question about new batteries

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.
Check out Red's site at: http://www.rcbatteryclinic.com /
JR
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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).
12. 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.
13. Handle all cells/packs with care, as they can deliver high currents if shorted. Shorting by a ring, for example, will remove a finger. 14. Always store cells/packs in a secure location where they cannot be shorted or handled by children. 15. 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.
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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.

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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On Thu, 25 Sep 2003 19:15:37 -0500, Robbie and Laura Reynolds
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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

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Thats 145 maH cell Sorry for the sloppy proof reading.
-Fritz

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Wow, now I'm interested again.

One pother hint from the E-zone. Dump suspect and rapidly heating packs in SALT water. Its sup[posed to cool, discharge safely, and generally ruin the ability of the pack to be dangerous fairly quickly.
I wopuld disagree on the 'don't charge them in teh model' thoo.
That's tantamount to saying 'never put methanol fuel in a model as the model may catch fire'
Its true, but an acceptable risk IMHO.
Red Scholefield wrote:
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JR wrote:
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Actually LI batteries are a cinch to charge right. Dump a voltage and current limited supply on them. Limit the current to the one hour charge rate and the voltage to (IIRC) 4.2v per cell, and when the current drops to bugger all, they are charged. Or near enough for most puroposes. You CAN get a bit smarter than that - using pulses to shorten charge time a bit, but that will get you 90% there very easily.
The big danger is overheating by applying too much of volts or current. They burn nicely, and may semi-explode (pop?) or turn into miniature rockets. They will also do this if shorted. Protection circuits introdce too much power loss for electric flyers, so we run em 'dangerous'
Precautions of a more strict nature than with Nicads are indicated, however for every LIPO fire there have been dozens of Nicad fires. Again, there are more Nicads out there...
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