Updated Oct 1, 2019
In May of 2013 I picked up a pair of Sena SMH5 helmet intercoms so that my wife and I could communicate while riding. I also wanted the ability to listen to music or make mobile calls without having to stop and remove my gear. My main riding buddy Robin jumped on the bandwagon shortly after with his purchase of two Sena SMH10s.
I love the Sena interface and it’s sound quality is quite good. It served me well during our cross-country trip to the northwest. During that trip, I discovered a design flaw with my communicator: streaming music for more than an hour or so quickly depleted the battery.
This problem continued to worsen until the module was basically unusable. Of course, this happened a few months after the warranty expired. As it turns out, this is a common issue. The manufacturer doesn’t offer a replacement battery or an end user solution. You can possibly ship it back to them but this would more than likely cost just as much as a new unit. Because it was basically bricked, I decided to dismantle it and see if I could replace the battery myself.
A bit of research lead to the purchase of this battery.
Live outside of the United States? Here’s a possible alternative that’s plug-and-play.
The batteries linked above certainly outperform the original by many amp hours. If said links suggests the battery to be sold out, here are some other options (note the “472540” identifier). Still, a bit of work is required prior to making the swap as the connectors might not be included.
In the end, it’s all about specs and dimensions. The SMH5’s circuitry demands a 3.7 volt lipo-polymer ion battery with dimensions of 40x25x5 millimeters. If all else fails, there’s always that “mayday” phone call to your local hobby shop.
Steps To Replace Your Sena SMH5 Battery
Again, we want the 3.7V 500mAh Lithium Polymer rechargeable battery. This battery is also compatible with the SMH5-FM. As for the process …
First, test the new battery’s polarity with a voltameter as it’s often reversed. The casing is held together using three T7 torx screws. A precision screwdriver is ultimately the right tool for the job.
Pictured above is the rear casing, precision driver (with T7 bit) and new batteries. Unscrewed, the case simply pulls apart. There’s a rubber seal that keeps it water tight, so pry gently. The battery connects via Molex connector (51021-0200) and is secured using double-sided foam tape.
Now open, you can see how it’s connected. Using a small screwdriver or pliers, you can wiggle the connector free and separate it from the unit. A little prying and scraping will dislodge the battery.
The battery is held in place with double-sided foam tape.
Once the original battery is removed, insert the new battery using fresh double-sided foam tape, connect it and put everything back together. Be careful with the rubber flap near the USB port as this protects it and can fall out or become pinched.
Charge the unit and enjoy what’s likely to be a successful test ride!
Here’s video for a similar model, the SMH10. While there are differences, there are also a lot of similarities to the battery replacement process. Use the following information as you see fit …
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Mar 10, 2015 at 8:14 am
Hi Travis! Thank you very much for your tutorial! This is just what I needed!
Matteo
Apr 15, 2015 at 9:59 pm
Thanks for your tutorial. I wouldn’t have tried otherwise!
May 18, 2015 at 3:20 am
Merci beaucoup!
I was looking for a compatible battery but couldn’t find one. Thank you very much and have a nice day!
Thierry (Nice, France)
May 22, 2015 at 2:51 am
Hello, Travis! Thank you for this very rewarding tutorial!
GRHUM
Jul 31, 2015 at 12:56 pm
Hi, Travis. I’m going to replace my batteries as well. Did you have any issues with the higher amperage?
Aug 2, 2015 at 8:42 pm
Dave,
“mAh” is Milliamp Hours. It refers to the capacity not the amperage output. As long as it’s 3.7V output you should be good. I haven’t had any issues with it other than longer operating time. It may be possible that the device firmware doesn’t recognize the extra capacity from the battery firmware (lipo batteries have a built in micro processer) but my experience is that it last’s longer than it did when new.
~Travis
Aug 3, 2015 at 1:09 pm
Travis, this is really great work and a really great description! It’s one of the reasons we have the internet! Thanks!
Aug 30, 2015 at 9:09 am
Update! I just ordered the batteries you mention. I’ll post more comments after I receive them and see what happens.
Sep 12, 2015 at 10:14 am
I installed one of the batteries (I ordered two) and gave it an hour charge. still showing red. My wife and I took a ride. all sounded good. So I put the charger on it and waited until morning. Low and behold I has the blue charged led. So I went ahead and swapped the second one out and put it on the charger. Everything looks and works great. They are 600 mah units, so I want to have them both fully charged and see if I get more time on them. I will do a followup on this next week after we use them a bit.
Sep 14, 2015 at 7:15 pm
OK, The results are in. After a complete charge in the morning, we rode a good 5 hours. Only turning them off a couple of times for short periods. When we got home, I checked the red blinks for power left. They both still had 3 reds left. I had no issues with overheating, quality of the conversation, or any recharge issues. Also no issues with getting the weather seal back in place again, which was one of the things Sena was worried about. Everything seems to be better than before. I am keeping the OEM batteries for the plugs, and mine wasn’t bad, just my wife’s. I checked the battery link from your post. They just added many more of these units for sale again. So have at my friends. I hope Sena is reading this.
