Our Robovac (Ecovacs 920) has developed a nasty habit of just dying. Only
way to revive it was to manually place it back on charging dock.
Suspected a failed battery cell, I ordered a cheap replacement via AliExpress. In for a penny in for a pound I decided to go for a higher capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart
from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
Gave it one more chance where it did the same.
Removing the battery, it had volts but **** all amps. I am guessing that
here again a cell has failed ?
Have started process for refund.
6800mAh battery was £12.99 inc P&P.
On 21/07/2025 15:46, Theo wrote:
Tip: never go for 'higher capacity' versions. The OEM battery on these is 3400mAh. Yours claims to be double, which means either they've somehow doubled the energy density of the lithium chemistry, or they're outright liars. I'll let you decide which...
(Comparing the weights might be fun too... unless they've added an extra slug of steel or cement in there to make it reassuringly hefty)
I don't know the design of the machine. Is there room inside for a
battery with twice the number of cells/ cells twice as big?
Jethro_uk <jethro_uk@hotmailbin.com> wrote:
Our Robovac (Ecovacs 920) has developed a nasty habit of just dying. Only
way to revive it was to manually place it back on charging dock.
Suspected a failed battery cell, I ordered a cheap replacement via
AliExpress. In for a penny in for a pound I decided to go for a higher
capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart
from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
Gave it one more chance where it did the same.
Removing the battery, it had volts but **** all amps. I am guessing that
here again a cell has failed ?
Quite possibly relabelled e-waste cells. Or just a whole battery from the e-waste bin.
Have started process for refund.
6800mAh battery was £12.99 inc P&P.
Not surprised at that price...
Tip: never go for 'higher capacity' versions. The OEM battery on these is 3400mAh. Yours claims to be double, which means either they've somehow doubled the energy density of the lithium chemistry, or they're outright liars. I'll let you decide which...
(Comparing the weights might be fun too... unless they've added an extra
slug of steel or cement in there to make it reassuringly hefty)
Be interesting to hear how the refund process goes. I think Aliexpress is wielding a bigger stick at their sellers nowadays, but not sure if there are loopholes.
Theo
GB <NOTsomeone@microsoft.invalid> wrote:
On 21/07/2025 15:46, Theo wrote:
Tip: never go for 'higher capacity' versions. The OEM battery on these is >>> 3400mAh. Yours claims to be double, which means either they've somehow
doubled the energy density of the lithium chemistry, or they're outright >>> liars. I'll let you decide which...
(Comparing the weights might be fun too... unless they've added an extra >>> slug of steel or cement in there to make it reassuringly hefty)
I don't know the design of the machine. Is there room inside for a
battery with twice the number of cells/ cells twice as big?
Here's a '6800mAh' listing. You can have any capacity but they look identical.
https://vi.aliexpress.com/item/1005008929003144.html
14.4V and they look like 18650s, so 14.4/3.6 = 4 cell pack. 3400mAh is
about the maximum you can get in an 18650. To get 6800mAh you'd need a 4S2P pack which would be 8 cells - if there was space you could do that, but it would be obviously twice the size.
Theo
Tip: never go for 'higher capacity' versions. The OEM battery on these is 3400mAh. Yours claims to be double, which means either they've somehow doubled the energy density of the lithium chemistry, or they're outright liars. I'll let you decide which...
Our Robovac (Ecovacs 920) has developed a nasty habit of just dying. Only
way to revive it was to manually place it back on charging dock.
Suspected a failed battery cell, I ordered a cheap replacement via AliExpress. In for a penny in for a pound I decided to go for a higher capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart
from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
On 21/07/2025 15:33, Jethro_uk wrote:
Our Robovac (Ecovacs 920) has developed a nasty habit of just dying.
Only way to revive it was to manually place it back on charging dock.
Suspected a failed battery cell, I ordered a cheap replacement via
AliExpress. In for a penny in for a pound I decided to go for a higher
capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart
from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
Hmmm.... Read enough bad stories about cheap cells from no-names on eBay
and ali-express.
So for compatible rechargeable batteries I made a point of looking for
Bricks and Mortar suppliers prepared to put their names behind the
items.
e.g. for Dyson, Sebo & Henry
https://manchestervacs.co.uk/
Batteries I've bought have been faultless.
Our Robovac (Ecovacs 920) has developed a nasty habit of just dying. Only
way to revive it was to manually place it back on charging dock.
