DC 3.7V 2100mAh 804050 li-ion Lithium Ion Polymer Battery Replacement for DIY 3.7-5V Electronic Products with Built-in 2-Wire Battery Replacement, Mobile Energy Storage Power Supply
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Availability:
In Stock.
Arrives
Wednesday, May 13
Color: 8×40×51mm 2100mAh
Features
- This battery is suitable for DIY electronic products with 3.7-5V and less than 7.77Wh 2100mAh built-in 2-wire battery replacement.( Not applicable to high-power electric tools and model aircraft)
- Please note that the specifications and polarity of the connector are based on the product display image,the red wire is the positive "+" and the black wire is the negative "-",Do not reverse-charge or reverse-connectreverse. The primary battery of some products has no plug or mismatched plug or mismatched polarity. It doesn't matter, you can cut and solder the plug directly or use our heat shrinkable insulating sleeve to connect the same color wire.
- 804050 rechargeable lithium ion polymer battery, size 2 x 1.574 x 0.314 inch(51408mm) (L*W*T),nominal voltage 3.7V, full charge voltage 4.2V, capacity 2100mAh, power 7.77Wh, Weight:1.16oz(33g),Maximum current:2.1A It can prevent overcharge, overdischarge, overcurrent, and short circuit..
- Its consists of of large-capacity A+ lithium battery, Japanese Seiko IC overcharge and overcurrent short circuit protection board, 3302-24 high temperature resistant silicone cable, and genuine JST Pitch 2.0mm 2 wire connector module.
- If there are any quality issues within a year, please feel free to contact us via email for replacement.
Number of Batteries: 1 Lithium Polymer batteries required. (included)
Brand: HXJNLDC
Battery Cell Composition: Lithium Polymer
Battery Capacity: 2100 Milliamp Hours
Recommended Uses For Product: Gps,Radio,Digital,Camera,Watch
Product Dimensions: 2.01 x 1.57 x 0.31 inches
Item Weight: 1.34 ounces
Item model number: 402030
Batteries: 1 Lithium Polymer batteries required. (included)
Is Discontinued By Manufacturer: No
Date First Available: April 16, 2021
Manufacturer: HXJN
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Wednesday, May 13
Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Top Amazon Reviews
Color: 8×40×51mm 2100mAh
Battery works great! I used it to transform some wired headphones into wireless using a Bluetooth receiver. I cut the connector pin on the end off and soldered the 2 wires onto the board and now I have a better sound experience than you can buy in wireless headphones with a battery that now lasts over a week of 24/7 use between charges! It's been like 2 years so far with zero issue. This battery does have overcharge protection. And if you need to replace the wires, it has convenient solder points.
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Reviewed in the United States on June 24, 2025 by Mal Calhoun Mal Calhoun
Color: 5×30×40mm 620mAh
Works great in Cozmo toys. Perfect fit. Installation isn't too hard but does require some time and patience. See the picture here of my son's Cozmo torn down to the point where the battery can be replaced. It looks like a lot of pieces but everything disassembles easily and goes back together pretty easy too. The head is a little tricky as there is a small spring that you have to fight as you put it together, but isn't too hard once you figure it out. Sort of like a puzzle. There is a video on YouTube by John that is super helpful. Just watch that once and you'll have it figured out. The hardest part for most people will be just soldering the wires to the circuit board. This battery comes with a JST plug, but you have to cut that off, strip the wires, and then solder them to the board. It's pretty trivial if you know how to solder, but could trip up people who've never used a soldering iron. You'll need to cut the red wire shorter and leave the black wire longer, since the leads come out the same side of the battery, so it's close to the positive tab on the board, but the negative soldering tab is on the other side. Anyway, so far so good. Cozmo is up and running for last few days now with no issues. Haven't timed the battery life, but so far it lasts longer than my son's interest in it for any given moment. Note that it charges quite fast too. So you can play with this thing off and on all day long as long as you park Cozmo on his home charger between plays. Can recommend this battery. And watch John's tutorial too. Happing fixing!
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Reviewed in the United States on July 24, 2021 by Dan M. Dan M.
Color: 5×30×40mm 620mAh
Bought a house with an expensive Skybell HD V4 Video Doorbell. The thing was working in short bursts, couldn't figure it out. Checked the connections, all was good. Found that the battery on these would expand and die, and that's what happened to mine. I pulled mine apart and found I needed a new battery. I found this replacement on Amazon. Don't do what I did....I threw out the old one before the new one arrived. The plug is not an exact match. You need to splice the wires from the old battery to the new one. The plug is slightly different. Since I didn't have the new one, I improvised. I followed my college engineering training. Step 1: Is it working now? No Step 2: Does the part jam? Yes, the plug doesn't fit cleanly. Step 3: If this battery doesn't work, whats the alternative? Spend $250 for a new doorbell Step 4: Follow the old adage of: If it jams, force it, if it breaks, it needed fixing anyway. I jammed the plug into the socket on the camera using a pair of needle-nose pliers and got it working. The doorbell has been working the last month without issues. I would call this battery a replacement, even if it was a bit more difficult due to me shooting myself in the foot throwing the old one away before I took the plug.
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Reviewed in the United States on August 9, 2022 by RG
Color: 5×30×40mm 620mAh
Good product fixed my doorbell camera install fit price was good. Excellent product.
Reviewed in the United States on November 28, 2024 by Tom
Color: 5×30×40mm 620mAh
Worked great to replace my failing Anki Cozmo battery from 5 years ago. The double capacity is a great plus, although you'll probably get bored before it dies anyways. It does take slightly longer to charge though with the larger capacity, about 2 times longer. Would recommend for anyone who wants to replace their failing Anki Cozmo battery!
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Reviewed in the United States on January 7, 2025 by Brendan Brendan
Color: 5×30×40mm 620mAh
Battery is good but now there is a bug with the cozmo app and currently doesn't work
Reviewed in the United States on January 20, 2026 by Kevin Ferguson
Color: 5×30×40mm 620mAh
My child found a cosmo that was sitting in the back of the closet from 7 years ago. Older sibling lost interest and was never a techie. Batter had died. This was used to replace the dead battery. Had to disassemble the cosmo and reassemble. Handy dandy was able to figure it out. My 11yr old is now harassing me for an emo pet thats about $400. This kid. Seriously. Wants only techie stuff thats more appropriate for an adult (3D printers, apple vision pro, oculus, and now the emo). I digress. Cosmo works perfectly now. But my kid now wants an upgrade. Sigh.
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Reviewed in the United States on July 24, 2024 by SBL
Color: 6.5×40×61mm 2100mAh
Using rhis battery in a camera monitor, it held a charge all day long for about 3 weeks. Then, on the fourth week it started draining really fast. Now it shows full charge when it's plugged in and within 2 hours of unplugging it goes dead. Just checked amamzon and the return window ended yesterday...
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Reviewed in the United States on May 18, 2024 by Sal