Charging a Scala Q2 from 12V

[racer7]

The Scala Q2 is a nice headset that pairs well with bluetooth phones, the Zumo and similar, and with other bluetooth headsets. I use mine with an I Phone and the BMW version of the Zumo 550. However, the Q2 is battery powered and this becomes problematic if one is away from 110V for multiple days as on a camping trip.

 

I found a solution for this. It is a cig lighter socket 12V to 9V charger for $25 sold by Radio Shack. It carries the Enercell brand on the plug and is labeled "custom made in China for Ignition LP, 3102 Maple Ave, Suite 450, Dallas TX" on the flip side of the plug. It's labeled catalog number is 273-0365 and is rated 300 mA continuous, same as the 110 V AC unit supplied with the Q2.

It comes with 4 sizes of the usual Shack interchangeable plugs and one is the same as the Q2 uses so no other tip needs to be purchased. This 12V charger is for some reason labeled as 600 mA on its packaging and is switchable by a simple slide switch on the plug to 3, 4.5, 6, 7.5 or 9V. I measured its output at the 9V setting needed by the Scala as 9.03V, precisely the same as the supplied 110V charger.

 

I made a few other measurements while testing but did not disassemble either of my Q2s. The Q2s size suggests its internal battery is likely no more than 500 mAH and may be only 300 mAH- the manual provides no info on this. IIRC, it takes almost 5 hours to charge a fully discharged unit with the 110 V charger. Obviously one could recharge it easily while the bike is running so the bike battery isn't drained but I wanted to be certain of the current draw of the charger so made some current measurements with my Fluke 189 RMS meter.

When plugged in but not connected the charger draws 29 mA so I wouldn't just leave it plugged into my bike when not in use- even as little as that can dent a main battery if left unattended for weeks. Once connected to the Q2 it draws 40.5 mA until the Q2 lights to signal recharge is happening then a few seconds later blinks off and instantly comes back on at 65 mA, tapering down to 40 as the Q2 charges. These measurements were made on a partially charged Q2. In any event, it is clear that the Q2 circuitry limits the charging rate to far less than the charger can deliver. The measured rate is consistent with observed times and estimated battery capacity of what is in the Q2.

 

I have done several successful recharges of partially discharged Q2 units from my non-running RT- relying solely on the bike battery- with no discernible impact to the main battery. These recharges took only 2-4 hours and one would not expect the low charger draw to have any notable impact on the much larger 12V lead acid gel cell cell in the bike in that time. I haven't yet tested recharging a fully discharged Q2 and leaving the charger plugged in overnight like I might do when camping, for example. But I would predict no issues. The worst math would be about 800 mAH (less than 1/2 of an AA rechargeable NiMH, for example) and its likely much less- that won't dent a bike main battery.

 

Anyway, mine is set up to be used in my electrified BMW R1200RT tank bag. Internally it powers my I Phone and the Q2 charger. It also has an outlet that with a short SAE to coax connector powers my Gerbings. All of this works fine drawing from the bike stock front outlet that is 10A rated on my 2008 model. Obviously there are many different ways to wire a version that you might like better. All my connectors are sourced from Powerlet.

 

Because I own a pair of Q2s, when not riding with the SO, I can simply take the Q2 off that helmet and charge it in the tank bag while riding- so 1 is in use and 1 is charging on a running motor. Haven't actually tested this bit yet- that will happen this week on my run to GMR.

 

Takes away one of the reasons for wanting a hardwired system......

[Caddis]

I have been considering getting one of these for charging our Scala Rider Q2 sets when on a trip. I already have a cigarette-style power outlet on the bike, and it seems like this would be just what I am looking for. Would this do the job as well?

[racer7]

Looks like it. Has the Cardo brand overstickered on it and only question is whether it is actually 9V that the Q2 requires. (If all Scalas use 9V its a non-issue but I don't know if that's true).

 

It appears to be a overstickered generic Chinese item and these are between 300 mA and 1000mA, plenty to charge any headset and the Scala limits charge current to a lot less (65 mA).

 

I'd just buy it, verify its marked 9V and use it. Price is certainy OK. You give up the multivoltage capability of what I've picked but that may not matter to you. The multivoltage allows charging other types of batteries in holders as well as other devices direct.

 

If you do mostly motels on the road its just as easy to use the wall plug unit but when away from 110V, some type of 12V plug in is the only easy option. Looks like you may have found the lowest cost option!