I was told by Andrew Penman on YouTube — who lurrrrrves the Onan Booster X2, a Mellow Chinese rip-off — that Mellow Board batteries fell out of their housing too, just like Onan’s could. The Onan problem was a bit different, however.
What’s happening with Mellow just shows how damn hard manufacturing is.
See the quoted post from Reddit after the break.
A message from Mellow Killian about the batteries
A message from our head engineer Killian about the batteries:
The main problem is that the bottoms of our battery housings are bent inwards – they are concave in the area above the battery label. This is the main reason for all the trouble we are having with batteries falling out and battery latches breaking.
The reason for the bent bottoms is the soft, blue TPE rubber that covers the battery. When the battery housings hard, black shell is initially molded it is perfectly flat. Once it gets over molded with the blue TPE, the TPE creates a huge tension on the housing while cooling off which then makes the housing bend inwards.
This inwards bend creates a gap between the battery and the metal rip of the Mellow Drive – and as a result the battery moves, rattles or falls out of the Drive now. We tried to fix this movement by adding the black rubber sticker to the back of the battery.
And now comes the real problem: Not all batteries are equally bent. Some are bent more than others. We are talking about a range of 0-1,5mm in the middle of the housing.
When a battery is bent less (has a rather flat bottom) then the sticker creates so much force on the tap lock that the hooks of the tap lock quickly break off. This has happened to some of our customers and was the reason we asked everyone to take off the rubber sticker.
Once the tab lock is broken, the battery won’t ever hold in the drive anymore and is basically trash.
The very bent batteries on the contrary need the rubber sticker in order to create enough tension on the tab lock to stay in place.
So whatever way we turn it – there is no one-fits-all solution to the problem right now. Please check your battery individually and decide upon how bent the housing is whether to use the rubber sticker, a thinner one or none. We are very sorry for this unsatisfactory situation!
As I mentioned earlier we are improving the battery housing production to completely get rid of this problem. We are changing the injection molds, reinforcing the bottom of the housing with ribs to avoid bending as the TPE-rubber cools thus making the batteries perfectly flat.
In addition the tab locks are being reinforced to allow for higher tension without breaking.
The first samples of these new housings are forecasted to arrive at Mellow in week 47 – so in about a month – will then be tested and if approved, produced in quantities towards the end of the year.
Timelines on tool changes are really long but the changes that are being made will bring real value to the product.
As you all know we are still a very young company and the Mellow Drive is an equally young product so situations like this are – of course very uncomfortable for everyone involved – but as well very normal.
You are all our first customers and are on this journey with us which we are tremendously thankful for your trust and your support in these rough times.
Of course we will not let you hang with a messed up battery and will replace it if you wish for us to do so ASAP.
Nevertheless I would suggest you wait until the new generation of housing is available so you will have the long term benefits of the tool changes we are investing in.
So again – I am terribly sorry for the stress and bad experience this is causing to some of you and I hope you will forgive us some day.
Please let us know if there is anything else you need assistance with at email@example.com
Greetings from Germany! Kilian
Boldfaced emphasis added by me.
Ugh. What a problem to have. One of those things that never crops up until units start rolling out of production.
Good luck, Mellow Boards and their customers!