question about new batteries

What's the big deal about charging? If it is a big deal, you need to simplify things, and maybe get a quick field charger. That will surely be cheaper than going lithium. You also need a regulator for each plane, too.

Just MHO.

-- Jim in NC

No big deal about charging. Just wondering if these batteries are more dependable, more durable, lighter, etc. Is there a real advantage, other than the charge lasting a long time?

If all I was concerned about was a low price then I wouldn't like four stroke engines or lithium batteries. I would be happy to spend the money just for the cool factor, as long as I can be sure that it's not going to cause me problems later.

In fact, I am a cheapskate. But if something gets me going then I will save my nickels and dimes and see if I can buy one.

Hi;

I've been very happy with the cells I bought - my electric plane went from five minutes of flight to unknown duration, because I haven't had time to run the battery down in one day of flying yet.

I've been told the same thing about the charger so I picked one up for the roughly thirty dollars you've been quoted. I've heard that the cells are sensitive to a certain level of discharging, although I can't seem to get mine discharged that low, so it hasn't been an issue. Yes, they do stay juiced a lot longer than NiMH's, although I still charge them up between each day's flying.

For an electric plane, they're outstanding. Their big attraction is that they hold a lot of power per ounce - about five times that of NiMH. If they're just going to run a receiver, though, I don't know that it would be worth the fuss. Glow plane flights are limited by the fuel tank size moreso than battery capacity, aren't they?

I haven't had mine long enough to answer the other questions about their longevity; they've been great this past summer, but I don't know if they're worth it just to power a flight pack, particulary if the plan is to run them repeatedly without charging...

Dan.

I had a cell failure last summer and ended up with a plane in a tree. I have a lot of old batteries that I never labeled with the date when new, so I always wonder how old they are. I also don't spend as much time as I should taking care of them. They don't get cycled, discharged, or maintained in any other way. I also usually forget to take my ESV to the field for some reason. I haven't had any real problems with batteries, except the tree incident, but if I can do something to virtually assure that it is never an issue then that seems like a good idea to me. It's just that I've been thinking lately that I have a lot of old batteries, and then I saw the lithium cells at the store...

Can someone give me a good source for ten-cell battery packs? All I see advertised are 6,7, and 8-cell.

I have had a few speed 400 models over the years. I was always a little disappointed with the performance and the weight and low run times. I have just converted my Lanzo Bomber oldtimer from a Astro .035 cobalt with gearbox to a PJS Outrunner Brushless motor and a lithium Polymer battery. The difference in performance and duration is startling. I fly for as long as I can and still land with plenty of power in the pack.

You do need to be careful with the cutoff voltage of your ESC (li-Poly's don't like to go below 3v per cell) ,and a Li-Poly charger is a good investment. If overcharged they can explode big time. Have a look at the e-flight groups. Overall I would say that for electric flight, I will never go back to Nicads again. (I still use nicads for my flight packs in my gas models)

Regards Tom Watson Sydney Australia

Where can you get LiPolys for $40 that will power a 40 size plane?

There are only two reatures of these batteries that hold me back.

1. you cannot fast charge them.
2. they are still fairly current limited. You have to parallel packs to get any where near the curent capacity of NiCds.

They are getting real close to wet power density, though!

No flame intended but that last sentence would be the deciding factor for me...lithium need care/caution. from what I read, they can be downright dangerous if care isn't taken...

cheers astroflyer

I got mine from aeromicro.com.

Would you be interested in a used pack? (2400mAh Sanyo NiMH, 20 oz.).

Dan.

I was hoping Red would reply. The Li batteries are much trickier to charge right. In commercial applications you will find three leads on the charger (cameras, phone, computer, etc.). The third lead is for a thermister that measures the temperature of the battery. It is the only way to be certain that the battery is properly charged. There are simply not enough Li batteries used in RC to generate that type of battery/charger system.

In our applications, that not a problem for e power. You just get a shorter run. The Rx pack is a different story. NiCad's are old technology and time tested. Unless weight is the primary concern, stay with NiCad's for radio packs.

Get a cycler, a digital voltmeter, and a load and use them. ESV's leave a lot to be desired. You can get a DVM for next to nothing and build a load for a couple of bucks. Checking the voltage keeps you out of the trees.

Lithium batteries offer a lot in electric flight applications but they must be used with caution. There is a good write up on them at the FMA web page that discusses some of the precautions one must take. And yes, you will need a charger designed for lithium batteries and MAKE SURE IT IS SET CORRECTLY.