Suspected a failed battery cell, I ordered a cheap replacement via AliExpress. In for a penny in for a pound I decided to go for a higher capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart
from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
Gave it one more chance where it did the same.
Removing the battery, it had volts but **** all amps. I am guessing that
here again a cell has failed ?
Have started process for refund.
6800mAh battery was £12.99 inc P&P.
The dynamic here is being careful with pennies, I am not going to spend
that much on a replacement battery for a 3 year old device. If I *have*
to spend £50, I'd rather it was as part of a new-with-guarantee unit. Possibly with better features .....
On 15:33 21 Jul 2025, Jethro_uk said:
Our Robovac (Ecovacs 920) has developed a nasty habit of just dying.
Only way to revive it was to manually place it back on charging dock.
Suspected a failed battery cell, I ordered a cheap replacement via
AliExpress. In for a penny in for a pound I decided to go for a higher
capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart
from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
Gave it one more chance where it did the same.
Removing the battery, it had volts but **** all amps. I am guessing
that here again a cell has failed ?
Have started process for refund.
6800mAh battery was £12.99 inc P&P.
I've not used AliExpress but presumably the battery was mailed from
China. In which case, who pays the return postage in this case?
The dynamic here is being careful with pennies, I am not going to spend
that much on a replacement battery for a 3 year old device. If I*have*
to spend £50, I'd rather it was as part of a new-with-guarantee unit. Possibly with better features .....
Our Robovac (Ecovacs 920) has developed a nasty habit of just dying. Only
way to revive it was to manually place it back on charging dock.
Suspected a failed battery cell, I ordered a cheap replacement via AliExpress. In for a penny in for a pound I decided to go for a higher capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart
from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
Gave it one more chance where it did the same.
Removing the battery, it had volts but **** all amps. I am guessing that
here again a cell has failed ?
Have started process for refund.
6800mAh battery was £12.99 inc P&P.
On 21:10 21 Jul 2025, Jethro_uk said:
On Mon, 21 Jul 2025 19:15:24 +0100, Pamela wrote:
On 15:33 21 Jul 2025, Jethro_uk said:
Our Robovac (Ecovacs 920) has developed a nasty habit of just dying.
Only way to revive it was to manually place it back on charging dock.
Suspected a failed battery cell, I ordered a cheap replacement via
AliExpress. In for a penny in for a pound I decided to go for a
higher capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart
from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
Gave it one more chance where it did the same.
Removing the battery, it had volts but **** all amps. I am guessing
that here again a cell has failed ?
Have started process for refund.
6800mAh battery was £12.99 inc P&P.
I've not used AliExpress but presumably the battery was mailed from
China. In which case, who pays the return postage in this case?
They are. I've already got the QR code for RM postage.
Is it worth it for the vendor? I would guess the postage costs more than
the goods (even at their full retail price).
Reminds me of when some SX CPUs could actually be DX.
And memory chips were made all the same and the ones that didn't fail at higher speeds were sold as faster ...
On 21/07/2025 15:33, Jethro_uk wrote:
Our Robovac (Ecovacs 920) has developed a nasty habit of just dying. Only
way to revive it was to manually place it back on charging dock.
Suspected a failed battery cell, I ordered a cheap replacement via
AliExpress. In for a penny in for a pound I decided to go for a higher
capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart
from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
Hmmm.... Read enough bad stories about cheap cells from no-names on eBay
and ali-express.
So for compatible rechargeable batteries I made a point of looking for
Bricks and Mortar suppliers prepared to put their names behind the items.
e.g. for Dyson, Sebo & Henry
https://manchestervacs.co.uk/
Batteries I've bought have been faultless.
On 22/07/2025 08:37, Jethro_uk wrote:
Reminds me of when some SX CPUs could actually be DX.
And memory chips were made all the same and the ones that didn't fail at higher speeds were sold as faster ...
And the transistors that failed were narked as 'Sinclair' and sold at
twice the price.
How he escaped jail beggars belief
Just tried them for my Dyson DC35 - the battery failed yesterday, by coincidence. No longer stocked - obsolete, they say.
Guess I'm at the mercy of Amazon etc. . . .
On 21 Jul 2025 at 18:33:54 BST, Adrian Caspersz wrote:
On 21/07/2025 15:33, Jethro_uk wrote:
Our Robovac (Ecovacs 920) has developed a nasty habit of just dying. Only >>> way to revive it was to manually place it back on charging dock.
Suspected a failed battery cell, I ordered a cheap replacement via
AliExpress. In for a penny in for a pound I decided to go for a higher
capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart
from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
Hmmm.... Read enough bad stories about cheap cells from no-names on eBay
and ali-express.
