Increase Alternator Output

Discussion in 'The Garage' started by sherloc, Aug 22, 2019.

  1. sherloc

    sherloc Been here awhile

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    Hi,

    Looking to increase the alternator output on a KTM 1190. Stock is 450w, having issues running aux lights, etc at the same time.

    Any suggestions on a good person/place to start to get the alternator windings redone?

    Thanks!
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  2. PeterW

    PeterW Long timer

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    The good news is it can be done in theory. In practice most alternators have as much copper packed in the available space as is practicable. And almost no one sells silver wire these days. There are also some more efficient regulators turning up now which MIGHT get you another 15W or so.

    LED headlights, taillight, aux or live with the shame and buy a BMW is the better answer.
    #2
  3. ragtoplvr

    ragtoplvr Long timer

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    when you reduce the number of turns in the windings and increase the diameter of the wire, you get more output but at a higher RPM. output at idle will fall a lot. Like the long duration camshafts, you sacrifice low to get high. And more turns gets more output at idle. Less at high RPM.

    You usually can only pack so much in the space, getting out the heat is a huge issue. Can something spray oil on the windings evenly. Most of the time only stronger magnets and more lamination's is effective and there is seldom room for that.
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  4. Steve_h

    Steve_h Been here awhile

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    you reduce turns and increase diameter, you get more watts but less volts requiring more rpm to make the same voltage. Low speed power generation will suffer.
    More turns, same diameter will increase voltage but not wattage. Probably over-volt and blow rectifier/regulator.
    Same turns, thicker wire, more watts at same volts as before. There is likely not enough room on the stator to do this. They are usually packed pretty tight. You have to worry about the 'stick-out' of the wire to the front and back of the stator as well as between the coils. There isn't much extra space on most bikes around the stator either.
    An experienced rewind shop can tell you if it can be done if you can show them the stator. You will have to know how far the coils can stick out from the front and back.
    If you can get more current out, this will put more load on your R/R and the charge circuit wiring. You will have to make sure they are up to the task or make adjustments.
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  5. sherloc

    sherloc Been here awhile

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    I had an 05 RT that had a 720w alternator, plenty of juice. Checked the new GS, it’s 510w (3 phase, does that make a difference)? Even the new RT is only is only 508w.

    What regulators are you referencing? Be willing to give that a try.

    Thanks!
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  6. sherloc

    sherloc Been here awhile

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    Idle is where the problem is already the biggest. I can run most of the load at speed, it’s at idle where the volts start dropping rapidly. Replaced the regulator (OEM to OEM) and it helped initial problem.

    Thanks for the reply. I knew there was a way, needed to understand the pros\cons.
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  7. sherloc

    sherloc Been here awhile

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    @Steve_h - Thanks for the info
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  8. ragtoplvr

    ragtoplvr Long timer

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    I have wound and tested at least 20 different stators. The number of turns limits the current, because of the impedance and core saturation. Making the wire larger does increase a little, very little. maybe 5 %

    To get a meaningful increase you have to reduce the turns, or make the magnet stronger less air gap. For example substituting Neodymium magnets for ferrite took a 38 amp stator to at least 70 amps. It lasted about 45 seconds though.

    Much bigger wire and fewer turns and increased air gap ended up at 35 amps st idle and over 65 amps at 5000 rpm. Had to use 240C wire. The leads would not fit thru the engine case. The heat over heated the oil around the stator and it turned to sludge, then the stator burned up. Had to make a regulator for testing. Next step would have been finding a way to get more oil in there. The cover already got hot enough to hurt if you touched it. You just cannot cram 75 cents of sand in a 50 cent hole. sales with drilling out the passage in case, adding oil control vanes, and finned primary cover would have been very low due to price. Later models have more area allotted to the alternator, and 55 amps is peak stock. you cant have it all. You need fewer turns so less excess watts are made at higher RPM to keep total dissipation under control at increased current.

    Rod
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  9. Steve_h

    Steve_h Been here awhile

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    I didn't mention the parasitic losses due to resistance in the wire. Something that @ragtoplvr has discovered. When you increase the temperature, resistance increases exacerbating the situation. When you make more current, you also have to deal with whether or not the wire can safely carry that much current without a melt-down losses to heat from internal resistance rise. There are eddie currents induced in the stator core that also contribute to heating. The fact that motorcycle alternators shunt extra power to ground through the r/r means that your stator is running at full output all the time. Everything in the system must be able to handle full output constantly or it'll die from one thing or another.

    3 phase lets you use a little more of the power by having 3 voltage pulses instead of 2. Pretty much all motorcycle alternators are 3 phase from the factory. If you have 3 power leads coming from your stator, it is 3 phase.

    More magnetic flux generates more current from the same windings. More rpm generates more voltage from that same set of windings. The whole things is a very finely orchestrated balancing act to get the desired functionality without anything giving up and letting out the magic smoke.

    You can get more power by using an excited instead of permanent magnet rotor but then you add slip rings and contact brushes with additional wires and electronics(susceptible to heat, vibration and water infiltration) to control the magnetic field so that you generate the amount of current and voltage required. It has been tried on a few bikes with meager success. The ones I know of suffered a high amount of generator issues compared to the normal bike generating system.

