Model Boat Mayhem
Mess Deck: General Section => Beginners start here...! => Topic started by: overthesea on December 04, 2012, 10:05:30 pm
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Hi all,
It's me again with another question, this time about battery charging. I have 5 'D', 1.2 volt, 2800 mAh Ni-MH rechargeable batteries wired in series to give 6 volts of power. On each battery it states to charge for 7 hours 560mA. Can anyone please help with the following three questions. 1: Will any 6 volt charger do to charge them as they are in series? 2:If so for how long? 3: What does the 560mA mean?. Thank you.
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You will need a specialised charger.
560mA is the charging rate 0.56 of 1 amp.
Bob
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Give Ian a ring at Component shop he will be able to help as regards choosing a charger
Dave
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I have found that if you want to know more about bateries and battery charging this website is the most comprehensive - http://batteryuniversity.com/
Grendel
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As long as you charge under the 560mA you should be fine... might take a little longer tho
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Hi all,
It's me again with another question, this time about battery charging. I have 5 'D', 1.2 volt, 2800 mAh Ni-MH rechargeable batteries wired in series to give 6 volts of power. On each battery it states to charge for 7 hours 560mA. Can anyone please help with the following three questions. 1: Will any 6 volt charger do to charge them as they are in series? 2:If so for how long? 3: What does the 560mA mean?. Thank you.
Hello from a practical point of view nothing is as exact as the numbers quoted on the individual cells. The manufacturer hopes they are 2.8 Ahr cells. Do not believe anything printed on cheap cells on the Internet!
So to charge the battery (a group of cells) you need to put in 40 % more than the battery capacity. (It is not 100% efficient) Call that 4000 mAhrs. that is (1.4 x 2800).
Trickle charging is 1/10th (C) where C is capacity of battery. In this case 2800 divide by 10 = 280 this is half the quoted rate of 560 m.amps. So they are saying charge at C/5 rate. (Twice the trickle charge rate) using this system you would charge at 560 m.amps times the 5 hours (C/5) times 40% which if you work it out is 7 hours, as quoted. But who can exactly supply 560 m.amps?
You will need about a minimum 9 volt output from a charger to give 1.5 volts per cell for charging.
So playing with the numbers, you can charge at 1/2 amp for 8 hours or 1 amp for 4 hours.
Do keep to the charging time as Nimh batteries do not like over charge, Nicads not quite so fussy. capacity.
Intelligent chargers will do the job for you. The advantage they have is that they can take into account the residual charge remaining when the battery is to be re charged after use.
If the above is difficult (i.e. no meters) then spend a little more money and buy an intelligent charger when you can leave it get on without you.
Hope this helps.
regards Roy
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Thanks everyone for your help and information. Have now enough info to sort this out.
Thanks to shipmate 60, Stavros, grendel, essex2visuvesi, and lastly to roycv just to tell you they were not cheap internet batteries,anyway once again thanks to everyone who replied.
Alan.