So for compatible rechargeable batteries I made a point of looking for
Bricks and Mortar suppliers prepared to put their names behind the items.
e.g. for Dyson, Sebo & Henry
https://manchestervacs.co.uk/
Batteries I've bought have been faultless.
Just tried them for my Dyson DC35 - the battery failed yesterday, by coincidence. No longer stocked - obsolete, they say.
Guess I'm at the mercy of Amazon etc. . . .
On 22/07/2025 10:44, RJH wrote:
On 21 Jul 2025 at 18:33:54 BST, Adrian Caspersz wrote:There are videos on Youtube showing how to dismantle a DC35 pack. You
On 21/07/2025 15:33, Jethro_uk wrote:
Our Robovac (Ecovacs 920) has developed a nasty habit of just dying. Only >>>> way to revive it was to manually place it back on charging dock.
Suspected a failed battery cell, I ordered a cheap replacement via
AliExpress. In for a penny in for a pound I decided to go for a higher >>>> capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart
from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
Hmmm.... Read enough bad stories about cheap cells from no-names on eBay >>> and ali-express.
So for compatible rechargeable batteries I made a point of looking for
Bricks and Mortar suppliers prepared to put their names behind the items. >>>
e.g. for Dyson, Sebo & Henry
https://manchestervacs.co.uk/
Batteries I've bought have been faultless.
Just tried them for my Dyson DC35 - the battery failed yesterday, by
coincidence. No longer stocked - obsolete, they say.
Guess I'm at the mercy of Amazon etc. . . .
can then fit some new LiPo cells. They look like 6x 18650 cells. Maybe
21700s but easily obtainable.
You can also get physical battery adaptors that let you use Makita 18V batteries in your Dyson. Also on AliExpress.
https://www.aliexpress.com/item/1005006808669898.html
Ah, many thanks (and Theo), hadn't thought of that. Think I'll try the recell.
Bewildering choice of spec and price:
https://www.fogstar.co.uk/collections/18650-batteries.
Any recommendations?
It seems that Ecovacs deliberately don't sell official replacement
batteries
On 22 Jul 2025 at 12:25:22 BST, mm0fmf wrote:
On 22/07/2025 10:44, RJH wrote:
On 21 Jul 2025 at 18:33:54 BST, Adrian Caspersz wrote:There are videos on Youtube showing how to dismantle a DC35 pack. You
On 21/07/2025 15:33, Jethro_uk wrote:
Our Robovac (Ecovacs 920) has developed a nasty habit of just dying. Only >>>>> way to revive it was to manually place it back on charging dock.
Suspected a failed battery cell, I ordered a cheap replacement via
AliExpress. In for a penny in for a pound I decided to go for a higher >>>>> capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart >>>>> from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
Hmmm.... Read enough bad stories about cheap cells from no-names on eBay >>>> and ali-express.
So for compatible rechargeable batteries I made a point of looking for >>>> Bricks and Mortar suppliers prepared to put their names behind the items. >>>>
e.g. for Dyson, Sebo & Henry
https://manchestervacs.co.uk/
Batteries I've bought have been faultless.
Just tried them for my Dyson DC35 - the battery failed yesterday, by
coincidence. No longer stocked - obsolete, they say.
Guess I'm at the mercy of Amazon etc. . . .
can then fit some new LiPo cells. They look like 6x 18650 cells. Maybe
21700s but easily obtainable.
You can also get physical battery adaptors that let you use Makita 18V
batteries in your Dyson. Also on AliExpress.
https://www.aliexpress.com/item/1005006808669898.html
Ah, many thanks (and Theo), hadn't thought of that. Think I'll try the recell.
Bewildering choice of spec and price:
https://www.fogstar.co.uk/collections/18650-batteries.
Any recommendations?
If high currents are involved, you need good connections between cells.
My blood pressure meter, for example, takes alkali cells, but the
current flow is significant enough, the contacts in the battery
compartment just aren't good carrying a little bit of current,
and the motor speed is all over the place. I can "perk it up"
by taking the cover off the battery compartment and rotating the
cells a bit to freshen the contacts.
When cells have spot-welded conductors on the ends, those
represent a more robust connection. You still have to figure out
how, or whether, you can package such things. Whether the design
of the conductors is suited to how you will package them.
