -25 & -30 trying to get an engine started. It would take a long time to get one to blow from steam pressure at those temps. You may have 30 years experience but you don't know batteries. I think there are others that will agree with me and not you.
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