Hi all,
Am new here so be gentle 🙂
With the nights drawing in i suddenly realize my lumicycle battery was knackered from last winter 🙁 And as times are a bit tough was hopeing to do my own repair to save a few sheckles.
I have a Lumicycle Li-ion 14.8v 4.4amp/h waterbottle battery, that i have stripped open in a plan to replace the cells hopefully like for like.
There are a total of 8 cells, I think the cells are connected in 4 paralel pairs, that are then in series if that makes any sense, however there are no indications what each individual cell size is ie volts or amp/h. They measure 65mm long by 18mm diameter approx, these measurements seem to coincide with 18650 li-ion cells 3.7v which add up to the voltage (i think) but what size mAh (milli amp hours) am thinking possibly 2200mAh.
Anyone tried anything like this before?
Any advice would be appreciated.

Cheers Rocktwang

FIRST ring lumi as they do pretty cheap repairs of batteries iirc.

Assume you are correct re each cell

each cell is 3.7 volts and 2200 mha
When connected positive to positive you increase the mha (just add them up
2200 + 2200 = 4400 the voltage is UNCHANGED
When you conect them neg to positive you increase the voltage (add up)
3.7 + 3.7 = 7.4 volts increas mha is UNCHANGED

By combination of above you get

2200 x 2- 4400 mah – your 4 double cells + to +

connect these (as if they were one battery) + to – with the other 3

3.7 + 3.7 + 3.7 + 3.7 = 14.8 v @ 4400 mah

AGAIN get a quote from Lumi first.

Please don't try to, Its not just a case of swapping like for like cells, all new cells have to be balanced, tagged to assemble etc also it may not be the cells but the protection circuit that is faulty.
Unless you are sure with what you are doing it could all go with a big bang in youre face.
Like junkyard says get a quote from lumicycle first if that fails I can build and post you a replacement.

+1 for 'leave well alone'. take a look on utube for 'li-ion fire'. the results are quite spectacular. think of magnesium burning – it's a similar sort of effect.
honestly – nimh is one thing, li-ion quite another.
smudge has a pretty good rep here for this stuff, otherwise speak to lumi. if you haven't gone too far with your disassembly they may be able to fix it for you.
oh! and welcome 🙂

get one from smudge, great bloke to deal with and a cracking product,

Hi
Thanks for your info.
I did contact Lumi last spring but they just wanted me to by a new battery £110.00 and then evenings started getting lighter 😉
Now i can barely get out for an hour 🙁
If you dont mind indulging me further….
I tried putting the volt meter on the cells at various points and each parallel pair was 4volts no load and increased 8 then 12 then 16 with each subsequent parallel pair.
With load, the lamps on, 1no 12watt and 1no 20watt the voltage started at 14.4volts and quickley dropped (2-3minutes) to 12.75volts at which point the 20 watt lamp started to cycle, turn on, turn off with increases and decreases in voltage. Which made me think the protection circuits were working correctly?!
Does balance and tag the cells mean the connection points and oriention ?(please excuse my ignorance) At present the cells are bound to each other by metal strips that look like they have minature spot welds to the cell terminals (+ and -).
How exactly can i avoid the big bang in the face, if i do decide to proceed?

Thanks Again Rocktwang 😀

I defer to Smudge I can explain the principles but he knows the stuff as it is what he does.
Sounds dangerous and best not to pi55 about from what the others are saying.

How exactly can i avoid the big bang in the face, if i do decide to proceed?

stop?
i don't mean to be funny mate but i have some electronics knowledge and i'd leave it well alone. you could just buy a cheap nimh pack to run your lamp you know? you could probably do it, including the charger, for 35 quid.

on the other hand at least video what you're up to and leave instructions that the results should be linked here. ta. 🙂

Balancing is charge balancing – each cell must be selected and fitted to match the other cells well otherwise you can end up with a situation where one cell is under or over-charged in relation to the others around it. New cells are not all the same.

It sounds as though the cells have sputtered their last, possibly because he control circuiry has let it under-charge at times, or possibly over-charge, or just through plenty of use.

You CAN replace the cells yourself but its very hard if the cells you get are not tagged and you dont have the test equipment and know what you're looking for it's not necessarily going to be as reliable or effective as the original. Without tagged cells you're going to have to solder tags on – which is a bad start (heat=unhappy cells). Then if you've got cells that arent matched you have other problems. Just be aware it's not like changing nicads or nimhs.

Also be aware that it may not fail in the first 10 uses, but one night when the family are tucked up and you put it on charge overnight it could burn your house down. Personally I'd mitigate that risk by charging in the garage in a metal tin, but you may not have that luxury and it is a faff. Plus I've a fair amount of experience with this sort of thing, making packs and my own chargers for fast-charging them (though not lithium based stuff)!

even with my HND in electrical engineering………………….see smudge.

It could all go horribly wrong

ok am starting to feel a little less confident now!

However.. i have seen tagged cells on ebay quite cheap but i guess not balanced, hmmm. Not sure i can get round that one 🙁

I think the cells have died from use, brought from lumicycle nearly 4yrs ago, used once a week for 6 months a year. Still have original charger can that become unreliable? is it testable?

Smudge would you mind getting in touch re cost of possible build and post of replacement.

Thanks for all your advise everyone 😕

Hi Rocky,
you had an email about 1/2hr ago 😉
By all means post me the battery and charger and I can put them both on a soak test (no that doesnt involve getting them wet!)