battery for corona
 

Hi guys, I bought a LM corona helicopter, my question is what batterie pack should I to use in it, I using right now a 6-cell 1900 mah battery, but I think that it's very heavy, because when I open the throttle, the helicopter flip to the right. This machine is very hard to fly
Thanks

RE: battery for corona
 

They will all lean to the right. Just dial in some left trim to compensate. This machine handles rock solid once it's set up right. A 6 cell pack is pretty small - you want 8 cells for good power. I use an 8 cell Saft 3200 and can get over 15 mins of fwd flight. 12.5 min hover.

RE: battery for corona
 

I got 7 cell GP-3300 mah NIMH from Cheapbatterypacks.com I get 10-12 minutes hover. They ship fast and are some of the lowest priced. The 3200's sound good too. I tried to use a 1900 mah 7 cell Nicad just to test the corona and it could hardly get off the ground for about 30 seconds.

RE: battery for corona
 

I also use 8 cell saft 3200 from www.battlepack.com good stuff

RE: battery for corona
 

I also have a basic corona battery question and thought i'd ask it here before making a separate post for something so closely related....

I've been looking into lipo packs, because my trainer (who is a nitro heli guy) scoffed a bit when I told him I had an electric, said I should get as much flight time in batteries as i can afford ... so i thought "well, I'll show him" :D

The lithium-polymer pack that I was looking at was the 2600mAh/7.4V one made by iRate on CBP, selling for $50. It weighs 3.5 oz ... which is a bit more than half of what some of the big 8-cell NiCad packs weigh, so I was thinking, is it possible to wire 2 in parallel and then have a 5200mAh/7.4V, 7.0 oz pack? That would be the voltage equivalent of a 6-cell NiCad -- I'm hearing that may be too low for fun flying, but would it be okay for learning hovering and forward flight?

Only thing I'm not sure about is whether it's safe to discharge two lipo packs in parallel like that. The problem might be, and I've seen this with other batteries, if one has a higher internal resistance than the other, they will discharge unevenly and you'll end up with one battery deep-discharged by the time you run the pair out to a "low" voltage. Also, they if they get uneven, the higher one can try to charge the lower one. Both scenarios would be bad (and expensive) given the cost of the batteries. I think it would be possible to protect them with diodes (zeners was my first thought) in series with the packs, that would cut them off at a certain voltage and keep them from charging while in the heli ... but I'm sure somebody has probably thought of this before though, and made some sort of cute device that does this all automatically.

Just throwing this out there. Any immediate thoughts?

RE: battery for corona
 

as long as they can handle the current. (about 20 amps), you should be fine with your li-pos. you may need bigger pinions though, but probably not since it is so light. as far as safety is concerned, if they were matched closely, you will not have problem with one draining before other. we parallel pack the cells all the time. the key is not to drain them below 3v per cell and balancing them out once in a while to make sure that we don't over charge them. i don't hink diode is going to help.

RE: battery for corona
 

i am interested in getting the Saft 3200 8 cell battery pack, went to www.battlepack.com but i don't see it...??? i only see the GP3300 in the packs section, am i looking in the right place or do i need to call and place special order

thanks

RE: battery for corona
 

Go to the loose cells section. They are there. Call Steve and Sarah - they will make a 3200 pack for you.

RE: battery for corona
 

if you want to go lipo, I would recommend 3S2600s. Irate and polyquest have them. they are rated 10C which is 26 amp and weighs about 5oz. (saving of over 10 oz over 8cell, with more power and more flight time compraed to 8x3200) they cost about 75 bucks though. you should be able to fly about 15 minute without problem.

RE: battery for corona
 

Kadin2048
Yes, there is always the chance of one pack not performing as well as another hooked in parallel. We see this situation rarely happen in Polyquest brand batteries due to their very consistent cell manufacturing and matching prior to assembly of their packs. There are low voltage cut-off devices already on the market that will prevent packs from being over discharged and devices are sure to come that will prevent individual cells from being over discharged. The thing is not to run the whole duration and bring the heli down. The other thing you can do, if weight is permitted, is to use a little higher capacity battery so you do not discharge it too low and extend the cycle life of your packs. I cannot reply to the diode scenario but I know diodes have a max current rating to them and don't know if they can withstand your present discharge rate.
hope this helps
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