Output voltage B&S alternator for 5 hp engine

[GBertolet]

I have a DR Powerwagon with a 5hp B&S electric start engine. I have always had trouble starting this engine, using the electric start. It never seems to turn the engine over fast enough to start it. One pull on the recoil start, gets it going every time. It came with a 12V 5.6 AH battery. I always suspected the battery was undersized, so I just used the recoil start. I use the Powerwagon to haul firewood from the woods, and the electric start would be handy, instead of cracking your elbow against a tree, in tight clearence situations, when pulling the recoil start cord.

I tried the electric start again this week, and the battery was dead, and I decided to test the charging circuit. This engine has a bolt on alternator along the flywheel, that looks like an ignition coil. The part # is 691991. Is the voltage leaving supposed to be DC or AC? I don't see a diode beyond the coil. Maybe it's inside. I am getting both 6v DC, and 15v AC on my meter on the wire leaving. I suspect the alternator is bad. I should be ultimately have around 14v DC, or 30v AC, depending on where the diode is. Any info would be appreciated.

 

[backhoelover]

Can u get me the model and type number. So I know what style engine you have so I can refer to the service manual. I can also send you a copy

 

[GBertolet]

124707-021501 Thank you.

 

[backhoelover]

http://www.tuks.nl/WFCProject/img/E...210-Briggs-Stratton-Service-Manual-L-Head.pdf

 

[backhoelover]

Should be 12v dc

 

[GBertolet]

Thank you, that's the information I needed. I found a new, open box OEM alternator #691991, on ebay for $15. It's on it's way. I downloaded and saved the manual. It will be useful for future reference.

 

[backhoelover]

Need to charge your battery. Stators are ment to charge a battery just maintain one

 

[backhoelover]

Are not ment to charge a battery just maintain them

 

[GBertolet]

I have several battery chargers. Is the 5.6AH battery provided, big enough? Should I go larger, If so, how much?

 

[backhoelover]

Battery should be fine for that engine. Just need to make sure it still good.

 

[GBertolet]

New alternator came, and installed it. Still around 6 volts output. I guess I bought a new alternator for nothing. Anyhow, only $15 + shipping. I recharged the battery, which tests at 12v, but still barely turns over the engine. I put my battery charger on the cables, and set in 10A, it starts the engine fine. On 50A boost, just bumping the starter switch starts the engine. Maybe the battery is bad. The battery is about 6 years old. Not used much, but they still go bad. Always turned the engine over quite slow, even when new. Probably the battery was never being properly recharged by the alternator at 6 volts. This is an OEM replacement battery, purchased from Country Home Products, the manufacturer of the Power Wagon cart. I think that the 5.6Ah of the OEM battery, is still too small. If I get another battery, it will be 10-20 AH. I can fit it in there, with some new mount brackets.

One possibility on the low voltage output is, the engine is designed to run at midrange speed. If I read it right, my vibrating tachometer says 1700 rpm at top speed. This engine is for a cart for hauling up to 800 lbs at walking speeds. I use it for hauling rocks and firewood on the trails of my woods. The cart has a transmission with several gears, for torque multiplication, and regulating forward speed. Maybe the engine is set to run that slow? Anyhow, maybe that is why the output voltage is that low. 3600 rpm would deliver the full 12v? Any thoughts or comments would be appreciated.

 

[backhoelover]

I’m thinking 3200 rpms on that engine. I’ll check when I get home

 

[backhoelover]

Is the battery only for starting?

 

[backhoelover]

Take battery to auto parts store and have it checked

 

[backhoelover]

Also do you have access to another meter? Make sure your getting same reading on both meters.

 

[GBertolet]

The battery is only for starting. I did try two meters, and got the same reading on both.

 

[backhoelover]

I would test battery and go from there.

 

[GBertolet]

The battery has been off the charger for several hours now, and the voltage is down to 11 volts. I think it is shot. I have been trying to contact DR power to ask them if the supplied engines that were made by B&S for them, were governed down to a lower rpm. I have been put on endless hold by their customer service. Still waiting as I am typing this. 40 minutes now. Probably went home for the day, leaving me on hold.

 

[066 redeye]

Most ope motors I have tested will put out approx 13v even at idle.

 

[Larry B]

That alternator has an unregulated output. The faster the engine runs the higher the voltage. It should put out approx 12v at around 3200 RPM. I would double check the RPM and get it up to normal operating speed of 3200- 3600 RPM and check the voltage.