The difference between Trickle Charge and Top off Charge

hello everyone
I read in some "HKJ" reviews that trickle charging is not good for Low self discharge batteries like eneloop
I have xtar vc4 charger that i bought to charge
my eneloop 2000 mah batteries
in the vc4 review he is telling this
'The charging terminates on voltage and then does a top-off charge, as can be seen in some of the other curves this top-off takes about 2 hours. It is done after the charger reports done.
Display shows 1605mAh"
is this the same as trickle charging?
I dont want to harm my batteries

Trickle charge is a low charge current, usually below 100mA that basically stays on forever.
Top-off charge is a time limited charge, usually in the 100-200mA range and stays on for 1 to 2 hours.

As long as you remove batteries within a few hours of charger termination the trickle charge will not do any significant damage, the problem is if the batteries stays in the charger for days or longer.

Hello gadits,

Welcome to CPF.

A top off charge is like a trickle charge for a limited amount of time. A trickle charge goes on and on until you remove the cell from the charger.

Some chargers have a conservative end of termination of the charge and the cell is left with a little less than a full charge. The top off charge is supposed to bring the cell to a full charge.

Trickle charging is designed to keep sells at full charge in an effort to offset the cells self discharge rate. Eneloop cells have a very low self discharge rate, so trickle charging results in overcharging and that is bad for the cell.

Tom

HKJ said:

Trickle charge is a low charge current, usually below 100mA that basically stays on forever.
Top-off charge is a time limited charge, usually in the 100-200mA range and stays on for 1 to 2 hours.

As long as you remove batteries within a few hours of charger termination the trickle charge will not do any significant damage, the problem is if the batteries stays in the charger for days or longer.

Click to expand...

thank you HKJ for your quick reply
now i understand the difference between Trickle and top off
But from your testing and review of the Xtar VC4 you wrote that the top off charging in this specific charger is 2 hours
But what happens after the 2 hours top off is finish?
does it stop to push current to the battery?
or after that his next stage will be trickle charging?!

gadits said:

But what happens after the 2 hours top off is finish?
does it stop to push current to the battery?
or after that his next stage will be trickle charging?!

Click to expand...

The VC4 stops completely (Some chargers may continue with trickle charging).

HKJ said:

The VC4 stops completely (Some chargers may continue with trickle charging).

Click to expand...

thanks HKJ
so if my XTAR VC4 stops completley after the 2 hours top off
then this quote by you is not relevant to me, and my batteries can stay in the charger for days am i right?

"As long as you remove batteries within a few hours of charger termination the trickle charge will not do any significant damage, the problem is if the batteries stays in the charger for days or longer."

gadits said:

thanks HKJ
so if my XTAR VC4 stops completley after the 2 hours top off
then this quote by you is not relevant to me, and my batteries can stay in the charger for days am i right?

"As long as you remove batteries within a few hours of charger termination the trickle charge will not do any significant damage, the problem is if the batteries stays in the charger for days or longer."

Click to expand...

Correct.

thanks HKJ
i am sorry for asking too many questions
but do you recommend me to charege my eneloop batteries over night
so in the mornning they will be completely full by the 2 hours top off
or is it better to take them from the charger right after the VC4 is saying "FULL" ?

from your review of the VC4 i understand it is doing voltage termination on 1.52V and the battery is not full
so the 2 hours top off will be filling the battery to its best full capacity?

I you want the longest life from the batteries you take them out when the charger say finished, I usual go for maximal capacity and let the top-off charge fill them completely.

thank you HKJ
you solved my mystery

by the way in what charger do you use?

gadits said:

by the way in what charger do you use?

Click to expand...

Mostly the SkyRC MC3000, I have a couple of them.
But for NiMH I often use a Xiaomi ZI5 PB400, mostly because it is small and I can keep it at the same table I take all my photos (I use NiMH for my flashes).

Skyrc mc3000 is too over kill to my use 😃
In your review of the Xtar vc4 you wrote
The charging terminates on voltage and then does a top-off charge, as can be seen in some of the other curves this top-off takes about 2 hours. It is done after the charger reports done.
Display shows 1605mAh
So if i will take my eneloop out of the charger right after it display "FULL"
the capacity i have in my cell will be 1600 Mah only,
and if i will let it stay in charger overnight it wil give 2 hours top off charge and after that it will stop completely,
In that top off Will it fill another 300-400 Mah only? (eneloop is 1900-2000 mah) or will it overcharge it?