Hi,

I need a little help with battery charging. Currently I charge my receiver and transmitter batteries the night before I fly for roughly 12 hours. I then unplug the charger and load the plane into the car so I can head to the field directly from work.

Here are my questions/concerns:
[ul][*] Is 12 hours enough for a full charge?[*] Should I continue to charge the batteries when I get to the office for the remainder of the day?[*] I do have a field charger, so I could charge the batteries on my way to the field (about a 30 min drive). Is it advisable to top up the batteries with a field charger after being off charge for 8 hours? Will this do any harm to the batteries?[*] If I should charge the batteries on the way to the field, at what rate should I charge them?
[/ul]

Thanks in advance for any help.

We need a little more info to accurately answer your questions. What type batteries do you have, and what are thier capacities? Are you using the typical walwart charger for the 12 hour charge?

The quick answer would be that you are probably fine with the 12 hr charge if you are using the standard receiver and transmitter battey. I would recommend you purchase an expanded scale voltmeter to check your batteries. This is the only way to truly know thier condition

I am talking about the Spektrum DX7 standard transmitter and receiver batteries that come as a package. The transmitter batter is a 1500mAh NiMH, but I am not sure what the mAh on the receiver battery is. I also have a spare 1500mAh battery which I will be charging on the way to the field in case the standard one runs down. I had a situation the other day where I wanted to fly more, but after checking the power of the receiver battery I found that it was too flow to continue to fly.

Will I do any harm to top off the transmitter and receiver packs after being dormant for 8 hours after a 12 hour charge?

You won't do any harm topping off your packs on the way to the field. I do that all the time with a 30 minute drive. Just don't charge at a high rate and get the batts hot-NiMH's don't like that.
Be safe in the way you charge-remember your driving a car and can't get to the batts quickly.

Regardless of what battery you have, you have to compare the mah (mili-amp rating) of the battery pack with what the charger will put out, and simply do the math.

For instance, if you have a 1000 mah battery pack and a 50 mah charger, then it will take 20 hours PLUS about a 20% overhead to take the battery from fully discharged to fully charged. If the battery is partly discharged, then it will take that much less time to re-charge.

CGr.

Look at your charger (aka: "Wall Wart"). If it says 125mA on the label than you will top off that 1500mAh battery in 12 hours. If it says 150mA then ten hours is enough. But if it says 60mA then you'd need 25 hours for a full recharge. Now here's the rub. The rating assumes you are at a discharge level of 1.0 volt or so. If you are higher you don't need as much time. If you are lower you will need more time.

At some point it will really pay to get a charger/discharger that displays battery and charge information. You really can't hurt a battery with the original wall charger. A Fast/Field/Quick charger, however, can fry things (battery or vehicle upholstry) if misused. Depends on the unit's output, of course. 1.5A would charge your battery from "empty" to "full" in 1 hour. I see people blasting AA size receiver packs with 5 amps to try for a 15 minute quick charge at the field and I think that's a bit alarming. You can maybe do that with C size cells but it's tempting fate with an AA size.

This is the charger I have:
http://www3.towerhobbies.com/cgi-bin...&I=LXCTZ5&P=ML

I was planning on charging at a rate of between 1.0amp to 1.4amps. Any recommendations for best results?

I also have a 1500mAh spare battery which I will charge once I start flying so that if I run out of power, I will have the spare. The spare I am going to charge at the same rate so should be fully charged in about an hour.

You are probably only partially discharging the battery on a 4-5 servo plane. The recommended rate for Nimh is C10. That would be 150ma for a 1500ma battery Charge it when you get home from the field and top it off on the way to the field. You could bump it up a little to 1.0 to top it off on the way to fly. Or get a Lion or Life battery that doesn't self discharge. It will be ready when you are. I had one of those chargers. They are good for the use, but another suggestion would be to buy one of the chargers from Hobby King for $30 or so. They are good chargers and will tell you how much they put in. Charging after a day's flying will let you know your ma consumption. I have three of them so I can charge all batteries at once.

as long as you keep the charge rate to 1C or lower, then you should be fine.

My advice only-don't do 1 amp. If you can set it for 1/2 that (.5 amps) would be much safer on the batts for a quick charge of a 1500 NiMH Batt.
A 1/2 amp for a 1/2 hour to peak your pack is all you'll need.

I think you ment C/10, or 1/10 of the rated capacity.

Since, we are on this conversation of batteries, I picked up a JR Sport JSP91030 1500mAh 4.8 V NiMh battery, but I have the Futaba wall charger. Output Rx 4.8 VDC, 100mA.which came with the radio for the nicad battery. Can I still use this slow charger with the JR NiMh battery?

Jim

If the connector is compatable to the Futaba J plug you can charge the NiMH with it.

Thanks for all the advice and help. I charged up my batteries in the way to the field and then charged my spare while I was flying around.
I charged at a rare of 0.5 and it all worked out well. Now I need to learn more about these batteries' technical points.

Thanks again.

Hi Guys,

I need help with battery charging also. I bought Hobbico's Life Source pack that is "Lithium Irom Phosphate" battery. My charger doesn't specifically say that on it it says Lthium Ion. I was curious if I can charge these batteries with the Lithium Ion setting and if so at what rate?
Pack say charge at 1.8amps but charger wants to know volts too? Pack is a 6.6v 1800mah.

Thanks!