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Joined: Jun 16, 2008 Posts: 397 Location: Michigan
Posted: Thu Aug 21, 2008 1:20 pm Post subject: Charging system question
I was doing some research on coils and stumbled upon some information about the rectifier and voltage regulator.
Anyway, as my bike warms up, the coils seem to crap out. Now as I looked up some information I found that if the voltage isnt be regulated properly and/or isnt charging right, then the coils/spark wont behave either.
If the voltage regulator is faulty, will it blow lights? And melt points? That sort of thing? Really curious, since my speedometer light just went out on the last ride and before that, my points were really out of whack.
Joined: Jun 16, 2008 Posts: 397 Location: Michigan
Posted: Thu Aug 21, 2008 4:07 pm Post subject:
Thanks, I'll check it out.
I just walked out and checked the battery and it's 12. something volts, so the battery is good. I think I'll try the trick of wiring up the tester to the battery as I drive around and see how it dips and surges.
Joined: Feb 15, 2007 Posts: 199 Location: Hewlett, Long Island, NY
Posted: Thu Aug 21, 2008 6:25 pm Post subject:
If your bike is a twin, goto to a good auto parts store and get a coil for a '73 Dodge Dart. It is a tad longer but will fit in the stock location. And it fires at 30K volts. While you're at it, get another to replace the other one. Cost is about $12.
Pep Boys sells an Accel or MSD signle coil for about $40 _________________ ...Brian
1980 CB750F Blue Thunder!
Joined: Feb 15, 2007 Posts: 199 Location: Hewlett, Long Island, NY
Posted: Thu Aug 21, 2008 7:52 pm Post subject:
Johnny5 wrote:
Seriously?
Do you know what size spark plug wires I'll need with this setup?
Yes I am serious. When I had my '76 CB360T I needed a set of coils, so I know that this works. Spark plug wires will be 7mm. Get a universal wire set from the same auto part store and Bob is your uncle! Cut to the proper length, crimp a coil connector on, and you're set. Enjoy the extra spark. _________________ ...Brian
1980 CB750F Blue Thunder!
Joined: Jun 16, 2008 Posts: 397 Location: Michigan
Posted: Fri Aug 29, 2008 10:05 am Post subject:
Now my battery is just about toast. I checked it last night on the meter and it read around 10.5 volts. If I rev the engine it jumps to about 11.5 volts.
If my voltage system is this weak, would this cause one of the cylinders to crap out? The bike seems to "kick in" at around 6,000rpms, but at low rpms, it runs on one cylinder.
Joined: Feb 23, 2007 Posts: 330 Location: Orlando, FL
Posted: Fri Aug 29, 2008 11:08 am Post subject:
Yes, absolutely. A low battery voltage can and will cause a misfire.
I had a KZ400 once that had a charging system fault - wasn't charging at all. I could charge the battery up to 13.5 volts and it would run great, but over 10 miles, the battery voltage would steadily drop and drop. When it got to about 10.5 volts it would begin misfiring.
I repeated this experiment several times with a voltmeter secured to the tank as I drove and it was very repeatable. Charge the battery back up, and it would run like a champ.
Joined: Feb 23, 2007 Posts: 330 Location: Orlando, FL
Posted: Fri Aug 29, 2008 11:50 am Post subject:
Each cell in every lead-acid battery runs at a nominal 2.1 volts. So, for a 12-volt battery, they're made with 6 cells. But 6 x 2.1 = 12.6 volts total. You can charge them up to as much as 2.2 to 2.25 volts per cell, which gives the battery voltage as much as 13.5 volts. They can run as low as 1.95 volts per cell, for a low limit of 11.7 volts but the battery is very weak by then.
So, if anything greater than ~ 12.6 volts is connected to the battery, the battery will be charged. If anything less than that is connected, the battery will not charge.
On your bike (as with most bikes), the charging system puts out anywhere from 12.5 to 14 volts. This is enough to run the bike and all it's loads and still keep the battery charged. If the charging system does not put out that kind of voltage, there will be a constant, steady drain on the battery.
So, if you have an otherwise-good battery that reads 11 volts and you install it in a bike with a charging system that puts out 13 volts, and you ride it around long enough, then yes, the battery will be charged.
On the other hand, if the battery reads 11 volts, and you install in into a weak charging system that only puts out 11 volts, then no, the battery will not be charged, and it may even discharge to just keep the engine running.
However, at the end of their lives, batteries will sometimes no longer accept a charge. In that case, it doesn't matter WHAT kind of charging system you hook it up to (either the vehicles, or your plug-in battery charger).
When does your battery read 11 volts? When disconnected from the system? Or when fully connnected up and the engine revving up? As you see, the answer can make a big difference.
Joined: Jun 16, 2008 Posts: 397 Location: Michigan
Posted: Fri Aug 29, 2008 12:04 pm Post subject:
Totally disconnected from the bike, it reads around 10.5. Connected and revving, around 11.5.
So what you're saying is that the battery will never really "recharge", rather it maintains as the bike's running. So if it's low to begin with, I can try recharging the battery and see if it holds a charge, if not replace it.
My first battery issue so thanks for the information. It's quite helpful.
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