Why do some batteries charge more slowly than expected?

Robert Crayton

Newly Enlightened
Feb 28, 2022
United States Washington Burlington
if anyone has the same question about this, hope the answer will help you.
I got the answer from my batteries store customer service team, they are very professional and patient.

several factors can affect the charging time:
1: the capacitiy of the battery, larger batteries will take longer more than charge smaller ones
2: the type of battery, different types of batteries have different charging characteristcs, for example, lead-acid batteries typically take longer to charge than li-ion batteries.
3: the charging method: different charging methods, such as using a standard wall charger or fast charger, can affect the charging time. charging a battery at a higher rate will typically result a shorter charge time.
4: The initail state of a charge: A battery that is completely discharger will take longer charge than one that is partially charged.
5: Temperature: high temperature can slow down the charging process while low temperature will speed it up( but not for all batteries and chargers)

How to calculate the batteries charging time( PS: they also taught me very patiently,haha)
charging time=( battery capacity/average charging current)+loss(1~3)hours.

battery: 1.2V aa 2300 mah
charger( below sepcifications about ebl battery charger, they said it's a slow charger, if fast charger, will charge more quickly)

charger Average charging current (in genearal, the more batteries are charged on a charger the lower the average current each battery can receive)
AA 1/2:500-1250mA @1.2 V,
AA 3/4:250-750mA @1.2V,
AA 5/6/7/8:150-350mA @1.2 V

if I charge 1/2 pcs ''aa 1.2V 2300mAh battery'', and take average data 800mah
Charging Time= 2300/800+loss(1~3h)= 3.5~6.5hours

if charge 8 pcs aa 1.2V 2300mah batteries, take data 150mAh
charging time= 2300/150+loss(1~3h)=16~19hours

For my last question, why my aa batteries takes longer than I expected, because my current charger charges slower than EBLofficial site. they promote battery charger time according to their own battery charger.

Welcome any comments.