Futurase

My Feedback: (10)

Guys,
I have a question about Li Ion packs and I ask it in this forum do to it directly has to do with a big bird and lots of gaint scale flyers use Li packs.

I have a Central Hobbies 2000 mah Li Lion pack that is a couple of months old. Has worked fine so far. I have a Accu-cycle Elite charger and it does Ion and Polymer packs and works great as I use it from all my electric stuff, (Foamies and Mini-funtana, etc.).

I thought I would discharge my CH 2000 Li ion pack to make sure it still at capacity. Fully charged it shows 7.4v with a 1A load. Sounds perfectly normal. If I discharge the pack from fully charged with my AccuCycle Elite at 1A I can only get about 900 mah before the charger cuts as the cut voltage is fixed at 6.0V. You can not change the cut point in the software for Polymers and Ions for your own safety. Charger lets you do anything you want to Nicads and Nimh's.

Is this normal??? or has my pack goen bad??? the pack is rated at a 4A continous rate. I know for a fact that my Polymers can take it. My charger will not discharge at more than 2A and doing it to my polymers doesn't faze them. My 1900 mah Polymer will put out 110% of its rated capacity at 2A. 2A is a joke to it.

I would like your opinions before this goes back into a plane.

I assumed the pack could sustain it rated amp rate. I know all the things about Li packs and that they do not need to by cycled, but I like to "cycle" them every 50-65 flights simply to verify capacity. I think this is a prudent thing. Has nothing to do with doing away with memory. I know it builds up none. I don't do that with my cell phone and laptop, but if the battery starts to have a short life all of sudden I drop a call or have to plug in my laptop, but go pick up 3k+ worth of balsa and covering[:'(]


Like I said I ask this in this forum because you guys have a lot of experience with them.

Thanks,
Norman Ross

JohnVH

My Feedback: (38)

cant say Ive heard of anyone discharging a liIon pack yet. Given the responces maybe nobody does? I dont with mine.

ptgarcia

My Feedback: (36)

Me neither. I just check them with a load: 1.0 A for my 2200 mAh packs, and 1.5 A for my 4400 mAh packs. So far so good.

JohnVH

My Feedback: (38)

as that was brought up, I check my 2200, 2400, and 4400 packs all with 1amp load, and charge once down around 7v

mglavin

My Feedback: (31)

You can cycle Li-Ion without issue. As you mention it's a capacity indicator and allows you to remain warm and fuzzy with your batteries... That said, routinely its not very common. Occasionally I see no reason not to check the flight system batteries, any chemistry for that matter. It simply makes sense.

Utilizing the depressed voltage to determine or derive a capacity level of any battery chemistry is a mis-nomer without knowledge of the discharge curve of the specific battery pack. This method is inadequate and mis-leading! On the other hand its very common.

Generally speaking a battery will provide its rated capacity at discharge, the thing is at what voltage. Lithium-Ion, unlike Li-Poly is NOT well not known for its current handling abilities.

Can you discharge at a lower level, which would cause and effect less voltage degradation to validate the batteries capacity?

Futurase

My Feedback: (10)

Liek I said I only discharge my Lithium packs every 65 flights or so for the warm fuzzy feeling. I mean we use them to power $3000+ models. It only makes common sense to me. I know it has nothing to due with memory or etc. I just do it to verify capacity.

MGlavin,
Yes I can get the full 2000 mah out of it if I lower the discharge rate to 500 mah. I ak this as I am not familiar with the discharge curve of Lithium cells. Not at least like nicads. I know how nicads act like the back of my hand.

My pack may be fine I would just like to know what to expect from the things. Every company I talk to tells me something different, but most all use the same cells they admit.[:@] Makes you begin to think if anyone knows how the things work[]

Thanks,

Norman Ross

Futurase

My Feedback: (10)

I had a nice long conversation with Kurt at Fromeco. seems he knows more about Li Ion and even polymers than anyone I have ever spoke to. Or at least he is willing to share his knowledge and not push me to buy one single thing. Actually he did make a a sale as for what He did I plan on buying Fromeco packs from now on.

There is nohting wrong with my pack at all. He explained the discharge curve and all the ins and outs of a Lithium cell. Very informative and sharp guy. Like I said, I'll be flying Fromeco packs in all my stuff rom now on for the same reason I run DA's. The product ain't bad and the service is second to none.

Thanks,

Norman Ross Jr.

ptgarcia

My Feedback: (36)

Yeah, I only buy Li-Ion stuff from Kurt. I can always count on him helping if I need it...and I have needed it! If you haven't already done so, buy his 8-Ball load checker, it's way cool.

Mike Bogh

My Feedback: (14)

I'm a Fromeco man myself, for the same obvious reasons stated above.
I called to ask a question or 2 a year ago, he took about 45 minuets answering every single question I had, without ever once putting down any other manufacturer.
That showed me what a class Kurt was, and he earned all my future business with one phone call.
Brilliant?
I'd say so.
Besides, he's a sick puppy modeler like the rest of us.
That goes along way with me.
www.fromeco.org
I'm not sponsered, get free stuff or anything else, just spend my hard earned doh-ray-me like the rest of you.