Who using A123 batteries?

[Stu_D]

	Quote: Originally Posted by Hammbone
	Are you using a Power Box or Power Expander as well? Jim

Sorry for the slow reply , Yes its the Power Expander .

I have put In some more gear being some Fromeco Weasel
gauges and also some Badger switches . I have found out
that both these things do consume some power on there own
(about 50 mah) but over the duration they dont effect things
to much .

I did one of the longest days flying I have done so far and the
whole package came through with flying colors . There was a
total of 50 min of air time and almost all was IMAC seq work .
Between the gauges and the actual charge there was 200mah
difference on one bettery and 100 mah on the other . Dont know
what the cause of this was but as long as i know how much
the gauges are going to be out after a day of flying then I wont
have a problem .

stu

[Hammbone]

Interesting..............
I have no proof of this, but I've noticed that guys that use Power Expanders and have systems with less restrictions on current flow, seem to consume less mah per flight than those guys that do not use Power Expanders.
I think this might be because when you have restrictions on current flow, the current has to work harder to pass through the system and current is wasted this way. If you have a better, more efficient system, with less restrictions on current flow, less current is wasted.
We are always taught in basic electrical courses that electricity is much like water. Well, we know that it is much easier to pass 50 gallons per minute of water through a 2" pipe than it is to pass the same amount through a 1/2 " pipe. It takes more force to pass the same amount of water through a smaller pipe.
I'm seeing that the systems using Power Expanders are using less mah's per flight. I'm assuming that this is because they are more efficient at passing current.
Again, I have no proof of this. I just noticed that several guys were reporting low mah consumption rates (not just in this thread, but in several other sources as well), and all of them are using Power Expanders in their systems.
There may be something to this, and there may not be. There may be a completely different reason for the low mah consumption rates. The similarity that I noticed though, was the use of some kind of Power Expander device.

Jim

[JimC-MD]

Hammbone, it makes sense.

You can use available energy to do work and be efficient. You can also use some of that energy to overcome resistance and it is transformed into heat. Where that choke point is located does not matter. I have been very happy with the performance. I was out again last weekend and after five flights of 12-15 minutes along with some time tuning on the ground for a prop and fuel change, I had not even reached the 50% range on my batteries. Each Kodiak showed .7

[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.