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Thread: 24 Volt alternator ??

  1. #1
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    24 Volt alternator ??

    Hi Guys,

    I need to charge 2 12V batteries connected in series for a 24V Lawnmower robot. I want to charge the batteries on the fly (whille system is in use) with 4hp lawnmower engine. The batteries are 12v 12amp so they dont have enough juice if I don't charge while they are in use and I am using smaller batteries to keep the system weight and size small.

    the question is what cars came with 24V alternator so that I can goto junk yard and get the alternator ?

    is there any other way to charge the 24V system with 12V alternator while its in use.

    Thx
    0-0-7

  2. #2
    Maximum Bitrate GoHybrid's Avatar
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    i actually built a circuit for this kind of thing... we had a 36V actuator driven by three 12V batteries in series, but only a 12V charger to charge them back up. I accomplished it using a DPDT relay and some diodes ( i think 6 or 7... it's been awhile) In essence, the relay "rewired" the circuit for series or parallel operation whenever it sensed the 12V charging current. The diodes simply served to prevent the batteries from shorting out against eachother in either mode.

    If you're familiar with how all that stuff works, you should be able to piece it together and just use a 12V alternator. If not, just let me know and I'll dig it up and post what i did.
    Et ipsa scientia potestas est.

    Worklog for my 2007 Civic Si ...f*** it...
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  3. #3
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    Quote Originally Posted by GoHybrid View Post
    i actually built a circuit for this kind of thing... we had a 36V actuator driven by three 12V batteries in series, but only a 12V charger to charge them back up. I accomplished it using a DPDT relay and some diodes ( i think 6 or 7... it's been awhile) In essence, the relay "rewired" the circuit for series or parallel operation whenever it sensed the 12V charging current. The diodes simply served to prevent the batteries from shorting out against eachother in either mode.

    If you're familiar with how all that stuff works, you should be able to piece it together and just use a 12V alternator. If not, just let me know and I'll dig it up and post what i did.

    I admit that I am not much familier with this stuff but I have built my own carputer and custom lcd bezel.

    so I should be able to charge my batteries while I am drawing 24V 40amps from the system ?

    I would appreciate if you can post some details. What sort of diodes that you used and how to wire it up etc...

    Thx

  4. #4
    Maximum Bitrate GoHybrid's Avatar
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    i guess i should have asked this first, but what charging current do your batteries require?
    Et ipsa scientia potestas est.

    Worklog for my 2007 Civic Si ...f*** it...
    Pictures of the Corolla (retired)here
    Need to make something? Here are a few ideas.

  5. #5
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    The way I understand it is that my alternator will putout 80 amps.

    most of it will be used by the drive motors and whats left of it will be used to charge batteries kind like car charging system.

    wouldn't it work that way ?

    My batteries will be either 12Ah or 33AH haven't baught them yet.

  6. #6
    Maximum Bitrate GoHybrid's Avatar
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    the alternator's output current is simply a rated maximum. The motors and batteries will only pull what they need to do what is being asked of them.

    well anyway, here's what i'd do: when you buy the batteries, look for a data sheet or ask the manufacturer what the ideal charging current should be. If it's at or around 1 amp, (which it might be for that size battery) you can do this with the relay and diodes... otherwise it may be out of the range of simple diodes. As soon as you know what the required charging current is, we'll know what to do.
    Et ipsa scientia potestas est.

    Worklog for my 2007 Civic Si ...f*** it...
    Pictures of the Corolla (retired)here
    Need to make something? Here are a few ideas.

  7. #7
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    thx for help Hybrid but I think I will go with 24V alternator.

    Does anyone know what cars came with 24V alternator ?

  8. #8
    lez
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    err, uk army landrovers, especially ones for radio comms.

    Just ask at a local motor shop etc, I'm sure some of the bigger trucks etc will be 24v

    Thats how it is over here, but it is getting harder to find them as 12v is so well adopted everywhere
    Lez, more widely known as flez1966

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