Battery finally failed

[Beemeridian]

21

[RGuy]

Is there a way to test the battery without removing the tank.

Gene, Did you get the answer you were looking for? A 'dead' battery is not necessarily a 'bad' battery. The longer your battery sits while 'dead' the sooner it will go 'bad'. A battery must be fully charged (100%) before it can be properly tested. Buy, beg, borrow or steal a battery tender charger ASAP (one that plugs into your accessory outlet) and see if it will accept a charge. Plug it in overnight, that should be all it needs. You may be okay.... or not.

Good Luck,
Neal

P.S. A half hour ride at leisurely speeds will most likely NOT fully recharge your dead battery. A battery, once dead, will take a while to recharge. I *think* that the ideal battery charge rate is 10% of capacity per hour. In other words a fully discharged 18Ah battery should charge for 10 hours at 1.8 amps. I am not sure what the charge rate of the stock alternator is.

P.S.S. Years ago I used to work at an auto parts store and more than 10% of the core charge batteries we received were actually okay (after a good charging). It was years before I ever had to buy a new battery for my car :-))

[CycleRob]

Today I jumped the battery using the external post and it roared right up. I drove 20 minutes to work @ high revs and feel confident that it will restart @ 5:00 when i leave tonight.

Concerning the "I drove 20 minutes to work @ high revs" part . . . . . there wasn't any "fast charging" taking place with the high revs. I know it seems logical that the faster the engine turns, the faster it charges the near dead battery - - - but that's not true. With the OilHead's car type, car sized alternator putting out ~475Watts (~34Amps, 14V), at only 2,500 RPM, you could have stayed in 6th gear and duplicated the same battery charge. The best thing you could have done is make the "one key start" trip to work last 40 minutes instead (twice as long) but at normal RPM's. Understanding why time is more beneficial than RPM's would be a whole lot easier if you watched an Ammeter & Voltmeter equipped vehicle with a near dead battery jump started. The changes occurring would be how a near dead battery responds to being charged by an alternator calibrated to maintain 14.1 volts, regardless of the power required. As the engine first ran you would see the Amps slowly decrease from initially 35A to around 15A after 3 minutes or so. Ten minutes later you may see 10 amps still being drawn by the battery. An hour later it would still be ~4A. All the while the Voltmeter would be nearly the same 14V reading for the whole hour. Now you can see why longer time is better. There is 1 benefit to using higher RPM's to charge a dead battery and that is better cooling from the alternator's fan. Generating high power (Watts) makes a lot of equivalent internal heat that must be disposed of.

1st, the basics: An alternator tries to maintain 14.1 Volts as long as it is turning at any speed, regardless of the Watts of power asked for by the electrical load. That load can be lights, heated clothing, fuel pump, Motronic ignition and a run down battery, all at the same time. It accomplishes that with an electronic voltage regulator that varies the power to the rotating field (rotor) changing the strength of the magnetic field that determines the output generated by the alternator's stationary stator field wires. That AC power is converted to DC power by a Diode bank. This type of alternator has been in every car/truck since the late 70's. It's a wonderful piece of engineering of which I wish I was the sole inventor. They do an amazing amount of precise work, under very hostile conditions, for many years, at a reasonable cost. Your vehicle won't go far without it working properly. When it fails, it sometimes takes a battery with it.

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