Re: Jump Starting?
 

Chisel The batteries aren't "bucking each other". They are in parallel. The voltage in the low battery will increase and the higher one will decrease. You will have a voltage lower than 12 volts out with this combination. Leave them connected a while and the 6 volt battery will get a fast charge and the 12 volt one will get lower in voltage. I'm not sure a battery will explode with the caps on it takes oxygen to have an explosion. G.M.

Re: Jump Starting?
 

Yeah, go ahead and try that. I dare you.
If those batteries are hooked together for more than a few seconds there will be smoke and melting of the insulation on the cables. Believe me, I've seen it.

You're thinking of hooking a good and dead battery together of the same voltage. That may have some of the charging effect you describe. But, you can't charge a dead 6 volt battery with a good 12 volt battery. No cable will handle the current and neither will the batteries.

Re: Jump Starting?
 

Hi GM
With due respect to your vast electrical knowledge and not trying to start a pissing contest. When a battery is installed in an old car there is no current flow from the battery until the ign sw is turned on. Now you come along and hook a 12V jumper battery on a 6V system. + to + and - to - you have a series circuit. 12V source bucking a 6V source. The 12V source will over power the 6V source and will cause heat in the battery and hydrogen gas will escape the battery and if there is a spark near by--boom. As a dumb young kid jump starting farm equipment daily, I have experanced quit a few explosions.
Your method of jump starting is a safer solution.

Re: Jump Starting?
 

I highly doubt that the cables hooking those two batteries of different voltage together would last long enough to heat up the batteries. In my experience the cable heats up and starts burning off the insulation way before either battery heats up as much.

Re: Jump Starting?
 

Any else confused?

Re: Jump Starting?
 

Old Henry
The jumper cables we use are home made. 4/0 welding cables 16' long with copper clamps and the batterys did get hot.

Re: Jump Starting?
 

Ah, now them right there are some mighty fine jumper cables. I can see how they could definitely heat up the batteries.:p

Re: Jump Starting?
 

I broght that battery blowing up because i see it happen.
Try to start a 38 dodge years ago after a bearing and ring job.
Hooked 12 to starter and battery under seat so direct to starter and not knowing the fusmes could exsplode,my friend touched to battery and blow the cap off,lucky he had glasses on.
I do remember years ago before 12 volts,you could put two 6s in series.
If you have a calibreted eye ball watch your amp gauge.I like a volt meter better.
From the first post i didn,t know it was a show and tell. atboy.

Re: Jump Starting?
 

Chisel, I'm pretty sure +to+\-to- equals parallel, not series. Series changes the outlet voltage, parallel Keeps it the same (-) drop!
Chuck

Re: Jump Starting?
 

I wonder why all batteries don't blow up when a large high amp shop charger is hooked up. Check the voltage being pumped in. You don't leave these on for long periods at the high range. As stated before the explosions are from gas comming from the battery and spark ignited. I have jumped old Fords with 12 volts for many years with no explosions. G.M.

Re: Jump Starting?
 

Barners, here's what I was thinking when I started this discussion...

Prof. Henry writes very entertaining descriptions of his multi-day travels. The V8 Club is trying to promote driving events. Even the Barners Bashes, like the recent Maine tour, and Georgia tour(s) are something that interests me. There are probably several caravans that are traveling west this year. (Tipping hat to all who work behind the scenes to organize these events.)

For group tours it's not too hard to find a set of suitable jumper cables and a 6v donor car.

But in other cases we're not traveling with buddies and are not going to have the luxury of going 6v to 6v if we need a jump start.

I didn't quite say it clearly in my original post, but in my 53 years on this planet I've broken more than a few things from my own stupidity. Usually these things can be fixed with time, money, and effort. But I and am trying to learn from those experiences and be smarter.

Towards that end I thank all contributors to The Barn, and to this thread.

I can see a time in the future where I'd like to more clearly understand the most gentle techniques for road-side breakdown solutions.

So that was were I was coming from.

-VeryTangled/Jeff

Re: Jump Starting?
 

Not that I'm going out to buy some, but there seems to be a big price for some of the heavier gauge jumper cables!

I just popped over to NAPA's site (just chosen because I knew they'd have more than one to pick from).

One thing that seems important is that it makes a difference if the dead 6v battery has enough charge left to fire the coil. If it does it seems you should connect to the starter, if it doesn't it seems you should connect to the battery.

