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[cbr900]

I have a dedicated Li-Poly battery charger, and the 3 cell 11.1 volt battery has the second set of leads for charging, I am told that this charging system balances the batteries while charging,
1/   What I would like to know is can it be left on trickle when charging has finished,  2/   and also can you recharge from any state of charge or do you have to drain the pack.....
3/   And do they need to be recycled and when............


Roy

[Model Boats Website]

To answer you're questions:

1) It is not a good idea to leave these batteries on a trickle charge since they're voltage will carry on creeping up until the battery itself becomes damaged.

A dedicated Li-Poly charger should ensure the voltage of the battery never goes too high. The charger I use regulates a:-

• 7.4v battery to 8.4v
• 11.1v battery to 12.6v

If the charge rate is say 1A it will apply a 1A current through the LiPoly until this voltage is reached, then it will start reducing the current gradually keeping the voltage the same. I'd be a bit worried if your dedicated LiPoly charger has a trickle charge setting! :-\

2) DO NOT DRAIN THE PACK! It will cause permanent damage if Li-Poly's go flat! If it does go flat for whatever reason charge it up as soon as possible!

3) The short answer is yes they do need recycling, but they haven't got a "use by date" so I'd wait until they loose there performance. You should be able to get a few thousand cycles out of them before that stage though.

I've been using the same pack for over a year now and it's still going well. If anything it seems to be taking a little longer to charge, however it still performs well and the duration time on the water has not changed.

Hope these answer you're questions.

Stephen

[cbr900]

Stephen,

Thank you mate well answered, learned a bit more today thank you...




Roy

[Model Boats Website]

Hold on theres more! (Not like you to be online... ::))

This is a rough graph of what my Li-Poly charger does (don't quote the values they are only approximate for an 11.1v battery pack)

First of all you select how many amps you want to charge at (in this case 2A) it then starts the charge at 0A and gradually increases it to 2A. It then waits for the cell pack voltage to reach the optimum voltage (in this case 12.6v), it will then start reducing the current so to maintain the cell pack voltage at the 12.6. This current will drop right down to 0.03A then it will stop charging completely (it does not trickle charge).

Let me know how you get on.

Stephen

[pneumatician]

Just a cautionery tale.  We with the Aeroplane bent have been using Li-po's  for a while and it always says do NOT leave them whilst on charge, do not charge them in the model, keep them in suitable containers etc etc ( I use crock).
One of my Aeromodelling associates received a call from his wife to say that the Police and Fire Brigade were outside whilst his garage burnt down.
Inside were all of his models and a motorcycle.  He had popped home from work to put his Li-Po's on charge ready for an evenings flying.
When these batteries do decide to ignite ( usually from overcharging) you just stand and watch, apparently you cannot extinguish the fire.

Steve
 

[bosun]

Hy Guys,
can anyone tell me where I can buy a li /po charger, and what is the best one to get, I want to charge batteries  11.1...9.6...and 7.2..., is there a universal charger avalliable, or will I need 3 different unit,s. I have looked on the Maplin site and they only seem to have chargers for camera,s.
Many Thanks
Bosun

[Trucker Willy]

A very good Charger is : Orbit Microlader V6.5 (Universal charger, up to 6 A, 1-30 NiMh/NiCd- or 1-11 Lithium LiPo / LiFP / LiIon cells) + Orbit Lipo Checker Pro (Voltage checker and balancer/equalizer for Lithium batteries)

More Information: http://www.orbitronic.de/

[wingertaz]

Hi,
   Most model shops should stock suitable chargers. We stock one which will do 3.7v, 7.4v, and 11.1v as well as charging Nmh/Ni cad up to 14 cells. The 9.6 & 7.2 voltages you mentioned are either Ni cad or Nmh.
regards Gary

[bosun]

Hy Guys
Thanks for the info, still a bit lost between  LI/Po and Nmh or Nicad ! electrics was never a strong point ???. (i recently burned out twp esc,s, how I dont know ) Would I need different chargers for each type of battery. I was thinking of just useing them for ligfhting.
Many Thanks
Bosun

[wingertaz]

Hi,
   You can get designated chargers for different battery types or you can get MULTI Chargers which are designed to charge all types IE: Pb (lead acid) Ni cad, Nmh, Lipo. The choice is vast and can be daunting.

Gary

[Faraday's Cage]

Bosun,

If you're going to use lipo's for lighting then you will need some form of battery voltage monitor. The reason being that lipo's can be damaged if they are discharged to deeply. Most controllers that the flyers use have some sort of cut-off or pre-warning should the lipo's become discharged.
There are other threads on here explaining some the dangers of using / charging lipo's. Personally I'd go for NiMH's.

Terry.