Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Is it impoosible to charge NiMH batteries at rates of 0.1-0.3C?

Status
Not open for further replies.

treez

Advanced Member level 5
Joined
Sep 22, 2008
Messages
7,595
Helped
564
Reputation
1,131
Reaction score
540
Trophy points
1,393
Location
cambridge
Activity points
76,358
I am baffled at the sixth paragraph down of the following web page from batteryuniversity.com, which states that it is impossible to charge NiMH at slow charge rates...............

http://batteryuniversity.com/learn/article/charging_nickel_metal_hydride

It is difficult, if not impossible, to slow-charge a NiMH battery. At a C‑rate of 0.1 to 0.3C, the voltage and temperature profiles fail to exhibit defined characteristics to measure the full-charge state accurately and the charger must depend on a timer. Harmful overcharge will occur if a fixed timer controls the charge. This is especially apparent when charging partially or fully charged batteries.


.....surely this cannot be right?.......if charge is going in, even if only slowly, then surely the battery is charging up?
 

BradtheRad

Super Moderator
Staff member
Joined
Apr 1, 2011
Messages
13,808
Helped
2,738
Reputation
5,473
Reaction score
2,648
Trophy points
1,393
Location
Minneapolis, Minnesota, USA
Activity points
103,058
The first sentence must mean it is difficult to 'smart'-slow-charge a NIMH.

At a high charge rate, the cell will start to heat up when it is full. Or rather it will heat up more than it has until now. This is used in some smart chargers as an indicator that charging should stop.

At a slow charge rate, the cell does not heat up as much. The charger cannot use temperature detection as a reliable indicator when to stop charging.
 
  • Like
Reactions: treez

    treez

    points: 2
    Helpful Answer Positive Rating

FvM

Super Moderator
Staff member
Joined
Jan 22, 2008
Messages
47,871
Helped
14,125
Reputation
28,507
Reaction score
12,808
Trophy points
1,393
Location
Bochum, Germany
Activity points
277,832
A good 0.1C NiMH charge method has been suggested by Panasonic.

 
Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top