Re: New to forum/CB650 and my first question!

Posted by sgtslag on Oct 06, 2011; 7:47pm
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/New-to-forum-CB650-and-my-first-question-tp3381249p3400859.html

That battery is rated at 14 Amp-hours:  that is, it will supply 14 amps for one hour, or 1 amp, for 14 hours.  You rode it for 20-40 minutes, and it went down to 30% of full charge... That means it was discharging at a pretty high rate.  I suspect the charging system is failing.

The voltage across the battery, while running at, or above, 4,000 RPM (under load, as in driving it down the road, or engine damage can occur) is critical.  This will indicate whether the charging system is supplying enough power to recharge the battery, or not.  If you have a wire connecting kit,  with a crimping tool, put a small gauge wire (16-20 GA), on a loop connector, on each battery terminal, with a small, inline fuse (1 amp, or less -- no current should flow, so size should be as small as possible, even a 100 mA fuse would work), and connect these leads to your DVM (Digital Volt Meter) set to DC 20 Volt range, and ride it down the road, at 4,000+ RPM.  The voltage, if everything is working properly, will be 13-14 Volts.  Anything less, and your charging system is not working properly.

The speed at which your battery is draining, suggests a heavy load -- the engine's ignition system -- without the benefit of the charging system to replenish the battery.  Get some sort of Voltmeter across your battery, and ride it at 4k RPM, and see what your charging system is doing.  If I were a betting man, I would wager cash on your charging system being the culprit.


By the way, you are deep cycling your 'new' battery.  Every deep discharge is shortening its life, dramatically, AGM, Gell, or lead-acid.  You need to get the problem fixed, or you will be adding a new battery to your parts shopping list, very soon.    Cheers!