The OpenReach ECI Battery Backup Unit (BBU)

Sellers on eBay sell some random stuff.. I’ve bought job lots of FTTC Modems and other useful items.

The other day I came across a rare item, something only listed as “OpenReach Modem” in it’s description – which often means it is just another FTTC modem.

This time it turned out to be a Fibre to the Premises (FTTP) modem! along with it’s associated Battery Backup Unit (BBU).


BT Item Code: 064635
Description: NGA ECI-BBU-Battery Backup Unit
ECI Model(Cat No.): Y33584
ECI : BBU 4AA/C AA27270L-A    Rev: AB
Input: 12V 1A
Output: 12V 0.67A

Inside is just rechargeable batteries – quite a good idea and saves on expensive “laptop style” battery packs when the batteries reach end of life and need replacing.


My intended use of the BBU is to plug into the BBU port on an ECI FTTC modem – which I have done and works!

However it was intended to power the following BT Fibre To the Premises modem – allowing emergency calls during a power cut:


T Item Code: 061082
Description: ECI – CPE – OPTICAL ONT
ECI Model : B-FOCuS 0-4G2PUb/e
ECI Cat No. Y33414
Power Rating : 12v  1.0A
Rev: G0502


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4 Responses to The OpenReach ECI Battery Backup Unit (BBU)

  1. bcm says:

    Interesting, thanks for posting this. I’m curious, do you have an OpenReach FTTC installation? (I’m assuming not FTTP, since you showed interest in this.) From my understanding of the ECI Manuals – the BBU connection is the same between the ONT (Optical Network Terminal) and the standard ECI B-FOCuS that OpenReach provides to about half of it’s FTTC customers. (Or at least, used to prior to the HomeHub 5) If you have one, I’d be fascinated to see if they work together. The B-FOCuS is interestingly a very hacked OpenWRT box, which also makes them interesting to play with.

  2. The BBU does work with the eci vdsl modems (tested with the /i variant).

  3. Rick says:

    Hi there, can you advise what the A/C power connections are like for this configuration?
    Does the ECI FTTC modem still need to be plugged into the mains as well as the BBU ?, or is it just the BBU that is connected to the mains and the Modem piggy backs of this ?

  4. AC –> Wall-wart (PSU) –> DC then into just the BBU as far as I can recall.

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