It’d been a few weeks since I’d used the chargers and I’d noticed nothing wrong then.
This time, though, I had the DC output turned on, and I had the charger sitting on top of the AC200MAX.
Is there any possibility that the magnetic field that the wireless charger was interacting with the coils in the charger, causing the charger to output more current than it was rated for?
sorry to hear that. Whenever I’m charging my AC 200 Max I put the charger on the floor. I noticed it does get a bit warm. Had my units for about a year, never had any of the cable or anything like that melt. Sorry to hear that but I would definitely give it a good several wraps with some electrical tape and try to avoid putting it on top of the unit while charging, if possible.
@jdege I’m sorry for the inconvenience. In general, it is recommended not to leave the charger on the AC200MAX while charging to avoid overheating. In your case, please contact the seller to replace the AC charger.
Hi @jdege sorry to hear you are having problems with your charger. In the picture has it melted the casing of the unit. Was it the full cable or just at the point where it melted the case that got excessively hot? I would definitely stop using the charger and get a replacement from wherever you bought it from just to be on the safe side.
The melted line along the case is where the charger cable was lying. The damage to the case was only cosmetic. The cable itself was hot from end to end.
I’ve already ordered a new charger.
I suppose it should have been obvious that the magnetic fields of the wireless charging pad would interact with any electrical coils placed on it, but I didn’t think of it until after I noticed the overheating.
It seems to me to be a potentially dangerous failure mode.
I sent an email to Bluetti support, asking them to see if they could replicate it, and suggesting that they might consider providing warnings against it, but I received only a canned response.
That’s interesting but will the magnetic fields interact if you don’t have the DC on? For example in that case there’s no magnetic charging I don’t quite understand why they would be active. I’ve put a tablet on top of a working unit before and I noticed sometimes it gets warm but I tend to think that’s because the machine is running And generating heat more than It has anything to do with the magnetic fields Also it’s not like hot enough to melt something like what happened in your case
There’s really no practical way for the wireless chargers on top of the AC200MAX to make the external power brick exceed its current rating. The magnetic field from a Qi-style charger is very localized and weak outside of a few millimeters, and it can’t interact with the regulation circuitry inside a sealed switch-mode power supply. The brick controls its own output current using an internal feedback loop, and that loop could not be affected by external magnetic fields.
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Also please note that the AC200MAX is the device that draws current. The brick doesn’t “push” more current on its own but it simply provides a regulated voltage, and the AC200MAX pulls whatever current it needs up to its internal limit and the brick’s limit. Even if some external interference existed, it wouldn’t cause the brick to force extra current down the cable.
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The damage you’re seeing on the DC cable and the marks on the AC200MAX chassis point instead to localized resistive heating in the cable. If the cable developed higher resistance due to a fatigued conductor, a bent wire, or internal damage then normal charging current can generate very high heat right at that faulty spot. That heat can easily melt insulation and transfer enough energy to burn or mark the nearby casing.
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So while the wireless chargers might have raised the general temperature in the area slightly, they did not cause an overcurrent condition. The most likely cause of the cable overheating is a high-resistance failure in the cable.
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It would be interesting to dissect the DC cable core to see its condition at the melted spot to better understand what happened.
