Motorcycle Repair/Battery drain


Bought a 2009 honda rebel with 46 miles on it , I replaced the battery , got the Carburetor cleaned , now the battery won't seem to hold a charge , I have a drain somewhere , it seems like a brand new bike , what could be wrong ...

Hi Jesse,

A few things could be happening here.  The first thing is to have
your new battery charged at a low rate with a battery charger.
Batteries need an initial charge to get them going, the bike is
rarely able to provide a decent charge.

Most of these bikes do not have enough charging power to charge
the battery on short city trips.  They need 15 minutes at about
4000 rpm to bring the battery to full voltage.

If you ride in the city or short infrequent trips you will have
to keep a battery tender on the battery. These are very low
about 1 amp chargers that maintain the battery.

The bikes do not charge much at all at low speed or idle speed.

Another thing you should check is the charging output.
Use a multimeter on the battery terminals and check the
voltage with the bike off, then at low rpm and then at higher
rpm over 3000. See if the charging system is reading over
14 volts at high rpm on the battery.

If your battery has been charged/tested good and your
charging system is working then try the battery tender
on it.

It is unlikely you have a drain as these small batteries can even
be faulty from new.  

To check for a drain remove your negative battery cable
and put a test light between the battery and the cable.
Turn the key off, see if the light is on or off.
If the light is on then you have a drain, if the light
is off then all is normal.

Some big street bikes may have clocks, radios etc that
will show some drain but very small overall.
Your bike most likely will not show any drain unless
something is faulty.

The batteries are often not prepared properly when new
and this adds to battery problems down the road.
You can have a load test done at some shops to verify
the battery is a good one.


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Wayne S.


Licensed Motorcycle Mechanic, Knowledge of motorcycles from 1960 up, Japanese, British and most other brand motorcycle repairs.


Worked for Yamaha, Honda, Suzuki, Kawasaki British: Triumph, Norton, BSA Other: Most Scooters and Mo-Peds

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