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NiMh charging method

R

Rob Horton

Jan 1, 1970
0
Hi,

I'm thinking of adding a battery backup system to a project of mine. I will
be using a NiMh battery pack of 7.2v with a capacity of 1.8Ah.

To keep things simple and cheap, I was thinking of leaving the battery
permanently connected to a trickle charge of about 18mA (1.8A / 100).

What I would like to know is:

(1) If the battery is in an initial discharged state, will the trickle
charge eventualy fully charge the battery?

(2) Can I really leave the battery permanently connected to the trickle
charge?

Thanks.

Rob Horton.
 
J

James Beck

Jan 1, 1970
0
[email protected]_horton said:
Hi,

I'm thinking of adding a battery backup system to a project of mine. I will
be using a NiMh battery pack of 7.2v with a capacity of 1.8Ah.

To keep things simple and cheap, I was thinking of leaving the battery
permanently connected to a trickle charge of about 18mA (1.8A / 100).

What I would like to know is:

(1) If the battery is in an initial discharged state, will the trickle
charge eventualy fully charge the battery?

(2) Can I really leave the battery permanently connected to the trickle
charge?

Thanks.

Rob Horton.
The quick answer is IT DEPENDS.
I doubt very seriously that .01C is going to bother the battery as a
trickle charge. Now, if the system drain or self discharge rate is
greater than the trickle rate then the battery will eventually go dead
or never charge. I would say, try it and see. At that rate I can's see
you hurting it.

Jim
 
J

JeB

Jan 1, 1970
0
Hi,

I'm thinking of adding a battery backup system to a project of mine. I will
be using a NiMh battery pack of 7.2v with a capacity of 1.8Ah.

To keep things simple and cheap, I was thinking of leaving the battery
permanently connected to a trickle charge of about 18mA (1.8A / 100).

What I would like to know is:

(1) If the battery is in an initial discharged state, will the trickle
charge eventualy fully charge the battery?

(2) Can I really leave the battery permanently connected to the trickle
charge?

I'm guessing you can find an IC "smart charger" that will handle the
details for you.
 
R

R. Steve Walz

Jan 1, 1970
0
Rob said:
Hi,

I'm thinking of adding a battery backup system to a project of mine. I will
be using a NiMh battery pack of 7.2v with a capacity of 1.8Ah.

To keep things simple and cheap, I was thinking of leaving the battery
permanently connected to a trickle charge of about 18mA (1.8A / 100).

What I would like to know is:

(1) If the battery is in an initial discharged state, will the trickle
charge eventualy fully charge the battery? --------------
Yes.


(2) Can I really leave the battery permanently connected to the trickle
charge?

Thanks.

Rob Horton.
 
J

John Fields

Jan 1, 1970
0
Hi,

I'm thinking of adding a battery backup system to a project of mine. I will
be using a NiMh battery pack of 7.2v with a capacity of 1.8Ah.

To keep things simple and cheap, I was thinking of leaving the battery
permanently connected to a trickle charge of about 18mA (1.8A / 100).

What I would like to know is:

(1) If the battery is in an initial discharged state, will the trickle
charge eventualy fully charge the battery?

(2) Can I really leave the battery permanently connected to the trickle
charge?
---
Note from:

http://www.panasonic.com/industrial/battery/oem/images/pdf/Panasonic_NiMH_ChargeMethods.pdf

that trickle charge is _not_ recommended.

Since the chemistries will be similar regardless of manufacturer, I
suspect the charging characteristics will also be similar. To be sure
though, you need to find out from the manufacturer of the cells.
 
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