Battery Charging time

[chris1991]

Hello, I am new to this and have just got a Honey Bee RC Helicopter. It came with an 8.4V Nimh battery and I had seen somewhere that you had to calculate the charging time for it but I can not remember how. Can anyone help me out please?

Thanks in advance,

Chris Farrants

[Pipistrelli]

Chris,

It all depends on what charger you are using?

If its the standard charger that comes with it, it probably takes about 3-4 hours. However, if you are using a programmable charger you can charge at higher rates.

Typically to get the best out of Ni-MH batteries you shouldn't charge at more than 1C, where C is the capacity of the battery.

For you that is 850mAh, or 0.85Ah, that will take about 1 hour to charge at a rate of 0.85A!

regs

Pip

[chris1991]

Thanks for the lightning quick reply! The charger is the standard UK charger that came packaged with it, so I will leave it on for about 4 hours.

Chris

[mattydred]

hi. the 8.4v ni-mh and takes an hour to charge from flat with the standard charger that comes with it. i had a hummingbird v3 and they are the same. well near enough.

heres my hummingbird(airwolf) - [ame]http://www.youtube.com/watch?v=0ZLBp55ISiI[/ame]

you can turn your honey into an airwolf aswell when you get the hang of it. all you need is the tri landing gear(3 wheels) and to change the boom for a slightly longer piece of carbon tube. took me about 3 hours to fit and make a good job of it the other week when i fitted an airwolf to my uncles twister v2.

[mattydred]

Thanks for the lightning quick reply! The charger is the standard UK charger that came packaged with it, so I will leave it on for about 4 hours.

Chris

noooooooo - only charge it for an hour - if it gets really hot then take it off charge.

also - when you just had a flight then let the battery cool before charging + when the battery has been on charge - let it cool before using.

if you leave it on too long it will blow the charger and battery. i used to charge my batteries for 1.5 hours and blown dozens of chargers and batteries.

hope this helps - matty

[chris1991]

Ok, lots of varied replies lol. I have just found a site which says that the battery should get warm towards the end of its charge, so I should be able to judge it by that.

Chris

Edit: Matty had posted before I had finished writing the above. Thanks all for the advice.

[Pipistrelli]

Chris have a look at the plug end of the charger and let me know what the output is please? That way we can be more accurate with charge time!

regs

Pip

[chris1991]

Output: 12V DC, 300mA

[Pipistrelli]

Chris,

With that charger output you will need at least 3 hours to fully charge a completely flat battery, my calculation:

850/300= 2.833 hours.

This is assuming no losses like heat, etc. Usually you allow a factor of 1.5 to make up for losses when slow charging (<200mAh), as this is medium rate we will allow a factor of 1.25.

2.833*1.25= 3.5 hours

Plug the battery in and check the temperature after 3.5 hours. If the battery is warm to the touch then it is fully charged. If its hot its overcharged, so reduce charge time to 3 hours the next time.

Hope this helps, but if not please ask.

regs

Pip

[chris1991]

Thanks for all the help guys, I think that I have just about got it sussed now.

Chris

[mattydred]

Thanks for all the help guys, I think that I have just about got it sussed now.

Chris

what have you sussed then chris?

[chris1991]

Well, the maths says that it should add up to about 3 hours but I'll just leave it on charge and check it every half hour or so until it gets warm.

Chris

[Pipistrelli]

Chris,

How did you get on? Can you post what time it took to get warm and how long flying time you get? Someone else might find it useful too!

[Bambeano]

can i quickly ask at what point should i stop using a battery pack when flying???

[mattydred]

can i quickly ask at what point should i stop using a battery pack when flying???

its best to stop flynig as soon as you hear/feel the power dropping. after this you dont have long (about 10 - 30secs) before the battery cuts off all together and your heli will drop very quickly.

you will get used to it and know when you should stop flying. i stop flying just before the power starts to drop.