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Do riders charge their own battery?

5305 Views 17 Replies 10 Participants Last post by  jayvee43
I have a Scotts (built by John Deere) V-Twin that'll kill a battery before it'll start. Hard starting is the primary issue, but I thought when it would start, it would charge the battery while it ran (apparently it doesn't).

The hard starting issue started last year when the engine backfired and then wouldn't start again. It was parked until just recently when I started investigating the problem.

The first thing I found when I pulled the plugs and valve covers was gas in the oil and it was blowing out past the rockers while turning it over. I figured the head gaskets were blown so I replaced them, but to my surprise they were in good condition. Changed the oil and filter and now I'm back where I started (hard starting)

Next - the spark was so faint I could hardly see it. Figuring the spark was too weak to ignite the fuel and allowing it to build up inside the engine, I replaced the plugs and coils. Well, that helped a little. The spark didn't improve much, but I did manage to get it to start a couple times. This required finding a "sweet spot" in the choke and starting it using my truck battery. It takes a while to find the sweet spot and then wait as it pops and chokes until if fires. Seem to run fine once it starts.

I cleaned the carb and for the most part it looks good. Doesn't appear to have any fuel or oil leaks, just some build up from over the years.

Does this sound familiar to anyone?
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Welcome Fossil Rock!

Yes, it should charge it's own battery unless there is a problem in the charging circuit. It might be since you are having such a hard time to get it started it is just running the battery down lower then what it has time to charge it back up. The charging circuit does not put out a lot of amperage and it takes some time (maybe a couple of hours or more to throw out a number) running at full throttle to recover after being drained down beyond the point of it being able to turn the starter.

As for the hard start issue, have you checked the flywheel key closely to make sure it is not dented/partly sheared?
Thanks for the reply Mark, I hadn't thought of the flywheel being out of alignment. I'll check that today.

Another question about the charging system... should the mower, once started, continue to run without the battery? I want to think about it like a car whereby the alternator provides the current while running, but obviously the mower doesn't have an alternator.
Update: Flywheel / key looks good. Adjusted the valves, which allowed it to turn over a little easier. Rebuilt the carb (60 smackers for the kit).

The picture below shows the remaining parts that didn't fit the carb and a little piece of tubing (yellow arrow). While cleaning it, this cam out of one of the passages. It appeared to be an almost perfect fit, and at first I thought it was supposed to be there, but on closer inspection it appears to have been broken off. It looks like it may be from a spray can nozzle.

Anyhoo, I finished cleaning and reassembling and reinstalled the carb figuring the piece of plastic was the culprit, but no such luck. It still spins and occasionally pops and coughs, but no joy. :confused:

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Another quick question. Shouldn't a lawnmower continue to run even when the battery is disconnected?

When I did get the mower started, I disconnected the battery (from jumper cables) and the engine shut off.
I suspect the mower needs a battery connected to keep the caburetor fuel solenoid open. I theory it would continue to run if you provided 12 volts to the carb. Roger
I was reading the pdf and it shows an alternator. The alternator should power everything even without a battery or am I wrong?
Is the alternator regulator working is the key question. Just because it is supposed to have one doesn't mean is is working. I know for sure on the older Kohler powered JD 200 series you needed to have a battery in the sytem as an electrical storage device to keep them running. Kind of a momentary back up source of electricity to make up for the electrical charging systems power fluctuations. Roger
i was told that you should never run a mower with out a battery..even if the battery is dead...maybe i'm wrong
I'm not recommending anything of the sort. I'm diagnosing a problem and need to know certain things to test for to find the problem.
Do you know or sure that the alternator isn't charging the battery at all while you're running. To confirm, measure the battery voltage before starting, once it's running, before you finally shut it off and then after you've shut it off. I suspect that it's taking so much out of the battery because of the hard starting that it can't fully recharge it while you're mowing. Of course, an old battery will also be harder to charge. Anyway, if you read a higher voltage when running than when stopped, it's at least trying to charge. If there's no change in voltage, then it definitely isn't charging.
FWIW, my Craftsman/Briggs engine has a hard start (turn key and the motor turns very slowly and then does a full turn and repeats. Sometimes it will start on the full turn that happens. What I learned from my trepair guy is that the battery actually needs more CCA's.
I had a head gasket go that I repaired but nicked the head with a razor while cleaning it up. Everything went together and it ran great after. After a few months it seemed to start smoking a lot again (the sign my HG was gone) and then quit. I kept trying and trying to start it but eventually burned up the starter. I called someone to look at it this spring and he found that compression was 150 psi but my battery was low on charge and the starter (I had replaced the burned up one) was bad. He replaced the starter and recommended a battery with higher CCA's. I have yet to get the new battery but do keep putting it on the charger every couple weeks to preserve the starter. I do still get the hard start but charging the battery fixes that. I believe you should try a battery with higher CCA's and see if the problem is fixed. I'm sure mine will be as soon as I get the new one. Good luck.
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Hard Start

