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bigger alternator

Discussion in 'Truck & Equipment Repair' started by wisbiker55, Feb 25, 2011.

  1. wisbiker55

    wisbiker55 Junior Member
    Messages: 4

    I have a 1997 F-250 heavy duty with a 8' western plow. I want to install a bigger alternator. I have a 95 amp now and would like to go to a 135, lights dim, heater slows , when plow is lifted. Can i run another heavier wire ( 6awg to a 4 awg) to the battery from the alternator right to the battery with the old wire from the alt still connected? Will this work? Thanks for any help..
     
  2. wastedwages

    wastedwages Junior Member
    Messages: 25

    Please see link below. I would also caution you on who you purchase an alternator from. There are some unscrupiouls people serving this market. I would ask for a test sheet and a video showing your unit on the test stand with verifiable marking on the alternator. So you know that your unit is putting out the advertised amperage. Also think about the other end of the ciruit, the ground side usually needs to be beefed up.

    http://www.dbelectrical.com/p-3478-ford-chevy-high-output-alternator-fuse-block-wiring-kit-101.aspx
     
  3. Ozark Hillbilly

    Ozark Hillbilly Member
    from Misery
    Messages: 53

    I think you would be better off to have your current alternator tested at the parts store if you want to, but I doubt that it is the problem. Your 95 amp alt should be able to handle things just fine as long as it is working properly and you are not thumping around with some hideous giant stereo system.

    It is more likely that you have a poor connection or weak battery problem. As long as you have good clean contact the current wiring should work fine. If you really want to increase the reserve capacity of your electrical system I believe you would be better off to look at the battery end of things. Do you currently have dual batteries? If not then installing 2 new identical batteries and cleaning up the connections at the batteries, solenoids, plow, and alternator should give you plenty of power to run your plow as long as the current alternator tests ok. In fact, a 60 amp alternator vehicle can run a plow just fine as long as the battery and connections are good. A plow is typically going to draw 200 amps or more when activated, but the duty cycle is low enough that your current alternator should not be the issue. Even a single battery system can work fine but the dual batts will last longer sharing the load. And as wastedwages mentioned, don't forget about both the plow and chassis ground connections.
     
  4. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    why not check our ford section for just this exact topic in the last week. Thumbs Up

    and there is a lot of info posted on it in there.

    welcom to the site. :waving:
     
  5. Mister Plow

    Mister Plow Senior Member
    Messages: 139

  6. wisbiker55

    wisbiker55 Junior Member
    Messages: 4

    Thank you all for your replies I am going to try upgrading my wires first
     
  7. forbidden

    forbidden Senior Member
    Messages: 392

    www.the12volt.com has two threads on the site that will directly pertain to this. How to upgrade the Big 3 and What is a proper ground. Ohio Generator makes a stellar purpose built alternator.
     
  8. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

  9. DIRISHMAN

    DIRISHMAN PlowSite Veteran
    Messages: 4,256

    To answer your question.I to have a 97 F 250 HD 5.8 liter If you have the same egine as I do you can just bolt on a 130amp alt from a 96ford explorer. No change or cutting needed just unbolt old one and install new one. I just did it one month ago and also installed a deep cycle battey and what a difference. One more thing there is another web site like this that is mostly for broncos but guys with P/U trucks are welcome as well .There is a link/thread on there and pic and graphs of what alt can be used from what vehicle it is called www.FSB.com or FullSizeBronco.com Hope this help PM me for any other advise if I can help. Good luck
     
  10. wisbiker55

    wisbiker55 Junior Member
    Messages: 4

    Thank you all very much. I plow snow for the city here and have my own truck to do mine and some of the neighbors. Been plowing with it since it was new. Just got used to the dimming of the lights. I talked to my brother in law and he told me about this site. Glad he did. I stopped at Fleet Farm today after work and armed my self with 4awg wire and connectors. Went home and reworked the big three. Hooked the plow up and what a difference. Still might put in a bigger alt if I find one. I can put more lights on it then. Thank you very much
     
  11. forbidden

    forbidden Senior Member
    Messages: 392

    Did you fuse the + line from the alternator to the battery? If not, this must be done.
     
  12. 2007gmchts

    2007gmchts Junior Member
    from MN
    Messages: 6

    Go with 2 batteries. I've been running 2 to power the stereo (big amp and speakers) heated seats, etc. I've never had a problem with lights dimming.
     
  13. ProSeasons

    ProSeasons Senior Member
    Messages: 624

    This is just plain wrong. I had 2 group 31s and a 136 amp alt and it could'nt keep up with plowing. I had to upgrade to Wyldman's 160 amp Leece- Neville. A 95 amp alt is woefully underpowered for the demands of commercial plowing. A 60 amp alt is just ridiculous.
     
  14. wisbiker55

    wisbiker55 Junior Member
    Messages: 4

    I did fuse the wire from the alt to the battery
     
  15. FordFisherman

    FordFisherman PlowSite.com Addict
    from 06611
    Messages: 1,593

    Go to the junkyard and grab a 130 amp from a Ford Taurus or many others. It'll bolt right up. Those 3G alts have been tested and put out up to 160 amps or so I've read.
     
  16. Ozark Hillbilly

    Ozark Hillbilly Member
    from Misery
    Messages: 53

    The odd thing to me about this is it means you think a lot of people on this site are using plows that must not be working. I guarantee you a LOT of people on this site are plowing away just fine with alts you consider woefully underpowered and unusable. I do not have a 60 amp alt vehicle out plowing anymore. Our '79 Chevy C30 that has plowed for over 30 years only relied on its 60 amp up until sometime in the 1990s when the alt failed and I replaced it with an 80 amp. So I guess the 60 amp one did only last 15 years or so. Maybe the 80 amp one will end up doing better.:) That truck recently plowed for 2 days nonstop with driver changes.

