Anyone out there have the Sena SMH10?

@mpenner,

You are placing a lot more faith in the internal charging circuits of various consumer electronics devices than I would.

I notice, for example, that Apple now makes two basic chargers, one for iPads and another, less powerful one for the rest of the iOS devices. I haven't measured current at the pins, but I know heat when I feel it and heat is not what li-ion batteries like to experience.

Sure, it will work, but how many times before battery service life is degraded?

To explore your Battery Tender metaphor a bit further, you wouldn't put an automotive 50-amp charger on your bike battery. The output is much more relevant than the input in that example.

-dan

There ya go, I was not aware of this circuit board. I only know that unless a lithium battery is designed to accept more than 1C charge, the charge rate should never exceed 1C.

1C meaning that if the battery has a 400 ma capacity, it should not be charged at more than 1 X capacity or a charge rate of 400 ma.

Danhams iPad vs iPhone is a good example. The iPad battery has a larger capacity that the iPhone and therefore, can accept a higher charge rate.

Many modern lithium chargers can automatically detect this, it would seem, based on mpenners post, that a USB charger is also capable.

Good info

Cheers

When you plug your Sean into the USB port on your computer you are charging it with the following current:

http://en.wikipedia.org/wiki/Universal_Serial_Bus

USB 2:
Battery Charging Specification 1.1: Released in March 2007 (Updated 15 Apr 2009).
Adds support for dedicated chargers (power supplies with USB connectors), host chargers (USB hosts that can act as chargers) and the No Dead Battery provision which allows devices to temporarily draw 100 mA current after they have been attached. If a USB device is connected to dedicated charger, maximum current drawn by the device may be as high as 1.8 A

USB 3:
Battery Charging Specification 1.2<sup id="cite_ref-battchargespec1.2_11-1" class="reference">[12]</sup>: released in December 2010. Several changes and increasing limits including allowing 1.5A on charging ports for unconfigured devices, allowing High Speed communication while having a current up to 1.5A and allowing a maximum current of 5A.

My understanding is the that the reason that Apple introduced the new charger for the iPad is that chargers for older devices did not supply enough current to charge the iPad at the fastest safe rate (1C as mentioned by Pete). I have an iPod charging on an iPad charging cord at this very moment and it will not harm the iPod battery in any way.

I agree that the output is much more relevant than the input. What I am arguing is that the charging cord is the input and that the charging circuit internal to the device that actually supplies power to the battery is the output.

The charging rate (current) is set by the charging circuit contained in the device and not the USB charging cord.

I have not reverse engineered the Sena unit, but I am pretty certain that it contains a circuit similar to the following:

http://cds.linear.com/docs/Design Note/dn250f.pdf

Of course, if a device applies the +5 Vdc from the USB charging cord directly to the battery as the charging voltage then your concerns are well founded, but +5Vdc is going to ruin a battery anyways since Li-Ion batteries require a 4.2 Vdc final charging voltage.

http://www.analog.com/library/analogDialogue/archives/31-2/liion.html

There is no way Sena is going to use a USB input as the charging input without an internal charging circuit and then offer a 1 year warranty. I also don't think that it takes a lot of faith to believe that a company like Sena that can design a BT interface can also design a simple charging circuit.

OK I will shut up now and go back to designing the circuits that I am being paid to design

@Mike:

Hey, I'll always defer to superior training and knowledge. And thank the bearer thereof for helping me learn something. Thanks.

But I hope you'll forgive me if I continue to worry that not all manufacturers are always going to do the right thing with their circuit design, are going to lsiten to their engineers and spend extra money when necessary to protect full battery service life, are going to put the consumer's interest ahead of short term profits.

So far my dealings with Sena suggest they are reputable. But I still go read the labels carefully before trying to charge any of my li-ion-powered devices with chargers other than the one that came with.

-dan

Mike,

Thought you might be interested in this blog, which describes a teardown of an Apple iPhone charger and, about a third of the way down the page, links to differences between this very sophisticated charger and a cheap knockoff, which the author says is downright dangerous in its design. Great example both of good design and the kind of cheap shortcuts I worry about [grin].

http://www.arcfn.com/2012/05/apple-iphone-charger-teardown-quality.html

-dan

Interestingly, I have a cigarette lighter adapter with a USB port and while it will charge various things, my iPhone simply will not charge from it. Attach the iPhone to an identical looking unit from a known brand like Belkin and it will charge, happy as a clam.

The Sena comes with a 12vdc cigarette adapter but I have thought of using the USB cord from the wall charger and sharing the same Belkin charger I use for the phone. One less cord to carry on the road. I hadn't got around to checking the specs.

So if I understand mpenner correctly, if the Belkin unit is capable of delivering 1200ma but the Sena only requires 600ma, the charger will only deliver what is needed ie 1C not 2C?

I completely agree that the absolute safest choice is to use only the charging cord that came with the unit, but even then there is always the possibility that even that charging cord will fail and damage the battery or charging circuit due to manufacturing defects or poor design.

Thanks for the link. There certainly are differences in quality of design and manufacture between the various suppliers. I always enjoy examining other's designs and Apple generally seems to get things right. Unfortunately the documentation that is supplied with consumer equipment is rarely enough to determine whether or not it is quality equipment. Often you have to rely on the reputation of the supplier.

Some of the best power supply designs can be found in avionics equipment since peoples lives depend on them working correctly under all sorts of conditions. These designs are tortured and tested in ways that Apple has probably never even dreamed of and the results are documented in a very large stack of paper.

That is exactly what I am suggesting and that is what I do. I use a USB cigarette lighter adapter with the charging cord from my phone to charge the Sena.

