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Description
BMT 4S LITH BATT CHARGE/PROT 40AS 40A Li Ion Lithium Battery 18650 Charger Protection Board Module 18650 Charger Protection Board Module Specifications 4 string 16. 8V 40A lithium battery protection board (comes with recovery function AUTO Recovery) Scope: Nominal voltage of 3. 6V, 3. 7V lithium battery (including 18650,26650, polymer lithium battery) Product Size: 45 * 55 * 3. 4mm (Standard Edition Enhanced), 46 * 60 * 3. 4mm (balanced version) Product weight: 9. 3g (standard
S 40A Li-Ion Lithium Battery 18650 Charger Protection Board Module
18650 Charger Protection Board Module
Specifications
- 4 string 16.8V 40A lithium battery protection board (comes with recovery function-AUTO Recovery)
- Scope: Nominal voltage of 3.6V, 3.7V lithium battery (including 18650,26650, polymer lithium battery)
- Product Size: 45 * 55 * 3.4mm (Standard Edition / Enhanced), 46 * 60 * 3.4mm (balanced version)
- Product weight: 9.3g (standard / enhanced version), 10.3g (balanced version)
- Charging voltage: 16.8V - 18.1V
- Continuous discharge current (upper limit): 40A (if the cooling environment is not good, please reduce the load current use)
- Continuous charge current (upper limit): 20A
- Equalization version: suitable for starting current below 80A, power 135W below the drill.
Project Min. Typ. Max. Units Consuming current 12 18 24 uA Overcharged protection voltage 4.2 4.25 4.3 V Balanced starting voltage 4.17 4.2 4.23 V Equilibrium current 95 100 105 mA Balanced heating power 1.56 1.72 1.91 W Overcharge recovery voltage 4.1 4.15 4.2 V Over-discharge protection voltage 2.4 2.5 2.6 V Overvoltage protection after over-discharge protection 2.8 3 3.2 V Overvoltage protection after over-discharge protection 3.2 3.5 3.8 V Over-discharge recovery voltage 2.9 3.2 3.3 V Conduction internal resistance 2.5 3 3.5 mQ Overcurrent protection current C 70 80 90 A Overcurrent delay time 100 150 200 ms Continuous operating current 0 40 40 A Continuous output power 0 672 672 W Ambient temperature -40 25 85 °C
Troubleshooting: Fault phenomenon Fault check and cause The solution Unable to charge Measuring the voltage of 4 groups of batteries.
when one of the battery voltages exceeds 4.25V,
the protection board will activate overcharge protection.Pair the battery pack well, do not mix
the good battery and the bad battery.Unable to discharge Measuring the voltage of 4 groups of batteries.
when one of the battery voltages is lower than 2.7V,
the protection board will activate the over-discharge
protection.Pair the battery pack well, do not mix
the good battery and the bad battery.Charging/discharging
failureOV, 4.2V, S.4V, 12.6V, 16.8V miswired Rewire or replace the new board
(human failure, no warranty)Overcharge/overdischarge
failureOV, 4.2V, 8.4V, 12.6V, 16.8V miswired Rewire or replace the new board
(human failure, no warranty)Discharge protection Check that the battery pack has sufficient discharge
capability and check that the load's starting current
exceeds the overcurrent protection current of the
protection board.Replace the battery pack with a higher
discharge capacity, or a protective
plate with a larger current
(super working range)Component soldering There is no connection between one of the components
and the PCB pad.Repair welding Component welding There is a short circuit between two or more pins of the
component.Remove the component and re-weld Electrostatic breakdown A In the unpowered state, measure the G, D, and S
poles of the MOSFET. If the forward and reverse
resistances of any two pins are 0Q,
it indicates that it has broken down.Remove the replacement MOS tube Electrostatic breakdown B Remove the MOS tube and measure the resistance
of the G and D, G and S poles of the MOS tube.
If there is a resistance indicating that it has broken
down, the resistance should be infinite.Remove the replacement MOS tube
Package includes:
1 x Battery Protection Board
Additional Information
| Device | Protection Board Module |
| Type | 18650 | Charger Protection |
Shipping Notes
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Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
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4.7 ★★★★★
Based on 24 reviews
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Product Reviews
★★★★★ 4
Good Multipurpose Hub, Some Limits on Power Draw
I use this with a Dell Latitude 7430 with a 65W charger, and it works fine as a docking hub. The only problem I've encountered is when rebooting, the boot will pause with a warning message to tell me that the laptop may encounter reduced performance because it isn't able to receive the full 65 watts. I don't get that warning if I'm not running the power supply through the hub.
