WPS Alternator 170A

Discussion in 'Technical' started by chewy, Apr 14, 2018.

  1. chewy

    chewy Active Member

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  2. rob260

    rob260 Moderator Staff Member

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    @chewy a couple years back I did a group buy on BNR 180a alternators. We bought ten, one failed and was refunded under warranty, the others are all still going as far as I know.

    You can purchase from their eBay store.
     
  3. geron

    geron National Petroleum Equipm

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    I installed a 120a in the Z. Was told anything greater will require a wiring upgrade, to the battery I guess??

    120a is a lot, IMO.
     
  4. rob260

    rob260 Moderator Staff Member

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    Nah the more the better really. The rating on the alternator is an indication of potential; it will never produce more current than the electrical system demands.

    Upgrading the wiring between the B terminal and the battery is still a good idea, but don’t think that a 180a alternator will put a greater strain on the wiring than a 120a or even a 90a alternator under identical operating conditions.
     
  5. rob260

    rob260 Moderator Staff Member

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    That being said though I suppose a lower amperage alternator is going to create less parasitic drain on the motor. I doubt the difference would be measurable though.
     
  6. Shane001

    Shane001 Well-Known Member

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    Or would it be the opposite?
    ie 80A draw, would a 90A alternator be working a lot harder than a 180A alternator, thereby the 90A putting more load on the engine?
    Have wondered this ;)
     
  7. rob260

    rob260 Moderator Staff Member

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    I don’t think so - if we’re talking more coil and armature windings I would think that the energy required to spin the armature would be constant? Happy to be corrected though.
     
  8. chewy

    chewy Active Member

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    The voltage regulator of alternators are about 14.4V so at max output on a standard 90A alternator means 1.3kW of power being generated. Worst case, an alternator might be 50% efficient so that means you are taking 2.6kW of engine power to run the alternator. Going to a 180A alternator means 5.2kW of engine power being used at max output. Not a lot of power being zapped from a standard engine at 200kW. Plus an alternator will only output as much current that is being demanded by the electrical system so if you only need 120A of the 180A then it will only produce 120A and hence less power taken from the engine. You don't want to have a demand of current too close to the max output of your alternator but you also don't want an alternator that has much more than you need as you are most probably sacrificing Amperage output at lower / idle speed. I suspect these high output amperage alternators are made by putting fewer turns of heavier wire on the alternator stator windings. That reduces the winding impedance and lets more current flow, provided you have enough changing magnetic flux to excite the windings. But low RPM performance goes down because there's less changing mag flux. More windings of finer wire make better use of the lower mag flux.
     
  9. ZXOCET

    ZXOCET Member

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    Should also consider the influence of having an underdrive alternator and crankshaft pulley assembly at idle and low revs if vehicle is used for stop/start city driving or used on the open road
     
  10. Shane001

    Shane001 Well-Known Member

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    Geron what 120A alternator did you use?
    Was it a direct bolt on?
     
  11. geron

    geron National Petroleum Equipm

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