building a 3S2P from scratch 18650s - how to charge?

Batteries and Chargers Rechargeable Batteries
1

Hello-ho-ho!

I’m currently on some portable-speaker-building and I want to use some laptop cells for that (these) - capacity is from 2214mAh to 2425mAh (at least my Lii-500 says so).

I have 6 of them, so I thought about a simple 3s2p configuration, so give me ~11,1V and 4.5Ah.

I have several of the little fake TP4056 boards with protection - can I just use them?
one for every cell - does that work in a series-configuration?

Thank you!

btw. the speaker will be these: just-imagine-speakers.de

2

So you’re planning to solder the output of each charge board to a pair of cells and leave them in place?

3

I searched a long time yesterday, just to find out, that that’s not porrible, because you can’t run these little charger boards in Series.

So, I will use them as a big ~13.2Ah 4.2V Battery and use a Step-Up Converter.

Thanks!

4

Somethings telling me it would work, not to series the charge boards but to have three separate charge loops with the cells remaining in series. Absolutely unsure of this though.

5

I think it can work too, though only if you keep the main circuit open.
I belelieve this is how balance chargers work?

Curious though…

6

It’ll be much safer like that. Avoid series Li-ion whenever you can.

7

Yes, but also the boost-converter is less effective :confused:

So, driving 6 TP4056 in parralel shouldn’t be a problem? Because every single board charges all of them, not that they disturb each other.

Thanks!

8

If they are all set in parallel then I don’t see the need for one board for each cell. The board(s) will read and protect voltage of one cell but cannot differentiate if there is more than one cell in parallel. If you are trying to implement individual cell protection then one board for each cell in series would work.

9

I just painted what I originally wanted:

dark red: 18650s
light green: TP4056 charger boards

I don’t want to have one charging board for more than one cell - because of the charging speed.

So, so far I understand, that making a bat-pack out of 18650s and those TP4056 boards isn’t really possible, except a 6P1S pack with one board, which takes ages to load :frowning:
Or all in Series with a board per cell? Then I have up to 25,2V - if I use a buck converter, I can bring that down to 12V for the Amp and 5V for the USB Output…

Or I make is the simple way - all in series and for charging - this module: http://www.aliexpress.com/item/CC-CV-high-power-Adjustable-Boost-Converter-11-35V-12V-to-19V-Car-Laptop-Mobile-Power/1383076897.html?spm=2114.01010208.3.20.WZ2JYF&ws_ab_test=searchweb201556_9,searchweb201644_5_505_506_503_504_301_10032_10020_502_10001_10002_10017_10005_10006_10003_10021_10004_10022_10018_10019,searchweb201560_2,searchweb1451318400*–1,searchweb1451318411*–1&btsid=254011d8-c115-47eb-8629-27bde445e912

10

suggestion: connect cells first to parallel (2 in parallel)

and then connect these 3 “packs” together in series

then use a balancing charger to charge them, such as for example:

you would also need a balancing connector

the problem with using the tp4056 boards to charge them is that I suspect the tp4056 might have common GND shared between the DC in and Batt charging terminals.
So if you would use those boards with one power supply, you would basically short all Batt- together.

Also note you should never charge Li batteries unattended. All the chargers above don’t have temperature control over battery.

11

Well, that’s what I needed :slight_smile:

I will order Hobbyking DC-4S (3rd link) - because I want to make this Car-Chargable.

So, then like I wanted it - 3S2P.
Nice <:-)

Thank you very much!

12

the 3rd charger is my favorite too, and it charges through balance connectors

you might need to open it up to improve heatsink connection/cooling or add some better heatsinks. I would definitely do that because it gets quite warm and in your case the charging (heating up) would take quite some time. I use it as my backup charger.

also see if 1/1.5A charging current is enough for you (that means it could take up to 7 hours to charge the pack if the capacity was 3500mAh per cell)

this one offers higher current selection

13

Hi!

I ordered the other one - 750mA or 500mA is enough charging for the ~2200mAh Cells. It’s quick enough.

Plus, I don’t have too much place to waste - I need a suitable power supply as well, so the smaller version is better for me because the Power supply is also smaller :slight_smile:

I will open that thing and glue some heatsinks on that. I will also include a little fan to the whole thing.

14

it’s 4400mAh if you have 2 cells in parallel. That’s 6 to 8 hours to charge full. If you would only charge it attended, after you’re back from work, you wouldn’t have enough time to do it during workdays. Just sayin’ :slight_smile:

This one has both AC and DC options for input, has built in power supply.

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=43038

(in hobbyking you have some time to cancel/change the order if you want)

15

it’s 4.4Ah - correct, but then the charging current will be at around 1250mAh I guess (I think it’s 1.5Ah@2S, 1.25Ah@3S and 1Ah@4S?) - I counted that in and halved it.

So 3 1/2 hours - that’s OK.




But one further question:


If I run this from 230V - I have the power supply to 12V DC, then the charger, then the bat-pack, then the amplifier and the speakers.

Is it possible to run this thing from 230V in that configuration, or should I bypass the charger and the cells (let the cells charge and let the power supply run the amp directly)?


Thanks!

16

I read your last post a few times but I don’t understand what your solution consists of, and what is connected to what :slight_smile:
what power supply are you mentioning? what it is it supposed to do? What is powering the speakers? What is powering the amplifier? Is the amplifier inside the speakers or outside?

can you copy the link to the charger you ordered ?

17

Hi

OK, I have time :smiley:

What I want to built, is a portable stereo-speaker.

How it will be powered:
230V Input -> 12V ~2Amp Power Supply -> Charger -> 6 18650s in 3S2P -> Amplifier

All inside the speaker -> http://up.picr.de/24817032zw.jpg in the 2 seperate spaces on the right side (the speaker-chassis will be on the left side, the cutting is missing at this point)

18

ok now I understand :slight_smile:

This is 15W amp, which means cca 1.25A @ 12V

typically amps need surge current here and there (when the bass goes thump) so you need to provide that extra current surge. I don’t know if the PSU can provide it, or better to run it from the batteries directly. If their internal resistance is too high also they will not be able to provide it. You need to test this a bit.

I personally would have both options of running the amp from batt and AC, and then only use batteries when I am off the grid.

And the charger and batteries I would mount inside the speaker box. Fire hazard.

19

Because of the maybe-overheating, I have a 40mm fan here that I will include in the compartment where the charger and the batteries will be in.
The speakers are tiny (2”) - the amp will never use it’s full monstrous 15W :smiley:
I think that the batteries make a good puffer if the amp needs more than the power supply can deliver - at least I hope so :stuck_out_tongue:

OK, so I think I have everything on order - thank you very much!

20

you can stack tp 4056 in parallel to increase their total charging current above their max 1A.
you can use one TP4056 per parallel set of batteries in the block of batteries but you must provide them with isolated power supply which is not economical or practical… ideally, you can use a constant current/constant voltage power supply and a BMS/protection board which is the best solution…
An alternative would be to bring all 6 cells in parallel and use 6 TP4056 boards also in parallel to charge them…. works with the simple TPs without the protection circuit…. you must make sure to add a couple more TPs in parallel to be able to both charge the batteries and supply the amplifier at the same time….