Otherwise, if I just use the hub as a port extender everything is fine. It has a compact design and is reasonably lightweight. It would be ideal for travel.
Like my other Anker hubs, it's well constructed and doesn't feel cheap although it's good value for money.
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Reviewed in the United States on June 9, 2026
★★★★★ 5
I don't know how I ever lived without it.
I'm very happy with this device. My laptop doesn't have an ethernet port and only has one USB-C SuperSpeed port, so I bought an ethernet to USB-C cable to connect my ethernet switch to the Anker and into my laptop's USB-C port, and it works great. I don't need a fast internet connection for the things I do, so my service is only a 50mbps symmetrical up/down connection, and that's what I get even while transferring files from my external between other devices, charging my phone, and using composite devices.
I bought the Anker 100W Compact and Foldable USB C Charger for it and it charges my S24 extremely fast.
It's very well built, yet super lightweight. I love the sleek, slender design. It's the perfect size to easily slide into a pocket, store in a desk drawer, or keep handy in a laptop case or backpack.
Using it is easy. Just plug it into your computer and plug your devices into it. Just make sure you have a power supply for it if you're charging or powering other devices, using external storage, or running anything else that taxes USB power.
I have had ZERO connectivity issues with it — no random disconnect/reconnect blips, no failed transfers for huge amounts of data that have taken up to 45 minutes, no static his or crackle when my headset is running through it... no problems at all. It's actually kind of spooky now that I think about it... I can't recall a time I've ever had a similar device that didn't have some nuance that got under my skin, like a loose connection, random disconnections, having to reinstall the drivers all the time, or having to troubleshoot just to get it connected for the first time.
The most stress I've put it through was with my keyboard connected, ethernet running through it, my S24 charging and transferring about ~20gb of pictures and videos to my 2T external HD at the same time that my laptop was transferring about ~500gb of media and documents to the HD, too, and I was surprised by how warm it DIDN'T get.
My only complaint is trivial and unique to my situation — I wish output cord was longer. About six inches would do. My laptop sits up on an adjustable stand that clamps to my desk, and the end where the output cord is hangs a few inches off of my desk. This puts extra stress on the USB-C port and can wear it out faster or damage it.
I haven't had a use for the HDMI port yet, but I eventually will. I use all of the other ports for my work and personal devices, though. These include: a 2tb external hard drive; a Poly Blackwire 3320 Series headset; a dongle for a wireless mouse/keyboard combo or a wired keyboard and a dongle for a wireless mouse; my Galaxy S24 charges and transfers files through it super fast; I have several thumb drives ranging from 20gb to 512gb that I regularly use; I recently bought an RCA/S Video-to-USB converter to digitize old home movies I plug into it, too.
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Reviewed in the United States on October 25, 2025
★★★★★ 5
Anker wins again.
Worked well for usb hub but hdmi was not reliable. Disappointed because usually Anker products are good quality. UPDATE: Anker voluntarily offered a refund so my faith in Anker has been fully restored.
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Reviewed in the United States on May 5, 2026
★★★★★ 5
Perfect with a MacBook
The Anker USB C Hub works great with my MacBook Air. I paired it with the Anker 100W MacBook charger which plugs directly into the USB C Hub so I only have to plug in one cable like a true docking station. My Apple MagSafe charger stays in my briefcase so I always have a charger when I'm away from my desk.
I also plug in my external monitor and an external hard drive.
I highly recommend this product!
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Reviewed in the United States on June 5, 2026
★★★★★ 5
ASURION 4-Year Housewares Plan - An Excellent ROI
The ASURION 4 Year housewares protection plan was definitely one of the best investments that I've made to date. I had a large, 12,000 BTU portable air conditioner that stopped working properly in its third year of use--one year after the manufacturer's warranty had expired--essentially leaving me with a glorified hot air fan. I proceeded to file a claim on my ASURION 4 Year housewares protection plan. The process could not have been easier and did not require much documentation since the plan was already linked to my prior purchase of the AC off Amazon.
I received an Amazon gift card within minutes of filing the claim, thereby definitively demonstrating ASURION's broad coverage scope, reliability, and overall value.
As such, I used part of the gift card to purchase another four-year plan on a replacement AC unit that's now sitting in my office. Hopefully, I will not need to use it, but it's good to know that I have coverage if needed.
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Reviewed in the United States on April 23, 2026