Is this statement true:
"Within the (lead-acid) battery, the electric current is primarily due to proton (hydrogen ion) current which is in the same direction as the electric current."
What are the implications of this statement?

Does proton current exist at all in the rest of the car circuitry, outside of the battery? And what effects does it have, if any, on the wiring, components, fuses, connectors, circuitry, etc. in cars?

How the Current Flows in a Car?
answer mentioning different flow types: https://electronics.stackexchange.com/a/95049/66759

  • 1
    \$\begingroup\$ The crucial point is possibly "Within the (lead-acid) battery" ... outside of the battery it's the same as any other power source. \$\endgroup\$ – Roger Rowland Jun 12 '15 at 14:26
  • \$\begingroup\$ I SEE! so then ... is there any proton current outside the battery in the rest of the car circuit? \$\endgroup\$ – Zero Jun 12 '15 at 14:31
  • \$\begingroup\$ Of course not! It's all electrons. \$\endgroup\$ – Leon Heller Jun 12 '15 at 16:29
  • \$\begingroup\$ any reason for the downvote(s) though? \$\endgroup\$ – Zero Jun 13 '15 at 0:23
  • \$\begingroup\$ The Navy taught its Electronics Technicians "hole flow theory". So all the dang arrows for PN junctions are pointing the wrong way. I probably learned the actual answer to this question in Physics 3 working to my BSEE. It's really best to stick to electrons are moving. \$\endgroup\$ – Chris K Jun 15 '15 at 4:13

Mobile charge carriers (the flow of which we generally view are electricity) are only electrons. There are 'holes' but those are just abstractions of electrons. As far as battery chemistry goes, it's referring to ion's, which are atoms that have more or less electrons than normal, which makes them non-neutral, and so a flow of ions can cause a voltage and thus current. The statement is referring to proton flow, again this is just an ion in this case (I'm not a fan of the term 'proton current'), but the ion is not flowing through the wires, it is only flowing within the battery chemistry. Current is the flow of electrons, and electrons will not flow without a voltage. A voltage is a potential difference between two areas. So, if all positively charged ions (as they lack an electron) move to the positive side of the battery, and all negatively charged ions (as they have an extra electron) move to negative side of the battery, you get a difference where the one side is more negatively charged than the other, and thus you have a voltage. Connect a wire between the two and you have a current. As far as anyone is concerned, outside of battery chemistry, all electricity is due to electrons. Though, really, even internally in a battery it's still due to electrons if you think about.

  • \$\begingroup\$ Your answer helped my understanding the most in relation to my question. Please add in the bit about how the statement i posted is true, but only within its own scope, for completeness =) \$\endgroup\$ – Zero Jun 12 '15 at 14:48
  • \$\begingroup\$ @Zero, I've expanded it to include more of an understanding of battery chemistry... Though, note that is is a very simple explanation just to convey the principle. Let me know if you have any questions. \$\endgroup\$ – Jarrod Christman Jun 12 '15 at 15:39
  • \$\begingroup\$ Minor aside, but in biological systems (such as the nervous system), electrical current use ions as the charge carriers. There is still a measurable voltage (which can result in current in metal conductors if probed into different places in solution), but there is no metal conductor in our nerves transmitting the current along the axons. \$\endgroup\$ – Dan Bryant Jun 12 '15 at 16:38
  • \$\begingroup\$ @DanBryant thanks dan, nice interesting tidbit to help relate to our own bodies, and to tie into other topics =) \$\endgroup\$ – Zero Jun 17 '15 at 6:35

The statement is - to the best of my knowledge - true, but only matters if you're concerned about the battery chemistry of lead-acid batteries; it has no impact on the rest of the system. Electricity is electricity, whether it comes from a battery, an alternator, or the power grid.

  • \$\begingroup\$ you do not explicitly state anywhere in your answer that there is no proton current outside of the battery. "it has no impact on the rest of the system" is helpful, but i still do not understand if there even exists a proton current or not in the rest of the system from your answer. so it isnt constructive at all when you say things like "I'm not sure how many ways we can say it." when, to me, you haven't said it yet... \$\endgroup\$ – Zero Jun 12 '15 at 14:57
  • \$\begingroup\$ it would help if you mentioned the word "proton" somewhere in your answer as well. answer is a bit unclear when you just start referring to it as "it" \$\endgroup\$ – Zero Jun 12 '15 at 15:02
  • \$\begingroup\$ @Zero I'm sorry it wasn't explicit enough, but I've really tried to be, phrasing it several ways. No, protons do not have any relationship to current flow except in a battery that uses them as charge carriers. \$\endgroup\$ – Nick Johnson Jun 12 '15 at 15:03
  • \$\begingroup\$ now if that ^ was in your answer, I would have LOVED IT! \$\endgroup\$ – Zero Jun 12 '15 at 15:04

The clause Within the (lead-acid) battery is important. Outside the battery, current is carried by electrons in metal in the normal manner. This has no implications outside the battery.

People are easily mislead by "current flows from A to B" when really we should say "current flows in a loop through A and B". It's a lot like a drive belt, really.

  • \$\begingroup\$ so is there NO proton current outside the battery in the rest of the car circuit? \$\endgroup\$ – Zero Jun 12 '15 at 14:32
  • 4
    \$\begingroup\$ @Zero No. I'm not sure how many ways we can say it. \$\endgroup\$ – Nick Johnson Jun 12 '15 at 14:38
  • \$\begingroup\$ @pjc50 maybe you can edit Jarrod's answer and add in your bit for completeness? Thank you for your answer! \$\endgroup\$ – Zero Jun 12 '15 at 14:57

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