Electrical: Jump Starting : Alternator and Generator

[jackb]

....been a while .... what are the precautions when jump starting a generator charged system and an alternator system ?

[rockne10]

Shouldn't make much difference, gen or alt. As long as voltage is the same.
From the live vehicle to the dead vehicle, battery positive to battery positive; battery negative to dead vehicle ground. You can go battery negative to battery negative but, there is less chance of spark and explosion if your dead lead is to a chassis ground. Just saying from experience.
If you are jumping a 6-volt system from a 12-volt system, hook up your grounds from battery to battery. Hook your positive to 12-volt battery positive; have someone in the car hit the starter while you lightly touch the positive cable to your 6-volt battery positive. Short 12-volt bursts to the 6-volt starter are invigorating but longer bursts can easily fry your ammeter.

The nice thing about a generated system vs. an alternated system is, once you are running, assuming your generator and voltage regulator are working correctly, you do not need a battery to keep you safely on your journey. Without a good battery, an alternator system cannot function.

[jackb]

.....for some reason, as in jumping a '62 and '63 GT Hawk(s) many years ago (1973)..... I thought you could only "jump" one way.....I thought you could damage one of the units if jumped wrongly.....??

[Deaf Mute]

+ to - is a big NO NO !!! If you do touch posts while starting the 12 to 6 method, Keep your head and eyes out of the way.... don't ask... I just know!

[northern]

Just out of curiosity, how would one boost a positive ground vehicle with cables connected to a negative ground vehicle. Still positive to positive and negative to negative? That seems obvious if using a battery that is not in a car for the boost. But I would be leery to try this if using a running 12 volt negative ground vehicle to boost a positive ground 6 volt vehicle. Who knows what would happen to the 12 volt vehicle given today's computerized systems.

Regarding boosting from one car to another when both are the same voltage and both are negative ground, it is better not to run the negative cable ends to the negative battery terminals. Instead, connect the cable ends to bare grounded metal on the engine block or nearby. This lessens the possibility of explosion, so they say. I expect the same recommendation would apply to vehicles with positive ground - that one would connect the positive cable ends to a grounded spot in the engine compartment. Also, always connect the ground cable last.

[GinettaG12P]

Years ago, I got a friend's car started with a length of heavy solder. We touched the front bumpers of the cars together and then used the solder between the positive posts of both batteries. The solder got hot, but the car started. Since then, I've used that trick twice, once even using a folding jack handle to connect the positive posts. Wouldn't try it on a modern car for two reasons: non-grounded plastic bumpers, finicky ECM.

[55s]

I did have a 6v battery case blow up when I boosted with a 12v, but I have done it many times before and after. Just stand back in case it does happen!

Remember that 6v cars were typically positive ground, while 12v were negative ground.

[Skip Lackie]

Just out of curiosity, how would one boost a positive ground vehicle with cables connected to a negative ground vehicle. Still positive to positive and negative to negative? That seems obvious if using a battery that is not in a car for the boost. But I would be leery to try this if using a running 12 volt negative ground vehicle to boost a positive ground 6 volt vehicle. Who knows what would happen to the 12 volt vehicle given today's computerized systems.

Yes, pos to pos and neg to neg, even if boosting 6v with 12v. I have done it several times, but it's best to be far away from the 6v battery and just touch the last (neg) jumper cable on the 12v ground for the shortest possible time. As soon as the circuit is complete, the 6v battery will be overcharging and outgassing hydrogen gas. Not a good thing to have around sparks.

[Greenstude]

When boosting a 6v battery with a 12v --- be sure the car doors are closed so you don't blow the interior light bulbs which come on automatically with the door open. And as Skip Lackie said above, do not have the negative cable in contact any longer than absolutely necessary.

[StudeRich]

.....for some reason, as in jumping a '62 and '63 GT Hawk(s) many years ago (1973)..... I thought you could only "jump" one way.....I thought you could damage one of the units if jumped wrongly.....??

I think this old "Worry/Concern" comes from MIS-remembering the warning that all early Alternator Equipped vehicles had similar to this Decal:

"WARNING, CONNECT POSITIVE TO POSITIVE and NEGATIVE TO NEGATIVE"

Really that is all you need to do, if you do not, DAMAGE will occur.

[Warren Webb]

I have always connected my jumper cables doing the ground to the engine block itself last, away from the battery & any chance of sparks or explosion. It also does away with the chance that the ground wire from the battery isn't up to par.

[Deaf Mute]

I have also touched bumpers... and then linked both jumper cables to get from battery to battery. Sometimes ya just gotta do what you gotta do!

[jackb]

OK.... hoping to clear this up now: can you always jump a 12V alternator equipped car to a 12v generator equipped car ? And visa versa ??? No damage to either generator or alternator when doing so ? AC vs. DC ??

[Warren Webb]

Although it creates alternating current I believe it becomes direct current when it passes the diodes so there is no difference & it is all direct current regardless of it being a generator or alternator. No vehicle made that I have ever seen runs on AC, all are DC.