Bike light battery PCBs don’t have balancing functions. It’s a COM V sense tap used to prevent overcharge and under discharge.
Lupine packs do have balancing, rest (CrapShine etc) don’t live long lifes.
Thanks again for all the help so far!
I’ve been doing some more research. But even if I fix the old battery pack I’d still need a backup battery pack (it sucks riding back in the dark). I’d prefer to build my own battery pack so I was thinking:
If I take 2x26650 simply in series and take some of the better ones (real capacity ~4000-4200mAh) then that should last me long enough for most rides and I can just take two battery packs with me just in case. So if I buy two protected cells can I just put them together and won’t need any PCB or balancing stuff, right? That’d be super easy and I might build 2-3 of them (for my buddy). Or would I still need a PCB even for protected cells? Why? Thoughts?
Thanks again for your help!
Cheers
where did you get that info? I haven’t seen any personally, but some online examples don’t have it
actually, that’s the only example I could find. I guess Lupine owners don’t often open their battery packs!
Yes, you can just put them together and use, but you have to charge them one at a time.
Got it! I guess I’ll ready through battery-university this weekend before continuing asking more silly questions.
I wouldn’t mind charging them individually. I guess I’d just let 3 wires hang out of the battery pack (I need to seal it because of the sweat). So if I didn’t want to have to charge them individually I’d need a PCM, correct? What is a good source for them? I didn’t find anything on KD, DX or Manafont. Is this a good:
Protection Circuit Module (PCM) with Equilibrium Function for 7.4V Li-Ion Battery Pack (20 Amp limit, PCM-L02S20-265) (that would work with a trustfire 26650 which is LiIon, right?)
Where do ppl on these forums get these electronic parts? Are there any more compact (with less spec’ed current) PCMs?
Cheers & thanks
The online RC retailers often sell protection circuits for pack building.
THIS is my Magicshine packet I had to change protection circuit. The cells were just fine.
And HERE is my backup pack I’ve made by myself. Still have some parts if anyone needs. I tear it apart twice a year and check if they are still balanced. If not I recharge each cell separately.
That replacement holder you made is oh-so-pimp.
Ok, so I’m about to order that hobby charger:
I do still have an old PC power supply which has a few functioning 12V outputs that I can use to run teh Accucel. What is that input thingy called that I’d need to put in the Accucel? I’d just need a name so I can google it to order the adapter.
Also, once I get the charger I’d need another adapter to charge the battery pack:
http://img.dxcdn.com/productimages/sku_82510_4.jpg
What are those two male/female plugs called? I can’t find anything in the spec. Are these the same:
Radio Control Planes, Drones, Cars, FPV, Quadcopters and more - Hobbyking ?
What else should i get for the start? (I do have some soldering stuff and would get wires etc. from the hardware store I guess).
Thanks again!!
Get this cable for charging: Radio Control Planes, Drones, Cars, FPV, Quadcopters and more - Hobbyking
It supports literally every possible connector (and it’s dog).
As for power input jack: it’s generic 5.5x2.1mm (or 5.5x2.5mm, depending on revision) DC plug. They’re very common.
Awesome! Thanks! Exactly what I was looking for. Searching for “5.5×2.5mm” shows up tons of results. I just didn’t know what to search for since I do zero electronics (I’m more of programmer/MATLAB kinda guy)
Magicshine has 5.5×2.1mm connectors, so check yours. Then if you plan to make packs by yourself buy some connectors like 2S JST-HX and make balancing port. So you won’t need to take your pack apart each time to charge cells individualy.
Little update:
I disconnected all 4 cells from each other and measured them: One was ~0.1V the other that was in parallel to it was at 3.7V and the other 2 were at 4.5-4.8V. After ~3h the two are back to 4.3V and the dead one is at 0.0V now.
Btw, they were connected in a star form rather than a pure 2S2P. Like the right side:
!http://lh6.ggpht.com/\_hYIZmJ5Igu4/StP-AYEZBqI/AAAAAAAAAVY/YGNFsNjOG9U/2s2p-2p2s.jpg !
Does this make them easier to balance? The middle of the star was connected to the COM pad, so I guess it did balance them but my battery just died? Just curious.
I’m almost through the battery university but I have a question since I’m gonna order the Accucell frm Hobbyking soon. What doe people think of the pretty cheap battery packs from them. Such as:
Any good? The price seems great for the capacity? I guess they’re just a lot bigger & heaving compared to a well build 4x18650 battery pack?
They’re not much heavier, price/capacity indeed is great, but they are unprotected - which means you have to keep in head for how long your light has been running, and turn it off before running down your pack. LiPo’s don’t like overdischarge at all.
That's weird if they were in paralell shouldn't they have balanced? Or at the very least the 3.7 one should have been fully discharged?
sounds like the 0.1V cell died completely and the surviving cell of that pair was shouldering all the load. That means that it will discharge twice as fast (or more) and trip the PCB via the COM line way earlier than you’d expect. However, because the PCB is not involved in the pack charging at all, the charger would just see a 6.7V (roughly 3V and 3.7V for each bank) and charge it up to 8.4V. In the process, it will massively overcharge the healthy bank, which is what the 4.5-4.8V you see means. You’re very luck you didn’t see a fire.
this was the reason for the huge, bankrupting recall Geomangear carried out on MagicShine battery packs.
Are they stable now or should I leave work and get them out of my room at home? (It’s been >24h so they should be stable AFAIK?)
I also ordered the Accucell and will probably make my own battery pack with 2x KK 26650 protected. And then have a JST-XH hang out of it for balance charging them. That’ll give me more restful sleep.
Thanks so far for all the help!
most li-ion batteries blow up when they’re being charged, so I wouldn’t worry about them enough to leave work. As soon as you get home I’d stick them in a bucket outside until you can dispose of them.
Don’t dispose PCB which might be still used in some other pack or even at your planed one. It would be fine if we can identify your cells (full cell pictures needed) which can stand so high voltage. Just to add it to our knowledge.