Can someone give me a quick explaination how the charging system works on a motorcycle. Specificly, how does the battery get recharged. I was always under the impression that all the left over juice (amperage) will go to chargeing the battery. If that's true why do I always here never charge a motorcycle battery at greater than 2 amps. People say charging at greater than 2 amps will damage the battery or shorten its life. My understanding is my bikes charging system is 22 amps. And it takes about 10-12 amps to run it (I don't remember exactly). Which means if I do not add any accessories it leaves 10-12 amps for charging while driving down the road. If it will damage a battery to charge it at a higher rate why do our charging systems not destroy batteries on a regular basis. I was recently told that the on "on board" charging system will only allow 2amps or so to flow to the battery. To which my thought was retard he implied that there was a built in electronic charger. If it only charged at 2 amps all the time the batteries would never get charged with the 15-20 min rides across town I'm always doing. For some reason I got to thinking about this. Will someone set me straight on this? Just to note I almost always charge all vehicle batteries would a trickle charger and I've always used a trickle on motorcycle batteries as my dad always said its best to charge em slow.

Thanks.

 

Your thinking is right on the money – the battery will not get damaged if charged at 15A.
That’s exactly what usually happens if you had a low battery and got a jump-start – as soon as you get over 2000RPM your rate of charging the battery will exceed 15A and will gradually slow down as the battery gets charged.
Theoretically you can charge the motorcycle battery with the full current the charging system is capable of but that never happens since at least 10-15 A are used up by lighting and engine ignition to keep the vehicle running.

As for the 2 A recommendation – that’s in case you are using a simple/cheap charger and you leave the charger unattended for extended period of time.
If the charger is set to 1A or 2A rate nothing will happen. But if the charger was set to 10 or 15 A and you forget about it then your battery may overheat and crap out.

If you are charging the battery in a hot environment (temperatures exceeding 140F) then it makes sense to lower the charging current down – every charging is associated with temperature and battery doesn’t like to get toasted.
Under moderate ambient temperatures it is perfectly OK to charge the battery at 10 or 15 A. Just make sure you don’t leave the charger ON for more than 2-3 hrs, or use a Smart Charger.

 

Inside the primary drive there is an alternator, attached to the crankshaft, which produces AC power. In the front of the chaincase there is a wire, that takes that power to the nearby rectifier, which changes the AC power to DC. That in turn charges your battery and powers all the electrics on your bike, while the engine is running.

As for charging your battery while the bike is in your garage, the best device is a battery tender. These things are clever chargers, which will regulate how much charge the battery gets. Much better than an old style slow charger!

The charging system on your bike provides all the electric power your bike needs and there is no need to plug in any sort of charger, if you are using your bike often. I don't normally bother unless I leave mine (I have several bikes) for more than a couple of weeks.

Hope that helps!

 

You hear to never charge the battery with a high output charger because the newer batteries are sealed and aren't made to vent rapidly, as in a high charge situation. Maintaining a battery with a tender, such as in storage, is a great way to extend the batteries life. I have run a 10 Amp charger (automatic) on my battery without any problem. Of course the charger tapered off as the battery got charged.

 

I agree with everything stated so far and would like to add a couple comments.

I have read that if you only take short rides and at lower RPM's, such as back and forth to work or around town, that there is a chance your battery may not fully recover the charge used to start the bike. Keep in mind that the battery supplies all the power to start the bike and after it's running, the power comes from the charging system to light all the lights, run the radio, turn signals, etc. The extra goes to recharging the battery. If you run lower RPM's, the charging system may not put out enough current to do both. That is why you may see some bikes lights get brighter when idling when the engine RPMs increase.

Also, if your bike sits for a couple weeks in the garage, it is a bad idea to start the bike and let it idle to recharge the battery. This just increases the possibility of getting moisture in the crankcase which is never a good idea.

If you ride your bike frequently and on longer highway speed rides, you may never need a battery maintainer. On the other hand, if you ever leave the bike sit for a while or only take it on short rides, connecting it to a battery maintainer while parked can help prolong the life of the battery and ensure it is fully charged and ready to go the next time you want to go for a ride.