Motorcycle Batteries and how they affect powering accessories?

Question by baggermike: Motorcycle Batteries and how they affect powering accessories?
Hi I have a bike that I am having a little problem with it powering my heated gear, the bike is rated at 432 watts at 7000 rpm and is a 3 phase 32 amp charging system, but the bike has a 10500 rpm redline and 7000 rpms at cruising is not good and around 4000 rpms feels good for cruising and on the hyway at 70 mph it is running at 4300 rpm so I do not know how many watts are being gennarated at that rpm, is there like a formaler to calcalate watts at that rpm, I have a program that you can put all the power the bike uses and with my heated jacket and gloves I have 35 watts left over. The battery is small and is rated for 200 cca and 12 amp hours, I can get a battery that has more power but do not know the benafites of the battery that puts out 250 cca and 18 amp hours, and if that would make the voltage regulator work more to keep it charged or hurt it, and only know that more amp hours would heat my gear better, so any info would help me allot. thanks Mike

Best answer:

Answer by Ryde on
Your battery is a storage vessel and matters very little while the engine is running.
So long as your charging system puts out enough juice, you don’t need ,nor will you benefit from a hotter battery.
The advantage to a more powerful battery is that it will turn over higher compression motors. ( cold cranking amps )

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4 thoughts on “Motorcycle Batteries and how they affect powering accessories?”

  1. I don’t know what kind of alternator your bike has, but if it’s a separate unit (not one on the end of the crankshaft), you may be able to find the power output curve for it. Delco Remy shows such curves for automotive applications on their web site. If your bike is Japanese, it might be something like a Denso and if European, it could be Bosch or Lucas.

    Find out the manufacturer of the alternator, get on their web site and see if they publish output curves. If not, try contacting them because I’m sure that somewhere and at sometime, they’ve tested their products. Just like dynoing an engine. Even if you don’t know the gearing ratio between the engine and alternator, if you can find your model alternator, it should give you an idea. If you find a chart and it shows, say 40 amps output at 15,000 rpm, just back down to the 32 amp level, see what the alternator rpm is and go down from there.

    Output curves are not linear and when compared to an engine dyno chart, they look more like the torque curve than the horsepower curve. In other words, double the speed and you don’t necessarily double the output.

  2. Rather than proving you’re okay or not through calculations, you should attach an inexpensive voltmeter on your bike and check the voltage as you ride. Calculations are never quite right.

    You’re not charging well if voltage drops below high 13’s. Depending on your battery you can keep riding for a while (especially if your low RPM is just for a light or otherwise temporary) or else dial down your clothing to keep the bike’s voltage up over, say, 13.5 V.

  3. Another issue you may want to think about is battery charging time.

    I heard, and I don’t know how accurate it is but I heard that it takes 30 minutes of riding or so to fully charge a battery.

    A lot of folks have their batteries die on them because they constantly run short errands and it takes a lot of charge from the battery each time they start.

    For instance, they start the bike up and go to the gas station
    5 minute ride – they shut the bike off.

    They start it up again after they are done pumping gas and they drive 5 minutes to a friends house to hang out. – They shut the bike off again.

    They restart the bike and go to Taco bell because they want some burritos and tacos and taco bell was 3 minutes away from the friends house…they shut the bike off again.

    Then they go home and on their way home they have to pay a bill so they go inside the post office – they shut the bike off again. They buy some stamps inside send off their envelope and get back on the bike..they start it up again lol.

    They then go home and shut the bike off.

    You can see how the battery is slowly losing its charge and especially if its an older battery and especially if folks are running accessories from it.

    I know what you are saying though..I wish they could put a huge Sears Die Hard battery in those bikes lol.

  4. Why dont you just put a Higher Output Stator in it?

    Bottom Line,,,that’s what’s required.
    There’s No Way around that.

    See if these folks have anything for Your Bike.

    I’d suggest contacting them about your output requirements at the rpm range you desire.
    See it meets your needs.
    They also have a rewinding service,I beleive.

    http://www.electrosport.com/index.html

    http://www.ricksmotorsportelectrics.com/index.php

    If your full output rating is at 7Krpm,,,,leaving you only a CALCULATED 35W,,,
    I Hope You included Battery Charging in your Load Calculations.

