Installing an IOTA 15a 3-stage charger in VW Westfalia

Discussion in 'Homework Help' started by ger32, Aug 25, 2010.

  1. ger32

    Thread Starter New Member

    Jul 5, 2010
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    I have mounted it in the engine compartment rear right. I have connected the 12v cables to the pos. and neg. on the alternator and the 120v cable to the outlet left of the frig. Q: Is this a correct installation? My voltmeter reads 14.3 at the terminals on the charger but my ampmeter reads no current flow. (I purposely discharged the house battery down to 11v overnight for this morning's test) it's been hooked up for about an hour now and the voltage isn't increasing.
     
  2. Heavydoody

    Active Member

    Jul 31, 2009
    140
    11
    I am not familiar with this chassis, a wiring diagram would be great if you have one. Since you specified discharge of the house batteries, I assume the vehicle has a separate chassis (cranking) battery. So then, what lies between the alternator and the separate batteries? On large motorhomes which have a common alternator one frequently finds an isolator (probably cased in heavily finned anodized aluminum) to prevent the separate batteries from drawing off each other. These fail on a regular basis. Or, there may be separate alternators (another common practice on larger motorhomes). Can you trace out the cables? By the way, what supplies the power to the outlet? Shore power, generator? I assume since you are installing a charger the house is not equipped with an invertor.
     
  3. Heavydoody

    Active Member

    Jul 31, 2009
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    BTW, the cable from the alternator to the house battery is also typically fused somewhere along the line.
     
  4. ger32

    Thread Starter New Member

    Jul 5, 2010
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    The alternator charges both batteries with the cables I have connected to but the charger won't. If I take the charger up front and connect to the house battery, it charges just fine--30 amps. Maybe there is a diode or something in the way. I may have to run a wire from the charger directly to the battery --about 10 feet--how heavy gauge should I use?
     
  5. Heavydoody

    Active Member

    Jul 31, 2009
    140
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    I just did a quick search and found this discussion http://www.thesamba.com/vw/forum/viewtopic.php?p=3158144 which seems to indicate the existance of a relay. Just a guess, but the coil of the relay is probably signaled by the relay post on the alternator so that the batteries are joined together for charging while the engine runs and separated on shut down (I did something similar to a coach on a much larger scale once). This would explain the failure to charge.
     
  6. Heavydoody

    Active Member

    Jul 31, 2009
    140
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    The sizing of this cable depends on the maximum current the circuit might see and the voltage. I found a calculator here http://www.freesunpower.com/wire_calc.php which calls for 10 gauge at 15 amps over ten feet. Make sure you install an inline fuse rated slightly higher than what you expect to see (20 amps would be good) close to the battery so a short doesn't burn your VW to the ground. Also, pay particular attention to moving components and hot (exhaust) components when routing the wire.
     
  7. ger32

    Thread Starter New Member

    Jul 5, 2010
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    So the fuse is next to the battery--not the charger-- why is that? You are being so helpful! Thank you.
     
  8. Heavydoody

    Active Member

    Jul 31, 2009
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    If you look in the manual http://www.iotaengineering.com/pplib/dlsmanl.pdf
    it actually calls for a breaker within 18" of the battery. If a short occurs between the battery and fuse, charging or not, the only limit to the flow of current is the capability of the battery to deliver current, which is sufficient to start a fire. If a short occurs between the charger and the fuse while charging, the charger's built in protection should prevent any problems from its end while the blown fuse prevents problems from the battery.
     
  9. ger32

    Thread Starter New Member

    Jul 5, 2010
    14
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    The accompaning manual does insist on the fuse and I was planning fusing it, I needed to know the "why" re location. Now I know with your help!
     
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