Phones often play tricks with the voltages on the D+ and D- lines on the USB connector so that they will only work with their chargers and I am sure that that is why your "generic" USB cig adapter will not work with the iPhone. The more expensive Belkin is emulating Apples tricks on the other USB lines, so it works just fine. In my case, my phone will not work with the Sena charging cord, but the Sena will charge with the phone cord so I take the phone cord.

Try this experiment. Charge your fully discharged Sena unit with the Sena supplied charging adapter and cord and measure how long it takes. It will take about 8 hours (the Sena does not charge at anywhere near a 1C rate or it would take only 1 hour). Then discharge your Sena unit again and charge it with the Belkin adapter. The amount of time that it takes to charge the Sena will be very close in both cases indicating that the charge rate is the same.

Or try this thought experiment. According the danham (I have not verified this, but I am sure that he is correct), the Sena charging cord supplies a maximum of 1A. I know from charging the Sena units many times that it takes about 8 hours to fully charge a completely discharged unit. If the Sena were consuming the full amount of current available from the charging cord for the 8 hours that they were being charged, they would have to have an 8 Ah battery (1A x 8 hours) which is equivalent to 8000 mAh. If Sena knew how to make a 8000 mAh battery would fit into these units, we would all be driving electric cars. Therefore, the Sena supplied charging cord has a much higher maximum current rating than what is needed for the units.

In summary, I contend that while there are differences in quality between different charging cords (and there is some risk in using poor quality charging cords), there is no danger in using a high quality charging cord with a different maximum current rating than the one that was supplied with the equipment if the charging input is a USB connector and the battery being charged is a Li-Ion battery. If you use a charging cord with a lower maximum current rating, it may take longer to charge the unit (or worst case, it will not charge the unit, but won't damage it.) If you use a charging cord with a higher maximum current rating, the charging circuit in the unit will only use the amount of current that is needed to correctly charge the battery.

I see revzilla has sena marked down 25% so Im getting ready to pull the trigger on the dual set of smh-10 and ear bud adapters. Ive never had an intercom before. Will be using with iPhones and nolan n43 and nolan 102 helmets. Im ordering tonight so would just like to make sure there is nothing else I will need to get me up and running. Thanks. I looked at the rocketmoto? site but it looks like revzilla is cheaper right now. Are the intercoms a different version?

firebrick - did you check with rocketmoto to see if they were still offering the advrider discount? If not, you may want
to do that. If the discount still stands, it will be cheaper than Revzilla. I just got my dual smh10's a couple of weeks ago.
They are the latest version that are firmware upgradable.

I didn't know they had that. Guess Ill check. Had never heard of them before this thread.

Got the SMH-10 dual set. I'm currently on a trip to AK using the headset. Unbelievable!!!!! I have my phone bluetoothed to it and my Garmin 496 hardwired to it (no bluetooth) for XM music and turn directions.

I snapped the mic cover on the front and while riding 70mph my girlfriend can't tell I'm on the bike.

When you have cell service, it works sooo good! Love listening to my music and then a call comes in and I answer it. Fun! It really is nice! Some will say unsafe and maybe it is, but I love it. Having commo with the little woman eases her worries a little about my looong ride. Waiting for a ferry is a perfect time to call a friend that is jealous of your ride to rub it in! Hahaha!

Excellent product! I'd recommend it to everyone!

Nice writeup...thank you..wish I was there...

If you have an Android phone and your Garmin quits working,
check out EMFB (Easy Map For Bikers)..might even be good as a backup.
It will do everything the Garmin will do and more.
..turns your phone into a super navigation device with real time weather display.
...cheap insurance for under 13 bucks.

Dennis

today was the first time I ever used the intercom. it works great. I never realized how loud my Wife's helmet is . I could hear her wind noise thorugh the intercom. I might need to do something for her about that.

Oh, and for the last poster, my Wife has an N102, standard clamp on mounting system worked find. Boom mic, just make sure it goes under the moduler front while closing.

I have a iphone 4s and a sena SMH10 both worked fine until I did the software upgrades for both devices. I am having a problem with the BT connection. Before I simply connected headset to phone and it stayed connected after power on and power off. With current setup I have to pair both units every time I power up the headset. The headset works fine but I never had to do this before. Has anybody had this problem and how do I make it simple again ?

Did you clear the BT pairings after the upgrade? Go into your iPhone and delete the previous BT pairing to the Sena. You might also look at the instructions on resetting the SMH10 and clearing all the pairings from that and start from scratch. One you do that, pair them once and hopefully things will be back to normal for you.

Went thru the entire pairing process and looks like it working like it did before the upgrade .... Thanks

OK, I've got a question. Got the Sena paired to my iPhone. I stream music through the phone, as well as receive calls. I'd love to be able to sync my Zumo 665 to the Sena for navigation only. Every time I try this, the Zumo supersedes the iPhone, and I lose both my tunes and phone connectivity.

I don't want to run the phone through the Zumo, as (I believe) I'd lose the ability to pause and skip with the Sena. Is there a way of pairing both?

You need to pair the handsfree profile of the iphone with the zumo, and the headset profile of the iphone with the sena. Pair the zumo with the sena with the handsfree profile and everything should work.

The problem is, unless the iPhone is jailbroken, I don't think it can split its BT connection between 2 devices simultaneously. Regardless, he doesn't need to do that if he has the SMH10 V4.0 installed.

If you have the SMH10 USB version with v4.0 installed on the SMH10, you can do this with the new multi-point pairing. It allows 2 HFP connections and 1 A2DP connection which is exactly what you need. The PDF for for SMH10-V.4 shows this exact setup for case study #2. It refers you to section 6.1 for the phone pairing which is your standard pairing for the iPhone for both HPF & A2DP. For the Zumo 660/665 pairing, it refers you to section 6.3.1 which is Multi-Point GPS Pairing.