quick question about parallel charging

Batteries and Chargers Chargers
1

Please forgive me if this is answered elsewhere… I did a search and checked the balance charging sticky thread.

I have a 1s4p holder I bought from flea bay http://www.ebay.com/itm/1-Battery-Holder-Case-for-Li-ion-18650-17670-battery-1S4P-w-PCM-output-3-4-2V-/220966395586?pt=Other_MP3_Player_Accessories&hash=item33729f9ec2

Is it safe to use this holder to charge 1, 2, or 3 batteries at once? I am assuming it is but just wanted to make sure before I blew myself up.

Also If I am charging 4 cells at lets say 2 amps - does each of the 4 cells get 2 amps or is the current “shared” among the 4 cells? So each gets 500ma in other words.

Thanks in advance :slight_smile:

2

Each would get 500 mah.

3

thats what I thought. thanks.

do you happen to know if I can use that holder for less than the 4 cells it was designed for since its meant for parallel charging?

4

ok - thats what I had figured but I just wanted to be sure

5

I ordered the same battery holder. I'll be charging 1 to 4 cells with my hobby charger. Hopefully it will give me the same results as series balance charging

6

Buy here and save.

They have other versions as well.

7

what type of hobby charger are you using? ive got a tenergy accucel 8… so far its been great. I can quick charge AW 18650 IMR @ 4.5amps and have a battery ready in 20-25 minutes (I dont do this often since its the max recommended current, but its nice to have the option)

I also use it to charge my 16x aa pack for my mag 458

edit: that fast tech price is great - wish I had seen that. Fast tech is growing as a great dealer from what ive seen here

8

I’m new to hobby chargers, but I thought it was a bad idea to charge in parallel. Something about if the cells are unevenly discharged, you could end up charging one cell at 4 times the amperage(1S4P).

9

I have an iCharger 106B and a Turnagy Accucel 6. I mostly use the iCharger because it does a better job at balancing.

10

thats a nice power supply you have there. I am using a 105 watt psu w/fan I salvaged from my attic… my charger can draw up to 150w but I never charge lipos or high current

11

I always monitor battery voltage. If they're not close, I won't parallel charge them

12

Me too - I only charge cells in parallel that are used together in the same light… ie my sky ray king uses 4x sanyo 2600s in parallel, and I charge them in parallel

13

Thanks man. I built it myself :) It's 3 amps at 12 volts continuous which is more than enough for my needs. The meter shows current draw.

Here's a picture of the internals before I installed the current meter. I bought the power module from ebay for $8.00. The rest of the parts I had in stock

14

I would like to add a cautionary note on charging cells in parallel. Keep the total charge current equal or less than the max charge current of one cell. There is no easy way to know how much current each cell is getting. Even minor cell differences can add up to major current variation.

I say this because in my former employment, I built large Li-Poly packs for solar lighting applications. During our initial ‘torture’ tests, we ran some cycles at various currents, including 1C of the individual cells, right up to 1C of the pack. The results were troubling; almost every pack we charged at a rate above the single cell maximum would show signs of damage (gassing, warm cells, etc.). Many of these problems are more apparent in a Li-Poly pack because of the enclosure. By the time you notice this on a cylindrical cell, it may already have vented, or worse.

Safe charging everyone.

15

That’s an excellent tip Relic. Thanks!

16

many thanks for this tip!

17

Agreed! I'm very careful when I charge my cells. I usually charge at 50% of the rated mAh. I monitor the temps as well

18

I’ll also add a charging-related horror story. I have a 1-5S charger that you select the cell count manually (this is homebuilt, works exactly as I designed it). I set it up, hooked up a 3S pack, double-checked and went away for a bit.
About an hour later I hear what sounds like fireworks going off. Not the booming ones, more like the sparkly-crackly ones. Strange for November… Oh S*&T!!! Run downstairs and my workstation is engulfed in flames. Black smoke is billowing everywhere (mostly from the plastic enclosure). I have a bucket of water in the area for just this sort of emergency, and sweep the remains of the battery into the bucket. I almost lost my house because of the simplest error; my error.
I’ll never forget seeing those perfectly shaped cells lying in a pile; glowing red hot.

It turns out, I selected 4S… not good. This is a surefire way to push any unprotected Li-Ion cell into thermal runaway (LiFePO4 are an exception).

I still have a reminder of my stupidity; there is a piece of one of the cells melted into one of my multimeters.

I do not use the homebuit charger anymore either.

As I said before; safe charging everyone.

19

relic38, scary shit man. Good thing you were able to get the fire out in time. I'm very paranoid of fire. I keep fire extinguishers handy just in case

20

Im glad your home survived that mishap. That was far to close for comfort. It doesnt take much to make a critical mistake when so many details are being monitored and executed at once (no matter how many times youve done it correctly). Thats why pilots use checklists for almost every procedure. Ive written my own condensed versions for specific scenarios tailored to my type of flying. I also use them in my work (applications systems/IT). You cant be overly cautious with lithium ion cobalt cells (LiCO). IMO, if you’re recharging them, you owe it to yourself and those around you to buy a descent digital multimeter (DMM) so you can test voltages before and after charging. Also nice for testing discharge currents with high powered flashlights.

Most of us are cautious because we’ve taken the initiative to become well educated online and heard the many horror stories of others. But every once in a while, someone with cash on hand buys a high powered rechargeable device (usually multicelled) and turns it into a frag bomb because they were ignorant and didnt do the research before playing. Then there are those that salvage old 18650 cells from wasted laptop packs and stuff dissimilar ones into multicell flashlights and wonder why their libs got blown off.

Although I never discharge/recharge non-matched cells together, your story of charging multi cell Li-Poly is yet another reminder of the explosive potential these cells contain when mishandled.

Thanks for posting your experiences Relic… and of course, the suggestions werent directed at you.