Example of an attempt at a spot welded connection (you still have
to figure out what to do with the ends of something like this).
https://www.aliexpress.com/item/1005007839513252.html
If you were expecting the cells to run at high current,
any "ohmic" connection points will generate local heating,
and that increases the temperature of the cells (above what
they already achieve on their own internally).
When cells have spot-welded conductors on the ends, those
represent a more robust connection. You still have to figure out
how, or whether, you can package such things. Whether the design
of the conductors is suited to how you will package them.
Example of an attempt at a spot welded connection (you still have
to figure out what to do with the ends of something like this).
On 21:10 21 Jul 2025, Jethro_uk said:
On Mon, 21 Jul 2025 19:15:24 +0100, Pamela wrote:
On 15:33 21 Jul 2025, Jethro_uk said:
Our Robovac (Ecovacs 920) has developed a nasty habit of just dying.
Only way to revive it was to manually place it back on charging dock.
Suspected a failed battery cell, I ordered a cheap replacement via
AliExpress. In for a penny in for a pound I decided to go for a
higher capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart
from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
Gave it one more chance where it did the same.
Removing the battery, it had volts but **** all amps. I am guessing
that here again a cell has failed ?
Have started process for refund.
6800mAh battery was £12.99 inc P&P.
I've not used AliExpress but presumably the battery was mailed from
China. In which case, who pays the return postage in this case?
They are. I've already got the QR code for RM postage.
Is it worth it for the vendor? I would guess the postage costs more than
the goods (even at their full retail price).
On Mon, 21 Jul 2025 22:12:50 +0100, Pamela wrote:
On 21:10 21 Jul 2025, Jethro_uk said:
On Mon, 21 Jul 2025 19:15:24 +0100, Pamela wrote:
On 15:33 21 Jul 2025, Jethro_uk said:
Our Robovac (Ecovacs 920) has developed a nasty habit of just dying. >>>>> Only way to revive it was to manually place it back on charging dock. >>>>>
Suspected a failed battery cell, I ordered a cheap replacement via
AliExpress. In for a penny in for a pound I decided to go for a
higher capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart >>>>> from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
Gave it one more chance where it did the same.
Removing the battery, it had volts but **** all amps. I am guessing
that here again a cell has failed ?
Have started process for refund.
6800mAh battery was £12.99 inc P&P.
I've not used AliExpress but presumably the battery was mailed from
China. In which case, who pays the return postage in this case?
They are. I've already got the QR code for RM postage.
Is it worth it for the vendor? I would guess the postage costs more than
the goods (even at their full retail price).
I took the parcel to the post office today and the refund was processed
by the time I got home.
Say what you like, but that level of customer service is hard to fault.
Or indeed remember, if you are British.
On 23/07/2025 17:12, Jethro_uk wrote:
On Mon, 21 Jul 2025 22:12:50 +0100, Pamela wrote:
On 21:10 21 Jul 2025, Jethro_uk said:
On Mon, 21 Jul 2025 19:15:24 +0100, Pamela wrote:
On 15:33 21 Jul 2025, Jethro_uk said:
Our Robovac (Ecovacs 920) has developed a nasty habit of just dying. >>>>> Only way to revive it was to manually place it back on charging dock. >>>>>
Suspected a failed battery cell, I ordered a cheap replacement via >>>>> AliExpress. In for a penny in for a pound I decided to go for a
higher capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart >>>>> from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
Gave it one more chance where it did the same.
Removing the battery, it had volts but **** all amps. I am guessing >>>>> that here again a cell has failed ?
Have started process for refund.
6800mAh battery was £12.99 inc P&P.
I've not used AliExpress but presumably the battery was mailed from
China. In which case, who pays the return postage in this case?
They are. I've already got the QR code for RM postage.
Is it worth it for the vendor? I would guess the postage costs more than >> the goods (even at their full retail price).
I took the parcel to the post office today and the refund was processed
by the time I got home.
Say what you like, but that level of customer service is hard to fault.
Or indeed remember, if you are British.
I had thge same. Took the parcel in yesterday containing one of twow
faulty components got a full refund of the total order.
I think the rationale is 'if the customer complains and can be bothered
to go to the post office, then full refund' simply because priocessing
a give back is so much easier than paying the customer a part.
