EBME Forums Forums Maintenance Technical Assistance Transport Incubator Batteries - Standard test

The Standard for transport incubators (BS EN60601-2-20) seems to be a bit confused/confusing?

According to clause 107.2 the TRANSPORTABLE ELECTRICAL POWER SOURCE (i.e. the battery) is tested by attaching the (warmed) incubator to a TRANSPORTABLE EXTERNAL ELECTRICAL POWER SOURCE, which should last for at least 90mins.

Is this a typo, i.e. should the word 'external' be ignored? (This particular phrase is not defined at the beginning of the Standard.)
Or is the battery only supposed to be able to support an external dc source rather than power the incubator by itself?

Any experts on this out there?

I ask because I have details for a transport incubator that claims the battery lasts for 15mins and then declines. This would appear to be in breach of the Standard if the word 'external' is a typo.

Thanks

Sue