IEC 60601 Charger requirement for Lithium Ion Battery Powered Device

#1
Hi,

We are in the process of designing a class I medical device that is powered by a 18650 lithium ion rechargeable battery. The battery is not removable by the user. So the device itself is solely powered by the battery enclosed, and a separate wall mount power adapter is used only for charging.

Under such circumstance, do the wall mount adapter/charger need to comply with 60601-1? Do selling the charger separately make any difference?

Thanks,
 
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PaulGr

#2
If you can guarantee the device cannot be used (connected with a patient) while being charged and charging is done outside the patient environment, you might be able to use a non IEC60601 compliant powersupply. Always recommended to discuss this sort of design choices with your testlab in an early stage.

Selling the charger separately won't help you as you need to specify the adapter type(s) in the manual and they will be included in the scope of the 60601 assessment.
 
#3
Thank you Paul.

But this is so frustrating in that a low risk class I device for consumers have to match up to the medical grade power source that cost 3-5x more than a regular certified power adapter.

For example, how is a $40 powered toothbrush (a class I) economically viable to sold with a medical grade power source, and really what's the point of it.

Is custom made power source the way to go? I guess a one time fee is better than the continuous high part cost.
 

Peter Selvey

Staff member
Moderator
#4
If the instructions for use state that the equipment is not intended to be used while being charged, then it is OK to use an off the shelf charger.

Your risk management should then consider the possibility of the user ignoring the instruction. The risk will depend on the nature of contact with the patient (impedance, duration, status of the patient). Some medical devices have fairly innocuous contact so the risk (probability of serious harm) is low even if the user ignores the instruction.

If the risk is deemed unacceptable, there may be strategies such as a hardware, software or mechanical interlocks, prominent labelling etc that work to prevent the situation of use while being charged. Or if the risk is really high, then use a 601-1 approved charger.
 
V

Velarde

#5
According to IEC 60601-1 + A1:2012 in the Epigraph 6.2: "INTERNALLY POWERED ME EQUIPMENT having a means of connection to a SUPPLY MAINS shall comply with the requirements for CLASS I ME EQUIPMENT or CLASS II ME EQUIPMENT while so connected, and with the requirements for INTERNALLY POWERED ME EQUIPMENT while not so connected".
No matter if you specify in the Instructions for Use that the equipment is not intended to be used while being charged, if the ME Equipment can be connected to a Supply Mains and simultaneously can be connected with its Applicable Parts to the Patient (if its physically possible), it must comply with the requirement for Class I or Class II ME Equipment.
There are alternatives to use a Medical Grade Power Supply, for example: you may have in your device a mechanical part that unable Applicable Parts while battery being charged, or you may isolate Applicable Parts with DC-DC, or other components.
 

Peter Selvey

Staff member
Moderator
#6
It is necessary to be careful here about what is the "ME equipment".

In the standard, equipment with an separate power supply can be optionally treated as a single item or as a system (see 8.2.1).

If the system option is used, the term "ME equipment" does not include the power supply, so paragraph 6.2 does not apply when referring to the supply mains.

Instead, when treated as a ME system, Clause 16 is applied. This allows the separate power supply to comply with the appropriate IEC standard, not necessarily IEC 60601-1.

Further Clause 16.6 only requires special leakage current limits within the patient environment. The patient environment is specified in the accompanying documents (16.2 c)).

Thus, if the instruction for use state that charger is not to be used while the medical device is connected to the patient, this means it is formally excluded from the patient environment, and no special requirements apply.

This is a rather long way but it gets the common sense result which has been stated previously.
 
V

Velarde

#7
Thanks for the reply.
But I have some doubts.
According to Clause 16.1:
"An ME SYSTEM shall provide:
? within the PATIENT ENVIRONMENT, the level of safety equivalent to ME EQUIPMENT complying with this standard"
What about with the Applied Parts?
Subclause 8.5.2.1 specifies that type F Applied Parts must me separated from other parts. Subclause 8.5.2.2 specifies the same for type B Applied Parts but specifying earth connection as a Mean of Protection. I think that in ME Systems the definition of other parts could be applied to External Power Supply, and therefor Applied Parts must be separated by a MOPP from external Power Supply (including earth connection in Type B Applied parts).
Is it correct?
 

Peter Selvey

Staff member
Moderator
#8
16.2 c) requires the instructions to state "which parts of the ME SYSTEM are suitable for use within the PATIENT ENVIRONMENT"

For this case, during charging there would be no patient environment, so 16.1 does not apply.

