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Car Battery Charger

Discussion in 'Technical and Troubleshooting Torque' started by mattb, May 27, 2010.

  1. G'day All.

    I bought a non-maintenance battery today for the SR500. I opted to pay $10 less for an uncharged one and went and spent $20 on a car battery charger - the same one two mates have owned and which they and I have charged batteries with in the past. The guy at Autobarn tried to talk me into buying the bike specific charger, because "the car charger is not right for the motorcycle", but when asked why - it was $80! - he said, "Umm, look: it's got the right connectors for the bike battery terminals!" Wow, that's worth an extra 60 bucks!

    Anyway, I got some more knowing advice that said that actually the car charger is a problem because it charges at too high amps per hour - the bike battery needs around 1, whereas the car charger does around 5.

    Now my charger says nothing beyond: "output DC 12V at 2.7A" and has 2700mA displayed loudly on the packet - I take it that refers to the amp output as per above?

    The battery recommends a slow charge at around 0.6A for 5-10 hours, or a full charge for one hour at 3A per hour. So I'm guessing one hour of full charge for my battery on my Autobarn charger should be fine, assuming I have understood all this stuff correctly? When I or my friends have used this charger in the past, always on slow overnight charge, we've never had an apparent problem.


  2. Yes you are correct, the short answer is slower charges are better for battery longevity. Fast charges lesson the batteries long term life. You should be Ok with your charger but don't leave it on charge for more than an hour and feel the temperature of the battery to see its not getting too hot.
  3. I've only ever used the cheapest car type charger I could find. I've charged car batteries, bike batteries including the gel cell from the R11, powered lights, tested starter motors, experimented with electrolytic rust removal (magical process BTW) and God knows what else with the thing. The only precaution I take is to not charge a bike battery for more than ~12 hours from completely flat. Your bike's electrical system, if healthy, will put a far faster boost charge into the battery than even the biggest trickle charger ever could, and if your bike takes a bit of churning to start in the morning, it'll be doing it every day. Compared to that, using a car charger is nothing. The whole bike charger > car charger has only really arisen recently. Until a few years ago, car chargers were all you could get and nobody worried about it.

    I've never had a problem and my batteries last a looooong time.
  4. Too bad you aren't in QLD. I have a trickle charger that would be perfect for that job. Though it was a bit more then $20 lol
  5. Would be handy to have a multimeter to check how much charge you're actually getting, you probably won't get the full 2.7 amps anyway, and it will drop off as the battery gets more charged.
    If you want to reduce the charge rate, just put a headlight bulb in series with the battery.
  6. The battery on my R1 was dead over the weekend when the buyer came to look at the bike

    I used a car battery charger to recharge it -- it has a 2 amp and 8 amp charge setting ( fast and slow I guess )

    It charged it up in 30 minutes then the charger shut down automatically so not as to over load the battery

    Have no idea where I got the charger from but it was cheap and who cares if it had car battery size terminal alligator clamps

    It worked fine for me on 8 amp charge
  7. I've got an el-cheapo 4 amp car charger, works fine on bike batteries down to even 3Ah. Given, its a quick affair to charge and you don't want to leave it overnight or anything silly like that...

    - boingk
  8. Well the Autobarn option worked fine. Came back twenty mins after setting it, and it was fully charged. I didn't think to check where the charge was at before setting it.