When do you consider the best time to change your battery packs
aside of finding a non functioning cell. Even though seems to be working
well.

Just to be on the safe side of flying.


E.N.T.

Using A123s when the capacity seems to start dropping I change them. Got one now thats holding much less then the 2300mah it is supposed to hold.

Using lipos same with capacity and I also watch for high cell (IR) Internal resistance.

I've never seen a 2300 A123 hold 2300. All mine are about 1900 on a 1 amp discharge.

Jason

Its holding about 300 mah and its a 2300 pack

Oh right, i'd say that was knackered

Even with my Tx's... I use a cycler of some kind when I charge... so I have a good idea of the capacity, and the general health of the pack. I voted Unknown since I change them when I notice a loss of capacity.

Hi

I have Kokam lipos that I am using for 4 years. They hold fine and charge for 90% of their capacity after 150 flights - 50 cycles in the lipos

I also have some Rhinos that I don't thrust that much. I would say every 2 years for lipos. Our rx system and turbines don't demand too much from them

Regards

Nuno

When I was running Nicad's and NiMH's I stopped using packs when their actual capacity dropped to less than 90% of their rated capacity.
I switched to A123's last year and have not needed to change out a pack so far. I will be interested in what the consensus is in this thread on when to dump old A123 packs though.

I have some A123's that have been in use for five years and still hold full capacity, mind you I do not change them above 0.5amps and always balance them.

Mike

I too have some packs that are 5 years old. They still hold a full charge, but mind you I have always been careful to charge at 4 amps and never without a balancer.



John

Use a cycler... more than 20% loss and they go to non-flying duties.

Hector: get them to me and I can test them for you

I try to change mine once I find them at a crash site. 

What type of cycler are you using do discharge??

If your using A123 cells then here is some useful info from Hangtimes<font size="3"><font face="Arial"><span style="color: black"><span style="color: black">http://hangtimes.com/a123_batteries_for_giants_faq.html


Here's an area where A123's are radically different than Nicad or NiMH packs...L</span>oad TestingA123's in the traditional way is ineffective for determining state of charge...the beasties just don&rsquo;t 'react' like we expect.. a 1 amp load for 10 seconds will convince somebody not familiar with them that there&rsquo;s something wrong with the load tester or the pack.. the needle starts to sag after a few seconds with some meters, (resistor impedance valuesjump up rapidly under the continuousload) anddecreasing voltage displayed on the meter usually indicates approaching doom for the resistors, switch &amp; connectors rather than reflecting any useful info on the state of charge for the pack. Continued loading can melt out connectors, meter resistors, switches, etc. ESV 'loading' just doesn't work with A123's in thetried and true sense as the cells are quite happy delivering enough amperage to melt out your gear, even when nearly discharged.Because of the incredibly flat discharge curve and the ability of the cell to deliver massive amounts of current, using a standing voltage level under load to decide when to recharge can lead to a disaster via damage to switches &amp; connectors... Further, when A123's DO go flat, they do so remarkably fast. So, we go to the next question..</span></font></font>

[link=http://www.revolectrix.com/]FMA PL8[/link]
(overkill, but I also got it for high end electric flight)

Replacing a perfectly good, and proven pack is actually less safe because you are now introducing an unproven pack that can have a manufacturing flaw just waiting to die.
As long as the cycler says that the battery is doing its job and holding a full charge, it stays in the plane. I have batteries that are over 6 years old and still hold full rated capacity

Deleted.

Let em sit on the balancer for a while...I had one doing the same thing 2 hours on the balancer fixed that. Those instructions came from
Andy at electrodynamics.

Thanks, I feel a little stupid here. I am now doing a discharge on the pack to 5.2v and the cells are matched, so I think that a discharge/charge cycle may fix it.
Regards,
Gus

90% capacity and then pitch them.

I use an CBA. This lets you plot the discharge curve over time, lay one curve on the other and you can see the behavior over time.

http://www.westmountainradio.com/pro...oducts_id=cba4

Works fine for A123 as well.