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All Forums >> Radios, Batteries, Clubhouse and more >> Batteries & Chargers >> how long to charge?
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how long to charge? - 4/4/2002 11:00:44 AM   
dan4466


 

Posts: 370
Joined: 1/8/2002
From: perry, MI, USA
Status: offline 		Have a 700mAh Ni-Cd pack and a 1200mAh NiMH pack. Just bought the H9 Sure Cycle Battery Analyzer, so now I also have a 150MA charge rate. How do I figure how long to charge them at this rate? Is there a guide line to use. I do notice they charge much faster at this rate than the 50MA wall charger. Only problem is that the Sure Cycle doesn't go to a trickle rate, so I am worried about over charging them.

Thanks

Dan
       Post #: 1

how long to charge? - 4/4/2002 8:16:04 PM   
f2racer



Posts: 1167
Joined: 12/7/2001
From: Bedford, MA, USA
Status: offline 		Here's how I figure out how much charge a pack gets. Take the pack capacity (say 700mAh) and divide it by the charge rating (say 150mAh). Then multiply that by 1.4 (or 140%) and you'll have the amount of time it will take to charge your pack from a totally discharged state (which in this example would be six and 1/2 hours). Problem is most of the time you won't be charging from a completely discharged state, and this is where you've got to either estimate how much charge you have left, or have a charger/multimeter that can accurately tell you how much charge is left on the pack. Or you can get a peak charger and not have to worry about time at all.

(in reply to dan4466)
       Post #: 2

how long to charge? - 4/5/2002 5:26:01 AM   
Jazzy



Posts: 1106
Joined: 1/8/2002
From: Erie, PA, USA
Status: offline 		Just an afterthought to what F2 suggested:
Regarding NICDs, it has been my experience that as you increase the charge rate above C/10 the multiplier decreases. I haven't charted the data yet... I'll start tonight.
If you're not using a peak charger designed for NIMH be very careful when charging above C/10.

If a pack gets good and warm before the predicted charge time is up-unplug it! Stick a fork in it 'cause it's done

Since I don't know the SureCycle's stats it is difficult to say more...

_____________________________

Aww $#!^.... I left the )@#& transmitter at home!

(in reply to dan4466)
       Post #: 3

how long to charge? - 4/5/2002 2:40:18 PM   
Steve Lewin


 

Posts: 904
Joined: 3/18/2002
From: Reading, UNITED KINGDOM
Status: offline 		[QUOTE]Originally posted by Jazzy
Just an afterthought to what F2 suggested:
Regarding NICDs, it has been my experience that as you increase the charge rate above C/10 the multiplier decreases. I haven't charted the data yet... I'll start tonight.
[/QUOTE]

The multiplier does decrease but not much. The manufacturers typically say 1.2 hrs rather than 1.4 for a charge at C rate. But of course with a peak charger it doesn't matter, when it's finished it's finished .

Steve

(in reply to dan4466)
       Post #: 4

Charge-Time Multiplier - 4/12/2002 7:34:57 PM   
Jazzy



Posts: 1106
Joined: 1/8/2002
From: Erie, PA, USA
Status: offline 		I mentioned I was going to check on my data relating to charge rates above C/10 and the decrease of the multiplier to find charge time.
Given that I was using only my SuperNova, (I don't have the time or the equipment for a more sophisticated analysis), this is what I found:

Using a stock 600mAH NiCD Futaba RX pack and starting at a charge rate of 100mA, (C/6), and ending at 1200mA, (2C), the input in mA required to reach the pack's peak did not vary much above a 200mA charge rate. I increased the charge rate 100mA for each carge/discharge cycle.
At 100mA only 744mAs were necessary to reach full charge. The corresponding multiplier was around 1.25.
From 200mA to 1200mA the multiplier was pretty steady at 1.15.
The pack only needed around 690mA to reach peak charge.

Remember that if you're using charge rates above C/10 the longer you leave the pack on charge past peak the more damage you may inflict. Using a simple voltmeter one can observe a particular packs peak while charging.

Since the SuperNova uses a microprocessor and frequently checks the pack's status, results may vary with different chargers.

BTW, the pack I used consistantly produced 630mAh at the end of discharge.

Jeff

Ater Trout fishing this weekend I'll see what I can do regarding NiMH packs.

_____________________________

Aww $#!^.... I left the )@#& transmitter at home!

(in reply to dan4466)
       Post #: 5

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