# Trickle Charge Question



## BillBrakeman (Jan 3, 2008)

I have three battery packs which have amperage ratings of either 2450 or 3000 mAh. I use two different chargers to charge the packs. After completing its charging cycle one charger drops to a trickle rate of 70 mAh, the other to a selected rate of 0, 100, or 200 mAh. Other than the zero rate, are any of these rates harmful to my packs? How does one determine what the trickle charge rate of a battery should be? 
Bill


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## Greg Elmassian (Jan 3, 2008)

It depends on the chemistry, so you need to identify the chemistry of the batteries first. (Lithiums cannot be trickle charged). 

Basically: (once you have determined the rate) 

Lead Acid - fine 
Nicad - tolerates it 
NiMih - nope, you have to eventually turn it off. 

the trickle is usually C/100, but it varies, you really want a recommendation from the manufacturer. 

Note well: trickle is defined as constant current, irrespective of charge state, forever. 

This is NOT the same as "slow charging" which always needs to be terminated after a certain time or damage will result. 

Regards, Greg


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## BillBrakeman (Jan 3, 2008)

Thanks for the quick response. All three packs are 14.4 V NiHM packs. Two are Energizer AAs and the other is maybe a "Pirahna" sub-Cs, but I am not sure.

Quote1, "Note well: trickle is defined as constant current, irrespective of charge state, forever. 

This is NOT the same as "slow charging""

I am aware of what "trickle charging" is and that is what I am asking about.

Quote2, "Basically: (once you have determined the rate) 

Lead Acid - fine 
Nicad - tolerates it 
NiMih - nope, you have to eventually turn it off"

Okay you're saying 70 mAh is too strong.

Quote3, "the trickle is usually C/100,"

What is C in your equation "Current", "Charge", or something else?

So what is your estimate as to what the trickle charge rate of my packs should be? 

Bill


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## Michael Glavin (Jan 2, 2009)

Bill, 

What is your reasoning for trickle charging the batteries after they are charged automatically and do the chargers trickle indefinitely or time out? There are regimens/chargers that go here. 

Michael


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## TonyWalsham (Jan 2, 2008)

Bill, 
A standard charge for NiCd and NiMh is 10% of the rated capacity for 14 hours. EG a 2,200 mah pack would be charged at 220 ma. 

As I understand it a trickle charge is anything less than that, but please don't quote me. Michael or Greg will know more than I do. 

Greg is correct about not leaving NiMh cells on continual charge, even a trickle. They must be switched off after topping out. I believe it is OK to leave NiCd's on a trickle.


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## Greg Elmassian (Jan 3, 2008)

"C" stands for Capacity, in amp hours or milliamp hours.... it's a constant you need to have "under your belt" if you are looking into the finer point of batteries, both charging and discharging. 

As Tony pointed out above, a standard charge is 10% or 0.1C rate... As you can see, a trickle charge is really tiny... basically if you are using this, then you most likely have to have another charge mode that precedes it. 

Regards, Greg


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## Randy Stone (Jan 2, 2008)

Not sure if these chargers will work, but they're not trickle chargers. 

http://batterytender.com 

The chargers are electronically controlled to keep the batteries at full charge without a continuous charge.


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## BillBrakeman (Jan 3, 2008)

Thank you gentlemen for trying to help me. However, the thread is not going where I want it to go. I will have to think on what I I really want to ask and then make another post. 

Bill


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## Greg Elmassian (Jan 3, 2008)

Well, we did answer the question you asked, as far as possible. 

You neglected, though, to identify the battery chemistry, which is critical to answering the question. When you ask your next question, please be sure to include that information. 

I've seen some trickle charging rates under 1/100 C, but battery manufacturers are out to sell batteries, not make them last forever! 

Regards, Greg


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## BillBrakeman (Jan 3, 2008)

Greg, You failed to give me the type of answer I was looking for BECAUSE I DID NOT ASK THE RIGHT QUESTION. i am sorry for any misinterpretation of what i meant to say. I truly did not want to malign any post or poster of replies to my question. 

In my previous last post all I really did mean was, "THANK YOU FOR YOUr EFFORTS, BUT MY QUESTION NEEDS A "RETHINK"". 

Again, Greg and all other reponders to my question, "thank you". 

Bill


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## Greg Elmassian (Jan 3, 2008)

Sorry Bill... no problem... sometimes we are so "eager" to help, the response can be overwhelming, and not what you wanted/needed! 

Regards, Greg


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## TonyWalsham (Jan 2, 2008)

Bill, what was the right question?


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## BillBrakeman (Jan 3, 2008)

Tony I will E-mail you the right question. 

Bill


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## TonyWalsham (Jan 2, 2008)

Bill. Why does it need to be private? 
May I respectfully suggest you please post it here. 
The question, and answer, may provide useful information that others could find valuable.


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