Efest luc battery charger and voltage question

[ROM 1]

I recently purchased an Efest LUC battery charger to charge my 18350, 18490, and 18650 batteries. I chose this battery after someone here in this forum highly recommending it, and also because this charger has a numeric LCD display indicating the voltage of the battery being charged. I think this feature is very important because you can actually see the voltage of the battery prior charging, during charging, and finally being capped out at 4.2volts. I'm not really fond of led lights going from a red light to a green light to indicate the state of the battery capacity. Anyway, I have a question about the total voltage after fully charged. I recently charged one of my 18350 and also a 18650 IMR battery with this charger. Once it fully charged, I removed both batteries from the charger and measured the voltage for each battery with a multimeter. I know that this charger has a voltage indicator built into it, but I wanted to see what the total voltage would be using a multimeter. The total voltage for each of the battery that I fully charged came to 4.25v. My question is, is this too high? I mean the battery has a label indicating 4.2v. Is 4.25v way too high and maybe even damaging the battery, or is this normal being that the charger is fully charging the battery to its fullest capacity?

 

[RaceGun59]

4.25 volts DC is not way over. It's only 1.1% above.That could just be the sensitivity of your VOM. MY "hey do you have a VOM I can borrow" will show a differant reading then my $400 "I bet my life on" Fluke VOM. DC batteries will read high fresh off a charger. It's takes a higher voltage then the battery rating to charge it.

 

[Coastal Cowboy]

You should let the batteries rest after charging. Give them at least 30 minutes to settle down. They should read at 4.2 or a hair below.

If you take them off of the charger when they reach 4.1v, you will greatly extend their lives.

 

[gmb225]

if i check my batt voltage with a vom there always .2v lower than my LUC charger says they r when i first put them in. this tells me the LUC is telling me the charging vol not actual batt vol. i think that sucks for the price. but ive never had it charge past 4.22v.

 

[dataangel]

What are you basing this information off of? Typically, lion devices come with instructions to "fully charge" the batteries.

 

[Coastal Cowboy]

What are you basing this information off of? Typically, lion devices come with instructions to "fully charge" the batteries.

From here.

How to Prolong Lithium-based Batteries - Battery University

Charging to 4.1v will essentially double the number of charge/discharge cycles, which is how we measure battery "life."

 

[SilverZero]

I don't have a high quality multimeter so the values I'm getting could be off slightly, but I've noticed with the LUC that the Efest IMR 2250mAh 18650s I have do meter out at 4.25V when the charger finishes charging them. However, my AW IMR 2000mAh 18650s meter out at 4.20 or 4.21. I'm not sure why that is exactly, just thought I'd throw that out there.

I have noticed that the charger displays 4.2V for a little while before the charging actually stops. I think the next time I have a battery that needs a charge I'm going to keep an eye on it and pull it off the charger as soon as it displays 4.2V and see what they measure out at with my meter. I'll try to post again with the results.

 

[jow350]

You should let the batteries rest after charging. Give them at least 30 minutes to settle down. They should read at 4.2 or a hair below.

I have an Efest LUC and that appears to be the pattern. Depending on the battery, they will be between 4.20V and 4.25V right after I take them off, and about 0.05 Volt lower later (between 4.15 and 4.20).

I have encountered a curious issue with the new Panasonic NCR18650B 3400mAh batteries I got a couple of weeks ago. They will charge to 3.9V (indicated on the LUC) and then stop. I take them off and they measure out at or just below 4.1 immediately, but after waiting a bit it goes down to about 3.90V to 3.95V. If I use the batteries after this they last significantly less than fully charged. If I put them back on the charger they finish charging to about 4.25V (4.20V or just under after rest), and they last significantly longer, I'd estimate at least 25% or more. Anybody run into this as well?

 

[ROM 1]

I don't have a high quality multimeter so the values I'm getting could be off slightly, but I've noticed with the LUC that the Efest IMR 2250mAh 18650s I have do meter out at 4.25V when the charger finishes charging them. However, my AW IMR 2000mAh 18650s meter out at 4.20 or 4.21. I'm not sure why that is exactly, just thought I'd throw that out there.

I have noticed that the charger displays 4.2V for a little while before the charging actually stops. I think the next time I have a battery that needs a charge I'm going to keep an eye on it and pull it off the charger as soon as it displays 4.2V and see what they measure out at with my meter. I'll try to post again with the results.

Silverzero, it was you who suggested this charger to me from a previous thread that I posted last week. Thanks for the suggestion of this charger. I am extremely happy with this purchase. According to others who responded to my question regarding 4.25v being high, it turns out that this is a normal voltage amount when batteries are being fully capped out when charging. IBCR Medial suggested that I let the battery rest for about 30 minutes after charge then check voltage. I did what he suggested and he was correct that the battery's voltage eventually drops about .5 volts. I'm happy now...thanks everyone for your answers!!

 

[dataangel]

Thanks for the link to Battery University, made for a good read. I'll have to try their advice on some of my other lion devices.

 

[Coastal Cowboy]

Glad to be of service. Just paying it forward.

When I first logged on here, this forum took me from rank amateur to semi-confident intermediate in under a month.

 

[SilverZero]

Silverzero, it was you who suggested this charger to me from a previous thread that I posted last week. Thanks for the suggestion of this charger. I am extremely happy with this purchase. According to others who responded to my question regarding 4.25v being high, it turns out that this is a normal voltage amount when batteries are being fully capped out when charging. IBCR Medial suggested that I let the battery rest for about 30 minutes after charge then check voltage. I did what he suggested and he was correct that the battery's voltage eventually drops about .5 volts. I'm happy now...thanks everyone for your answers!!

Glad it's working out. I attempted my experiment with pulling a battery off of the charger as soon as it read 4.2V yesterday and got the same results. My AW IMR 18650 2000mAh batteries meter out at 4.21V and my Efest IMR 18650 2250mAh batteries meter out at 4.25V when fully charged. Both batteries have rested for about 12 hours and I'm getting the same readings. I guess I'll have to wait and see what kind of long-term life I get out of them, since it has been said that they appear to be overcharged. I think in the future I'll try to pull them out of the charger when they are at 4.1V but I don't have the patience to be looking at the charger every five minutes. We'll see.

 

[JuRuKi]

cliff notes for battery university?

 

[dataangel]

After going through the information at the "Battery University" link and looking at the depth of discharge (DoD) chart; I have a question that maybe someone could answer. How does DoD relate to Battery Voltage shown on a device such as a VAMO.