Choosing Correct Charge Current

[jeesiss]

Hey Team,

On someone's recommendation, I purchased a spare IMR 18490 3.7V 1100mAh battery and an UltraFire 3.2/3.7 V charger. The charger has a switch, where you have to set to either 300mA or 650mA charge current. What option should I choose, and why?

Sorry if I missed a separate discussion on this and thanks in advance for any of your help.

 

[Hoosier]

Is this mA switch in addition to the voltage switch?

 

[echofinder]

my ego charges at something like 450mA I believe; don't quote me on this but I bet you would be fine using 650

 

[jeesiss]

Yes, indeed. It also has the voltage switch.

 

[Hoosier]

If you have an 1100 mAh battery, then go with the 650 charge.

 

[jeesiss]

If you have an 1100 mAh battery, then go with the 650 charge.

Thanks for the advice, but what makes you say that? I'd just like to understand "why", so I can make an informed decision, if/when I get a different battery. Is it just about how long it takes to charge, and if so, then why wouldn't I just pick the highest setting? I can only assume that it'd kill the battery, if it were too high.

 

[bigtiime]

The mAh switch is on the side of the charger. Both settings will work but the 300 mAh will be slower.

 

[Hoosier]

Ah, well, you want a charge current that is less than your battery.

So if you had a 400mAh battery, you'd go with the 300.

But you have an 1100mAh battery. You could charge it at 300, but as bigtime points out, it would take quite awhile.

 

[jeesiss]

So, since it allows for two batteries to be charged simultaneously, do I pick the setting to match the lowest mAh, or is it one of those deals, where each position only gets half of the available charge curent, meaning at 650mA, each position would get 325mA?

 

[jimbalny]

Every battery has a recommended charging current, generally I always charge at the higher rate unless its the first time charging ill put it at the lower - or if I accidentally discharge the battery to below 3.8 then ill recharge at a lower rate. I use all aw imr and aw power protected.

 

[Hoosier]

Depends on the actual channel configuration of the charger.

A true dual channel will apply the correct voltage and maximum current based on the battery condition for each individual battery. The feedback loops for each side are individual circuits, so each side would get 650mA.

I've seen spec's where the charger was physically configured like a dual channel, but operated like you posted, split the charge. I have avoided those types of chargers because I do not understand how it can determine the proper points of the charge cycle curve. (Is the battery voltage averaged or is one set of terminals primary?) Scary stuff.

I would assume that a charger that can be used for different voltages and charging currents is a true dual channel and therefore charge each battery at the switch's labeled current, but I cannot say for certain without knowing the circuit spec's. So you would want to avoid mixing batteries in a charger unless you do have the full knowledge of what is under the plastic "hood".

That is also why one of the standing rules on charging Li-Ion is to remove from charger as soon as the batteries are charged. (There are too many different methods to do the same function and not all of them are the "right" way and quite a bit of crap is out there.) Even if you have a great charger, it is best not to rely on the safety circuitry all the time as it does fail. All safeties can fail.

 

[jeesiss]

Gotcha.

I just want to say that as a new vapor-er (?), having so many very specific questions without any answers is almost paralyzing. I appreciate all of the help I've gotten so far on the forums. Thanks again!