Marvin's charging strike is over

Remember Marvin, our robot mower, clocking off at 45%? Turns out he wasn't slacking — the charger was quietly feeding the wrong voltage.

A quick recap for anyone who missed it: a few weeks back Marvin started docking, beginning to charge, then quitting somewhere between 38 and 45%. Every light was green, every menu said "normal." Mammotion's live chat walked me through the usual suspects — firmware, cleaning the contacts, a photo of the power supply's batch number — before landing on the culprit: a faulty charging-station power adapter.

I put a multimeter across the base-station contacts and it read 33.5 V — a good five volts higher than the dock should ever deliver. Whatever the exact failure, the charge kept stalling around 45% and wouldn't budge, and both Mammotion and our retailer confirmed it was a charger fault, rather than battery.

I forwarded the diagnosis to Robotech Australia, from whom I bought Marvin back in 2024. Vinni opened a warranty claim within about an hour and a half to ship out a brand-new power adapter and charging station — no quibbling. It was on our doorstep less than a fortnight later – having shipped all the way from Queensland to us in Victoria.

New adapter wired in, the same meter back on the same contacts: a steady 28.5 V. Marvin sailed straight past his old ceiling to a full 100% for the first time in weeks, and he's back patrolling the block.

All up, a robot mower fixed under warranty for the cost of a multimeter check and a couple of emails.

Ever had a "dead" gadget turn out to be nothing more than a dud charger?

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2 comments

  1. Frank Norden via Facebook ↗
    Yep, had two Dyson stick vacs do that. Common assumption that the batteries have failed, but our experience was the chargers weren’t delivering any charge!! New wall chargers…fixed.
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    1. Frank Norden Excellent! We were considering throwing away our Dyson stick vac, years ago, thinking it was clogged somewhere we couldn’t clear. But a replacement battery bought on line gave it new life.

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