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Battery drain

Discussion in 'The Garage' started by joebeets, Oct 9, 2012.

  1. joebeets

    joebeets XS400 Member

    What we have here is a 1980 400xs. something is draining the battery very slow when the ignition is off. Anyone know how to trouble shoot this so I can find the problem?

  2. HoughMade

    HoughMade XS400 Guru Top Contributor

    Take the negative battery cable off. Hook a 12 volt test light between the negative battery post and the cable. If the light glows dimly, you indeed have a draw. Remove the fuses one at a time. When the light goes out, you have found the circuit with the draw. Then you have to trace down what in that circuit is drawing the power. You could do this by unplugging things in that circuit one at a time until the light goes out again.

    But first things first- how slow is it draining? I find that if I don't ride about once a week or keep it on the charger, the battery will be low and it will not start as easily. The charging system may produce enough power to keep the engine running fine, but it may not keep the battery up to 13 volts. I don't think there is anything wrong with the system in that situation, it's just that 30+ year old charging systems are not as robust as what we expect today. It could also be a bad battery or new lights or accesories that draw more power than the original equipment.
    jaeg and Danu like this.
  3. xs400newbie

    xs400newbie XS400 Enthusiast

    Good point. If I let my battery sit a few days, bike won't start. My bike seems to want a fully charged battery to start up.
  4. joebeets

    joebeets XS400 Member

    Thanks for the advice I will check that out.....
  5. HoughMade

    HoughMade XS400 Guru Top Contributor

    I keep my bike on a smart charger when I am not riding. I am on my 3rd year with a cheap Walmart battery and the bike has never left me stranded no matter how long the ride.
  6. Danu

    Danu XS400 New Member

    Joe, did you ever test this power drain issue? I'm having the same problem with the same year bike, but I'm pretty sure it's just the old age. I also know my battery won't charge unless it's around 3k RPMs, so cruising around town at low RPMs can be a drain too.

    Curious to see what you found out!
  7. jaeg

    jaeg XS400 Member

    Thanks for this guidance! I had a gut feeling that I had a slow draw somewhere but after testing it (and validating by turning the ignition on) I found I actually do not have a draw, which means I can cross something off my list. Thanks again!

    Also, I’ve found mine starts easiest if I’ve been letting the battery sit connected to my Battery Tender. I wish I didn’t have to rely on that though. I’m currently using an Origin Battery (OR12A-A / 12V12AH) but I’m not convinced it’s the best one for me as I’ve said I don’t like having it on the Tender. What do you use? I’m supposed to run (based on the manual) this - YUASA 12N12A-4A-1. I did find this at BatteriesPlus:
    Last edited: Dec 28, 2021

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