Lawn Mower Battery - What's Up with That?

[Astro_Guy]

This is not oil related, but I had a strange experience with the battery on my riding mower last weekend. I pulled the John Deere D140 out of winter hibernation on Sunday. It spends its winters in an unheated shed. It wouldn't start without 1/2 hour on a battery charger. After getting it started I drove it up to my garage to top off the tires with air. Then it refused to restart, even after another 1/2 hour on the charger. I did manage to jump start it but found the battery so weak that the PTO clutch wouldn't stay engaged. Off to Wally World for a battery...

The good folks at Wally World seem to know nothing about stock rotation, meaning I found a 230 CCA U1 battery with a 3/19 date code right up front, while the rest of their stock had date codes going back as far as 8 months. The original battery was rated 190 CCA, so I figured 230 was more than adequate. I installed the new battery and connected the charger for 20 minutes, just to be sure. After that I turned the key and nothing, other than headlights, not even a click. Next I tried jumping in and still nothing. At this point dinner was calling, so I decided to sleep on it.

In the morning I tried jumping it again, but still nothing. Called the John Deer dealer, who immediately blamed the battery and said that I should have used a 300 CCA battery. I found that to be less than credible, given that a 190 CCA battery came out. Running out of ideas, I disconnected the new battery and ran my jumper cables to it. Presto! She fired right up. Then I reconnected the new battery, and presto, she fired right up. Let it sit 20 minutes and once again she fired right up. Put her back in the shed, went to work, came home and again she started right up. I guess all is well that ends well, but why did it refuse to start on the first few attempts?

 

[Brian123]

I always have my lawn mower battery on a trickle charge during the months when the riding mower is not in use,

 

[Donald]

The people at Wallworld may not stock the batteries. Typically a company comes in, pulls expired batteries and put new ones on the racks. You could have got one someone pulled off the rack and put back, or other explanations.

You should not blast power into a small lawn mower battery. I would have put on a low setting and let it go overnight.

The charger in a lawn mower is pretty basic. If a lawn mower battery really needs charging, it should be done on AC charger.

 

[meep]

my guess,

starter solenoid or any of the failsafe switches was feeling a little crusty after sitting, since you said you had lights. That + the dead battery means you were chasing a couple different things. The only thing you could have done for more clues would have been to meter the new battery while trying to start to see if it was adequate, weak, taxed, or not seeing a load.

 

[Dave Sherman]

I'm thinking either a flaky connection at the battery or a safety switch that isn't working quite right. Check the other ends of the battery cables, make sure they are tight at the starter solenoid and chassis.

 

[dwendt44]

"Called the John Deer dealer, who immediately blamed the battery and said that I should have used a 300 CCA battery. I found that to be less than credible, given that a 190 CCA battery came out."
Blame the owner gets him out of a possible warrantee claim.
Some new lawn tractors come with the larger/stronger battery to begin with.

There's no such thing as 'to big of a battery'.

My 2¢

 

[Astro_Guy]

Originally Posted by dwendt44
There's no such thing as 'to big of a battery'.
Yes and no. The capacity of a battery in amp-hours is a function of the mass of available reactants (plates + electrolyte.) CCA is a function of the surface area over which those reactants can interact. If we take two batteries from the same group size, group U1 in this case, yet one offers 190 CCA while the other offers 300 CCA, we must conclude that the second battery has a greater surface area. The only way to do that in two batteries of the same physical size and weight is to make the plates thinner on one battery. Thinner plates wear out faster. This is why deep cycle batteries have lower cranking capacity than starting batteries of the same group size.

 

[Astro_Guy]

Originally Posted by meep
starter solenoid or any of the failsafe switches was feeling a little crusty after sitting, since you said you had lights. That + the dead battery means you were chasing a couple different things. The only thing you could have done for more clues would have been to meter the new battery while trying to start to see if it was adequate, weak, taxed, or not seeing a load.
It did not trip the breaker on my 6 amp battery charger when attempting to start, so my guess is there wasn't much load. The load did go up from 2 amps to 4 amps with the headlights on.

Originally Posted by Dave Sherman
I'm thinking either a flaky connection at the battery or a safety switch that isn't working quite right. Check the other ends of the battery cables, make sure they are tight at the starter solenoid and chassis.
Agreed. The battery had nothing to do with this.

 

[HangFire]

Originally Posted by Dave Sherman
I'm thinking either a flaky connection at the battery or a safety switch that isn't working quite right. Check the other ends of the battery cables, make sure they are tight at the starter solenoid and chassis.

This.

Also starters can have a "bad spot" where they just don't want to get started from.