Oct 3, 2015 at 1:30 pm
Travis and Dave, thank you both for this very valuable information. I’ll be swapping mine out when the new battery arrives and will compare it to the new SMH5 I just ordered for my wife. Cheers.
Oct 24, 2015 at 9:49 am
Thanks for all of the info.
Being impatient, I stripped the wires on the new battery, inserted them directly into the plastic connector and used a miniscule amount of super glue. Plugging the connector in, it charged up and low and behold it worked! I tested it via streaming music and am getting near seven hours of playtime which is cool :-)
Once again, thanks to everyone as this cost me only $25 (including the mini-tools which have the Torx 7-bit) versus a whole new system.
Cheers.
Feb 18, 2016 at 8:43 am
HI guys.
This is one of the most useful posts I’ve read regarding the Sena battery issue.
Does this fix work for SMH10 as well? I’m not sure what the differences are between the two devices. The internet suggests the Sena SMH10’s battery is 560mAh and 6mm x 22mm x 48mm with a 3.7 voltage rating.
I’d Appreciate if someone can share a link or provide some details on how I might go about changing it out. Im a total noob and don’t really own any tools apart from a simple Ikea toolkit (spanners/ screwdrivers, no solder iron etc).
Much thanks,
Mihir
Feb 18, 2016 at 9:42 am
Hello Mihir!
If not identical, the process of swapping out an SMH10 battery is quite similar to the instructions above.
With regard to battery differences, mAh isn’t something to concern yourself with beyond the fact that more = better. The mAh figure simply expresses milliamp hours, meaning how long a battery can go before needing to be recharged.
Size and voltage rating, on the other hand are enormously important. Make sure that whichever battery you purchase is within the boundaries of the stock dimensions (if not equal to those exact figures). Voltage, on the other hand should be precisely what’s specified by the SMH10 itself (3.7 as you’ve stated).
One other concern that everyone should be sure to employ is the battery type! For the SMH5 (not sure about the SMH10), IT HAS TO BE LIPO POLYMER ION, i.e. “Polymer Lithium Ion” or the like. Any other format is likely to explode, melt or even catch fire.
As they say in motorcycle safety school … “S.E.E.” (search, evaluate, execute)
Feb 23, 2016 at 4:59 am
Thank you for the very useful info and especially for keeping it current. I have no problem tinkering with electronics but links to a good battery that fits are a great help. Keep up the good work!
Apr 1, 2016 at 4:04 pm
Hi, sorry if I’m asking a stupid question, but how do I test the battery polarity when they arrive and what do I do about the result of the polarity test?
Apr 1, 2016 at 5:12 pm
Hello, Steve.
Such questions are more than welcome!
To test your battery’s polarity, you’ll first need an electrical multimeter. If you press the meter’s red probe to the battery’s red wire (and the black to black) but are met with a negative reading, your battery’s polarity is reversed. If that’s the case, you’ll want to disconnect the Molex connector (if included) and reverse the wire destinations.
https://www.youtube.com/watch?v=tc8rkOYWZuE
Here’s a more in-depth video about multimeters and their uses …
https://www.youtube.com/watch?v=bF3OyQ3HwfU
May 14, 2016 at 3:37 pm
Hi guys.
Thanks for the battery replacement tips. I ordered and received batteries, fitted them and used the unit for a 5-hour ride. Listening to music and taking two phone calls, I’m still left with a battery level of “high”. Awesome.
Thanks again.
Jun 13, 2016 at 1:42 pm
Thanks Travis, very helpful.
I have two SMH5 units for about 3 years. One had no issues but the other had gotten to where it would shutdown after 45 minutes.
Ordered the batteries and Torx set per the article links. My new batteries only had wires and no Moldex connectors. I carefully unwrapped the old and new battery, unsoldered the wires on both and made the switch of the old wires with connector to the new battery, and charged until blue.
Went for a 5 hour ride, no issues. Compared reserve and both units showed 3 red flashes (>50% battery life remain).
Very happy……….
Oct 5, 2016 at 10:05 pm
Thanks so much for this guide. I DID IT! Not too difficult. The new battery leads did not have a connector so I had to splice on the old connector. That was the trickiest part. Beside that it was easy.
Nov 18, 2016 at 5:14 pm
Did it with both of our headsets. What should I say? They are like new … even better performance! Thank you so much for this very helpful guide!
May 11, 2017 at 4:16 am
Hello. Where can I buy the battery for my SMH5-FM? Thanks.
May 11, 2017 at 8:49 am
The casing for both the SMH5 and SMH5-FM are identical. So are their batteries … https://www.amzn.com/dp/B00M6L9MCS/
May 12, 2017 at 2:11 am
Wouldn’t this battery be better? It’s 32x20x5.0 whereas the battery you link to (originally) is 43x25x4.3
May 12, 2017 at 9:45 am
@Floppy968
THANK YOU!