Essentially we have two configurations:

- in normal use (excluding charging): internally powered only
- while charging: ME System with no patient environment

Another point is to be careful with 16.1 and 8.5.5.2, the full clause needs to be read as there are provisions which would allow non-ME equipment to be used with ME equipment having Type B applied parts, without any special 601 style isolation. There are a variety of approaches available.
 
M

mylene

#9
Hi,
I posted my question in another topic, but I think this one is more appropriate. So here it is again:
Hi,

We are the manufacturer of a class IIa device. We aimed at distributing it along with a separate IT charger (60950-compliant) in the European market. The device is battery powered and in contact with the patient during the provision of a treatment (applied system). For charging, the battery (LI-ON) has to be removed from the device and inserted into the separate charger docking station. There is no physical link between the charger and the device. The charger is connected to a SUPPLY MAINS. Therefore, the device cannot operate while charging and there is a separate battery charger which is incapable of being connected to a SUPPLY MAINS and to a PATIENT simultaneously. The charger is off the shelves (not custom).

Our Notified Body is not allowing us to access European market with this charger under the existing “IT” standards certifications. They claim our device cannot operate without its charger, therefore the charger is part of the device system and has to be compliant with the defacto safety and EMC standards of ME SYSTEMS (60601-1 & 60601-1-2).

Do you think it is right? If this is really what we have to do, I know testing is one way of demonstrating compliance, but it is costly, especially for a “distributed” charger. I know a gap analysis and risk assessment for the gaps along with mitigations is another way. But will such a gap analysis be sufficient or testing will likely be needed especially for EMC as mitigations would hardly be applicable on that standard? (On one side, we have one accredited lab saying no testing will be require, only risk assessment of gaps and mitigations where applicable will be sufficient (quoted us 2k for it). On the other side, we have a second accredited lab saying risk assessment for the gaps along with mitigations will be sufficient only for the safety standard and testing will be needed for EMC as mitigations would not be applicable (quoted 9k for it)).

What is your view of my situation? Any guidance and advice?
 

Peter Selvey

Staff member
Moderator
#10
This is a case where the NB (notified body) looks to be completely wrong, but there are some issues to consider.

It is a common mistake to automatically assume that an object used in a medical application automatically falls under the directive.

The correct interpretation is to consider the labelling manufacturer's intended purpose.

If a doctor buys an ruler from Target's stationary section, and then uses it in her clinic to make diagnostic measurements, the ruler does not become a medical device. But the same ruler bought from a medical catalogue and labelled for medical use is a medical device.

For the battery charger, if it is bought off the shelf, and the original label indicates it is just a battery charger, and all the original labelling remains (including the user manual), then it remains a non-medical device and the notified body has no jurisdiction. The charger falls under the low voltage (LVD) and EMC directive, which I guess it already has been CE marked for.

If it is re-labelled, things get a little messy.

First it becomes a medical device, so various legal matters need to be handled (which are too long to explain here). Really, it is better just to keep the original labelling to avoid these problems.

Assuming it was re-labelled, next is the question of what standard. EN60950 does not appear in the official list of harmonized standards for medical device, so it looks like EN 60601-1 could be the only choice.

There is an argument that EN 60601-1 is not applicable (out of scope) because the charger does not contact the patient. And EN 60601-1 is clearly written for equipment that contacts the patient, much of the standard does not make sense otherwise. In this case, it should be the appropriate EN/IEC standard, even if not harmonized. There is no legal path through which an out of scope standard becomes a harmonized standard by default.

But ... there is also argument that the scope of EN 60601-1 includes "all accessories". This is is a poorly written definition, it is too broad, not workable in practice and conflicts with regulation. It is likely to be changed in the future. While some NBs and test agencies highlight this definition, they do it selectively (when it suits them), not consistently.

Assuming the NB insists on using the "all accessories" definition, for external power supplies (separate power supply) the standard anyhow has an option to use either EN 60601-1 requirements or the appropriate IEC standard, plus the requirements of Clause 16. Since the charger is not used while connected to the patient, Clause 16 is basically not applicable. So the obvious option would be a simple application of IEC 60950.

So no matter what way we go (even using questionable interpretations) we always end at EN 60950.

One caveat: Li-ion batteries are not to be treated lightly. Irrespective of the above discussion the risks of overcharging, short circuit should be considered in the risk management file. Compatibility between the charger and battery is an important part. That does not make the charger a medical device, just part of the input for risk assessment. To assess the risk you may need to access technical information from the charger manufacturer and the battery manufacturer. If you are not qualified to assess this risk, get some outside help.
 
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