    Newer vehicles do have a higher base vehicle electrical load due to the requirements of computers, injectors, stereos, etc.. But even on a newer vehicle that load can still be handled by his 95 just fine as long as the battery and connections are good.

    Of course you may be doing a completely different style of plowing than I am familiar with anyway Proseasons, It may well take a ton of juice to move a plow that is going at the speed you need 550 hp for. I'm guessing that by the time you reach 100 mph it is throwing the snow pretty far. Sounds handy.
     
  17. forbidden

    forbidden Senior Member
    Messages: 392

    2007gmchts - Batteries do not run the vehicle, the alternator does. If the vehicle was struggling to have enough current with one battery, by adding a second all you have done is increase the strain on the alternator. While the alternator may handle this on a temporary basis, the alternator is going to fail. It is only a matter of time. Yes two batteries are going to supply you with more current when needed, current that is dumped into the system when the alternator cannot supply the needed current. It does not solve the problem though. The vehicle runs at 14.4 volts, this is the supply voltage from the alternator. The batteries supply 12 volts. Get a meter out and check this for yourself as it will confirm instantly to you why you should be running a high output alternator for any vehicle that has a large current draw, from snowplows to stereos.
     
  18. Mister Plow

    Mister Plow Senior Member
    Messages: 139

    Quite the statement here. I think you will get a lot of disagreement. The alternators main purpose is to recharge the battery, and it is the battery that supplies the large load power when needed. (Like, say, the starter motor for instance.) You can get by just fine with a small alternator if you have a large enough energy sink (battery) to supply your electrical needs.
    When the battery does not have enough juice and is a drain on the alt, along with the standard electrical loads, is when the alt needs to be bigger.
     
  19. Ozark Hillbilly

    Ozark Hillbilly Member
    from Misery
    Messages: 53

    The vehicle just needs electricity. It does not care where it comes from.

    If I just want to plow a couple of neighbor's driveways I could take my alternator belt off and go get the job done. I just can't plow for long that way. If I remove my batteries then I will be staying home.

    It really just boils down to duty cycle of the equipment used. Plow manufacturers are able to effectively utilize electric instead of engine driven pumps on their plows because of the relatively low duty cycle an electric plow pump needs to be operated at.

    As most anything dealing with something electrical does, the best way to look at it is with math. Just for fun and to illustrate how to do it with some real world example numbers in case anyone would like to know how the duty cycle is applied then here goes:

    These numbers came off a '96 F250 5.8l with a 7.5' Western, two batteries, factory 95A alternator.. I used a digital ammeter with an inductive pickup and a separate multimeter that was just monitoring battery voltage.

    The battery voltage at rest read 12.83v coupled together and uncoupled they read 12.81v and 12.83v individually. This indicates that the batteries are in good shape and charged.

    Started the truck and I got steady 14.1 -14.2v. Everything looked good.

    Put the truck in a typical plowing configuration with lights on, defroster blower on medium, radio on. Still showing 14.1v at battery. With my ammeter clipped over the alternator output wire I got about 42 amps that the truck is drawing in this configuration. I will round up to 45 amps so I end up with a conservative duty cycle.

    To work the alternator hard I lifted the plow and ran it side to side continuously for about 30 seconds. This provided amp readings in the high 80's for the alt output while simultaneously dropping voltage at the battery to the high 11's while the pump was active. Voltage would recover quickly when the pump stopped. I will round down alt output to 85 amps. This minus the 45 amps that the truck requires leaves 40 amps of charge output headroom available to the battery to handle the plow load over the normal truck requirement.

    After clipping the ammeter to the plow pump wire I got about 205 amps running the pump side to side and 215 or so while lifting though the numbers bounced around some. Again to be conservative I will round the plow draw up to 225 amps.

    So the available duty cycle of the plow on this truck is 40 amp charge headroom divided by 225 amp plow draw equals 0.177. That gives a 17% duty cycle. So as long as the pump is running less than 17% of the time during a plowing session the alternator should keep up fine. Any more than that and it will be using battery reserve in excess of what the alternator can supply and is going to run out of electricity eventually while plowing.

    I really have no clue what percentage of the time I have the plow activated when out plowing. I'm sure it depends quite a bit on the individual lot. I suspect it might not be more than 10%. Must be less than 17% anyway cause it has been working fine. Our electric pumps also will not be rated at a continuous duty cycle. Just like a starter motor, you can burn one up by overusing it.

    I did not repeat the tests with just one battery but if I had what would have happened is the voltage at the battery would have been lower with the pump active while the single battery provided all the excess current on its own while absorbing twice the amp hour discharge of its capacity as it would have with dual batteries. The main downside to this would be shortened battery life as it was being discharged and recharged at higher rates.

    This also shows that if you want an alternator truly capable of powering both the truck and the plow without needing to borrow from the battery reserve that even on this older truck with a small plow it would need an alternator in excess of 250 amp capacity.

    A bigger alternator can get you increased duty cycle if your pump can handle the heat and will also let you have more lights and luxuries running, but often it just is not really needed.
     
  20. forbidden

    forbidden Senior Member
    Messages: 392

    Mister Plow, I read that after I wrote it and was going to go back to edit it out (the wife factor came into play). Both alternator and batteries are essential for the proper operation of the vehicle. A good alternator is no doubt a super important part of the equation in the case of any vehicle that has a serious electrical draw. It still stands to reason though that the alternator is doing the majority of the work when the vehicle is in operation and the voltage is not dropping below the normal charge state of the batteries. If the voltage is down below that of the batteries, then indeed it is the batteries that is doing the work as well as the alternator trying to keep up. In that case, not long before rather nasty voltage and currrent problems are going to develop.
     
    Last edited: Feb 26, 2011