I have a Samsung robotic vacuum cleaner. It was running but has developed an issue. The batteries have been checked as ok but it fails to start. On a simple test I found the voltage at the out put of the charging station was only 7.6 volts while the battery is at over 20 volts and the input power to the charging station is 24.6 volts.
Had a electronics person look at it and they put a resistive load across the output of the charging station thinking that the voltage may have risen when a load was applied but the voltage remained at 7.6 and they were not interested in going further.
The board internally looks relatively simple. Two mosfets a resistor and 3 capacitors.
Looking for any clues as to why the voltage is low at the output and how to rectify. I believe the unit won’t start until the batteries are fully charged and can’t reach that stage with a low feed voltage.
Hey @Rodney101660, welcome back to the forums!
This is an interesting issue! I wanted to make it known before going any further that we recommend extreme caution when working with Lithium batteries. Misuse of this kind of hardware can result in combustion and other dangerous scenarios.
It’s very hard to say what may be the actual problem here. From looking online it seems that these batteries either come in a 4-cell or a 6-cell variant. And from the assumption that the battery is discharged it is safe to say we are dealing the the 6-cell, though a confirmation on your end would be great.
The “electronics person” you had look at it may be correct that the voltage rises after being connected, though our team would think it would rise after receiving some communication from the vacuum, thus a resistive load would not trigger the voltage to rise.
At the end of the day, this kind of issue could arise from protection mechanisms in both the vacuum and the charger, or really it could be caused by something else entirely! A loose wire, dead FET, etc. It would probably be best to contact Samsung about this issue, as we don’t have access to many schematics and info regarding their products, though I’m not sure you’ll get much information out of them either.
Hope this helps!
A dead Fet ? A dead mosfet is an easy replacement as the charger base is about $300 and there is no warranty due to age of vacuum. Is that what you meant
Hi @Rodney101660,
Zach was just listing that as one of the many possibilities as to why the vacuum might not be working.
Without access to things like schematics, it can be hard for us to know exactly what might be the cause of the issue.
The battery being at 20V for a 6-cell Li-ion is very close to 0% state of charge which would explain why the vacuum isn’t powering on.
I have two theories as to why it isn’t charging:
One the Vacuum or the Battery itself has a protection circuit that has tripped and isn’t allowing the battery to charge. I’ve had issues with Ryobi One packs that have done this before.
Or the charging base may have a safety feature that won’t expose the full 24V on the contacts unless it can confirm contact with the base.
This is speculation though as I don’t have access to any documentation of the electronic components of the vacuum or more information on the vacuum itself.
This is why we recommend contacting Samsung as they have more information at their disposal to determine the cause of the issue.
Fair enough
