Topic: Can I use a battery charger directly to my terminals to get the bike started?

[Vintage Esquire]

I am trying to get my 78 cb550 started after 13 years.  Rather than go buy a battery at this point, can't I just clip the terminals of a battery charger directly to the +/- battery wires on the bike to try and start it?  Any issues with that?  What setting should I use on the charger if you think it's ok?

[drones76]

Some chargers have an 'Engine starting feature".  I would think if yours does not, it cannot generate the current to start the bike and it may not be a good idea to try it.  I would suggest that you jump it from a car or truck that is NOT running. 

[Duke McDukiedook]

You are gonna have to buy a battery anyway so why delay the inevitable?

[kck3]

A battery charger does just that-charges the battery.  It will start your bike, but the battery will have to be charged completely to do so.  If you want to get the bike started use a non running car-it will do the trick.

[BobbyR]

Some chargers have an 'Engine starting feature".  I would think if yours does not, it cannot generate the current to start the bike and it may not be a good idea to try it.  I would suggest that you jump it from a car or truck that is NOT running. 

+1 a jump start charger pushes into your starting system. A jump start form a battery is a pull, only what is called for by the starter will be used. 

[Gordon]

You are gonna have to buy a battery anyway so why delay the inevitable?

+1

And as has been stated, you can also jump from a car.  Don't worry about if the car engine is running or not.  Makes no difference as the bike's electrical system will only draw the current it needs.  The car's charging system can't force additional current. 

[bollingball]

Just don't hook it up backwards your rectifier won't like it

[Gaither]

Vintage

FWIW -

You might want to check the water level in the bike battery before Jumping it. If the water is low, there will be room for a lot of vapor which just might explode the bike battery when you connect the jumper cables. Not a common "happening" but I've seen it done on cars. Dangerous and pretty messy.

Just a thought.

Good luck with your bike.

[TwoTired]

Depends on the charger.  The bike needs about 5-6 amps without the headlight and about 10-12A with the headlight on.

The electric start needs 50 or more amps to operate, in addition to the rest of the bike.

If your charger has these capacities, the high charge rate may well damage the battery (that should only be charged at 1-2 amp rate).  Depends on how long the battery is left on a high rate charger and how depleted the battery is.

You are going to need a battery to keep the rectifier happy, as it smooths out charging voltage spikes and voltage spikes from the starter motor.  The rectifier may take the abuse, or it may get damaged.
You decide if it is worth the risk.

Cheers,

[scottly]

I used a large gas-station charger with a "start" setting to start a car with a battery that was so sulfated that it might as well not been connected at all. Got the motor started, but wasted the regulator in the process.

[Spanner 1]

Rule of thumb ( that nobody does ) !.... unplug the bike's rectifier when attempting to start the bike from a 'boost' type charger or even jumped from a running car... IMO , in case of increased voltage as the SOHC rectifiers are sensitive to over-voltage and can fail.

[HondaMan]

Rule of thumb ( that nobody does ) !.... unplug the bike's rectifier when attempting to start the bike from a 'boost' type charger or even jumped from a running car... IMO , in case of increased voltage as the SOHC rectifiers are sensitive to over-voltage and can fail.

Like he said...

Many "boost" type chargers have high voltage output. A typical 20 amp charger generates 32 volts peak: the early rectifiers on these SOHC4 bikes were only rated to 15 volts (25 volts in the late 1970s), which was raised to 50 volts in the 1990s. A 50-amp charger can generate almost 80 volts, which will punch out one of these rectifiers, quick. 

Get a battery: it's cheaper than a new rectifer. 

[Vintage Esquire]

Thank you for all of the advice.  My main goal was to just see if the bike runs, but I think I might as well buy the battery now and take the safer route.