Unresolved questions: Does jump starting have to be a two person job to minimize the time the 6v system is exposed to 12v?

Are there any portable hot-shot solutions for 6v?

Where are good attachments for the dead car's positive cable? Nominees are: Battery positive, unpainted chassis, starter mounting bolt, starter case.

Will the starter spin faster or with more torque when hooked to the 12v system?


-VeryTangled/Jeff

Re: Jump Starting?
 

The starter spins much faster with a STRONG 12 volts. The engine will also get a stronger spark. Also a set of 12 volt jumpers are usually very small wire size. The heat you feel in these cables is like a resistor and causes a voltage drop so you don't get 12 volts any way. Solution,12 volt battery pack with a built in switch, no current to the cables until the switch is turned so you can hook it up to the starter and a good ground, turn the ignition switch on THEN turn the battery pack switch to spin the starter. Even with a low 6 volt battery there should be enough voltage to fire the coil as the coil volyage is not being pulled down by the starter. The engine will start with a crank, pushing by hand or coasting down a grade for the same reason, no voltage drop from the starter load. More fuel will also be pumped spinning the engine on 12 volts. You can also check the oil pressure spinning on 12 volts, mechanical gauge, remove the plugs and the oil pressure you see will be the oil pressure driveing downthe road. G.M.

Re: Jump Starting?
 

Hi G.M. Thanks for helping.

Does your jump box have something like the switch on this one? Having the switch seems a good idea.

What Make/Model is yours, if it's close by?

This one has 4 gauge wire, comments anyone?

-VeryTangled/Jeff

Re: Jump Starting?
 

Main comment - this, again, is a 12 volt jump box. Not ideal for 6 volt.

Again, of all of the times I've had to start my car with a dead battery, 90% of the time it's by a quick push - not a jump. As others have said, battery jump is a last resort when pushing just won't do.

Re: Jump Starting?
 

It does unless you hook up a remote starter trigger to the starter solenoid so that you can run the jumper cable clamp and the starter at the same time.

I've always clamped right onto the positive battery post clamp - eliminates any weak connections between that and other alternatives. Even then, I really have to "work" that clamp contact to get it to really contact (wiggling, etc.) I've never tried directly to the starter terminal because it's so awkward and inconvenient compared to the battery post.

Re: Jump Starting?
 

When a battery is fully charged, it will start producing Oxygen and hydrogen gas.
from the water in the battery (H2O);and that gas mix is very explosive.

Thats the reason you always connect the positive post's on the two batteries.
and then connect the last Connection to Earth somewhere on the Engine or body.
Not on the battery post, preventing to get at spark igniting the explosive gas.

This is for a car with Negative Earth.

Avoiding sparks is the name of the game.

I have started 6 Volt cars with 12 Volt and even with 24Volt. and used the method above.

Keeping the Connection time as short as possible helps.

Re: Jump Starting?
 

The best answer i can come up with is carry another 6 volt battery.
Up here in the north are plows have a quick disconnect.
The end before stater wire put a selinode,and wire a push botton in dash.
Other end to frame.
Now you need the male end on battery.
Quick disconnect Made for Fisher plows.
Now if you have a dead battery with no power to start you have a spare battery.
Or call AAA

Re: Jump Starting?
 

I agree with this too. In your recent cases, #1 thick oil/very cold, and #2 warm, but not enough charge to spark the coil, I have been able to learn from your contributions.

I think I like the idea of carrying a starter switch, they are small enough and useful for other electrical troubleshooting too.

One thing I experienced after installing a battery cut-out switch is that you can roll-start a car with the battery cut-out in the off position. You will get the thing started but it will break the coil pretty soon. <Skip I owe you some money.> So even when roll-starting there are pitfalls.

I was thinking about your situations though, in neither case was rolling or pushing helpful. Have you noticed any ill effects from the trip?

Enjoying the conversation.

-VeryTangled/Jeff

Re: Jump Starting?
 

Henry no pushing for Me .I wouldn't want dents etc ,Jumping is a one man job, and one of the easer things to do on a flathead ,done it hundreds of times .on a 47/48 Whats wrong with hooking up to the starter side of the solenoid you will get a few sparks ,use a charger on the 6 volt if its completely flat .If you plan on hooking to the battery be sure to ware some high strength goggles ,My 78 year old friend can see like a cat now because of a battery explosion,he has got a new retina ..