Charging Li-PO

[temannis]

Hi guys

Need some advice on this. I noticed my heli flight time will be shorter if i charged my 2 cell 1300mAh Li-Po at 1000mAH. But flight time will be longer if charged at 250mAh. Why this problem???

Your replies is appreciated!

Using :
Prolux 3834 charger
GWS 1300 2 cell

[Super-Hornet]

Charging your battery at lower C compare to higher C will give u a bit of longer flight but not much...maybe like 1 minute or 2.

For your case, I suspect is that your Prolux suffers from overheated when u charge at 1000mA and therefore, it goes to thermal shutdown long before it is fully charge.

What is your i/p power supply? Try to use a constant power source like from Lead Acid/Sealed Lead Acid battery or computer power supply or from any switching power supply.

To verify this, u charge at 1000mA and when u think it is fully charge, measure the battery voltage. It should be 8.2V (For unmodified/untuned prolux charger). If it is less that that, then it suffers from thermal shutdown.

If your charger still suffers from thermal shutdown and u still want to charge at 1000mA, then just put a small fan at any of the ventilation hole at the charger. (Computer fan also can)

Super-Hornet

[temannis]

Originally posted by Super-Hornet
Charging your battery at lower C compare to higher C will give u a bit of longer flight but not much...maybe like 1 minute or 2.

For your case, I suspect is that your Prolux suffers from overheated when u charge at 1000mA and therefore, it goes to thermal shutdown long before it is fully charge.

What is your i/p power supply? Try to use a constant power source like from Lead Acid/Sealed Lead Acid battery or computer power supply or from any switching power supply.

To verify this, u charge at 1000mA and when u think it is fully charge, measure the battery voltage. It should be 8.2V (For unmodified/untuned prolux charger). If it is less that that, then it suffers from thermal shutdown.

If your charger still suffers from thermal shutdown and u still want to charge at 1000mA, then just put a small fan at any of the ventilation hole at the charger. (Computer fan also can)

Super-Hornet

Hi

I am using SLA battery for this case. And usually I will let it charged until the charger emit beeping sound, which indicate end of charge. It measured 8.2V at this point of time.

I think I will let the battery charged at 250mAh to 500mAh for the time begin.

BTW, what mod can be made to the prolux charger???

Thanks!!

[Super-Hornet]

What Li-Poly are u using? Wondering whether your battery is weak or unbalance.

As for the Prolux charger, the full charge is 4.1V per cell. That means at 2 Cell, it is 8.2V and 3Cell is 12.3V. What I do is that I open up the charger and u will see there is a potential port (Variable Resistor). I tune it in such a way for 3Cell at full charge is at 12.5V instead (I can make it go 12.6V also can but I do not want to)

Super-Hornet

[temannis]

Hi super-hornet

I am using GWS 1300mAh 2 cell which i bought 1 week ago. I observed this when I charged this battery at 1A last night and the heli fly abt 7 mins. Usually I will charged it at 250mA, which give me abt 15 mins flight time.

Was thinking was it because the SLA battery i am using was weak at the moment when i charged at 1A.

[Super-Hornet]

That is possible. Don't tell me your SLA is just a 1AH type. That is why for us normally we use computer power supply.

Super-Hornet

[X34]

Reading from the thread, sounds like source power supply insufficient for high current charging. The beep from the prolux could be low batt instead of full.

[temannis]

Ok, i tried it again tonight!

Thanks!

[Vifo]

Cell Balancing + Computer Power Supply

Hi Super Hornet,

Can you share your experience on how to Balance individual Lithium Cell in charging, most charger charges 2 or 3 cells at one go. Someone advises that we can make individual tapping from the Cell and then charge them individually. Thereafter charge the combined cell together. Can you comment.

On Computer Power Supply, are you referring to those Power Unit in PC, do they have 12Volt DC outlet?. Believed that Regulated AC to DC transformer is Good, but expensive. Can you guide on this matter as well.

Thanks

[PhiBeR]

Usually charging at a different rate wun affect the flight time by so much!
7 vs 15mins? that is too much a difference!

Maybe if u can repeat tis experiment a few times to see if ur batt
is the prob or if it's the charging..

I get the same flight time (almost) at most 1min diff depending on
my flying style for the pack when i charge my 1700mah pack
at 1500ma or 2000ma, using the prolux 3834 too.

Check ur pack voltage before and after flight, are they the same each flight?

If u're doing normal hovering each flight, the flgihttime shld not differ much..

[temannis]

Hi

I was doing fig of 8 and circuit for both occassion.

Ok. I have just charged the battery using ATX PSU. Will try it out tonight!

[temannis]

Sad Sad

Both my GWS 1300 2s1p lipo almost died. One i bought on 27 Dec 04 and the other one on 14 Jan 05. Now I can only get 5 mins useful flight out of each pack. After which my honey bee can't climb at all.

Was told by the guy who sold me the batt that I overdischarged it, but i usually fly until it hit 7.3v - 7.2v, is that overdischarging?

Is it normal for the battery to last less then 2 mths?

[Mathieu]

What motor you used with it?

[Adrianli]

Originally posted by temannis
Sad Sad

Both my GWS 1300 2s1p lipo almost died. One i bought on 27 Dec 04 and the other one on 14 Jan 05. Now I can only get 5 mins useful flight out of each pack. After which my honey bee can't climb at all.

Was told by the guy who sold me the batt that I overdischarged it, but i usually fly until it hit 7.3v - 7.2v, is that overdischarging?

Is it normal for the battery to last less then 2 mths?

Have u check if it is the main motor that is dying??? I presume u are on brushed motor.

Buy a new motor n try it.

[temannis]

Originally posted by Mathieu
What motor you used with it?

Hi Mathieu

I am using the stock main motor(brushed), which I bought 2 weeks ago, and gw/EPD-50 for the tail motor.