A brand new 2020 YZ450F battery failure?

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

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

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

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

Rider 5280 wrote:

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

Shori & WPS are both good units that will last.

Paw Paw

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.

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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):
https://www.amazon.com/gp/product/B083K7PXYY/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

(2) This is the Battery Tender charger I am using (4.9 stars on RMATVMC, so I went for it):
https://www.rockymountainatvmc.com/parts/deltran-battery-tender-junior-selectable-charger-p

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!

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.

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

Update:
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.

Thanks for the info.

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.