Tired of AA's...
 

So I got a Summit, and I'm pretty much stuck with the TQ4 radio. I'm not spending $400 on a 4PK....

So I was at Linc's and we kinda got on the topic as we were running of these stupid cheap radio's with AA battery power. He said he had a solution for my problem.

Behold the beauty of cell phone. The pack was made from 3 cell phone batteries. These batteries have their own low voltage cutoff built in. They are around 1000mah so they should last a good while on a charge. The pack was made with a regular Rx pack connection. So I simple soldered a female rx connector to the radio's positive and negative's on the battery tray and viola! Worked like a charm.

Thanks linc! :party:

Here's a pic of the battery tray on the TQ4.
http://i11.photobucket.com/albums/a1...r/P1010129.jpg
http://i11.photobucket.com/albums/a1...r/P1010130.jpg

And I got them from Sikeston34m a while back. Good setup, I still have 2 for my 2pl futaba radio. Cheap too, think it was 20 bucks or something like that!

It definitely lightened it up as well.

Aaaahem. Did I read my name? LOL

You know something? I've made/sold a number of these setups.

The first two original setups that I made, I still use today! After countless cycles, they will still play all day.

I still have some other sets if yall need more.

I'm glad you like that. I never use AA Batteries anymore.

You didn't set him up with the female charge jack?

Thats ok. I have a Rx charge adaptor for my Hyperion 720i and I don't mind unplugging this. Its works great!

Cool. You're gonna enjoy it. They provide some nice run time too.

What I did on mine, I opened the radio case. Then I drilled a hole to mount a female "M" style charging jack. My Charger has the male plug.

I just plug it up every so often and it stays fresh. Don't even have to open the case anymore. Haven't opened the case in a year and a half now. :yes:

I set them up with the male radio style plug, as my 3pm and the other radio I had at the time had a female in the battery tray. Also nice if it goes dead, I can jsut swap a fresh one in, as I had 4, now have 3. I also have 3 of the bigger format cells that you sold me a while back. Need to dig them out and arrage them to fit as well. The futaba is my boat radio, so it is nice to have spares while I am at the pond!

Hey Linccccc

Check out your LiPo Repair Thread, had a question for ya in....

Okay, I'm done hijacking threads..

I might have to try that one day.... :mdr:

I kind of did the same thing for my MX3 Cell batts are a great idea. I used batteries I got from Snellemin. They are perfect for 3 to fit in the TX case with the tray removed. there is actually a lot of wiggle room even with the balance connector and foam I added to the back. My radio shuts off at 9V and I think these batteries can actually go down to 2.8V They charge as Li-po and are about 1800mah.
Not a very good pic but.

Oh snap. Hand porn!

Sorry I'm a little hairy right now...

Now someone do it for the DX3R?

I dont own one... lol

The same thing will work for the DX3R. It takes 8 AA Batteries also doesn't it?

4 actually.

4 or 5 cells.

So would a fully charged 2s pack be too much voltage? If not, they should fit in there.

Probably.... Probably not.

Small 2s lipo and a ccbec, the radio may be able to handle the voltage if the bec fails, so you should be covered. Not sure what to use as a lvc though, someone makes a regulator designed to be used with a 2s lipo as a nitro rx pack that has a lvc. Not too sure who though, maybe novak?

Or just use 2 of the 1100 a123 cells in series. Around 6v, so it should work great. No need for a lvc either, if you leave it on it will not melt the radio. May even be able to fit a 2s2p pack in there.

Yes, in the case of 6v input. Some other Battery Chemistry would be the way to go.

Or like you said, use a voltage regulator.

It's really hard on any battery to completely kill it though.

Don't most radios already have a low battery warning? The Traxxas blinks (IDK what voltage) and my MX3 shuts off at 9V and warnins at 9.1V which is perfect for my setup.

Jeff

We kinda went over this before for the DX3r, but here goes anyway:

Wondering about "raw" 2s voltage, I emailed Spektrum. They said it would not like 7.4v, not to mention a fully "peaked" lipo is 8.4v. So, we're shooting for 6v to 6.5v MAX here.

Yeah, a switching BEC could be employed, but it will be about as efficient as a linear regulator on 2s. So, to get the switching BEC to be efficient, you need over 2s. Otherwise a linear regulator would actually be better. For example, a switch regulator is around 80% efficient at lower currents. Assuming the radio is drawing 200mA @ 6v, and the battery is 7.4v: That would mean a switching regulator would bes drawing 203mA from the battery. A linear regulator will only draw 200mA, so the linear one is actually more efficient on 2s.

To reap the benefits of high switching BEC efficiency, you need higher voltage, which means 3s+ is the minimum voltage. But, if the regulator goes out, that means the radio will receive the full 11.1v. The radio MAY survive 2s for a short time, but I doubt it will survive 11.1v. Another plus for the linear regulators; they are all but bulletproof. You really have to try to break one.

And, most any regulators of any kind need at least 0.5v (for LDO types) or 1.0v (for regular types) above the rated output to work right, which would be troublesome near LVC. To get around this, you could get a LDO style rated for 6v (or get an adjustable one and fix it at 6v), or a regular regulator like an LM7805 (5v).

