Old Sena SMH10 With A Dead Battery
I have been using this thing for a lot of years. Last year I noticed it would hold a charge for maybe 3-4 hours, as opposed to its original 8-10. This spring it went down to half an hour, and that's basically dead. The stickers are for identification. My whole riding club uses the same comms, and when we all pop them off our helmets to charge at the lodge at the end of the day it can get confusing!
I found an online retailer, Battery Clerk, which offers a compatible battery for this particular Sena unit which has (bonus points) the correct plug already attached. Hooray, I do not have to solder these tiny tiny wires!
The Battery Clerk site, part number CS-SMH100SL, is here, but note this is ONLY for the Sena SMH10. If you have a different Sena device this battery is not the correct fitment.
Unscrew The Back
For this step you will need a T8 Torx driver. Nothing else will fit, trust me. Do not try to cram an Allen wrench in there; you will strip the bolts and then you will be sad. These fasteners are tiny, so be careful unscrewing them and make sure your driver is completely seated before turning it.
Pull the tiny little bolts all the way out and put them down on a light colored surface, somewhere they won't roll away. Yes, we've all had that moment of "where is the third little bolt." Be careful.
Carefully Lever The Back Off
First, grab the springy lever at the top of the unit and pull gently to pry the back off, just a hair. Then, using your favorite trusty pocket knife or similar very thin metal, get the blade just under the back of the housing and follow it all the way around. Be extra careful around the pins; they are a press-fit into the housing and you want to pull directly up so that none of them is damaged.
Remember, don't poke the blade all the way into the housing, there's fragile stuff in there. You're only using it to lever the back off, so be gentle and take your time.
Take Note Of Plug And Battery Position
Pause here for a moment and take this all in. You'll want to pay close attention to how the old battery is oriented in the housing, and how the wires are plugged into the unit. Hot tip: the red (positive) wire should be in the plug so that it is closest to the pins.
Carefully Unplug The Battery
Since you don't want to put any undue pressure on these little wires, or the plug, or the circuit board, you'll want to unplug the battery from the unit. Find the tiniest pair of tweezers you can manage for this task. You'll probably find some in your, ah, medical kit. Yeah. Medical kit.
Grab the plug (NOT the wires) with your tweezers, and gently pull the wire plug out of its housing. Wiggle it side to side a touch, but be careful not to damage the board with your tweezers. This will separate the back of the unit from the circuit board so you can move on to removing the battery.
Peel The Battery Out Of The Housing
The battery is attached with double-sided foam tape, so you'll need to very carefully peel that away. Your pocket knife can be handy here, too. Be very careful not to pierce the battery itself. Lithium ion batteries can be dangerous, so don't be rough with it.
Plug The New Battery In
Press the new battery into the housing exactly like the old battery was. Use double-sided tape and make sure it isn't going to move. Orient the new battery's plug correctly (positive wire closer to the pins), and using your tweezers again, squeeze the plug into the housing until it's seated all the way in.
Make sure to route the wires so that they are not in the way of the holes for the fasteners, and prepare to begin reassembly.
Press The Back Onto The Housing
Be sure you've oriented the back of the module correctly, and very gently push it back over the pins and onto the back of the unit. It may not seat all the way yet, but that's OK. Make sure the bolt holes are clear of any wiring.
Reinstall the fasteners with your T8 driver, but just like reinstalling anything with a bunch of fasteners, seat them all first, and then tighten them all a little bit at a time, so that no single fastener is loads tighter than any other, wedging the back at an angle. Hop from one to another and tighten them all a little at a time to keep the back cover straight on the housing.
Plug It In And Make Sure It's Charging
The moment of truth: plug your Sena headset module into your closest handy micro USB charger and make sure it's taking a charge. If the light illuminates and is red, that means it's charging!
Hooray It's Charged!
Keep an eye on it, and charge it up to full for the first run. It's done charging when that light turns blue.
Now you can chat with your riding buddies and listen to music again! Wasn't that satisfying?
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