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I have a Craftsman 1991 10 hp lawn tractor. After a winter's storage, it won't start without a jump. The battery is only a couple of years old. I've cleaned the battery terminals and checked the cables. They are in good condition. The tractor fires right up with a jump and runs fine, but the battery doesn't seem to get 'recharged'. Is there a charging system on the engine? The wiring diagram doesn't show one. When I put a meter on the battery it shows that there is some charge in the battery. The reading doesn't change when the engine is running, though.
Answer -
Do you have a DC voltmeter or a DC shunt?
Let me know.
Eric
6/28/2005 Response to your question....( your site has been "maxed out" for a couple of days !!! )
Eric...
I used a multimeter set for DC, 15V range. On checking the battery, before attempting to start the tractor, the meter registered 5 volts.
Ray Bedard
rbedard@peoplepc.com
Answer -
The mower does have a charging system. There are magnets in the flywheel and a stator mounted under the flywheel. The alternator produces AC current which gets converted to DC via a diode. For the most part these charging systems are fairly reliable. Once in a while a diode will short but it's not very common.
Sounds like the battery is bad. Do you have trickle charger. If so, try to charge the battery. Those small mower battery usually don't last more than a couple of years. One method to extend the battery life is to use a Battery Tender or similar trickle charger when you store the mower.
Sorry about being "maxed out" all the time but I get so many questions these days that I get overwhelmed and do not have time to answer all of them.
Try charging the battery, check the voltage with your meter. If the battery holds 12 VDC then put it back in the mower. Leave the meter connected to the battery when you try to start the mower. The battery should hold at least 10 VDC when you start the mower.
Let me know what you find.
Eric
Saturday, July 1: Follow -up:
Eric,
Put a trickle charger on the battery. After a minute or so, I smelled something 'funny' and noticed some smoke coming from under the engine. I quickly disconnected the charger and , using a bright light, did a real careful check under the engine. Upon close examination, I found the "diode assembly" wire - found it listed in the parts diagram of the owner's manual - was broken...looks like the diode itself (small round object which is crimped into the wire) split in half, and one end of the wire was shorting out on the chassis. So there is the reason the battery would not charge !!!
I disconnected the battery from the engine and continued to charge it overnight...it now has a full charge.
Can I just replace the diode assembly wire with a new one? The diagram shows it to be part of the alternator ...but it appears to be 'replaceable' without having to replace the whole alternator. Is it OK to splice in a new one?
AnswerA good Briggs dealer should be able to supply the diode. I'm pretty sure Briggs sells the diode seperately. Several years ago while at the Factory school we snagged some diodes but have ran out.
Try your dealer...you should do this first but if they say they can't get you the diode let me know.
Remember...diodes are polarity sensitive...do not hook it up backwards or you will fry the new one.
Eric