Then, you need some kind of LVC/LVA, or some kind of indicator showing the voltage level of the actual battery.

So, after this is all said and done, it seems more trouble than it's worth. But, if you insist on using lipos, the best/safest/most efficient setup IMO is 2s using a 5v linear regulator with an LVA/LVC.

Thank you for that explanation professor... lol

I'll go ahead and use my TQ4 with pride because I can easily use Lipo's! :lol:

When does the TQ's start to flash anyway? If no one knows I'll try it tonight.

Jeff

Just got off the phone with Traxxas on this issue. He said he was never asked that question before and he was discussing it with another guy there. The best he could say was it's around 10v. I told him I was trying to see when at what voltage the light started blinking so that I could possibly use that as a LVC. He actually suggested the smart thing in saying to get a LVC for 3s and be safe that way.

So Jeff, if you wouldn't mind trying to see at which voltage it will start to blink that would be nice. I would like to know as well. My cells have internal cut offs tho.

I made this pack last week... dremeled a slot for the wire to come out from (soldered onto the lead springs inside), and I just used a Deans connector because that's the one that was on the pack in the first place. I also am running a 2s M1 receiver pack as well(I don't trust BEC's for racing), but I would like to get something lighter...

It's a 4s A123 pack, if you couldn't figure it out. Runs at 12.7 volts for the entire runtime, of which is over 24 hours! I have alot more range as well, about 1/3 mile now.

Although I would like to get some 18650 A123 cells for lighter weight, but it's not bad, it makes it stable i guess for at the track.

HERE you can get the G3 LiFe receiver packs, they are brand new, just became available two days ago.

Does the DX2.0 have a voltage regulator? Because it holds 12.7 for almost the entire runtime, and the M1 cell would normally hold 3.2volts average over the discharge.

jtr and nitro, easiet way is to remove 1 AA, jumper the tabs, remove another, repeat until you get the flash.

ZP that is awesome and I want to do the same with my DX3.0.

Does anyone know what voltage the alarm sounds on a DX7? I am trying to convince a buddy to ditch his Nixx's and use an older TP 3S 2100- but he's all scared he'll leave the TX on and puff a cell or worse.... anyone?

I'll set it up on my power supply tonight and watch the voltage with my Fluke and give it a few tries and see. I have a TQ3 and a friend has a TQ2, can't imagine that they would be different, but I'll do it anyway.

Jeff

I would guess around 9.0 - 9.5 volts the TQ3/2 would blink at, maybe 10.0volts. I can't even remember what my DX2 alarms at... I think it's 9.1 volts?

I was guessing <9V, out of curiosity I just used a 9V out of a smoke detector, at 8.6V on my DX3.0, no alarm. But we know that a DX7 has one because it woke him up one night when he left it on. He doesn't remmber the voltage it was reading tho. And the Nixx are hardwired on the DX7, and he wants to know before he clips the lead..... told him he was gonna have to put a jst connector on anyway- but he's friggin stubborn.

DX2 is probably the same as my DX3... 9.0 volts... chirps like a cricket, lol.

my dx3s goes nuts if you leave it on the voltage drops down, i has the same battery compartment as the dx3r so im thinking why cant we get a 2s lipo thatll fit in there and run the ccbec set on 5.5 volts and then even close to the lvc its would still be supplying .5 volts more than the bec is putting out..... you can get a novak blinking LVC and mount it ontop of the base and just wire your on of swtich BEFORE the lvc and bec

so youd have the lipo, plug, switch, lvc in parrell, and then the ccbec before it goes to the radio power leads .....

did i confuse anyone else or just me?

honestly i use the energizer lithium AAs and they last for 6 months getting used every weekend alot...

Yeah, but how much do those primary Lithium AA cost again? $12 for 4? You can see that it wouldn't be long before a rechargeable transmitter pack would pay for itself, one year maybe. I would also get a LiFe pack, as weight is not a concern, plus it will last a decade at the very least running something as low powered as a radio.

OK, date with the wife got in the way of testing, but here are my results. This is in the TQ3 I have, have to wait till John comes back over to see what a TQ2 will do, but I don't expect any difference except for normal manufacturing tolerances.

At 8.03V the light starts to flash.
At 4.2V it starts to dim while flashing.
At 3.353V it's really dim and still flashing.
At anything under 3.25V it completely shuts off.

To test this I had to use an old Protoboard with built in power supply 0-15V. The meter I used is a Fluke 112. I did both rising and falling voltage to test hysteresis 3 times.

Jeff

do these cell phone battery not need to be balanced?

They should be they are just like any other Lo-po/Lo-ion, and now they are made into a pack, and they came from different devices that probably had different charge/discharge cycles. The ones I am using are from the same laptop pack and they are out of sink by up to a 1/4V, that's why I put a balance plug on mine. I also have a ton (about 50) of the Fat/Long aa size Li/ions and they act the same way in packs. No 2 cells are alike.

Jeff

Okay, I have had my DX2.0 running for 16 hours now, and the voltage is still at 12.7volts... there must be a voltage regulator in there.