Discussion Which batteries and why? How about LiFePO4 for DLG?

[tai626]

John:
I have read this post and was really helpful, although a little too late :-)
"Last but not least, don't inhale the smoke guys. Use a small fan while soldering!"
What is the consequences? Can I blame my short memory because of the vapor?

[John255]

Originally Posted by tai626

John:
I have read this post and was really helpful, although a little too late :-)
"Last but not least, don't inhale the smoke guys. Use a small fan while soldering!"
What is the consequences? Can I blame my short memory because of the vapor?

Tai,
I would hate to tell you how many years I've been soldering.
So far the consequences are significant increase in being with mature women, drinking dark beer, and sleeping in every opportunity.

So, be careful what you smoke!!
John255

[tai626]

Lol. I can't say anything about women, only a woman (wifey is watching :-) I drink bock since I was in College and with a 2 year old and a 2 month old, I sleep in every oppotunity. Last night was a good one. 3 hours straight. I have to quit inhale cheap solder pasta smoke...

I've decide give K2 a try. If I don't like it, I will shipped it back at a fraction of their freight.

[JonyEpsilon]

Originally Posted by kcaldwel

I've been using the eTec 450mAh liPo, with a switching regulator, and that gives me over 500 mAh of usable capacity for 30 grams total.

Hi Kevin,

I've been looking for a switching regulator suitable for a DLG- could you share where you got yours from?

Thanks,


Jony

[JonyEpsilon]

Originally Posted by G_T

The LiPOs I'm using now are from RCBuilder. They are pretty good packs with a nice form factor. The ones I used before that were 450MAh packs with a nice form factor. They became very hard to find. Most were wider in that capacity. I don't think they are made any more.

Over here in the UK, RobotBirds are still selling the eTec slimline cells:

http://robotbirds.com/catalog/index.php?cPath=63_149


Jony

[JonyEpsilon]

Originally Posted by tai626

John:
I have read this post and was really helpful, although a little too late :-)
"Last but not least, don't inhale the smoke guys. Use a small fan while soldering!"
What is the consequences? Can I blame my short memory because of the vapor?

I think the problem is mainly with the flux in the solder. Some people are hypersensitive to the the vapour from rosin-based fluxes, and prolonged exposure brings on an asthma-like condition.

A lot of solder these days is made with "colophony free" flux. You can tell if that's what you're using as it usually smells strongly of candy floss (cotton candy in North America?).


Jony

[John255]

Just for those who've forgotten, and have a junk box of old GWS can motor 2A ESC's, the BEC output is 5V/1A which will hold most 4-servo, 72 Mhz. planes.
Weight about 2g.

If I were amorous toward lipo for HL think I'd lean toward the highest capacity single cell I could jam in there...no regulator.

Cheers,
John255

[kcaldwel]

Originally Posted by JonyEpsilon

Hi Kevin,

I've been looking for a switching regulator suitable for a DLG- could you share where you got yours from?

Thanks,

Jony

http://www.dimensionengineering.com/DE-SW050.htm

I tried this with a Berg 7 receiver, and it definitely did not like being in the same DLG fuselage as the switching reg. I've been flying with a Corona dual conversion Rx that has worked great, but I mostly fly alone so I have no idea how it would handle a contest.

The switching reg is nice, because you get an additional 100 mAh or so above the rated battery capacity. It doesn't throw the extra battery voltage away as heat.

A single LiPo voltage really isn't enough for most servos. There are some exceptions.

Kevin

[pldaniels]

I'll be bringing out a 3A and 5A class BAC in the near future to compliment the existing 1A units that I already manufacture for 2S lipo packs specifically for DLG use.

Remember though folks, most regulators will shut down well below their 'rated' current rating due to thermal limitations. A 1A unit with a small heatsink will provide more continuous current than a 3A unit without a heatsink.

The jury is still rather out on the subject of switchmode regulators, some people have success, others have disasters.

Paul.

[tai626]

Paul
thank you for your ingenius contribuition!

[tai626]

Btw, here is Paul's website for bec:
http://nqrc.com/?page=products&catag...nics-switching

Just ordered LiFePO4 600 mAh from K2. The UPS ground is a little cheaper: $7.13. 4 cells ($6.00 each)for $31.13 shipped.

I received email from Hyperion and it hsn't plan to produce 400 mAh LiFePO4. Oh, well...

[pldaniels]

Try this URL for the actual BAC units, the other URL you provided is for the various on/off/charge switch units.

http://nqrc.com/?page=products&catagory=electronics-bac

Regards,
Paul

[eteet]

In all the photos the LiFePO batteries are shown charging individually . Is there a way to charge a two cell battery pack in the airplane through a switch jack?

Pardon my ignorance...

Eric

[tai626]

Nice find!

http://www.amazon.com/RCR123A-LiFePO.../dp/B001EYHO9G

here is Kevin's review:
http://www.rcgroups.com/forums/showt...hlight=lifepo4

This one of the questions I will try to clear before I put them on my airplanes. You can also charge them balanced, with extra ballance wire.

Other questions are?
1. What is the maximum charging rate? (0.5C or 250mAh?)
2. How long it take to dischage to 2.5V at 100mA? (5 hour at 0.2C?)
3. Are they stay in balance when charged in serie?

I use a couple of A123 as receiver pack. I charge them at 2C, in serie, without balancing, with a NiXX charger + Dan BaldwinTerminator II + wattimeter. I do check the cell voltage individually after charging and they are always ballanced.

[eteet]

The answer is yes, LiFePO4 cells can be charged in series. There seem to be a hundred chargers out there, here are a few.

I guess I should have checked before I asked.

Eric