    I have seen pictures of older goldwings with holes cut in the timing belt covers so a belt can exit from a pulley added on top of the timing pulley to drive a car alternator.
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  10. nk14zp

    nk14zp Long timer

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    I have a SH 847 RR and a led headlight in my 950. I have all I need for juice. Voltage holds good with carb heaters, heated liner,heated grips and a 6" led light bar.
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  11. nk14zp

    nk14zp Long timer

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    My idle is 1400-1500,13.8v at acc2 port.(bat reads 2 tenths higher at the terminals) if it helps.
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  12. Beezer

    Beezer Long timer Supporter

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    the easy fix is LED aux lights??
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  13. NJjeff

    NJjeff Long timer

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    Excellent replies, I have little to add but note your RT has a different type of alternator than your KTM.
    The RT is a field excited alternator (just like a car) where the KTM is a permanent magnet.
    The RT's unit can supply additional voltage to the field to increase output at low RPM.
    The KTM relies on permanent magnets rotating over the wound stator so the output is not variable. It only increases with RPM.

    Agree with others. Reduce you demand via LED's.
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  14. ragtoplvr

    ragtoplvr Long timer

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    H4 goldwings had a hitachi car style alternator driven off the cam shaft, when it failed required engine removal. They spun so slow, they tended to overheat if loaded to capacity. There were stators made with the biggest wire that would fit, but the stock turns so they did not get as hot and rectifier heatshinks made of copper rather than aluminum. They lasted much better.

    Rod
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  15. sherloc

    sherloc Been here awhile

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    The aux lights are LED’s, Clearwater Erica’s, 60 W total when burning @ 100%. It’s the halogen headlights that are causing the major load (55W 2x). Will be investigating the Cyclops LED headlight bulbs, they save about ~50W according to Cyclops.

    I just did a bit of road testing, reading bikes volt meter. Tested, Volt meter reads the same at battery. Here’s the results.

    DRL on ( since it’s daylight, low beam is off) rolling down the road ~70 mph
    Erica’s @ 30% = 13.9v
    Add heat grips = 13.7-13.8v
    Add 1st heated jacket and gloves = 13.6-13.7v
    Add 2nd heated jacket and gloves = 13.5-13.6v
    Above load in stop and go traffic = 12.9-13.1v
    Turn On high beam with above load = FAIL, falls quickly below 12.v in stop and go, at speed it will slowly fall below 12v. Erica’s go to 100% when high beam is selected.

    Low beam on (DRL off) - same load as @ night rolling down the road ~70mph
    Erica’s @ 30% = 13.8v
    Add heat grips = 13.4-13.5v
    Add 1st heated jacket and gloves = 13.2-13.3v
    Add 2nd heated jacket and gloves = 12.5-12.6v
    Above load in stop and go traffic = 12.1-12.2v
    Turn On high beam with above load = FAIL, falls quickly below 12.v in stop and go, at speed it will slowly fall below 12v. Erica’s go to 100% when high beam is selected.

    When the fan comes on, that’s good for .2-.3v of draw

    Agreed, LED headlight bulbs will be the next step. Also will be planning on adding a switch and relay for the heated gear circuit, to be able to fine tune when stuck in stop and go or low speed riding, without needing independently switch off each item.

    Thanks for the input, would still like to understand if a different regulator would add additional watts..

    Craig
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  16. Johann

    Johann Commuterous Tankslapperous

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    In general there are two ways to attack the problem...

    Increase the output
    Reduce the consumption

    In every scenario where I´ve come across the same problem (bikes and boats) reducing the consumption is always the smarter move. Heat is the #1 killer of stators/rectifiers/electronics, anything you can you can do to give everything in your charging circuit an easier life is a step in the right direction, the OEM specc´d wiring is OK if everything is 100% but there is normally very little extra capacity if something goes wrong, like a small amount of corrosion on a connecter to a R/R or stator. if the aux lights are already LED then LED conversions for the headlights(s) is the next logical step.
    #16
  17. cagiva549

    cagiva549 whats a cagiva

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    Custom rewind in Birmingham boosted my stator about 15% , it ran 275 watts of lights , electric jacket liner and gloves and all the bike incendentals without issue on my old 950 . It’s got swapped into new 950 two weeks ago when stator in new 950 crapped out , as soon as I get home the burned one will get shipped to them for an upgrade to install in my spare motor . I don’t work it as hard now , with a tourtech hid headlight I can see without needing all the extra headlights . I only have ditch lights now .
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  18. sherloc

    sherloc Been here awhile

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    What’s the cost of a rewind? Custom Rewinds URL is dead, hopefully they are still in business.
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  19. Johann

    Johann Commuterous Tankslapperous

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    Add heat grips = 13.4-13.5v
    Add 1st heated jacket and gloves = 13.2-13.3v
    Add 2nd heated jacket and gloves = 12.5-12.6v

    Not being facetious but heated grips and gloves at the same time? A set of handlebar muffs would look bloody awful but kill windchill 100% and use zero leccy. I don´t know what temperatures you are riding in but I´ve ridden through a fair few winters in the UK including two years despatching full time using just handlebar muffs. On the rare occasion I had access to a bike with heated grips (normally K series BMs, the odd R80/100) it was very welcome but with muffs I was normally wearing summer gloves with no problems.
    #19
  20. cagiva549

    cagiva549 whats a cagiva

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    It’s been a few months since I talked to them , they don’t internet , phone only and I’m on the road and won’t be home for a month or so . It was a few years back but somewhere a little over a hundred bucks to rebuild my stator .
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