Your battery link is better. I’ve updated EVERY link on this page to use it instead.
Thanks for helping us keep things up to date!
May 12, 2017 at 10:50 am
I’m from Italy and can’t buy through amazon because the sender doesn’t ship here. Any suggestions as to another source?
Nov 29, 2017 at 5:35 pm
This just in …
Reader “J. La” reached out to me via email (apparently the site was giving him trouble when he tried to post a comment). He says that the following fits “plug-and-play” and comes with a torx screw driver. It took three weeks to arrive (ebay.de) but maybe … HOPEFULLY that will make things easier for those of you viewing this page who don’t live in the United States.
https://www.ebay.de/itm/Sena-SMH5-Bluetooth-Headset-Intercom-battery-replacement-Screw-Driver-DIY-NEW/332396187758
Dec 1, 2017 at 4:17 am
Hi, Travis.
Mine took a tumble at high speed and snapped the retaining clip that’s on the back battery cover.
Any idea whether I can get that part replaced?
Dec 1, 2017 at 5:49 pm
Heath,
Do you mean the part that attaches to the helmet? You may have to shop around as they are discontinued. But I found it on BikeBandit
https://www.bikebandit.com/riding-gear-and-accessories/communication-cameras/communication-bluetooth-systems/sena-smh-5-mounting-kit/p/41389
Best regards,
Travis
Jan 28, 2018 at 8:38 am
Bonjour, Qui peut me donner le lien sur Amazon et me dire quelle batterie je dois acheter pour mon SPH10H-Fm?
Jan 28, 2018 at 9:18 am
Nous n’avons pas encore étudié ce modèle de communicateur. Parce que nous n’en avons pas un avec qui travailler, je crains que nous ne puissions pas vous donner d’instructions claires.
Cependant, si vous suivez notre philosophie de base (démonter, mesurer, chercher des numéros de série) … Je suis sûr que vous serez en mesure de Google l’information nécessaire.
Patience + focus = succès ;-)
Apr 15, 2018 at 7:52 am
Thank you for taking the time to write such a complete how-to on replacing the battery. I wouldn’t have attempted it without your thorough step-by-step. The polarity warning saved me from a potential disaster. The hardest part of the “surgery” was changing the polarity with these 74 year old eyes. Even with a magnifying glass it was a challenge. I practiced on the old battery and that helped build some confidence. The hot links to the needed tools etc. were exceptionally helpful. Thanks again and keep up the good work!
Aug 30, 2018 at 2:29 pm
Thank you for the guide! I just replaced my SMH5 battery after 2 years, and all seems to be well. I did run into two problems with the battery you linked to, so I thought I would leave put the information here here, along with hopefully clear and simple instructions for making it work perfectly.
The first problem: the red and black wires were reversed in comparison to the original battery in the headset. (i.e., the polarity was reversed.) This is not a huge problem–NO SOLDERING IS REQUIRED–but you will need to take the wires out of the small plastic plug and swap them. To do this, take the smallest flat mini screwdriver you own, very gently pry up the two plastic tabs on the top of the plug (as seated in the headset) one at a time, and gently pull the wire out of the plastic plug. Don’t yank! There will be a metal clip on the end of the wire that actually makes contact and holds the wire in the plastic plug.
A second problem: It was nearly impossible to take the plastic plug on my out of the headset once it was plugged in. By the time I got it out, the plug was utterly destroyed. I strongly recommend you use the plastic plug from the original battery. Luckily, this is not much of a problem either, because you have to take the wires out of the new plug anyway to reverse them. Just do the same thing as above to the old battery and insert the new wires fully into the old plastic plug. Make sure that the wires are out of the way when you put the headset back together.
Good luck everyone!
Sep 14, 2018 at 4:55 pm
Haven’t had much of an opportunity to use our intercoms since I bought them awhile back. When I did try to charge them, they were both dead. Found this website and what a great help!
My wife and I are taking a back roads ride tomorrow and now we won’t have to yell at each other.
Thank you.
Nov 28, 2018 at 12:38 am
Thanks so much for your post! Have been using my sena about 1.5 years almost daily but now it’s only lasting about 40 minutes. Cant wait to get the battery swapped.
Dec 11, 2018 at 4:50 pm
Great. Sena replaced mine when they initially stopped taking a charge. Now, 3 years later the life is down to half an hour and my attitude is repair not replace. Thanks for doing the homework to track down the replacement battery assembly.
Sep 7, 2019 at 9:08 pm
Couldn’t have done it without your instructions, Travis – thank you! I did run in multiple problems along the way:
– The replacement battery’s red and black wires were revered
– I accidentally yanked one of the wires from the replacement battery), but multiple attempts at cutting, splicing and soldering and eventually I got all the connections working and the new larger battery installed.
Many thanks for creating this page!