FP Lipos taking longer to charge ??

[Zilla]

I have a FP EVO25 2170 and 2500 that I use in my Mini Titan. The 2500 has had about 70 charges and the 2170 has had about 30.
What I have noticed is that they are taking longer and longer to charge each time. When I first started charging the 2500 it took about 108 minutes to put back 80% (2000mah) when balance charging at 2.5amps. Now it takes close 180 minutes to do the same thing.
I always balance charge both batteries and I either charge at 2 or 2.5 amps. I use an IMAX B5 charger.
These are the first Lipos I have ever owned so they did recieve a few over discharges while figuring them out.

Is this a sign of my batteries wearing out ? Is there anything I can do about it?

Also ... just recently, the carbon fibre (plastic) part of the Mini Titan canopy has shrunk down towards where the battery sits underneith it. My batteries do get warm to hot but I would not say very hot and they are not getting any warmer now then they ever have. Has anyone else had this happen ?

Thanks

Tim.

[DebianDog]

Yep you overcharged and have a bad cell or two. Does you charger/balancer tell you how far they are out of balance when you plug them in?

If you were in the US I would say call them. Not sure what to tell you in Australia.

[RC Accessory]

Part of the problem is the IMAX charger. it is known that it over charges the cells and this is taking the toll on the batteries. when the pack is full check the voltage of the pack. It should be 4.2V per cell. You'll find that the IMAX charger is putting in a bit more.

[Zilla]

With the imax B5 I am able to check the voltage of each cell once i start charging. I looked today and the cells started at about 3.95, 3.91 and 3.95. This is not very accurate though as it had already started charging.
Towards the end of the charge it sits around 4.20 but does not go over it. It seems to do this for ages and at the moment I have a 180 minute time limit set and that is where it stops charging.

Any thoughts ?

Thanks

Tim.

[DebianDog]

What is the imbalance when you plug it in. (Voltage difference between the cells. High/Low)

[RC Accessory]

check each cell on DVM and comapre it to what the charger is reporting the voltage to be. That is where you will see the issue.

[Zilla]

So the voltage per cell that it is showing may not be correct? and really it is a higher amount? and here I was thinking it had been charging to a perfect 4.20 volts per cell every time.

Sorry but I new to this ... what is a DVM?

Am I up for new batteries and a charger or what should i do ??

[RC Accessory]

So the voltage per cell that it is showing may not be correct? and really it is a higher amount? and here I was thinking it had been charging to a perfect 4.20 volts per cell every time.

Sorry but I new to this ... what is a DVM?

Am I up for new batteries and a charger or what should i do ??

DVM - Digital Volt Meter. A must have for electric's.

Batteries. FP are very good, I also like the Air Thunder, Dualsky, and Kokam 30C's.

Lots of good chargers available depending on the what you are looking for.

[Zilla]

But how long will my FP's last if I keep using the Imax? I really dont want to spend $200+ on a charger just now. Is there anything I can do to stop or minimise the overcharging ?

Also, How often do I need to balance charge my batteries? dose it have to be done every time is that un necessary ?

Tim.

[kingiggy262]

Just get a Cellpro 4S charger for $75 and be done with it! Best value for your money no doubt.

http://www.fmadirect.com/detail.htm?item=2218&section=45

Here is the adapter for your battery:
http://www.fmadirect.com/detail.htm?item=2125&section=45

You can even purchase the interface adapter to connect to your pc and see all the cell info from your batteries as they charge.

[MrMel]

Also, How often do I need to balance charge my batteries? dose it have to be done every time is that un necessary ?




Everytime, there is no reason not doing it.

For sample, your "bad" pack, if say you balance only every 5 times, what would happen? It would go more and more out of balance, and your fully charged pack would perhaps be 4.20, 4.10, 4.30 = overcharge, FIRE HAZARD!

So Balance, EVERYTIME.

Btw, Do your charger have a "fast lipo mode", most chargers do, its the last few 0.0x volts that takes insanly long time, most chargers have a fast mode where it charges to 97% full, going alot faster.

[michael503]

Just get a Cellpro 4S charger for $75 and be done with it! Best value for your money no doubt.

http://www.fmadirect.com/detail.htm?item=2218&section=45

Here is the adapter for your battery:
http://www.fmadirect.com/detail.htm?item=2125&section=45

You can even purchase the interface adapter to connect to your pc and see all the cell info from your batteries as they charge.

and they're on sale now for 60 bucks, I got the flier this morning.

"Just in time for Christmas --
Check out our Cellpro 4s Charger at the fantastic price of $60.
Offer valid on orders between December 6th and 13th only.
"
doesn't show on their site, you may have to contact them.

great charger, I have one but am waiting to see what the 10S goes for in January

[SilverFoxCPF]

Hello Tim,

As Li-Po batteries are used, their internal resistance increases. This is normal degradation and the only way to avoid it is to not use them.

Charging a Li-Po battery involves charging at a constant current until the voltage reaches a maximum value, then holding the voltage constant while gradually reducing the current. This is known as Constant Current/Constant Voltage (CC/CV) charging. The reduction in charging current is why charging at 1C takes longer than 1 hour.

Now, if you charge a battery with low internal resistance, the CC phase takes around 30 - 40% of the charge time, and the CV phase tops the cell off. If the battery has higher internal resistance, the voltage jumps up faster and the CC phase time is greatly reduced. This means the battery is mostly in the CV phase and that takes a longer time.

If you want to try to reduce your charging time, try reducing the charging current. You may find that charging at 0.5 - 0.7C results in a faster charge time than charging at 1C.

The increase in internal resistance is also responsible for the voltage drop when you remove the battery from the charger. As a general rule, if the pack drops below 4.0 volts per cell (resting voltage taken 15 minutes after being removed from the charger), it is below 80% of its initial capacity and is ready to be recycled.

Tom

[Pinecone]

and they're on sale now for 60 bucks, I got the flier this morning.

"Just in time for Christmas --
Check out our Cellpro 4s Charger at the fantastic price of $60.
Offer valid on orders between December 6th and 13th only.
"
doesn't show on their site, you may have to contact them.

great charger, I have one but am waiting to see what the 10S goes for in January

I ordered 2 CellPro 4S chargers. I figure they wil still be very nice to have around. And the 10S doesn't go it for me. If it had been 12S (2 x 6S at one time) I would have jumped on it.

But in talking to their tech people, I was told that the Cell Pro 6S is not dead, and should be their next product. A couple of those will be on my list to buy.

[VyNNeR]

I have a FP EVO25 2170 and 2500 that I use in my Mini Titan. The 2500 has had about 70 charges and the 2170 has had about 30.
What I have noticed is that they are taking longer and longer to charge each time. When I first started charging the 2500 it took about 108 minutes to put back 80% (2000mah) when balance charging at 2.5amps. Now it takes close 180 minutes to do the same thing.
I always balance charge both batteries and I either charge at 2 or 2.5 amps. I use an IMAX B5 charger.
These are the first Lipos I have ever owned so they did recieve a few over discharges while figuring them out.

Is this a sign of my batteries wearing out ? Is there anything I can do about it?

Also ... just recently, the carbon fibre (plastic) part of the Mini Titan canopy has shrunk down towards where the battery sits underneith it. My batteries do get warm to hot but I would not say very hot and they are not getting any warmer now then they ever have. Has anyone else had this happen ?

Thanks

Tim.

Hi there Tim,

I have the same problem ... my IMAX B6 stuck in 4.2 each cell for a very long time too.
Did you manage to find a solution?

Thanks