    Even if so,,,You’re PROBABLY running at a LOSS at 4,000rpm range.
    Almost Certainly.

    How much amperage is it Drawing at 4,000?
    What’s the Voltage under full load at that speed?

    If you have a 32A system,,,the Voltage Regulator should be sufficient to handle a higher output stator reliably.

    If you want “cheap life insurance” for the Rect/Reg ,,
    Stick a 12v Computer CPU/Case Fan on the Reg’s Heatsink.
    $ 5/5Minutes>>>> “50% Increase” in Life Expectancy.

    If this Mystery Machine of Unknown Make/Model/Year happens to have a unitized Rectifier/Regulator,,,,as most all do these days….
    You can Disable the Internal Rectifier and drop Heat thru the Floor by installing some cheapie Single Phase Bridge Rectifiers in each leg of the Alt’s Output.

    Real Simple,,,basically splicing them inline.
    That way,,,the Internal Rectifier is precluded from having to BLOCK anything.
    No Load=NO HEAT.
    They Dont Care if they Idle and simply Pass the Pre-Rectified DC thru.
    The Big Benefit is,,It Removes 32AMPS of HEAT off the Regulator’s Heatsink.
    Ya’d need 3 @ less than 10$ Each.

    If one fails SHORT—conducting FullWave AC,,Oh Well,,,the Internal one is redundant and the outboard one fails onto that.
    It automatically Resumes it’s Normal Function .

    If one fails OPEN—conducting NOTHING…
    Put a Jumper wire across it until you can relace the 5~10$ Diode.

    Just My Opinion,,I’d rather risk a under $ 10 discrete component than a entire $ 100~150 integrated device.
    Makes Sense to me,anyway.

    But You AINT likely to smoke a 35Amp/600Volt PER PHASE Diode Bridge.

    I Doubt the Original Bridge has any heavier than 10A or15A Diodes.

    I cannot suggest anything Specific,,,because I have No Idea what bike I’m talking about.

    Thought about LED Replacements for Running and Tail Lights?

    Incandescents pull about 1~2 Amps Each.
    LED’s will reduce that to less than 1/4 of current total.

    The 2~3 Amp capacity Gain dont sound like MUCH….
    Till you consider the difference of trying to charge Batt with Maybe 2A versus 5 or more.

    All the BS and Calculation and Grand Theory in the world WONT power your electrical system.

    What you Need to DO,,at Minimum,,,is Upgrade to a High Output Stator.

    It would also be Very Wise to add an Overkill-Sized, Fused power bus wire directly from the Battery to supply all your extra accessories.
    You can Manually Switch It,,,or use a cheap,simple Relay to correlate it’s energizing with your Key Swich.

    Bike Harnesses seem to be invariably Marginal-Sized wire gauge,,,and almost always induce Some voltage drop even with Normal equip.

    *Get yourself a H.O. Stator
    *Get the Load OFF the Bike’s original Wiring
    *Force Cool your Rect/Reg
    -Optional>Upgrade Your Rect/Reg to a HighOutput Rated one
    -Optional>Pre-Rectify each AC Phase to unload oem modular unit
    -Optional>>Use a Trio of Big Diodes,,,then into a Marine Regulator,,,Merc Outboard 40Amp one for example.
    They’re Cheap and Tuff.
    -Optional>Unload the Demand a bit with a LED Swap for a small gain in capacity

    Whatever You do,,,,
    Until You Increase OUTPUT,,,You’re getting Nowhere towards a Solution.
    Increased Output= Aftermarket Stator or Custom Rewound Stator.

    No Other real way to Increase Available Amperage output.

    Source:
    I was a Fan of the 60’s TV Show “Green Acres” and recall the Hanie Farm 🙂

    Moral: If You want to USE More Power…You gotta HAVE More Power.

    Or Else Decide what to Unplug,,so You can Plug In Something Else

    Good Luck with it,,hope Ya get it going good.

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