# A wandering mind and diminishingly relevant questions **URL:** \ **Category:** General Discussion\ **Created:** [June 22, 2020, 2:47am UTC](https://community.cartalk.com/t/a-wandering-mind-and-diminishingly-relevant-questions/166139 "2020-06-22T02:47:55Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Dakotaboy](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/dakotaboy/32/21842_2.png) [@Dakotaboy](https://community.cartalk.com/u/Dakotaboy)\ **Post date:** [June 22, 2020, 2:47am UTC](https://community.cartalk.com/t/a-wandering-mind-and-diminishingly-relevant-questions/166139/1 "2020-06-22T02:47:55Z")
So I had my portable power source out to get the cord I use to charge my phone when a question popped up unbidden in my mind. When using jumper cables you generally hook up negative to negative and positive to positive because for 99% of cars on the road that’s what works. Then my questionably inquiring mind wanted to know (because I don’t know), what if you’re charging an older Ford? Back in the day they used positive ground instead of negative ground. So, would you hook up neg./neg. and pos./pos. or hot/hot and ground/ground? Then I remembered back in the day most electrical systems were 6 volt instead of 12 volt like most are now. Can you safely charge a 6 v. system from a 12 v. source? Then my mind really wandered: any issues with charging a car that has a generator instead of an alternator? Does any of this really matter? Would it help if I hooked up battery cables to my ears to generate some electrical activity in my brain? ---
**Author:** ![Purebred](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/purebred/32/46796_2.png) [@Purebred](https://community.cartalk.com/u/Purebred)\ **Post date:** [June 22, 2020, 12:08pm UTC](https://community.cartalk.com/t/a-wandering-mind-and-diminishingly-relevant-questions/166139/2 "2020-06-22T12:08:07Z")
On a positive ground car you hook up negative to the negative post first then the positive lead to the positive post. It is extremely risky to jump a 6 volt system with 12 volts, it is possible for the 6 volt battery to explode, not to mention the possibility of causing damage to the 6 volt vehicles electrical components. There was a series in either Popular Mechanics or Popular Science magazine In the 50s and 60s called (I think) Gus’ Garage which covered problems in a short story format. One of Gus’ customers did that. ---
**Author:** ![It\_s-Me](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/it_s-me/32/12660_2.png) [@It\_s-Me](https://community.cartalk.com/u/It_s-Me)\ **Post date:** [June 22, 2020, 12:12pm UTC](https://community.cartalk.com/t/a-wandering-mind-and-diminishingly-relevant-questions/166139/3 "2020-06-22T12:12:58Z")
> [@Purebred](#): > > On a positive ground car you hook up negative to the negative post first then the positive lead to the positive post. What if one car is positive ground and the other car is negative ground? And your last connection shouldn’t be to a battery post. ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [June 22, 2020, 12:19pm UTC](https://community.cartalk.com/t/a-wandering-mind-and-diminishingly-relevant-questions/166139/4 "2020-06-22T12:19:00Z")
> [@Dakotaboy](#): > > Can you safely charge a 6 v. system from a 12 v. source? No, but you can boost a weak battery with a 12v source to get a car started. But you don’t want to charge it with a 12v source. Too much voltage drop, too much heat, battery can explode as others have posted. > [@Dakotaboy](#): > > any issues with charging a car that has a generator instead of an alternator? No. As long as both are the same voltage. An alternator is just a more effective way of creating electrical power. ---
**Author:** ![Purebred](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/purebred/32/46796_2.png) [@Purebred](https://community.cartalk.com/u/Purebred)\ **Post date:** [June 22, 2020, 12:32pm UTC](https://community.cartalk.com/t/a-wandering-mind-and-diminishingly-relevant-questions/166139/5 "2020-06-22T12:32:49Z")
When dealing with a neg ground car to positive ground car you must make sure cars are not touching. Hook up jumper cables to posts of the dead/low battery first. Then to the donor car, ground side last. Though jumper cable manufacturers usually instruct you to attach the ground cable to a ground point rather than the battery post, back on the rare occasion when I might jump a battery I preferred attaching directly To the terminals. Last hookup is to the donor car ground whether to the battery post or chassis. But I do not jump start any vehicle scene the early 70s, too many systems that can be harmed. ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [June 22, 2020, 1:09pm UTC](https://community.cartalk.com/t/a-wandering-mind-and-diminishingly-relevant-questions/166139/6 "2020-06-22T13:09:27Z")
Negative to negative, positive to positive, regardless. I wouldn’t jump a 6v with a 12v. ---
**Author:** ![Dakotaboy](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/dakotaboy/32/21842_2.png) [@Dakotaboy](https://community.cartalk.com/u/Dakotaboy)\ **Post date:** [June 22, 2020, 1:28pm UTC](https://community.cartalk.com/t/a-wandering-mind-and-diminishingly-relevant-questions/166139/7 "2020-06-22T13:28:38Z")
Thank you all for the information. It’s not too likely that I’ll be in some parking lot when I run into someone needing a jump start for his bone stock 1950 Ford, but it’s nice to know I’ll be able to help in the off chance I do. Thanks again. ---
**Author:** ![Purebred](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/purebred/32/46796_2.png) [@Purebred](https://community.cartalk.com/u/Purebred)\ **Post date:** [June 22, 2020, 1:52pm UTC](https://community.cartalk.com/t/a-wandering-mind-and-diminishingly-relevant-questions/166139/8 "2020-06-22T13:52:06Z")
Lol, other positive ground cars out there, but you probably have to go to a classic car show to see them. I think the Brits continued with positive ground into the 60s.