How to use bench psu to charge batteries ?

[Blord]

I have a bench psu with adjustable voltage and current. I was wandering how it can be use as a charger for batteries. Are there different ways to charge Li-MH like AA/AAA and Li-Ion like 18650 ? What current and voltage do I have to set in order to charge them safely. Any information and tips are welcome, thanks.

 

[ARG]

I really have no idea, but I do not believe this is safe. For charing Ni-MH I believe the charger will cycle on and off to charge, the same with li-ion and you don't want to risk charing li-ions wrong, or they'll explode.

Again, I really have no idea, I'm just going off my terrible memory here. (So don't take my word for any of this)

Edit:
http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries
http://en.wikipedia.org/wiki/Nickel–metal_hydride_battery#Charging

 

[jimdt7]

I really have no idea, but I do not believe this is safe. For charing Ni-MH I believe the charger will cycle on and off to charge, the same with li-ion and you don't want to risk charing li-ions wrong, or they'll explode.

Again, I really have no idea, I'm just going off my terrible memory here. (So don't take my word for any of this)

Edit:
Charging Lithium-Ion Batteries
Nickel

I agree with you, i think it's better to buy a charger !

 

[Cyparagon]

Set the voltage to the full-battery voltage, and set the current to... however fast you want to charge it. It's totally safe (provided you set a reasonable current) and I've done it many times, but it is easier to just buy a charger.

 

[Blord]

I do have a DX universal charger for 3.7V Li-Ion but sometimes it refuse to charge the battery. It must be "tickle" on my bench PSU before I put it in the normal charger.
Then I asked myself the question why not just use the bench PSU for the charging process. It can provide much more current and shortened the charging process considerabely. So I asked around for the proper way to do it.

I set for the 3.7V battery the maximum voltage to 4.2V and the current 1C but if there is a little current going thru, that means the battery is almost full ?

 

[Meatball]

You set the current to what? 1C?

Set the current to 50mA for a nice and safe slow charge, that's all that I feel safe recommending to you. You can go higher for a faster charge period, but the chemistry of your particular cell type will put a cap on the "safe" current setting you can use.

 

[foulmist]

for Li-Ion I use my PSU like so:

1. I hook up the battery...
2. Increase the voltage to the point where 500mA of current is drawn...
3. Let it sit for a while.....
4. When the current drops to around 200mA i rise the voltage until the current gets to 500mA again
5. Repeat the same until the voltage reaches 4.2V and then just let the current drop down to 0.00A -> perfect charge ! :beer: works as well on unprotected and on protected!

never go beyond 4.2V it will shorten the battery life and capacity!!!
:beer:

 

[Cyparagon]

Well, if you have constant current mode (and most do), you can set it and walk away:

1. set voltage at 4.2V
2. set current to 0
3. hook up battery
4. turn current up to desired value

It will charge at the current you set it. The current then drops slowly as it approaches 4.2V. This is pretty much what an actual charger does anyway.

 

[weeba2kv]

USE4.1 volt! 350mA check after 2 hours then turn down to 75 mA for 1 hour

 

[bobhaha]

You set the current to what? 1C?

Set the current to 50mA for a nice and safe slow charge, that's all that I feel safe recommending to you. You can go higher for a faster charge period, but the chemistry of your particular cell type will put a cap on the "safe" current setting you can use.

1C is 1 times capacity... So if the battery is rated for 600mAH, 1C = 600mA, 2C = 1200mA (1.2A)... etc

 

[Bionic-Badger]

Bad idea.

You should use a real charger, especially for LiPo or LiIon batteries, or you risk damaging your batteries or even causing them to burn. Many batteries require a specific charging curve in phases to get the most out of the batteries. If you want a fast charger, just buy one.

 

[Cyparagon]

The graph you linked is sill almost identical to how a bench power supply would behave in my outline.

 

[LarryDFW]

A good digital power supply will charge lithium ion cells of all types:

Set the current @ 1C (capacity in mah).

Set the voltage @ 4.20 for most lith-ion cells.

Charge until current drops to 50 ma.

LarryDFW

 

[lasersbee]

Bad idea.

You should use a real charger, especially for LiPo or LiIon batteries, or you risk damaging your batteries or even causing them to burn. Many batteries require a specific charging curve in phases to get the most out of the batteries. If you want a fast charger, just buy one.

Agreed....
I've been flying electric R/C for years and the only sure way
to get a full fast charge is with a Charger designed for the
batteries you use.

The problem that I found when not using a non specific Charger
(a standard Supply) for fast charging was that I am sometimes
distracted and don't notice the batteries heating up. That will no
doubt damage them or at least decrease their capacity.

Using a well designed charger for the batteries you choose will
ensure the batteries are fully charged (Fast or Slo) without
stressing the batteries.

Of course I've tried straight charging different types of batteries
from many kinds of PS including from a car battery. It definitely
works but you need to closely monitor the batteries in case of
overheating....

I've seen batteries explode and/or catch fire... Ultimately the
choice is yours.


Jerry

 

[foulmist]

Agreed....
I've been flying electric R/C for years and the only sure way
to get a full fast charge is with a Charger designed for the
batteries you use.

The problem that I found when not using a non specific Charger
(a standard Supply) for fast charging was that I am sometimes
distracted and don't notice the batteries heating up. That will no
doubt damage them or at least decrease their capacity.

Using a well designed charger for the batteries you choose will
ensure the batteries are fully charged (Fast or Slo) without
stressing the batteries.

Of course I've tried straight charging different types of batteries
from many kinds of PS including from a car battery. It definitely
works but you need to closely monitor the batteries in case of
overheating....

I've seen batteries explode and/or catch fire... Ultimately the
choice is yours.


Jerry

you are right Jerry, but if one does the math and sets the current appropriately the battery will never heat up :beer:

it's always better to charge at lower currents than at higher ..

i have even succeeded in charging the buttons lithium cells several times after full discharge .. you know those little ones... at very low currents and they never even exploded or heated up ! but I have been lucky with those I admit ... they shouldn't even be attempted to charge

:beer:

 

[lasersbee]

you are right Jerry, but if one does the math and sets the current appropriately the battery will never heat up :beer:

it's always better to charge at lower currents than at higher ..

i have even succeeded in charging the buttons lithium cells several times after full discharge .. you know those little ones... at very low currents and they never even exploded or heated up ! but I have been lucky with those I admit ... they shouldn't even be attempted to charge

:beer:

Yeah... I've done that as well when in a pinch...

I agree that at lower currents there is a lot less danger but
it takes much longer to charge those larger capacity batteries.

When we are at the flying field we want a Fast charge to get
back into the air and for that we use Fast charge chargers...:beer:

Haven't ignited a battery since....


Jerry