1DMF said:
I took the scooter for a test run and this is definitely a junk battery. I have a 19A 350w (MY1016) scooter, and was replacing 2 x 12v 7000mah SLA batteries coz they only lasted 20 minutes and 4 laps of the park.
This Li-ion battery when I checked this morning was showing 27.8v so it appears to be self-draining from full charge of 28.2 last night. When I went to use the scooter, it had barely any power and got me less than half way round the park, before dying.
I'm honestly not surprised at your results.
The seller link from ebay is here. https://www.ebay.co.uk/itm/255277740335
The seller appears to be one of those "random item" types, that probably gets good deals on single items or groups of them, to resell. There's a lot of those on ebay, aliexpress, banggood, amazon, etc. They usually have no idea what anything they sell actually is, so if the info isn't on the label, they can't help (and typically don't care) though there are some exceptions.
Is there a reason they put 'fire' in the name
Probably because it sounds "cool" to marketing departments. They do lots of dumb things (worse when they have control over the actual products!).
I notice there is another make heavily marketed currently (GTF) and wonder if the 'F' also stands for fire!
Wouldn't surprise me.
However, I have just found the most amazing 18650 cells available as it is a 19900mah and 7s3p would make a 29v 60AH battery :lol:
If I didn't know that lots of people were being scammed out of their money with them, that would be hilarious.
I'm currently in the middle of trying to return the battery for a refund and might just build my own, but to make a 30AH I would need @ 63 batteries as 7s3p @ 3400 mah = 10AH so would need 3 in parallel. I'm a little nervous building my own, as getting it wrong can equal disaster via explosion, fire or electrocution.
At the low voltage you have, elecrocution is unlikely, but the other two are possibilities with any battery if something goes wrong enough.
What is the physical size of the space you have to install the batteries in? That is the limit on how much you can cram in there.
3.4Ah/cell is realistic with known good grade A new brandname cells from a known good seller. They're likely to cost at least a few dollars each.
Remember, you also want cells that not only have good capacity, but also a high enough "C-rate", meaning how much current they can provide without sagging much in voltage or heating up inside. A typical generic 18650 is a 1C or at best 2C cell; meaning if it's 3.4Ah it can provide 3.4A at 1C, ro 6.8A at 2C, etc. A good one can do a little higher; some will claim very high C-rates (like 30A each cell!) but that is typically only burst, not continuous, and will heat up the cell and cause significant voltage sag while under the load, neither of which you want.
I dont' know what your scooter's motor/controller system specs are, so I don't know how much power you need from the battery; or how you ride, terrain, wind, etc, so I can't do more than guesstimate how many Ah you will need for any specific range.
The SLA only gives you about half the listed capacity, because of the way it works at higher current draws, whereas Lithium will give you most of the listed capacity. So if you had 12Ah SLA, a 6-7Ah Lithium could probably give you the same actual delivered capacity.
SLA can give a lot of current while they're still charged enough to do so even with very small ones, while a too-small LIthium wiht a BMS may sag below the BMS LVC and shutdown.
So, if you use good Li cells, the sag will be less (probably much less) for the same current draw, and you'll need less parallel cells that with cheap ones to get the same power out of the pack, while still getting more range than the SLA.
If your controller is unmodified and has a current limit printed on it, it will help determine how much current your pack must provide to be similar to or better performing than the SLA.
It will also help determine how big the pack must be to provide the range you want.
Would you recommend Vruzend Solderless kits?
I don't have any direct experience with them, but there are threads about them here on the forum.
This list is just any thread that has vruzend anywhere in it
https://endless-sphere.com/forums/search.php?keywords=Vruzend&terms=all&author=&sc=1&sf=all&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search
this one is just with it in the title of the thread
https://endless-sphere.com/forums/search.php?keywords=Vruzend&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search
and just first posts
https://endless-sphere.com/forums/search.php?keywords=Vruzend&terms=all&author=&sc=1&sf=firstpost&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search
Regarding solderless packs in general: If you don't have bumps or vibrations then solderless packs can work alright, but if there is a lot of bumpiness, etc., then connections may be a problem within the pack between cells. Most of these will be momentary issues, but if the pack shape distorts enough it will leave some cells at higher resistance than others, and those cells won't contribute well during higher loads. If any actually become disconnected permanently, the pack loses capacity and puts a higher load on the remaining cells.
There are plenty of other solderless pack discussions, too, including several development threads (like one presently active by APL), that have a lot of good info on problems and solutions. I dont' have any links, but they are mostly in the Battery Technology subforum; the sticky index thread in that section probably has some links.
or I could make 2 x 12v 3s7p as that is 24AH, which is good enough.
Using these kits...
The image doesn't show everything you would need to make a pack (other than cells); can you link to the actual sale page, so I can see what specifically they don't provide that you'll need, plus info about the BMS, etc., to be sure it would work for you?
I want to be able to run my scooter @ full power for at least an hour, so 2 x 12v 24AH would suffice though that only makes a 26v battery pack, and 29v would give that extra oomph without fully overvolting.
So there are 7s (29.4v) power wall kits I could link up...
It's likely that powerwalls and the like are designed for relatively steady loads spread over large amounts of cells. An EV, especially with very small batteries, may need to put short high loads on small amounts of cells, so I don't know if the powerwall stuff will do what you want. Without a link to the actual page with all the info (assuming they have it there), I couldn't tell you much about what they use.
I will say that it's likely those cell holders won't hold up under riding conditions; they're only meant to work in a stationary application (and even there, they're not generally good for much outside of a narrow temperature range unless the plastic that keeps compression on them isn't flexible or brittle beyond room temperatures. I would also question the "gold plating" on the terminals; it should prevent corrosion if it's real, but....
Depends on budget, power needs, space constraints, etc. If I had budget and space, I'd probably start with the LiGo packs Grin Tech sells,
https://ebikes.ca/product-info/grin-products/ligo-batteries.html
because they are well-tested, individually protected, environmentally sealed, and designed to be connected together in parallel, etc, and designed for use on things like eskateboards, etc....but they are 36v. (10s1p). So it could require replacing the controller, and/or limiting the throttle mechanically or electricaly so you don't go beyond the original speed / power, or learning to do that manually, to prevent crashes or motor damage from overheating. I don't know how many packs would be required in parallel to provide the power and capacity your scooter needs (i'd guess at least three or four), but they are typically at least $140 each plus shipping (depending on where you live the shipping could add significant cost). Not cheap at all.
If those aren't a possibility, then I'd have be researching what sellers are presently known to be good, and what battery packs are presently known to be good, and get one of those from one of those, that fits within whatever the budget is, and the space constraints of the battery compartment. My general good experiences are with larger sized packs; the smaller ones I've used have all been insufficient for their claimed capabilities.
If budget is too low, you might have to compromise significantly on your expectations, or carry the battery in a backpack with a cable to the scooter (because a cheap enough one that can still do what is needed might be too big for the space available).