The Natural Philosopher <tnp@invalid.invalid> wrote:
On 23/07/2025 17:12, Jethro_uk wrote:
On Mon, 21 Jul 2025 22:12:50 +0100, Pamela wrote:
On 21:10 21 Jul 2025, Jethro_uk said:
On Mon, 21 Jul 2025 19:15:24 +0100, Pamela wrote:
On 15:33 21 Jul 2025, Jethro_uk said:
Our Robovac (Ecovacs 920) has developed a nasty habit of just dying. >>>>>>> Only way to revive it was to manually place it back on charging dock. >>>>>>>
Suspected a failed battery cell, I ordered a cheap replacement via >>>>>>> AliExpress. In for a penny in for a pound I decided to go for a
higher capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart >>>>>>> from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
Gave it one more chance where it did the same.
Removing the battery, it had volts but **** all amps. I am guessing >>>>>>> that here again a cell has failed ?
Have started process for refund.
6800mAh battery was £12.99 inc P&P.
I've not used AliExpress but presumably the battery was mailed from >>>>>> China. In which case, who pays the return postage in this case?
They are. I've already got the QR code for RM postage.
Is it worth it for the vendor? I would guess the postage costs more than >>>> the goods (even at their full retail price).
I took the parcel to the post office today and the refund was processed
by the time I got home.
Say what you like, but that level of customer service is hard to fault.
Or indeed remember, if you are British.
I had thge same. Took the parcel in yesterday containing one of twow
faulty components got a full refund of the total order.
I think the rationale is 'if the customer complains and can be bothered
to go to the post office, then full refund' simply because priocessing
a give back is so much easier than paying the customer a part.
They're trying to compete with Amazon which usually gives 'free returns' - either refunds the moment the parcel is dropped off, or a refund without any return for smaller items. It's all automated.
I suspect what then happens is the returns parcels are collected and then sold off by the pallet for pennies, where small time ebayers buy them and break them up into individual listings. With or without quality control...
That or they just chuck them in landfill. But that costs money, so better
to sell on your waste to somebody else, especially if they can get consumers to pay you before landfilling it.
I think the seller must get some kind of subsidy by the Chinese government
as an 'exporter', as I don't think the economics work otherwise. Maybe they collect the subsidy even if the item was returned, who knows?
Theo
On 23/07/2025 20:58, Theo wrote:
They're trying to compete with Amazon which usually gives 'free returns' - either refunds the moment the parcel is dropped off, or a refund without any
return for smaller items. It's all automated.
I suspect what then happens is the returns parcels are collected and then sold off by the pallet for pennies, where small time ebayers buy them and break them up into individual listings. With or without quality control...
That or they just chuck them in landfill. But that costs money, so better to sell on your waste to somebody else, especially if they can get consumers
to pay you before landfilling it.
Amazon has a thing (now) called Amazon Resale, where you can buy
returned items. Maybe AliExpress can't do that, since their 'new' items
are already so cheap it would be hard to undercut them.>
Sam Plusnet <not@home.com> wrote:
On 23/07/2025 20:58, Theo wrote:
They're trying to compete with Amazon which usually gives 'free returns' - >>> either refunds the moment the parcel is dropped off, or a refund without any
return for smaller items. It's all automated.
I suspect what then happens is the returns parcels are collected and then >>> sold off by the pallet for pennies, where small time ebayers buy them and >>> break them up into individual listings. With or without quality control... >>>
That or they just chuck them in landfill. But that costs money, so better >>> to sell on your waste to somebody else, especially if they can get consumers
to pay you before landfilling it.
Amazon has a thing (now) called Amazon Resale, where you can buy
returned items. Maybe AliExpress can't do that, since their 'new' items
are already so cheap it would be hard to undercut them.>
Aliexpress is different from Amazon in that they don't sell anything themselves. Amazon run their own warehouses and source/sell a lot of the products themselves - when those get returned some of them end up on Resale.
Aliexpress is just a website and a now a parcel operation. Their sellers going by names like Store110042345 don't have any UK presence, and Ali don't have any channels for selling returned parcels themselves - for one thing, they wouldn't want to stand by the quality of products that have been sold
by random sellers of unknown quality.
Theo
Our Robovac (Ecovacs 920) has developed a nasty habit of just dying. Only
way to revive it was to manually place it back on charging dock.
Suspected a failed battery cell, I ordered a cheap replacement via >AliExpress. In for a penny in for a pound I decided to go for a higher >capacity version.
Arrived Friday (2 weeks wait). Looked identical to the old one, apart
from the sticker with the rating.
Dropped it in, charged it, and ... second clean it just died.
Gave it one more chance where it did the same.
Removing the battery, it had volts but **** all amps. I am guessing that
here again a cell has failed ?
Have started process for refund.
6800mAh battery was 12.99 inc P&P.
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