Lithium-ion batteries from eBikes now have in some cases a capacity of over 600 Watt hours and are thus storage media with a very high energy density. Since such power units must be safely designed, produced and tested accordingly, there are various requirements (EN 50604-1 and UN-T 38.3), which such batteries are required to pass before they can be transported and put on the market.
The UN-T 38.3 test plan includes various safety tests on a prescribed number of rechargeable batteries, in which the test specimens are guided to their load limits and in some cases beyond (overload tests, impact tests, short-circuit tests, vibrations, thermal tests, etc.). Battery manufacturers must conduct such test series before the products are put on the market.
When the cells originally installed are replaced with alleged identical single cells or in the case of manipulating the batteries by e.g. an increase in capacity, disabling of the battery management system or the conversion of charging sockets, this is all wilful interference as these are all safety-relevant components. This would mean new tests in line with EN 50604-1 or UN-T 38.3 would be required. However, these are not possible for individual cases, as the required number of test specimens according to the test plan is not available.
According to the dangerous goods regulations, the successful completion of the test series according to UN-T 38.3 is a basic requirement for the commercial transport of eBike batteries by land, water and by air. If manipulated batteries are noticed by a commercial company, these batteries may only be transported on a case-by-case basis with regulatory approval and in line with approved procedures. The cost of observing these requirements exceeds the value of the battery several times over.
As a result, you as eBike retailers are well advised not to accept any obviously manipulated batteries in the first place or to send these to the manufacturer as you would be committing an offence.