honda 919 elec system power, battery

Yep - get smaller audio. The alternator is the generator that produces power. It's a spinning magnet that generates electricity in surrounding stator wires. They go through power diodes to convert generated AC into DC for the battery etc. The regulator regulates the alternator output - ie, tries to keep it with (say) 13.8V and no more than 14.4V. For cars & bikes alternators almost always a spinning electromagnet and the regulator varies the the spinning rotor's current to vary the stator output. Brushes are used go connect the regulator's electricity to the rotor. (When these are too worn, alternator output drops.) Boats and some bikes (like my old Ducati) use a permanent magnet rotor. Their output varies with engine speed. Since the rotor can not be regulated, their regulators usually dump excess voltage (eg, a big Zenor diode) though some only pass what is required.

oldspark wrote: Yep - get smaller audio.  The alternator is the generator that produces power.  It's a spinning magnet that generates electricity in surrounding stator wires.   They go through power diodes to convert generated AC into DC for the battery etc. The regulator regulates the alternator output - ie, tries to keep it with (say) 13.8V and no more than 14.4V.   For cars & bikes alternators almost always a spinning electromagnet and the regulator varies the the spinning rotor's current to vary the stator output.  Brushes are used go connect the regulator's electricity to the rotor. (When these are too worn, alternator output drops.)  Boats and some bikes (like my old Ducati) use a permanent magnet rotor.   Their output varies with engine speed.  Since the rotor can not be regulated, their regulators usually dump excess voltage (eg, a big Zenor diode) though some only pass what is required.

First - thanks for all your guys help.  I mean that... Second - so if I after I'm done riding, if I shut off the stereo and rev the bike and hold the rpms for  some period of time (30s-1 or 2min) that will accelerate the battery chargiing, correct?  If yes this might be good to give the battery a little charge/energy bump before parking (hopefully)... Lastly - can the regulator be modified to not "dump" energy so it goes all to charging the battery?  Or am I misunderstanding this, or assuming Honda  would have already done this very efficiently?  Or is winding the alternator less of a monster scary project than it sounds?  What about adding a 2nd smaller battery into the system somehow?  Going smaller audio isn't as fun as going bigger, so trying to find a reasonable countermeasure to the power drain issue is my goal... Thx!

Yes & No. Running without that radio means spare power for the charging (it's not "acceleratinge the battery charging" - it IS charging). Whether is is enough, you'll just have to find out. Most cranking batteries probably replace most of their (lost) cranking power within a minute or 2, but complete charging takes longer (it's a of a 90/10 rule - the last 10% takes 90% of the time). You may not need 100% recharge for sustainable starting, but the battery won't last as long (the further fro 100% charged, the more/faster a battery sulphates). Jigging the regulator - not really. You lack TOTAL power. You could disconnect the battery all together. Or the audio. That's your choice. That the alternator "charges" both makes no difference. You can give rewinding a go, but it may require a rotor boost. And if it's a perm-magnet motor, you may get no gain. My Ducati perm-Mag rewind (or rather reconfig from "center-tapped" 2 phase stator to single-phase end-tapped stator was merely for charging at ~1,000-1500 RPM instead of 3,000 RPM - but that was at half the current.... (ie, a voltage boost, but no power boost).

Sadly your SOL, bikes like yours just weren't meant to have additional electrical loads added to them. The bike doesn't even put out enough power to charge the battery at idle and at cruising speeds has just enough to charge the battery and run the bike. If you must have tunes I'd look into battery powered setups that aren't connected to the bike. Alot of rocket riders that ride with tunes have a earbud or helmet speaker and ipod setup; not legal in alot of places but that's how they have it.

catback wrote: Sadly your SOL, bikes like yours just weren't meant to have additional electrical loads added to them. The bike doesn't even put out enough power to charge the battery at idle and at cruising speeds has just enough to charge the battery and run the bike. If you must have tunes I'd look into battery powered setups that aren't connected to the bike. Alot of rocket riders that ride with tunes have a earbud or helmet speaker and ipod setup; not legal in alot of places but that's how they have it.

That's how it seems to keep turning out - battery keeps dying and I have to jump it... So two questions: 1. Is there any kind of battery meter component i can put on the bike instrument panel to indicate battery level/power so i can see when low? That will let me know to rev engine after riding to charge it before shutting off bike. 2. Are there ANY creative alternatives to add some extra cells or battery(s) and some minor circuitry to charge it/them once the main battery has been fully charged by the alternator? Something has to be possible, and I'm committed to having tunes on the bike (non-headphones based) as long as the cost is not outrageous. ???

oldspark in his 2nd Reply wrote: A voltmeter across the battery. ..... The above is a rough guide....

That's your battery & system level meter. Maybe attach alternators off the crank, else gearbox. Or maybe wheels. Else solar power or wind generators. Extra batteries extend up time (reserve time) but need charging some time...

I did not read this entire topic, but I do have something to say about Honda charging systems.  I ride a Honda Silverwing.  It is a 600cc twin.  It is outfitted with a stator type charging system.  The only Honda that I know of that has an alternator is the GL models.  At 75K miles my Stator failed.  I ride with my High beams on in the daytime.  Probably about an extra 4 amps of current there.  I have an alpine head unit under the seat.  The way I listen to it, no more than 3 or 4 amp surges.  I do not know if the stator was just going to fail or if the extra amperage all the time may have caused the failure.  I now ride with the low beams on and only pulse the high beams when deemed necessary. 

I know it is illegal to ride without a headlight.  On my bike while I was awaiting the arrival of the new stator, I could press and hold the start button to turn the headlight off.  My bike requires the left brake lever to be depressed really hard for the starter to engage.  I am sure your bike will not spin the starter unless in neutral or the clutch is depressed.  You may be able to do that to charge the battery a bit.

oldspark wrote: oldspark in his 2nd Reply wrote: A voltmeter across the battery. ..... The above is a rough guide.... That's your battery & system level meter. Maybe attach alternators off the crank, else gearbox. Or maybe wheels. Else solar power or wind generators. Extra batteries extend up time (reserve time) but need charging some time...

anybody have any ideas here on how i can add some extra batteries to the system? perhaps something for extra reserve power that i can take inside and charge nightly after rides... could i just hook up some 12v cells in parallel to the main battery? other ideas?

Well yes - you said it. Connect another 12V battery in parallel and recharge at home. Common ground and fused +12V feed at each battery end (unless you are sure you have good connection security - no chance of shorts).

I can't say much about motorcycle batteries, but just had to post about how ironic your bikes are: I had brand new 2007 919 AND I had a 91 Nighthawk 750. What a coincidence! I'd probably faint if you said you used to have an 82 GS-750 and a 76 KZ-650!