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'Bit Of An Upgrade': This Tesla Had A Dead Battery. Then This Mechanic Swapped In A Better One

Why one type of Tesla battery is better than the rest.

Tesla Model 3 Battery Swap

Photo by: Out Of Spec Renew

Andrew Lambrecht

By: Andrew Lambrecht

Sep 5, 2025 at 4:10pm ET

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EV batteries rarely fail, but when they do it doesn't have to kill the car.
This new video shows that not only can it be cost-effective to replace a battery, but in some cars you can actually upgrade to a better battery for not much more.
In the end, a battery replacement seems about as complicated and expensive as an engine replacement. But it seems easier to make a 250,000-mile battery than a 250,000-mile engine.

People worry too much about EV battery longevity. Pack replacements are expensive, of course, but so are engine replacements. And based on recent data, it seems much easier to make a battery that outlasts a car's average lifespan than an engine that can survive 250,000 miles without major repairs. Batteries made after 2015 rarely fail outright.

When a battery does fail, however, that doesn't have to be the end of the road for an EV. As a recent video from Out Of Spec Renew shows, it can be a good excuse to upgrade the car.

The EV in question is a 2019 Tesla Model 3 Standard Range Plus with 144,000 miles on it. That's pretty early to have severe battery problems, as Model 3 packs tend to do 200,000+ miles without issue. We've even seen Model S packs last over 430,000 miles. But like with gas cars, there are lemons, and some cars inevitably need engine or battery transplants prematurely. Used Tesla packs appear to cost around $4,000, which is about in line with what a used engine would cost on an equivalent car.

The good news for Tesla owners, though, is that you don't need to use the same battery pack your car came with. That means you can quite easily source batteries from crashed cars. Plus, as the video shows, you can actually treat a dead battery as an excuse for a big upgrade.

"So we're going to be swapping this pack out. The customer actually sourced the pack for this one, but upon my recommendation, we went ahead and sourced a lithium-iron-phosphate 60 kilowatt-hour pack," Alex from Out Of Spec renew says.

More Battery Longevity Stories

How A 217,500-Mile Tesla Model 3 Battery Compares To One With 3,000 Miles

EV Battery Degradation Just Isn't Much Of An Issue

Modern EV Batteries Rarely Fail: Study

This Tesla Model S Taxi Has 430,000 Miles. Here's How Its Battery Holds Up

While most Western EVs use nickel-manganese-cobalt (NMC) chemistry, lithium-iron phosphate (LFP) technology is more common in China. While it offers less energy density, it makes up for that by being more stable. LFP packs don't mind being charged to 100%, and they also tend to suffer from less overall degradation than NCM batteries. So by swapping in a larger LFP pack, the customer here is going to get more range while also improving the car's long-term degradation curve.

The video is quite long, in Out Of Spec fashion, but it's a good watch. You get a solid appreciation for how robust Tesla's service data program is—the service mode in a Tesla gives you far more information than you can get out of any gas car without an external scan tool—and for how relatively plug-and-play new packs are. Besides physically mounting the pack, there's not much to do. You update the pack information in the car's computer, purge the cooling system of air and that's mostly it.

Well, it would be. In this case, Alex hits a minor snag. On the test drive he gets a "power reduced" warning after the inverter starts to get hot. After poring over the car, he realized that he forgot to remove a rag that was plugging one of the coolant lines in the battery for shipping. The rag got sucked into the cooling system and, well, coolant lines really aren't supposed to have rags in them. Once he cleared it out, though, everything worked as normal.

Tesla Battery Degradation

Degradation tends to be worst during the first couple years of ownership, then levels off.

Photo by: InsideEVs

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It's no more invasive or difficult than an engine swap. And while battery packs are expensive, the wide availability of Tesla batteries means it isn't too prohibitive. Plus, as more cars get crashed or scrapped, and as new vehicle batteries get cheaper, it should become much more affordable.

Contact the author: Mack.Hogan@Insideevs.com

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