T540i fail


Jun 8, 2022
Hi. I have been loving my electric saw since the day I bought it. I waited till the battery technology was right to pull the trigger and had an awakening since it became my go to climbing saw. Then…maybe it got slightly wet when using it in some rain last week but I had used it fine since then. Maybe I carry it in the hot passenger footwell of my truck and even take it on vacation in the back of the family car because no gas and I use canola bar oil. But I got to the top of a maple I was removing and turned it on and it would not run. Power light on and full battery but no throttle response. If I held down the trigger the red triangle flashed. Chain brake was off and I could spin the chain smoothly by hand. Reseated battery several times till I did what I could with my silky and tried the other battery to no avail, later climbed back up begrudgingly with my 201t.
Got home and checked the forums and blew out the casing with compressed air. Tried both batteries again. Left it sitting on the work bench and worked on other things. After ten minutes or so, heard a sizzling noise and made a jab to pull the battery out but by the time I picked it up the saw let out an explosion like a bomb or an engine backfire. My ears were ringing for several hours. Long story shorter, the blast came from the left side cover vents and no outward sign of damage. It smoked for a while. The saw was not turned on. I pulled the battery and it was cool and unaffected and has since worked normal in the string trimmer.
It was kind of a surreal day because we soon we had a derecho wind come through and uproot a bunch of trees around but I can’t stop thinking about first, not having this saw to use anymore, and what could have happened if it was inside the cab with me or up in a tree hanging on my butt cheek or being held in use above shoulder height. I had heard about plenty of liion batteries exploding but something must also be amiss inside the saw case.
Can’t find any other reports of 540i fails so just wanted to put this out to other arborists to be aware of this possibility when using and storing said saw. I’ve tried to contact husqvarna about a different saw issue and can’t any response from a human so excited to post it here for some feedback.
Shit! That's serious. Persevere in your efforts to contact Husqvarna
And I wouldn't trust that battery any more.
Welcome to the House!

No idea what happened to your saw. Can't even think what would cause an explosion that left the battery fine. Weird

Actually, I do have an idea. Capacitors can blow with some force, especially the big ones. Maybe that saw has some big capacitors.
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Welcome Woodsongtree! Sorry to hear about your saw. 😔

I certainly hope Husqy has an answer. Did you call/visit your local dealer?
thats not pretty 🙁

our first impressions of this saw were very similar and while nothing this serious happened to me, one battery is dead (rain), happened to a couple of coworkers, too. apparantly the warranty doesnt cover rain damage. and the saw is not starting properly, always acting like the battery is empty, need to press the trigger 3 times to get it to cut, very annoying...

good luck!
Failing transistors or diodes can make a fireworks show, especially if they're in the power switching path and fail in short circuit mode. But that's no guarantee they are what failed, it could have been the control telling a translator to persist in doing something ridiculous. Bad command, transistor pays the price. Was it an acrid smell or a musty steamy smell? Overall, you're fortunate is wasn't a faulty battery cell. Electronics are complicated voodoo. If no structure is melted, you might get away with replacing the speed control/trigger guts. Best of luck.
I let a T536i and two batts sit overnight in a few inches of water - that didn't do them any good.

I've been meaning to take them apart and clean up contacts etc. After reading this I think I'll recycle them and call it a lesson learned about not keeping $40 toolboxes with cracks that can let in water.

(Stanley 28" Fat Max Toolbox will hold two T540i's with 14" bars, two extra batts, and a charger. Waterproof seal.)
Have you tried them? Might be a good idea to charge outside for awhile, but they may be fine.
They're built pretty environment proof. If you start a thorough non-rushed drying out you may be ok. Give it time to really get dry in the innards. Not likely to corrode in such a short time span. Re-greasing the gears if no gear case enclosure different story, or maybe it's a direct drive.
A bang and 'smoke' is not good.
the 'smoke' from a damaged Li battery is actually toxic, explosive vapour.
Tonight at Fire training we are having a presentation of EV batteries and Li battery storage systems and the implications for emergency responders.
I went to a seminar last month given by Professor Paul Christiansen of Northampton University on the whole Li battery failure issue. Jaw dropping and eye opening.
There are reasons why charging systems are being banned from basement carparks...
Li batteries that are subject to trauma are unpredictable and are the only battery that gets worse with age.
Old worn out lithuim batteries can be quite harmless as far as lithuim batteries go. And smoke can come from anywhere in electronics as materials vaporize from overheating and arcing.
Old worn out lithium batteries can be dangerous. You cannot just chuck em in the trash. They have caused fires inside dump trucks when they ignited after being crushed.
Granted, any electronics can overheat and smoke, and even that smoke is nasty, but if fhe 'smoke' comes from the Li battery, it's not smoke it is toxic, explosive vapour.