Dumb Charger Questions

[usherwdp]

Sorry in advance for this question :oops:

I've just put my first real heli together Raptor E325. Which was great fun!!!!

Now I want to charge the battery. Should be simple surely?

I've got a Thunder power Lipo 2070mah 11.1 (charge as 3 cells 25c cont/50c burst(5aA cont/103a burst) extreme series.

I've got a pro peak prodigy ii charger.

Now to the questions


I set the charger to Lipo c=2050 11.1vp does this seem correct?

The display as its chagrining is a mystery. Any ideas?

The guy at the shop said that as it is a new battery, I should charge it with less C and work up to full C. Think he is talking about Mah, but what should I set for how long.

Lastly, I've read that I should discharge and recharge new batteries. I can navigate to the page on the charger, but could do with some pointers on parameters.

Lots of questions, sorry :oops:

Cheers,

Peter

[WayneBrown]

for the first flights, charge at 1.5 - 1.8A or so, only fly 3-4 minutes per charge.
This will allow you to charge at less than the max rate, and discharge less than the full capacity of the battery to allow it to 'break in'.
After a few flights, increase charge rate to no more than 2 A, and fly to 6 minutes, but you need to work up to your final flight times gradually. If your 5 minute flight puts back 1900 mAh, that's all you ever want to discharge.. your flights are 5 minutes or less.

[spork]

Peter,

I'm not familiar with that charger, but here's what I can offer:

Never cycle LiPo's. Only discharge them by using them.
Never let them go below 3.0V per cell (some say 3.3V per cell) while under load. If you test them after landing you're measurements will be way off. People tend to use either a low voltage alarm, a timer, or both. Over-discharge can ruin a LiPo in a single cycle.
Never walk away from a LiPo while charging it.
Always charge them outdoors or in a firesafe container.
Balancing is important. Some chargers balance while charging. Otherwise you can buy a separate balancer to use while charging.

As far as a lower charge rate I think he's referring to the current. You should generally charge at 1C or less. For your pack that would be about 2A.

By the way, the parameters sound about right.

EDIT:

Looks like Wayne beat me to the punch. His advice is good. Also, you want to make sure you're using no more than about 80% of the total capacity (as measured by how much you put back in).

[usherwdp]

Spork & WayneBrown

Guys, thank you for taking the time to reply !

Just so I understand......and don't blow myself up !


What do you mean by If your 5 minute flight puts back 1900 mAh, that's all you ever want to discharge.. your flights are 5 minutes or less. ? Does this mean that if after 5 mins I have to put 1900mah back in to make it up to its capacity then 5 mins is my limit with that battery ?

Never cycle LiPo's. Only discharge them by using them. The battery instructions read "we recommend a 3-5C max average discharge for breaking in new packs? Also the charger instructions seem to indicate that it is ok. Have I got it wrong?

Thanks again for your help

[spork]

What do you mean by If your 5 minute flight puts back 1900 mAh, that's all you ever want to discharge.. your flights are 5 minutes or less. ? Does this mean that if after 5 mins I have to put 1900mah back in to make it up to its capacity then 5 mins is my limit with that battery ?

That's right. Basically, fly 5 minutes and see how much you put back in. You should aim for putting back 80% of capacity. If you put back less than 80% you can increase your flight time a bit. Just do this until you're putting in about 80% capacity. I personally like to use a LiPo alarm because it's hard to know what 80% of an old battery is. But you can always end your flight when you're reading 3.3V/cell under load.



Never cycle LiPo's. Only discharge them by using them. The battery instructions read "we recommend a 3-5C max average discharge for breaking in new packs? Also the charger instructions seem to indicate that it is ok. Have I got it wrong?

I don't think the manual is suggesting that you "cycle" them. It's just suggesting that you be gentle with them on the first few flights (i.e. 3-5C discharge rate). That might be a bit optimistic in that 5C discharge would be a 12 minute flight - which might just be possible if you do nothing but hover. But I wouldn't sweat that too much. Just go real easy on them for the first few flights.

[BarracudaHockey]

When it comes to safely dealing with LiPo's there are no dumb questions and you don't have to appologize for being smart enough to ask before you smoke a battery or worse.

[Pinecone]

On the amount of discharge, fo r your 2050 pack you never want to fly it so low you put more than 1640 back into the pack.

So you fly for 5 minutes, and charge the battery. See how much you put back in. It should be less than the 1640 mAH. Divide how much you put back into the pack by 5 to get mAH draw per minute. Then divide 1640 by the draw per minute nad you get the safe flying time.

So if you fly for 5 minutes and put back in 1200 mAH, you are drawing 1200/5 = 240 oer minute. So your safe flying time is 1640/240 = 6.8 minutes. I would then set my timer to 6.5 minutes for safety.

Also get a lipo alarm. This is a backup to your timing and in case you hook up a partially discahrged pack or bad bearings increase the amp draw. Efliernz on this forum makes some very nice lipo alarms and even will do custom work if needed. Nice guy also.

[usherwdp]

Thank you all for your time.

I think i've got it and I feel much safer!!

Cheers,

Peter