Alternator but no battery

[Maxwell-8 4,367]

Maybe a stupid question, Would it hurt the to run an engine with an alternator under the flywheel, to not be hookup up with a battery for longterm? I has a starter but i like to pullstart stuff, and i have no battery for it at the moment.

 

Thanks

[Handy Don 14,061]

Generally, yes, it can hurt. The battery, even a nearly dead one, is an essential part of the electrical system on non-magneto engines. Such tractors usually have a decal warning about this under the hood near the battery. This is not a joke.

[oilwell1415 563]

The battery acts like a shock absorber for the electrical system.  It dampens every voltage and current spike and helps protect the other components.  If you've got a magneto it should be fine as long as you don't try to run the lights or anything.  You could always disconnect the charging system if you wanted some insurance.  If you don't have a magneto you won't be able to start it without a battery anyway....unless you can pullstart it at idle speed.

[Handy Don 14,061]

15 minutes ago, oilwell1415 said:

The battery acts like a shock absorber for the electrical system.  It dampens every voltage and current spike and helps protect the other components.  If you've got a magneto it should be fine as long as you don't try to run the lights or anything.  You could always disconnect the charging system if you wanted some insurance.  If you don't have a magneto you won't be able to start it without a battery anyway....unless you can pullstart it at idle speed.

Not sure what engine you have but you can disconnect (and securely insulate) the lead (or leads) from the stator to "safe" it. But in a non-magneto engine, this also stops the coil from getting juice so it won't run!

If you prefer to pull start, and not maintain a battery, best bet is to get and install a "dead" 12v lead-acid battery that fits in the tractor. That way, you can run it safely as well as have lights and instruments work when there is sufficient juice. It may not be easy to start, though--normally the battery is providing juice to the coil for ignition until the engine is up to speed and able to generate its own juice.

[gwest_ca-(File Mod) 11,473]

If you have a two-wire or three-wire electronic regulator just pull the connector off the regulator. These regulators must first see battery voltage before they can regulate the charge current.

It is better to run with the regulator disconnected than run it with a known bad or undercharged battery because there is a good chance something will get overloaded/overheated trying to bring the battery up to the running voltage. Then you will need more than a battery.

 

Garry

 

[oilwell1415 563]

16 hours ago, Handy Don said:

Not sure what engine you have but you can disconnect (and securely insulate) the lead (or leads) from the stator to "safe" it. But in a non-magneto engine, this also stops the coil from getting juice so it won't run!

If you prefer to pull start, and not maintain a battery, best bet is to get and install a "dead" 12v lead-acid battery that fits in the tractor. That way, you can run it safely as well as have lights and instruments work when there is sufficient juice. It may not be easy to start, though--normally the battery is providing juice to the coil for ignition until the engine is up to speed and able to generate its own juice.

????That's what I said.

[Handy Don 14,061]

18 minutes ago, oilwell1415 said:

????That's what I said.

Yep, you did. Missed that post. Sorry.

Still confused by Garry's assertion that a dead battery can harm the system.  The stator cannot generate more than it's rated output and there is typically a fuse between it and the non-ignition parts of the circuitry that is equal to, or lower than, that rating. As long as there were no hacks to the wiring to circumvent this, what components would be at risk other than the fuse itself?