 

[wrcsixeight]

The secondary weird start issues are definitely some crusty electrical connection somewhere, which will likely rear its head again when most inconvenient.

As far as too small a battery,

I have used UB12180 by itself, an 18AH capacity battery I will estimate has 170CCA, to start my 5.2 liter v8 engine in 80f ambients. it did not quickly turn over, it definitely struggled to start the engine which had not been started in 2 weeks, but it started.

The starter is rated at 1.4KW, or 140 amps at 10 volts. The total wattage my starter consumed according to my meters during this experiment was closer to 1800 watts.

While this battery's case and spec sheet says to apply no more than 5.4 amps of charge current. I have hooked it, when depleted more than 50%, to a 40 amp charging source set to 14.7v.

Peak amps were 38 but quickly dropped to 32amps as voltage plateaued at 14.7v. 5 minutes later is was still over 24 amps at 14.7v. 5 minutes later I could no longer closely monitor the battery for heat build up( none to that point) at these rather extreme charging amperages and lowered voltage until only ~10 amps were flowing and then in stages raised voltage back upto 14.7 until amps stopped tapering in the 0.15a range, many hours later.

So this 'too small' a battery was both discharged at extreme rates when starting a large v8 engine, and accepted nearly 6x the amount of recommended charging current with no significant discernable heat build up. It still performs as it should powering other loads.

Don't let the 'trickle' charger fans fool you. Lead acid batteries do not instantly explode when charged at high rates, or discharged at high rates.
They are quite tolerant of abuse, and the abuse they tolerate the most day in day out the world over, of by chronic undercharging, resting undercharged, or allowed to be slowly drawn to dead by light parasitic loads.

I'd be following the battery ground cable to the engine block removing it and polishing the mating surfaces, and those of all that carry starter current to avoid the rise of Murphy the next time.

 

[SHOZ]

Originally Posted by meep
my guess,

starter solenoid or any of the failsafe switches was feeling a little crusty after sitting, since you said you had lights. That + the dead battery means you were chasing a couple different things. The only thing you could have done for more clues would have been to meter the new battery while trying to start to see if it was adequate, weak, taxed, or not seeing a load.

This. I use to wash my John Deere off every time after mowing and developed many problems with the switches.

When you turn the key to crank do you hear a click from the relay?

 

[Donald]

My starter Bendix drive was all clogged with mouse nest junk.

 

[Chris142]

I was at napa looking for a battery for our side by side. The one napa has in stock has a 9/17 date on it! I walked.

 

[Eddie]

I always put a new battery on a taper charger until it is fully charged, which can take 6 to 12 hours. Lawn tractors, I'm told are capable of maintaining a batter and not good for charging it up from way down.

 

[spk2000]

Sounds like the starter solenoid. Google your mower and solenoid. Usually only a few minutes once you find it. Some are right under steering wheel.

 

[9050lx]

Originally Posted by SHOZ
Originally Posted by meep
my guess,

starter solenoid or any of the failsafe switches was feeling a little crusty after sitting, since you said you had lights. That + the dead battery means you were chasing a couple different things. The only thing you could have done for more clues would have been to meter the new battery while trying to start to see if it was adequate, weak, taxed, or not seeing a load.

This. I use to wash my John Deere off every time after mowing and developed many problems with the switches.

When you turn the key to crank do you hear a click from the relay?

My crappy 22 year old Murray with bald tires and Peerless trans (and flawless 15hp Kohler Command) never gets washed, and is always under roof.

 

[gotnogunk]

I use to have a lot of trouble with my B&S in a Craftsman, there is a fuse that would rust . Might want to check it if you have one in the JD. Mine was coming off the ignition switch.

 

[Astro_Guy]

Originally Posted by gotnogunk
I use to have a lot of trouble with my B&S in a Craftsman, there is a fuse that would rust . Might want to check it if you have one in the JD. Mine was coming off the ignition switch.
I saw only one obvious 20 amp fuse, which I removed to check and then replaced. There are three interlocks that I can think of that might prevent the machine from starting: The dead man switch under the seat, the brake pedal, and the PTO clutch. Have I missed any? Is there an electrical latching circuit at play here that I managed to reset by disconnecting the battery?

 

[SHOZ]

On my JD F510 there is the seat switch, and a brake switch. Brake must be on to start.

 

[ragtoplvr]

with the advent of electric blade clutches lawnmowers have much larger alternators. If the lights are off they usually have 6 to 10 amps of excess capacity with the blade engaged, add another 6 to 8 with it disengaged, this would be at over 3000 RPM, to charge the battery, for a 30 amp hour battery it would take as much as 3 or 4 hours while mowing, and 2 hours just sitting running. Not very efficient.

Rod