I have a question I was wondering if i could get some answers on. Its about charging batteries.
Say I charge the batteries 8 hrs like I normally would on Friday night so I can fly my plane on Saturday. But I end up not being able to fly my plane on Saturday, but i can fly on Sunday. Do I have to charge the batteries at all again before I fly on Sunday or will they keep the charge from me charging it on friday night. Thanks
___________________
SoneDeaf

More than likely you will be ok charging Friday night and flying on Sunday. How much charge you lose depends on a lot of things like the type of battery, the age of the battery, the condition of the battery, and a few others too. But you get the general idea. The best way to find out is to check it out yourself. Charge your batteries normally as you would on Friday night, then skip a day, and use an extended scale voltmeter to check the voltage of your batteries on the morning of the second day.

A great resource to learn just about everything there is to know about the batteries we use in this hobby can be found at [link=http://www.rcbatteryclinic.com]www.rcbatteryclinic.com[/link] . It's well worth the time spent to spend a couple of hours on his site reading up about batteries.

Hope this helps

Ken

If you're using a good old 50mah wall wart charger you might want to go to 14 or 15 hours charge. The nicads self-discharge anout 1 or 2% per day, so one day idle won't appreciablly cut your time.

Visit Red Scholefield's site for the definitive scoop on charging. I follow his ideas and charge all mine for 1 hour every day on a 12 outlet powerstrip set to a wall timer; or 15 hours after a day's flying.

[link=http://www.rcbatteryclinic.com/]R/C Battery Clinic (click me)[/link]

As a follow on to what RC Ken said above, another good method would be to use a battery discharger and cycle the battery pack to see what the actual capacity is. This will do two things for you. It will give you a good idea of the real capacity (if it says 700 mah, then you should get around +/- 10% of capacity. The second benefit is that it will help rejuvinate (for lack of a better word) the battery if it is an older battery.

One of the top manufacturers and battery guru's said that he has rarely found a battey that was useless. He used this discharge/recharge cycle to actually rejuvinate or re-energize a battery that seems to be losing it's capabilities.

There are several on the market, the better chargers, ie. Triton or ICE for instance, have the discharge/recharge capability and will show you the current drained out during the discharge cycle. You can set these up for several cycles, over several days for instance, which will leave you with a very well prepared and peak charged battery pack. This goes for NiCad's as well as NiMH packs.

DS.

I used the method Charlie mentioned all thru this summer. Never a problem. Also shows when a battery is starting to go crappy if your ESV reading changes.

So I should be charging the batteries for 15 hours instead of 8 or 9 hours. I use a Futaba 7C. The batteries in the plane and RC are 600mH I believe.
_________________
SoneDeaf

Definitely. Charge them for 15 or 16 hours. If you are using the "wall wart" that came with the radio for only 8 hours you aren't getting a full charge on them.

Ken

The length of charge they need depends how low they were to start with. If you flew the prior weekend and drained them completely, you'll need a much longer charge than if you were ready to fly on Sunday, but got rained out. This is one of the reasons visiting the site Ken suggested is so important, it'll help you understand the background behind all this information.

Do the math, StoneDeaf. 600 mah battery pack, if you use a 50 mah charger, that's 600/50 = 12 hours for a full charge from completely discharged with that charger. If you have a 1000 mah battery pack, same charger will be 1000/50 = 20 hours charge time from fully discharged.

There is a fudge factor there, allow about 10 to 20% more time to cover losses due to heat, and so on. But, that's a pretty good rule of thumb. Overnight will charge at full capability till full, then trickle charge to maintain once it's fully charged. So, if you suspect you used, say 300 mah of a 600 mah battery, overnight charge will produce a fully charged battery in 6 hours then leaving on charge for the rest of the night no matter what with that charger will definitely produce a fully charged battery.



DS.

Thanks alot. I appriecate the comments.
_________
StoneDeaf

Advice from FMA direct supplied with their Cycler/ charger suggests UP TO 6 HOURS at C/10 overcharge (past full) is OK. Beyond that you could be shortening your battery lifespan.