Out comes your Stihl charger and you’re expecting that familiar quiet hum of life being restored to your depleted battery. But what you get is a flashing sequence of red light blinking in an urgent rhythm. Ten times.
Then nothing. Still no juice. It is not a random defect, though.
That is the charger’s onboard computer signaling you something. When you see those little red lights on your power tool accessories, most folks panic, thinking that their battery are dead forever or the hardware is broken. In most cases, what’s actualy happening isn’t nearly as dramatic.
The charger is talking to you and it has seen something in condition preventing it from charging safe. Knowing what it’s saying will save you time, money and aggravation of running back to shop with perfectly good equipment. A ten-blink red sequence is nearly always indicative of a voltage mismatch.
Decoding Stihl Charger Flashing Red Ten Times
Understanding the Ten Blink Red Light Code
In other words, it means the charger’s voltage profile don’t match the battery pack it thinks it should be charging. Stihl has several line-ups that produce batteries at 18 volts, 36 volts and now 60 volts. So if you accidently plug a 36 volt battery into an 18 volt charger, the unit recognize right away there is a problem.
It won’t charge because that can harms both the circuitry and the cells themselves. That’s why it matters what kind of battery goes in what charger, and the charger matches the battery exactly (check label). This is where if you have various Stihl tools that are used interchangeably like I do, that mistake happens.
Voltage Mismatch Causes
Swapping batteries from your chainsaw to your hedge trimmer and didn’t realized one was higher voltage then another. The charger isn’t stupid; it shuts down the process before something bad occur. Feature, not bug.
Temperature Issues and Safety
This particular error code can be caused by temperature issues as well. Lithium-ion battery do not like being in either hot or cold environments. If the battery has been used recently, then it could be too warm; if left outside, then it might be to cool.
The battery’s status will register with ten blinks, which almost always points to a voltage mismatch, though it can also mean that it’s in an environment that’s too hot or too cold to charge safely. Leave it out on the counter for several hours to allow the battery reach room temp, and oftentimes you won’t need to do anything else for it to correct itself. Check the charging contacts.
Cleaning Charging Contacts
Any corrosion, sap, or dirt build-up on the metal charging contacts can throw off the charger’s sensors. This can cause it not connect properly or to read a false voltage. Use a clean, dry cloth to wipe down the contact on both your charger and battery.
You’d be surprised how many issue are solved by that simple task. This is because a bad connection is similar to reading a faulty voltage. However, if you clean the contacts and check the voltage and the lights still won’t go out, then the battery might have some kind of internal problem.
It’s also possible the battery management system in the pack isn’t communicating with the charger properly and it think there’s something wrong with the battery. That’s unlikely though. Either way, call up Stihl support.
Don’t force it. Their chargers is built to shut down gracefully. Trust the engineers who build them.
It doesn’t mean your tool is dead. They just don’t think it’s ready yet. That is why they’re flashing their red light at you.