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BT battery backup plus

davegorm — Tue, 29 Sep 2026 14:11:18 GMT

I bought this from a private seller and I assumed it was compatible with my smart hub 2 however the barrel power plug that fits into the router is too small . I contacted BT and they said they would send a different cable. I then received a text saying the order had been cancelled due to a technical issue. I am assuming that this is due to me not buying it from BT. I sourced an adapter on line this fits the router but unfortunately the plug from the backup unit won’t fit into the adapter. The plug that is meant for the ont box will fit into the adapter. I don’t have fibre so can I use the ont lead instead of the lead meant for the router.

thanks

Re: BT battery backup plus

WSH — Tue, 29 Sep 2026 16:30:04 GMT

You can gauge the hole in the centre of the plug with a metric drill bit. If a 3mm doesn't fit, try a 2.5mm if that doesn't fit it's probably a 2.1mm

The SH2 is a 3.0mm plug. I believe most of the ONT's are 2.1mm.

Re: BT battery backup plus

Ali_A — Wed, 30 Sep 2026 16:09:09 GMT

HI @davegorm

While some adaptors may fit the device, it's the power rating and polarity of the supply that has to match the equipment correctly. You can compare this by the details shown on the labels.

Using an unauthorized, third-party, or incorrect power supply can cause serious harm and damage to our router and your equipment. It is essential to use power supplies that match your device. We strongly advise against tampering with your electrical equipment to make it fit. We recommend using approved Battery Backup units.

You can find out more, along with how to request one from us, at About Battery Back Up

Ali

Re: BT battery backup plus

WSH — Wed, 30 Sep 2026 16:26:08 GMT

I assumed the OP had already taken this into account, but you are quite right, it is essential that the voltage/current output & polarity is correct for the device.

Re: BT battery backup plus

davegorm — Wed, 30 Sep 2026 16:53:46 GMT

Hi thanks for the replies. It is a genuine bt battery backup unit brand new in box although I bought it from eBay. I have now ordered what appears to be a genuine bt splitter cable from eBay which seems to have a bigger plug on the end of the power cable that fits into the router. The one on the backup unit I received was much thinner and longer than the plug for the ont box. I noticed EE were selling a cable splitter on their website but the plug for the router looked similar to the one I have which is way too small. Hopefully I will receive the new cable by Friday