I'm not familiar with your specific mower. But I have been working on my own mowers for 50 years. You don't tell us your level of experience? So please don't take offense to my questions! You didn't say if it started easy with the auto battery? How old the mower battery is? Those little batteries take a lot of babying to get more than 3 years out of them. I agree that it could be that you need a new battery or a larger (more cranking amps) one. But other things can cause hard starting. Are you sure you set the valves to the right specs. 2. How did you check the flywheel? You can't be sure unless you pull it. The key sometimes looks like it is okay when in fact it is cut below the surface. How did you clean the carb? Did you soak it in a chem. cleaner? This is especially important if fuel was left in the carb last time it was used. Today's gas is only good for 15 to 20 days. Ethanol is a killer of carbs in engines that aren't used everyday! (Ask any boat owner!) NAPA used to have a great cleaner but O'reilly has the best now. Be sure and follow the instructions carefully, this stuff is strong. Kits often are made to work in more than one carb, so extra parts are not unusual. They sometimes put a little tube like that over the tip of a needle valve. (just my guess). While you are at it, try checking the compression.
If you don't have a gauge, just try turning the flywheel by hand while you have the cover off. Hope this helps you a little, good luck!
OH! As far as I know, just about all small engines that have electric starters, have a charging system, even little DrTrimmers. Small as they might be. They do make a few that use A/C to start (no battery)
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Just to add to what Old Chipper said, the batteries in riding mowers lead a hard life, since they're sitting idle for almost half a year. That will kill any battery if you don't look after it. I store my vintage Camaro during the salt season and was killing batteries prematurely, so I invested in a Battery Tender. Now I bring my mower battery into the garage for the winter and hook it up to the Battery Tender once in a while. That keeps it healthy without boiling any water off like a regular charger would do in the spring. Even a cheapie trickle charger will boil a battery if left on for a long time.
Yes, I pull mine out too. I have a small budget so I use the $5 HF trickle chargers. I have half a dozen of them but they seem to do a good job keeping my batteries alive. Its always a good practice to check the water levels on batteries anyways to assure the plates never get dry and start to oxidize. Guaranteed battery killer there. I have some very old batteries that work year after year because of regular maintenance.
The old "Ounce of Prevention" saying comes to mind. :)
A riding mower will run with out the battery
Not necessarily. It depends on the ignition system. Some have a magneto or magnetron, but others need the battery, just like a car.
This is interesting reading. I enjoy everyone's different opinions and possible causes and solutions. I have a thaught also.

In the past I have experienced this very same problem and the (hard to start) issue was caused by the fact that the flywheel was not turning fast enough. If I used the tractor LOW Amps battery, it turned slow, almost stoped at compression stroke and past the compression stroke it picked up speed, and sometimes coughed or started depending on it being Cold, or warmed up.

I would BOOST off my truck,. just like our O.P. here, and it would turn easier and start eventually.

My solution was to open the startor motor, and clean the brushes and the stator assembly throughly, I can't remember if i replaced the brushes, but anyhoot, A cleaning helped me 100%. I was told that I was loosing all my Amperage off my start cycles, due to the amount of dirt in the startor motor.

I agree, a small engine will have a charging system to re-charge the BTTY. However, lets examine a couple. There is a common one wire voltage regulator that puts out may be 4 amps, (not very fast) then there is a 2 wire stator to voltage regulator that charges twice as fast, it can reach 14 amps may be a little better, and there is the alternator/regulator assembly that can provide 30 amps.

As a rule, most v twin briggs, have a two (yellow) wires regulators, and they put out just enough amperage to run a pair of low watts head lamps, a electric pto clutch and dump some amps left over into the battery. provided there is no more resistance in the electrical circuits.

It would be a lot easier to help, if we knew the model of the engine in question and a picture of the stator assembly below the flywheel once the flywheel was removed.

Hope this also helps.

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