Who using A123 batteries?

[Sukhoi08]

Might be a dumb question, but my two 33% planes have a 4v ignition battery. How do you replace these with an A123?

current plane im considering changing out has
1 2700 NiMH 4 cell (ignition)
1 2700 NiMH 5 cell
1 2700 NIMH 5 cell

Any suggestions on converting this? Id like to still use my JR switches if possible and just change out the batteries and rebalance. Id like to use two 2300mah for redundancy but have no idea what to do about the ignition.

[dmcquinn]

Sukhoi08 - I use a single two-cell A123 pack (2300 mAh) through two JR switches for receiver/servos. I use a single 4-cell NiMh for ignition (2100 mAh). This is on a 35% plane with 10 digital servos. I need to field charge the A123 pack after three (maybe four) flights. To use A123 on the ignition would require an ignition capable of handling either 3.3 volts (typically not enough volts to drive it) or 6.6 volts (typically too high a voltage) or a regulator (I don't like regulators - especially on ignitions).

[xed]

DA ignitions support A123 voltages and DA has stated so themselves.

The voltage drops to 6.6V almost instantly under the load of the ignition. Been running a self-made A123 1100mAh pack for several months now on my DA-50 without issue.

[Scott Gerber]

	Quote: Originally Posted by xed
	DA ignitions support A123 voltages and DA has stated so themselves. The voltage drops to 6.6V almost instantly under the load of the ignition. Been running a self-made A123 1100mAh pack for several months now on my DA-50 without issue.

Me too.... VPX


Scott

[Sukhoi08]

great info, i'll remember that if i buy a new plane. However, I cant put a DA motor in my plane or, its not recommended. To much power. So... for my old junkers, keep the NiMH on the ignitions, and possibly convert to A123 on the RX. I guess thats what im hearing. Kindof stinks. Also, I have one battery, for each switch, and both running from switch to receiver. Do i need to add some sort of balancer in there? Sorry for the stupid questions, but one of my planes is a fiberglass 3W and it was made by someone else and seems to be a few years old.

[gareth.ky]

I'm running a pair of A123 2300mah packs built from a 36v Dewalt Drill pack. Each pack goes into its own Kodiak switch and then into a Spektrum Powersafe Rx, all over 16 gauge wire. The output from the switch on the right side of the airplane also powers the DA ignition.

I don't have a lot of time on the setup but I have made some interesting discoveries:

First surprise (or non surprise) is that the packs stay balanced. The Rx draws power from the pack with the highest voltage so to me that makes sense. Its nice because I have eliminated a battery from the setup. If one battery, switch or connector were to fail, the worst that can happen is the engine stops running.

The second thing is the Kodiak switches seem to count high and they don't seem to agree. So the two switches may be as much as 0.2Ah different over 1.0Ah. When I charge the packs the mAh counter on the cell pro tells me the packs are within just a few mAh or so.

I think that's in line with what Fromeco has advertised as far as the accuracy of the switches. Its a guide only. I think you want to learn what the skew or error is on your particular switches so you know your being safe.

[Hammbone]

If you want to use an A123 pack on an ignition that is not capable of using 6.6v, all you have to do is put a diode inline between the battery and the ignition. A diode will drop the voltage by about .7 v.
It's simple, it's cheap, and it works.

Jim

[Sukhoi08]

Scott just helped me discover i dont have the wiring or switches to support A123s. So its a complete change out, or I just leave them alone and fly NiMH.

[dick hanson]

	Quote: Originally Posted by Sukhoi08
	Scott just helped me discover i dont have the wiring or switches to support A123s. So its a complete change out, or I just leave them alone and fly NiMH.

Change only what you want to change
A123 cells require nothing special
-except a proper charger
buy a CellPro 4 and that's all you need except for the cells
All the other electronic do dads are simply individual choices.

[Judge]

Good point Dick. It just fascinates me to no end how giant scale planes have evolved to a point that they have so much equipment that is seen as a "must have" that they look like a UAV inside.

How this got started beats me, but I know for a fact that 2 RX packs, two switches and 1 RX works fine. I believe in the KISS principle.

[Hammbone]

I don't understand why they keep improving car designs either with new, better technology. Everyone knows that cars 40 or 50 years ago worked just fine.

Jim

[Judge]

	Quote: Originally Posted by Hammbone
	I don't understand why they keep improving car designs either with new, better technology. Everyone knows that cars 40 or 50 years ago worked just fine. Jim

You missed my point. I am not and never have been convinced that all the nifty add on electronics that are so popular in giant scale are needed. The analogy to improvements in other areas of technology does not apply.

True technological developments like lithium ion packs, Lipos, A123, 2.4 SS radios, reliable regulators (when needed based on battery technology) are all fantastic and have been real improvements.

But all the other stuff to me is just bling. Isolators, power boxes, power expanders, etc. I feel they add un-neccessary complication and potential for problems. As I see it they are nifty bits of electronics, but they are far from required and you can set up a plane just fine without them. But many people are convinced that they cannot fly without them and nothing could be farther from the truth.

But to each their own.