Here is the material from the FMA-Kokam web page;

WARNING Safety precautions for Lithium Polymer and NiCd cells/packs stocked by FMA Direct

1. Never fast-charge any battery type unattended.
2. Never charge LiPo cells/packs at any rate unattended.
3. Only charge LiPo cells/packs with a charger designed specifically for lithium polymer chemistry. Example chargers include the Kokam USA, LIPO 402, LIPO 102 and LIPO 202; Bishop Power Products Apache S1215 and S1500; Great Planes Triton; and Schulze chargers with lithium charging capability.
4. LiPo cells can ignite because of unmatched cell capacity or voltage, cell damage, charger failure, incorrect charger settings and other factors.
5. Always use the correct charging voltage. LiPo cells/packs may ignite if connected to a charger supplying more than 6 volts per cell.
6. Always assure the charger is working properly.
7. Always charge LiPo cells/packs where no harm can result, no matter what happens.
8. Never charge a cell/pack in a model. A hot pack may ignite wood, foam or plastic.
9. Never charge a cell/pack inside a motor vehicle, or in a vehicle's engine compartment.
10. Never charge a cell/pack on a wooden workbench, or on any flammable material.
11. If a cell/pack is involved in a crash:

a. Remove the cell/pack from the model. b. Carefully inspect the cell/pack for shorts in the wiring or connections. If in doubt, cut all wires from the cell/pack. c. Disassemble the pack. d. Inspect cells for dents, cracks and splits. Dispose of damaged cells (see below).

1. Dispose of cells/packs as follows:

a. Discharge: with the cell/pack in a safe area, connect a moderate resistance across the terminals until the cell/pack is discharged. CAUTION: cell/pack may be hot! b. Discard:

- NiMH: place in regular trash.

- NiCd: recycle (cadmium is toxic).

- LiPo: puncture plastic envelope, immerse in salt water for several hours, place in regular trash.

1. Handle all cells/packs with care, as they can deliver high currents if shorted. Shorting by a ring, for example, will remove a finger.
2. Always store cells/packs in a secure location where they cannot be shorted or handled by children.
3. When constructing a pack, use only cells of the same capacity (mAh).

FMA, Inc. and KOKAM USA, its successors, heirs and assigns are not responsible in any way for any and all bodily injurie(s) and/or property damage that may occur from the use of or caused by in any way the lithium Polymer and NiCd cells/packs stocked and or distributed by FMA, Inc. and KOKAM USA.

Having just bought a couple of the brand new 'Platinum Power' Lipoly packs from Batteries America, I am totally astounded at their duration when used as flight packs. 46 minutes compared to 10 minutes on NiMH. And they're about 40% lighter to boot. But for a receiver pack, there would be no particular advantage other than the slight reduction in the plane's all-up weight. NiMH's for the Rx have more than enough duration at the low current draw. Economically, there'd be no sense spending $$ on Lipolys for the Rx pack ('specially if you're a cheapskate).

Bill (oc)

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Depends.... For welded packs, there are many suppliers - check the vendors that advertise on ezonemag.com for best prices. Dave at RadicalRC.com is a good guy to deal with and ships fast and cheap. If you need packs for more than 20 A draw, go with an end-to-end soldered pack, as the thin welded straps and small contact area of the spot welds are high resistance (okay, milliohms actually, everything is relative) - they will light up like a toaster if you go over 30 A. Steve Belknap of Diversity Model Aircraft (flydma.com) does top quality work, not cheap though. I use 10 cell Sanyo CP1700 packs from DMA in my Phasor 30 powered ElectroStreak. Draws 38 A at WOT with a 10/6 folder, and the packs are just warm after a full flight averaging 1/2 to 3/4 throttle.

Abel

The reason I don't use them for Radio pack is because there is no real need to save weight and nicads do such a good reliable job. Read Larry's reasons why he does not sell them at SR Batteries.

Regards

Tom Watson Sydney Australia

I'll keep my eye on them for a few years. New technologies usually have some rather complicated procedures, until they become more mainstream. I was particularly interested in tiny batteries for 020 powered models. These planes have to weigh around 8 ounces or less. But if it's that big a deal just to charge them then I think I'll stick with what I have.

Thanks for all the info.

Check out

I ordered two 8-cell KAN950 packs from them for my Zagi and was very impressed with their service and the way their packs are made. You can specify as many cells as you want in the pack in whatever configuration you want, as they charge on a per-cell basis. If I remember correctly, they come with Deans Ultra Plugs at no extra charge.

-- Morris Lee snipped-for-privacy@verizon.net

A few posts back I mentioned the new 'Platinum Power' Lipoys I got from Batteries America, that give 46 minutes run time over NiMH's 10 minutes. Li-ions and lipolys have a quirk, and there's a caveat to using them: if the supplied charger does not bring them up to full rated voltage of 8.4V (4.2V per cell), the pack's mah capacity will fall 'way short. Every tenth of a volt low causes a large drop in capacity. The supplied charger I got puts the pack up to 8.1V and tops off. So I had to build a 'finishing charger' to bring it up to 8.4V to get full rated capacity. (the circuit's based on the LM317T regulator chip.) I guess the factory purposely sets their charger a little low for a 'safety margin'. Bill (oc)

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In that case, go for it Robbie! I use a single Kokam 45ma cell to power my FMA M-5 and 2 GWS Pico servos for my .010 powered pattern ship. The cell weighs jsut 3.5 gm and costs $4.25, cheaper than the the cost of 3- 50 ma nicads that I was using before. The whole plane weighs 3 oz including radio.

You get micro-flight plus the noise. :)

-Fritz