A brand new 2020 YZ450F battery failure?

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9/27/2020 7:41 PM
Edited Date/Time: 1/24/2021 2:42 PM

I was moving my new, never-ridden 2020 YZ450F out of the garage today to gain access to some stuff and thought "hey - probably a good idea to start her up!"

I'm too busy at this time in my life and my new bike has sat for the last 60 days. In that time, I've only started it a few times, it ran great, and the battery seemed strong.

The bike only has 7 minutes on it!

Today when I pushed the starter button, it turned over weakly like ~ 2 times and didn't start.

I've never charged the battery since taking delivery of the bike - and that's probably a bad idea.

Things I've tried this far:
(1) I put a Lithium Ion compatible Battery Tender on it and have been letting it sit/charge - but it doesn't seem to be improving anything. Pressing the starter button results in no activity whatsoever
(2) I checked the fuse near the battery - it looks great, I swapped it with the spare as well, still no dice
(3) I've now pulled the battery out of the bike and am just charging it standalone - not connected to the bike in any way. Below are the setup pics and voltages I measure when charging (105.3 mV) and when the battery sits alone (~ 0 mV). Note that when I was measuring it on the bike while it was charging, I was getting 10.5 V, but it seemed to be dropping ... which I'd say it's dropped all the way to 0 now. Dead dead.

So, guys ... any ideas?

Any tests you recommend running?

I was so excited to go ride this thing finally and then, BAM ... makes a guy wish he had a kickstarter, that's for darn sure.



9/27/2020 7:44 PM
Edited Date/Time: 9/28/2020 5:10 PM

And I bought the bike out of state, so nog sure how warranty coverage works. Any ideas on that front as well?


9/28/2020 11:26 AM

I would still try to contact where you bought it and ask. If not, get a WPS Firepower battery to replace it.


Take it to the limit, one more time!

9/28/2020 11:46 AM

The OEM batteries are junk. You need to replace it with a good quality aftermarket LI battery. Yes it will cost a few dollars, but you will not have any further battery problems, if you start the bike once every few weeks. I have some that have lasted over 5 years and have never seen a charger.

Paw Paw


9/28/2020 12:38 PM

Really appreciate the feedback. What's the most reliable battery in your opinion?


9/28/2020 1:13 PM

Rider 5280 wrote:

Really appreciate the feedback. What's the most reliable battery in your opinion?


Any Western Powersports dealer can get them, or you can find them online.

Take it to the limit, one more time!

9/28/2020 1:28 PM

Shori & WPS are both good units that will last.

Paw Paw


9/28/2020 3:37 PM
Edited Date/Time: 1/24/2021 2:43 PM

OK - here's an update on the stock battery - which **appears** to be fully recoverable. Yamaha evidently sees this all the time with bikes on their showroom floor.

I called Heinen Motorsports in Osseo, MN, where I bought the bike in July. They were really receptive to assisting me - THANK YOU! Overall, these guys have been GREAT to deal with. So they patched me into their tech, Rich. Rich listened to my issue and thought it was probably that I have run the bike a few times but never really allowed it to charge (duh - I am such an idiot), hence the dead-dead condition. He said once dead, lithium-ion batteries often have to be "woken up" to take a charge again, but they are very resilient in this regard - meaning they come back from the dead-dead condition very well and **can** live long healthy lives.

Here's the procedure Rich had me perform that the Yamaha Techs have been taught to resolve this very issue:

(1) Connect up a battery charger to the dead battery, but don't plug the charger in yet (wait until Step #3)

(2) Connect the dead battery to a known good 12-volt battery of similar amperage, like another MX-bike battery (a car battery will do in a pinch, but you'll want to limit the time duration of connection to like 30 seconds given that the car battery has a lot more amperage on tap, otherwise allow the connection for a few minutes). This step "wakes up" the dead battery (assuming it's otherwise healthy), enabling it to take a charge again.

(3) After roughly 30 seconds of battery-to-battery connection (I used my Honda Civic's battery), plug in the battery charger and then disconnect the known-good battery from the dead battery.

(4) If successful, the dead battery should start taking a charge immediately (and show ~ 13.5 volts as shown below). Let the dead battery charge for ~ 6-8 hours and it should regain a full charge if the battery isn't damaged.

That's it. That's how dealerships evidently resolve this common lithium-ion battery issue successfully.

So far so good for me. The voltage that it would accept when being charged immediately shot up to ~ 13.5 volts and it's been holding that way for a few hours. I'll provide an update later on the overall success of the charge.


Lastly, here's the setup I recommend to accomplish the above --- I will be keeping these items in the truck toolbox from now on in case I need to do the above at the track/trail:

(1) Small, but robust alligator clips like the following (because the battery terminals are so small that getting auto jumper cables on them + battery charger clips is almost impossible):

(2) This is the Battery Tender charger I am using (4.9 stars on RMATVMC, so I went for it):



9/28/2020 5:05 PM

Ok - charge complete (it took about 5 hours), battery installed on motorcycle, it fired right up.

Fully charged the battery reads at 14.2 volts and here's what the Battery Tender's indicators show when a battery is fully charged for reference.

I am chalking this up to learning how to live with modern lithium-ion batteries (how to "reawaken" them when dead-dead) and understanding how to be prepared to do so (tools, time, etc.).

I hope this was a useful "adventure" for others!


9/28/2020 5:09 PM
Edited Date/Time: 9/28/2020 5:11 PM

And to Paw Paw's + MX317's points, I plan to have a quality Shorai or WPS battery on standby. Not worth losing a day of good riding.


10/5/2020 3:39 PM

Mine died after 20 hrs but it was the regulator rectifier that broke then the battery went 🤙 Yamaha bought me new battery


11/17/2020 8:57 AM
Edited Date/Time: 1/24/2021 2:44 PM

My OEM battery is still going strong after the above "reset" / "wake up" of it.

Learn from my mistake and when you do periodically start your bike, give it a few rides around the block after warming it up to let it fully charge.


11/25/2020 10:55 PM

Thanks for the info.


1980 trail70, 84 xr80, 84 cr125, 93 cr250, 04 crfx250, 74 Husqvarna wr450, 08 crf450, 87 cr80, 05 crf450, 16 fc250, 19 crf450 Smartop. EKS, O'neal, Bell, SIDI and Kyle Lewis MX Academy.

11/27/2020 3:04 AM

WPS Firepower battery...replaced the oem with these with my last 2 YZs before I even rode them. Never had an issue no matter how long they sat idle.


"A rule is a rule and without rules, there is Chaos"....Cosmo Kramer