Operating w/o Battery Installed

[TheLastWord]

The engine-start function on the charger provides 200 amps (many more than necessary). Any concerns using this powerful device on the small engine of the garden tractor? The tractor is a 12V system, as is the plug-in starter. I've started it this way a handful of times, and it seems to work fine.

Yes, serious concerns!! 200 amps engine start function on a small battery?
Sounds like a old "dumb" charger, not a newer smart type that provides electronic sensing and regulates the charge.

Do yourself a favor.......buy a new battery.

 

[wag123]

The engine-start function on the charger provides 200 amps (many more than necessary). Any concerns using this powerful device on the small engine of the garden tractor? The tractor is a 12V system, as is the plug-in starter. I've started it this way a handful of times, and it seems to work fine.

As long as the starting mode of the charger isn't supplying way over 14v, no concern. The starter will only draw the amps that it needs. If the charger's voltage is too high in start mode it will eventually damage the starter. Furthermore, if your engine has a fuel shutoff solenoid, the unregulated output of the tractor's alternator can also be producing way over 14v and can burn-out the solenoid. Take these things into consideration when contemplating whether or not to replace the bad battery.

 

[zzyzzx]

Operating w/o Battery Installed​

 

[viscous]

As long as the starting mode of the charger isn't supplying way over 14v, no concern. The starter will only draw the amps that it needs. If the charger's voltage is too high in start mode it will eventually damage the starter. Furthermore, if your engine has a fuel shutoff solenoid, the unregulated output of the tractor's alternator can also be producing way over 14v and can burn-out the solenoid. Take these things into consideration when contemplating whether or not to replace the bad battery.

Thank you for this guidance. It does indeed have a fuel shut-off solenoid, so I guess I have to replace the battery. The unit has operated fine with the dead battery before, but perhaps the dead battery was providing just enough voltage to maintain system functionality. Hopefully the dead battery was able to protect the solenoid, as would NOT be the case if I disconnected the ground cable as we discusses previously?

 

[Dave9]

No. It won't hurt a thing to run the garden tractor without a battery. The ignition and charging systems are completely separate. The ignition system is a magneto and doesn't use the battery or electrical system. The alternator is very crude, low output, unregulated, and is really only used to keep the battery charged and in some cases to power lights, an electric clutch, and/or fuel solenoid.

When my old B&S (19HP Intek V-twin) based mower's battery crapped out, leaving the battery connected it would run from a jump start but ran rougher compared to normal and/or after replacing the battery.

I never investigated further because a new battery solved it, but best guess is that the unregulated (single diode rectification) alternator output circuit opened the fuel solenoid enough for it to run, but was either oscillating open/shut (w/engine RPM) to some extent, or the weak battery was pulling down solenoid voltage too low so a slight fuel starvation and not running as well as it should.

It wasn't running horribly on the old battery so I mowed for an hour, then saw that it was cooking away the electrolyte, had a wet rim around the battery caps.

 

[wag123]

Thank you for this guidance. It does indeed have a fuel shut-off solenoid, so I guess I have to replace the battery. The unit has operated fine with the dead battery before, but perhaps the dead battery was providing just enough voltage to maintain system functionality. Hopefully the dead battery was able to protect the solenoid, as would NOT be the case if I disconnected the ground cable as we discusses previously?

Dave9 answered this appropriately. When the battery is connected it will sink the excess voltage and smooth it out, protecting the fuel solenoid, but leaving it connected when it is obviously bad can overload the alternator and rectifier and you risk burning one or both of them out. I strongly recommend replacing the battery.

 

[willbur]

What wag123 said. Older cars also needed the battery to stabilize the alternator. Disconnecting the battery could cause the alternator to rail at something higher than normal and start zapping things. My MG has a big warning label under the hood that specifically says to never disconnect the battery while the engine is running so you don't zap bulbs, ignition modules, the radio, etc.. I know someone who did this on a motorcycle and he ended up replacing several bulbs afterward.

What wag123 said. Older cars also needed the battery to stabilize the alternator. Disconnecting the battery could cause the alternator to rail at something higher than normal and start zapping things. My MG has a big warning label under the hood that specifically says to never disconnect the battery while the engine is running so you don't zap bulbs, ignition modules, the radio, etc.. I know someone who did this on a motorcycle and he ended up replacing several bulbs afterward.

Yes- I seem to recall that an alternator will spike 200 volts when disconnected suddenly.

 

[billt460]

This looks to be a case of it becoming too expensive to try and save money... Replace the battery.