Samsung and Redilast 18650s

[Cenobite9]

I just purchased two of the Samsung 18650 3000maH batteries from hkequipment on ebay and I got one Redilast 2900maH 18650 from Tactical HID. I haven't tried either one of these before so I hope someone here can chime in on the quality of either of these.

 

[BShanahan14rulz]

User reports have confirmed that the redilasts are NCR18650 cells. According to the datasheets I could find, the redilasts go from 4.2V down to 2.5V, while the Samsungs go from 4.3V down to 2.75V. I think both look like great cells, and the limiting factor will probably be the protection circuit if anything.

These are the DS I could find:
Samsung ICR18650-30A
http://www.meircell.co.il/files/Samsung ICR18650-30A.pdf

Panasonic NCR18650
http://www.lighthound.com/assets/panasonic18650.pdf

Another great thread for info on the Panasonic NCR18650's use in AW and Redilast is topic# 293785 at CPF.

 

[Cenobite9]

Cool, from what I've been able to dig up on the Samsung cells it looks like they need to be charged to 4.35v to get the full benefit of their capacity. Unfortunately I do not own a decent hobby charger that can do that kind of charging. I've been looking but I would not know what to buy even if I found some. Any good direction on a good hobby charger that can charge beyond 4.2v? I've heard they are expensive but worth the money if you want the most out of your batteries.

 

[LarryDFW]

Cenobrite;

I am using some 4.35 VDC cells in my direct-drive 445nm lasers.

Many new cells are using this safer new "nickel" technology.

I just charge them with a digital adjustable switching power supply:

The 5 Amp capacity lets me charge several cells at once.
LarryDFW

 

[Cenobite9]

That's a nice looking PS. I found it on Amazon for $259.00. Once I have the available funds I am going to get on of those. So when charging with a PS like that, do you just use the dials to adjust the maximum voltage? Also, does the PS know when to stop charging the batteries or is that something you have to keep an eye on?

 

[BShanahan14rulz]

You'd probably have to watch it. Charge the cells at the manufacturer's rated charging rate (Amps, sometimes denoted in terms of capacity with a coefficient). You want to charge the cell up to 4.2V with the constant current. Once it hits 4.2V, you want it to hold that charge at 4.2V until the current that the cell accepts at that voltage drops to around 10%.

 

[Cenobite9]

Cool, thanks for the information. Those data sheets are very detailed! Now I just have to solve that lack of funds issue so I can get that PS. The cheap-o $15 charger I got from BatteryJunction doesn't always charge to same level. It started off charging my batts to 4.2v. Now it ranges from 4.05v to 4.15v.

 

[Cenobite9]

Alright, I received my Samsung 18650 cells yesterday. HKEquipment did a good job of getting them to me quick (for a Hong Kong based company - I received the batteries in the mail within two weeks). I charged them in my crappy TL-100 charger and they charged up to 4.25v. Actaully a little better than I expected from that charger. Now I just got to see how long these batteries will last.

 

[benmwv]

So, BShanahan14rulz, what you are saying is that if I want to charge from a power supply all I have to do is set it to 4.2 and wait until they are full? I was under the impression you had to start the voltage low a slowly adjust it up as you are charging them until they hit 4.2

 

[LarryDFW]

That's a nice looking PS. I found it on Amazon for $259.00. Once I have the available funds I am going to get on of those. So when charging with a PS like that, do you just use the dials to adjust the maximum voltage? Also, does the PS know when to stop charging the batteries or is that something you have to keep an eye on?

It is a great supply for charging up to 5 cells in parallel or series.

All you have to do is set the charging voltage to exactly the voltage you want
(4.20 or 4.35).

Maximum current can be set also.

When the current per cell drops to 50 ma, the charging is complete.

It is great for testing Laser diodes, either by current or voltage.

I can get you the "digital power supply" for $229, if you decide to buy one.

LarryDFW

 

[Flaminpyro]

Power supplies do not know when to stop charging only a lithium charging ckt will do that !
Here is what I like to use it goes between a 12 battery or you power supply and the cell/cells
you want to charge and it can do all different types of cells
It's a ultramat 12 made by Graupner but there are many different ones out there. this one was
about $80.00 there are more and less expensive modeles, it just depends on what you want,
rember you usuly get what you pay for
This unit will discharge also so you can use this to ballance cells by finding what there capacity realy is
I got this one from a hobbie site. it will stop charging your cells at the correct point of charge !
I took a broken TR-001 charger and ripped out all the usless stuff put in one switch so I could
switch between charging one cell or two cells, and that is all you will need to correctly charge
your lithium or any othe cells

That's a nice looking PS. I found it on Amazon for $259.00. Once I have the available funds I am going to get on of those. So when charging with a PS like that, do you just use the dials to adjust the maximum voltage? Also, does the PS know when to stop charging the batteries or is that something you have to keep an eye on?

 

[BShanahan14rulz]

To charge your cells, limit the current to the charging current recommended by the cell's manufacturer and charge the cell up to 4.2V. Once it's at 4.2V, keep charging at constant 4.2V until the charging current tapers off. This is the recommended charging algorithm for Li-Ion, but if you know what you are doing and have the right tools, you'll be able to find some shortcuts, esp. with better cells. Better cells can usually handle higher than recommended charging currents in the first stage, and this can result in a faster charge (at the risk of charging the cell too fast)

I think most manufacturers recommend 0.5C charging current, which is already over an amp with most good 18650's.

If you google it, there is a battery university something or other link. They're trying to sell a book or something, but the page still has a good graph for better understanding.

 

[Cenobite9]

Cool, nice to know I have options. I may still go with the programmable power supply as that would also give me a much better means for testing diodes and setting drivers. Eventually I amy even pick up something similar to that Ultramat 12 as well and use it with the PS to charge batteries. Then I would hae a more complete laser building and testing setup Now where's that darn tax return!!!