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Wire Gauge and Scooter Batteries

I have posted on this newsgroup in the past with regard to my scooter, which is used for all of my mobility outside of the home. Recently, because it was becoming cumbersome to re-charge one battery at a time by unlocking a cabinet, I asked a friend to "revamp" it so that all I need to do is hook up the charger to either one of two leads, one positive and one negative, while also marking each lead with respect to the battery. However, the wires chosen are no thicker than "one strand" of a telephone (single) wire from the wires that lead from the charger to the respective batteries. Given this information, would it be logical to assume that the batteries would not receive the adequate supply of current? Here, I am referring to a "step-down" of wire that is first consistent with an extension cord, then the current goes to the single wires, leading to the respective batteries. Because I am not receiving as much "power" as I once did receive from the scooter (in terms of performance), I am thinking that such a step-down is resulting in a poor charge. Am I correct?

There are two other issues: (1). I am currently using the "3 step charger," and I have been told (by some members of this group) that it is probably best to keep the batteries on charge when the scooter is not in use. The light is first red, indicating a need for a charge, then it turns green. Is this a good idea to continue, or should I charge "only when needed?"

(2). I am wondering if there is such a battery that will accomodate my scooter rather than using the two "acid-free, lead" batteries, each with 12 volts. Given that each battery weighs about 4 to 5 pounds, would it be better to look for a larger battery that will do the same work as two individual batteries, yet also fit in the compartment?

Thanks in advance,

Mark

Reply to
mea305
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Hi, Mark. Good to hear from you again -- hope you're doing well.

If you've got that skinny phone wire or something of equivalent thickness, it'll cause problems with your charging cycle. Phone wire is typically 24AWG, which has a resistance of around 30 milliohms per foot. If you've got a 6 foot run, and two wires, that means you've got the equivalent of a .36 ohm resistor in series with your charging setup. That will cause a voltage drop of a volt or so for every 3 amps, which will mess things up. The series resistance will limit the current going to the battery. And if it's a "smart charger", the control will think the battery is fully charged and kick down to a trickle well before it is charged.

I know you're on a budget, here. See if you can at least scrounge a two conductor extension cord, and replace the wires with that. 18AWG wire has only 7-1/2 milliohms per foot, which will make only a 0.09 ohm resistance. Much better. 16AWG (heavy-duty) will mean 4.7 milliohms per foot, or .056 ohms for the 12' round trip. That means you have to draw 17 amps for a 1 volt drop. Thicker the better, but anything's better than 24AWG here.

The best solution, though, would be to have a friend go to the local auto wrecking yard, and look in car trunks for a set of good thick jumper cables. Usually, they've got so many of those, they'll let you have one for a buck or two (and you might be able to talk them into helping you out pro bono, especially if your friend is buying something else). These typically have 8AWG or better wire, which will be perfect (and you'll have two bonus pairs of honker alligator clamps, which might help you down the line if you don't use them for the project).

Many smart chargers kick it down to a trickle charge once the charging is complete. Trickle charging isn't harmful to gel cell batteries, if the charging rate is correct. As mentioned before, the gel cell is actually a lead-acid battery where the acid has been stabilized as a gel. As you know, there's no harm in running your car all day with no accessories or major current draw. If your alternator and voltage regulator are working correctly, it will just trickle charge the battery all day, with no adverse effects. But your case depends on the charger you've selected, and if the charging rate is matched to the batteries. Again, more info would be appreciated (e.g. charger name & model, &c).

Unfortunately, lead batteries are all basic chemistry. The capacity is directly proportional to the amount of lead, and size is proportional. Many variations of specs on gel cells have more to do with measuring methods and the willingness of manufacturers to stretch the truth than they do with actual differences in capacity.

Good luck Chris

Reply to
Chris

Hi Chris:

I want to thank you for taking the time to address my issues. You did an excellent job in addressing each of those I presented. Many thanks. Hope life is going well for you.

Mark

Chris wrote:

Reply to
mea305

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