Looking for a charger for 4S configuration 18650 battery

[msacco]

Hello, I have 120 NCR18650B batteries which I'll be using to build a 4S configuration battery.
I'm looking for recommendations on a charger from aliexpress/ebay, I don't really need a fast charger so I don't really mind if it would take very long to charge. As far as I understand I simply need a charger that outputs 16.8V to fully charge it.

I have seen some extremely cheap 2A 16.8V chargers like this:
https://www.aliexpress.com/item/32973210801.html?spm=a2g0o.productlist.0.0.27863118tJ10yi&algo_pvid=80c2759c-34d9-424a-ae52-61183c4456a7&algo_expid=80c2759c-34d9-424a-ae52-61183c4456a7-1&btsid=4a0caa30-932e-4549-99db-f5fec2a548f5&ws_ab_test=searchweb0_0,searchweb201602_4,searchweb201603_53

I have also seen some more expensive 10A chargers like this:
https://www.aliexpress.com/item/4000166668163.html?spm=a2g0o.productlist.0.0.560f548aZYQAf5&algo_pvid=e9d837fe-f21e-4483-a8fa-e01e87e4eaf4&algo_expid=e9d837fe-f21e-4483-a8fa-e01e87e4eaf4-0&btsid=7fec563a-a47d-4393-82eb-655020212809&ws_ab_test=searchweb0_0,searchweb201602_4,searchweb201603_53

(Looks rather cheap..), or this:
https://www.aliexpress.com/item/32816453570.html?spm=a2g0o.productlist.0.0.560f548aZYQAf5&algo_pvid=da00caee-d639-48c2-bc25-2590bbd6e20f&algo_expid=da00caee-d639-48c2-bc25-2590bbd6e20f-8&btsid=8f11118a-b5c7-4523-99c6-5b3afc540ab5&ws_ab_test=searchweb0_0,searchweb201602_4,searchweb201603_53
Which looks rather ok(?)

I know I can probably make a charger myself, but I'd rather just buy something.
I didn't really found anything useful on amazon, and I don't have free shipping from there anyway, so I'd probably rather just buy something from aliexpress or ebay.

Thanks for the help!

 

[jonyjoe303]

I like the 36 dollar one, that looks like it will actually last you. Usually they don't show the insides of the charger, but it looks like they take pride in its construction. On the inside of the charger it looks like buck converter circuitry, and those are very reliable and will give your battery a safe charge. I use a laptop charger and a 5 dollar buck converter to charge my 3s, and it has never let me down. 10 amps will give you a good charge without stressing your batteries.

My advice is also get a tenergy lipo alarm (12 dollars) and just connect to the balance connector, it'll sound an alarm if the cell voltage goes over 4.22 volts (example if the pack goes out of balance). I don't trust the bms to protect me everytime. I use these when I charge my 3s li-ion. I now keep it plugged in to the battery all the time. I had 2x 3s packs that drained to less then 6 volts(min 9 volts) for no reason (either bad cell or bad bms), now at least an alarm will sound if cell voltage goes under 3 volts. Cells are too expensive not to monitor everytime. This will also show you the battery pack/cell voltage in realtime.

 

[msacco]

I like the 36 dollar one, that looks like it will actually last you. Usually they don't show the insides of the charger, but it looks like they take pride in its construction. On the inside of the charger it looks like buck converter circuitry, and those are very reliable and will give your battery a safe charge. I use a laptop charger and a 5 dollar buck converter to charge my 3s, and it has never let me down. 10 amps will give you a good charge without stressing your batteries.

My advice is also get a tenergy lipo alarm (12 dollars) and just connect to the balance connector, it'll sound an alarm if the cell voltage goes over 4.22 volts (example if the pack goes out of balance). I don't trust the bms to protect me everytime. I use these when I charge my 3s li-ion. I now keep it plugged in to the battery all the time. I had 2x 3s packs that drained to less then 6 volts(min 9 volts) for no reason (either bad cell or bad bms), now at least an alarm will sound if cell voltage goes under 3 volts. Cells are too expensive not to monitor everytime. This will also show you the battery pack/cell voltage in realtime.

tenergy checker.jpg

Thanks for the reply! I also think I'll go with the $36 charger. I'll also take your advice for the alarm, but isn't it extremely bad having the battery charged all the time?
As far as I know, when the battery is in store it should be kept at around 3.6-3.7V or ~14.6V.
Do I also need 2 different alarms for the lower voltage and higher voltage? Or I could configure the safe voltage range or something like that?

Thanks a lot

 

[msacco]

Bump

 

[john61ct]

[ isn't it extremely bad having the battery charged all the time?
As far as I know, when the battery is in store it should be kept at around 3.6-3.7V or ~14.6V.
Do I also need 2 different alarms for the lower voltage and higher voltage? Or I could configure the safe voltage range or something like that?

Yes only charge to (near) Full when you're about to start pulling it back down.

Anywhere from 30-60% SoC, 3.6V up to 3.75 or so is OK. Just ensure they aren't going lower if stored long term, disconnect fully

 

[msacco]

[ isn't it extremely bad having the battery charged all the time?
As far as I know, when the battery is in store it should be kept at around 3.6-3.7V or ~14.6V.
Do I also need 2 different alarms for the lower voltage and higher voltage? Or I could configure the safe voltage range or something like that?

Yes only charge to (near) Full when you're about to start pulling it back down.

Anywhere from 30-60% SoC, 3.6V up to 3.75 or so is OK. Just ensure they aren't going lower if stored long term, disconnect fully

Yes that's what I was aware of as well, I'm currently discharging all my battery to be somewhere between 3.6V-3.7V before actually building up the battery pack so they're all at pretty much the same voltage.

How long is long term? ^^
Or in other words, after how long I should re-check that the batteries are still at 3.6V-3.7V?

Thanks

 

[john61ct]

If a BMS is in there I'd start out checking weekly then monthly, then continue scaling back once I see no danger.

Temperature makes a huge difference, cooler the better