To be crystal clear here, what I’m trying to find is something like this but in 9000mAh.
18650 30SE vs 30SP
CookieMunster6006 As I said, 4-wire for 3S is standard. But it’s not mandatory. Yes, the one you linked says it has a built in “BMS” or Battery Management System, which handles balance charging, as well as over-charge and over-discharge protection. Most battery packs in my experience do not have that built in, it is separate, which is why 4-wire is standard.
Now it seems that your pack is actually rated as 3S 3,000mAh. The packaging says 9,000mAh because that’s the equivalent rating at 1S. 3×1 is the same as 1×3, essentially. If what you have is a 3-cell, 3S1P pack, then the one you linked above will work and actually provide greater overall capacity, but you’d have to solder wires to the little tabs to make the connections. But this is always risky as if you’re not careful the cells can themselves get overheated which can cause damage or again fire, and if you don’t connect the wires in the right spots then you can fry the electronics. If you choose to do this, do so at your own risk and be very careful.
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@LikeTheSandwich Here are some pictures for context. I can tell you for sure that the batteries are each SW18650-30SE and wired in series. I have yet to find an example online of something like this available for purchase.
The batteries are definitely wired like this:
The battery ends are definitely “flat” so I’m assuming they are “unprotected” cells and all the charging regulation is handled by the primary board, hence the extra wires.
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The 3S1P pack you posted is exactly like that, just has little solder tabs instead of wires, and it’s a little more than 10% bigger.
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I’ve posted several things, so I’m not sure if you’re referring to the picture or one of the links I already posted. I think what you’re saying here is that I’m misunderstanding the listings on AliExpress which are admittedly hard to understand because it isn’t even in English. Take, for example, this link:
It is very difficult to understand if each cell in the series of this product is 3000mAh or the whole pack is 3000mAh. I interpreted this as 3×1000mAh cells for a total of 3000mAh. But it seems like you’re suggesting this is actually 3×3000mAh cells since they’re in series? That makes sense by itself, but not when considering the label on the Smatree (see picture), Perhaps it is actually the battery case itself (Smatree) which is misleading by saying it is “9000mAh” since these are wired in series. Is that what you were trying to say earlier?
CookieMunster6006 The battery pack you have, it is a 3S1P, rated at 11.1V nominal, 12.6 peak, 3000 mAh, which is mathematically equivalent to a 1S3P, 3.7V nominal, 4.2 peak, 9000 mAh pack. When you combine batteries you either get to add the mAh together or the voltage together, but not both. The pack in your device is only a 3000 pack, but it’s 3S. You posted a picture that says 100% NCR18650B 3400 mAh 12V 3S1P. That one is functionally identical to the pack that’s in your device. What you need is a 3S1P, rated around 3,000 mAh. On the back of your pack when it says 9000 mAh, they mean that it’s equivalent to a 1S3P 9000, but physically it’s a 3S1P 3000, which is different electrically, but mathematically the total energy is the same. If you take that 33.3Wh rating in the picture, divide that by 9Ah (9000mAh=9Ah), you’ll get 3.7, which is the nominal voltage of the cells in your pack. A 3S pack rated for 9,000 mAh, would be a 3S3P, meaning it would be a large brick of nine cells all together, and in total it would be about three times the capacity of what you have, in addition to three times the size.
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Thank you @LikeTheSandwich this has been very informative. Now to find something that’s maybe slightly reputable with decent cells…
Happy Thanksgiving (if you celebrate)! 
6 months later
hey @CookieMunster6006 I’m trying to repair the exact same charging dock as you had. Did you get the batteries in the end? It would be really useful to know how you got on?
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TimRobinson No, I have yet to order anything. It’s still on my long Todo list if the Echo Gen1 doesn’t go belt-up first. If you end up tackling this first, please post how you get on.
CookieMunster6006 Thanks for quick response. I’m not really much of an electronics person so I’ll only tackle it if I can get something that’s a direct replacement.
I bought another charging base (different brand same spec) off ebay for £10 GBP but it was DOA. I reckon it’s been sat in the warehouse for 7 years and the battery pack had died
TimRobinson if you’re ok with a little experimenting, that replacement may be salvagable.
LikeTheSandwich the way it works is that you daisy-chain the Alexa off the battery base. While the base is plugged in, the base delivers 15v and the Alexa works fine. As soon as you unplug the base from the mains, the voltage drops to almost nothing and the Alexa dies - this is what makes me think it’s the battery pack itself. In any case, since I’ve only just bought it I’m inclined to cut my losses and get my money back (though I’ll see if I can get a replacement first to see if the problem was a one-off)
Up to you if you want to try and fix the new one or not. New batteries for the other one will likely cost the same or more.
