Einleitung
This guide describes how to change the speaker's (expired) rechargeable battery. At the end of the guide you'll find advice, some of it essential, to help ensure that your replacement battery serves you well.
Was du brauchst
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The Cambridge Audio Bluetooth speaker has an aluminium wrap-around case, grilles at front and rear, and connections for recharging etc at the rear of the enclosure. On its base, a silicone pad to ensure it sits on a surface without rattles. To replace the battery, you do not need to separate the aluminium sleeve from the speaker's interior.
Frag FixBot
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The original battery has a 2600mAh capacity. 18650 cell technology has improved, you now have the opportunity to install, e.g. 3400mAh battery - if you find one higher than that, that may be a sign of a fraudulent supplier. Poor quality lithium batteries carry risks: it's best to purchase from a reputable source and ideally a named manufacturer.
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Lithium batteries, for their safety and yours, need inbuilt protection circuitry. This guards against overcharging or high current draw - which may cause thermal runaway, over-discharging - from which the cell may not recover - and generally helps with its longevity. This speaker requires a battery with built-in protection.
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To work with the speaker grille, this old style of table knife proved useful, with its thin flexible blade and a rounded end - you might want to find something that has a similar form and function.
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Both the front and back of the speaker have a metal grille. To replace the battery, you will remove the front grille, revealing screws that secure the enclosure.
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The metal grille's edges are held in a groove. Small protrusions on the inner face of the grille's edge catch ledges on the inner face of the groove. Before removing the grille, it's useful to know where the ledges are.
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The image shows the projections onto which the grille protrusions latch - seven on each long side - there are also two on the short sides at either end and it's there that you can use a blade or putty knife to gain traction on the grille, lifting its edge from the groove.
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An alternative method: the photo shows one end of a removed grille with arrows to indicate the position of a pair of enlarged holes - possibly provided as purchase points for a removal tool. If you have something that will hook into those holes, this will better enable you to lift that end of the grille.
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Once you've lifted one end of the grille, use the long blade of e.g. a kitchen spatula - run it beneath the length of the grille and free the grille from the other projections. Your blade will be passing the speaker so keep it close to the grille.
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With the grille removed, you'll see a set of recessed Philips screws. Remove them. The front of the enclosure - on which the speaker is mounted, is now free but constrained by the speaker wires. Work on one end then another, use, e.g. two knives to grip the edge of the white plastic inner enclosure, easing it from its mount.
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Once removed, the speaker mount is constrained by wiring. Gently reposition the wiring to familiarise yourself with the interior of the enclosure - containing the battery, main circuit board, and associated connecting wires linking the speaker, the battery, and the second circuit board.
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Connecting leads are sheathed in a foam wrap to minimise the chance of rattles. Gently free the battery lead, identify the (red) connector that attaches the lead to the main circuit board, and disconnect it, gently working the connector out of its socket. Lift the freed battery from the enclosure and put it aside for careful disposal by recycling.
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Before connecting your replacement battery, you need to check the polarity of its connector as this is not standardised. Double check that the polarity of the replacement battery's connector is the same as the one you removed from the speaker - if not, swap the wires in (or to) the connector. When doing so, do not short the battery.
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You'll have seen that the battery you removed has padding to ensure it was a good fit for the speaker's battery holder, and the lead has a foam wrap to guard against rattles. Your replacement battery may or may not need the padding, and the foam wrap for the replacement battery's lead is not essential: route the lead sensibly though.
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Before reassembling the speaker and with the replacement battery connected, take the opportunity to turn on the speaker and see that it powers up. If you've replaced the battery because the speaker was completely dead, the chances are that this was because the protection circuit in the old battery had tripped, so it should now be ok.
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While reassembling the speaker, if the plate with the loudspeaker mountings does not seat properly, check for trapped leads/padding. Before re-seating the grille, if it's been distorted during removal, gently reform it so that it is reasonably flat, make a note of the positions of the 'pips' that retain it, apply gentle pressure at those points.
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Before using the speaker, charge the battery for at least four hours. This will ensure that the battery's two cells are charged and also balanced. Partly charging the cells is fine, but once a month or so, it's good to give the battery a four hour charge and this will keep the cells balanced.
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With the replacement battery installed and if the speaker is now working, it's useful to know the following. Do not use the USB port - its output is insufficiently regulated. Device charging has evolved. Devices may now draw more power from the port than the battery's protection circuitry will tolerate, permanently disabling the battery.
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Do not connect/disconnect the charger lead whilst the speaker & charger are powered up. This risks a power spike that trips the lithium battery's protection circuit, permanently disabling the battery. Switch both charger and speaker off before connecting/disconnecting the lead.
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If you find that you cannot pair the speaker, the cause may be radio interference from other devices - take the speaker somewhere that's likely to be 'Quieter' and try again. Once paired, the speaker connection is more robust, but the pairing stage relies on timely exchange of security information and that step is more fragile.
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Once used, the speaker 'Remembers' the last four devices to which it was paired. In some circumstances, it can be useful to discard the contents of its memory. To reset it, turn on the speaker and hold down the 'Volume up' and 'Volume down' buttons until it announces that it is resetting itself - you'll see buttons illuminate and hear chimes.
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Set two Cambridge Audio G2 speakers up as a stereo pair and this results in a big step up in the perceived quality of the soundscape you hear. Set the switch on the rear panel to 'A', on one, 'B' on the other. Then a double press of the 'Bluetooth' button on each. You'll hear a series of strange converging beeps as the speakers synchronise clocks.
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As with bluetooth pairing, the process of synchronising two speakers to use as a stereo pair can need a 'Quiet' environment (from the point of view of other devices using the 2.4g radio spectrum). Also, once connected, in 2026, some sound sources are more successful in enabling reliable stereo sound with these 2014-era speakers than others.
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With a 3400mAh battery, the speakers will charge in ~ two hours using the original charger. When the speaker is part-discharged, try this: charge for up to an hour and forty five minutes - it's the top 20% of the charge that causes the most wear to lithium batteries. Save a full charge for the days that you may need a full run-time.
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Every month or so, though, charge the speaker for four hours - this ensures that the cells in the lithium battery are balanced, that is, charged to a similar level. This avoids the situation in which one of the cells risks discharging below a voltage that is healthy for it.
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Strengths: this speaker, while obsolete, is well constructed and can provide a coherent solid sound that's easy on the ear and doesn't fatigue. Pairing two as a stereo pair can be rewarding.
Weaknesses: their Bluetooth implementation is 'of an age', and the stereo pairing implementation is an early one - they may sometimes struggle to work in an environment with many other devices using the 2.4g radio spectrum. The speaker may not work well with particular devices - for example, a pair working in stereo may struggle when paired with an Apple laptop running MacOS.
Finally: the USB charging port they provide should not be used as its use to charge modern devices is liable to permanently disable the speaker's internal battery (and may well be the cause of the reason you've needed to replace the battery).
