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My yardbug's 1 year old battery keeps going dead and I think its not being charged by the Briggs & Stratton engine but I don't know how to check the charging system. Its a 12 volt electric start L head 1 cylinder engine. Any help would be appreciated. thanks

pappy71 said:

My yardbug's 1 year old battery keeps going dead and I think its not being charged by the Briggs & Stratton engine but I don't know how to check the charging system. Its a 12 volt electric start L head 1 cylinder engine. Any help would be appreciated. thanks

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:welcome:

you help us and we will help you.
Start with the engine make & model numbers
Follow that with what you know about electrickery and what electrickery testing tools you have.

bertsmobile1 said:

:welcome:

you help us and we will help you.
Start with the engine make & model numbers
Follow that with what you know about electrickery and what electrickery testing tools you have.

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Engine make Briggs & Stratton Model #109707 I know a little about electrickery, I have a multimeter and a probe that lights up I think its a circuit tester, and another tester that beeps when you place it next to a live wire. I will also taking the battery in for a load test.

Thanks for the engine number but we need the code as well to access the correct B & S engine information ie 109707 ????-??
On those small engines B & S generally fit a 3 amp unregulated alternator which will have a single red wire that gets really thick just before it goes into a plug.
Find that and disconnect it.
Pinch a pin from SWMBO and poke it through the wire a few inches back up the wire.
With the mulitmeter set on Ohms check between the pin and the end of the plug.
One way must be open circuit and the other way ( leads reversed ) must show continuity.
If not the diode ( the thick bit ) is cactus and needs to be replaced.

If it is OK then start the engineand measure between the pin and ground with the meter set to AC volts.
you need to be seeing at least 26V AC ( +13 V and -13 V ) and hopefully around 30 to 40 at full speed.
Be careful that the pin does not touch the engine or you will see how a welder works to the detriment of your alternator.

If that checks out OK then remove the pin and push it through the wire on the mower side of the plug.
You should see at least 13 V DC and closer to 14 V is better.

Let us know how you go with that.

Re: yardbug charging system

pappy71 said:

My yardbug's 1 year old battery keeps going dead and I think its not being charged by the Briggs & Stratton engine but I don't know how to check the charging system. Its a 12 volt electric start L head 1 cylinder engine. Any help would be appreciated. thanks

Click to expand...

the rest of the engine code is 0105-3A question?? what is a SWMBO and how can I pinch a pin from it? Also I looked closely at this engine and there are only 2 red wires. One is from the solenoid to the battery and one is from the solenoid to the starter,there is no thick red wire near the plug

Re: yardbug charging system

pappy71 said:

the rest of the engine code is 0105-3A question?? what is a SWMBO and how can I pinch a pin from it? Also I looked closely at this engine and there are only 2 red wires. One is from the solenoid to the battery and one is from the solenoid to the starter,there is no thick red wire near the plug

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She Who Must Be Obeyed.
If you are married you will know who I am talking about.

The alternator has 1 or 2 wires connecting it to the mower.
So you can remove the engine there is generally a plug ( electrical type not sparking type ) and it is usually lutking around behind the starter motor.
If you have a single wire alternator ( 3 amp ) it will have a round plug about 1.5" long that sits close to the wire so you can not poke a probe down the bum of the plug to get a reading, hence the pin of the sewing kind.
Some mowers will also have a second round plug with the kill wire for th magneto in it if you turn it off with the key.
The aalternator wire is usually red and the magneto wire is usually black.

I would first hook up my VOM to the battery and check the voltage at idle and full throttle. Should range from 13.2-14.7 volts. If it is below 13.2 or stay at the same voltage, you have a charging system problem.

Rivets said:

I would first hook up my VOM to the battery and check the voltage at idle and full throttle. Should range from 13.2-14.7 volts. If it is below 13.2 or stay at the same voltage, you have a charging system problem.

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I did this and the readings are: 13.74 at idle and 14.27 at full throttle so I guess I wont have to take the engine out. Is it also true that I can check for a charging problem at the key switch (round) by checking the red alternator wire and the black magneto wire?? thanks. Ken

pappy71 said:

I did this and the readings are: 13.74 at idle and 14.27 at full throttle so I guess I wont have to take the engine out. Is it also true that I can check for a charging problem at the key switch (round) by checking the red alternator wire and the black magneto wire?? thanks. Ken

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OK so the 90 day warranty on your battery has expired and its time to take it to an auto parts store and have them load test it. If it fails then purchase a new one. Do not ever buy a battery from walmart.

BlazNT said:

OK so the 90 day warranty on your battery has expired and its time to take it to an auto parts store and have them load test it. If it fails then purchase a new one. Do not ever buy a battery from walmart.

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I would never buy anything from Walfart ( I'm a union man) we have a Batteryman store in our town and I have been dealing with them for 25 years for all my battery needs The warranty on all their batteries is 1 year.

I remember this yardbug. Make sure connections are clean and tight.
I recently replaced a battery on my dodge ram only 7 months old.