Can I jump start a lawn mower battery (12v) with a car battery (12v)

Old 09-27-16, 03:36 PM
Thread Starter
Join Date: Aug 2014
Posts: 22
Upvotes: 0
Received 0 Upvotes on 0 Posts
Can I jump start a lawn mower battery (12v) with a car battery (12v)

The biggest part of my question is whether or not it's safe to turn the car on while doing so. I tried without and it didn't get it to start. A new battery is in the future but for now is it safe to try?
Old 09-27-16, 03:41 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 65,136
Received 3,996 Upvotes on 3,586 Posts
I would recommend the engine not be running when using a car battery to jump start a lawn mower battery.

It sounds like you may have other issues there.
Be very careful when the car battery is connected as its higher available current can smoke things on the mower.
Old 09-27-16, 04:03 PM
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 27,801
Received 2,189 Upvotes on 1,959 Posts
Your car battery should have more than enough juice to start a lawn tractor without the car's engine running. Make sure your jumper cables are making good contact. If the battery on your mower is pretty dead a lot of current will have to make it through the small contact points of the clamps. Also don't forget to make sure the battery to cable connections on your mower are clean and tight.
Old 09-27-16, 04:23 PM
Group Moderator
Join Date: Sep 2012
Location: USA
Posts: 1,757
Received 259 Upvotes on 207 Posts
Since the car battery didn't jump start the mower, I agree with others on making sure that the jumper cables have a good connection, make sure the battery cables (especially the ground cable) are clean & tight. Lastly, check the battery with a volt meter to ensure that the battery is not, either completely dead (shorted out or something) &/or if the battery is possibly a good battery with another problem like a key switch, a solenoid or the starter is locked up etc.

If the car battery wont crank over the lawn mower engine, I suspect another problem besides just needing a jump.
Old 09-27-16, 05:56 PM
BFHFixit's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jun 2007
Location: USA.
Posts: 1,511
Upvotes: 0
Received 0 Upvotes on 0 Posts
What was the reason and how was it any different when you jumped it than with no jump?

To answer the question yes it is safe, but not necessary, or should not be. It could also mask other problems if it does work. The worse you can do is blow a fuse, and that is not likely either as most good OPE batteries have nearly the same cranking amps as an auto battery does.

If you confirm your connections and know the battery is just dead, connect the cables and let the car run for 5 mins, then turn off the car with the cables connected and try it. If you get the same results then connections, or other issues are likely.

Can you spin the engine freely by hand?

Thread Tools
Search this Thread
Ask a Question
Question Title: