Lipo Transmitter batteries??

2984 Views 31 Replies 9 Participants Last post by ChuckAuger, Oct 28, 2004

glowbum

Discussion Starter · Oct 25, 2004

I've noticed on occasion that my Futaba TX will show 11.1 volts if I've left it plugged in for too long. What's to keep us from using a 3 cell lipo to power our tx's? They have a built in volt meter, so it would be easy to catch if they were close to being over-discharged. Plus, you would only have to charge the battery every couple of weeks. Is it the oxycodone talking, or could this work?

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dhooks

· #2 · Oct 25, 2004

Well thats the nominal voltage on a 3 cell lipo.....fully charged it would be over 12 ......dont know if that would do anything or not....surely the voltage is regulated.

Spaz

· #3 · Oct 25, 2004

it think it would work great i want to do it bad also, i know some of the big guys are doing it, but not sure if they are using a regulator, could check on DOD, when i was a teacher i would set up my futaba super7 on a 12v lead acid which is 13V full charge no problem

the best would be that if you didnt fly for a week the batt would still be ok, very little self discharge
what cells would u use? i know 2100 thunderpowers dont fit, without case mod

ChuckAuger

· #4 · Oct 25, 2004

I run a 1650 NiMh battery, it lasts quite a while without charging. I think they make a 2100 or so NiMh TX pack now, check with Radiacl RC...if they make one, he'll have it.

3d-aholic

· #5 · Oct 25, 2004

What's to keep us from using a 3 cell lipo to power our tx's?

Why do it? There is no reason....for the added expense. Normally, you use LiPoly's to save weight...but weight is really of no real significance on a TX. I'd get NiMH and fly for a month without charging.

Gordo

· #6 · Oct 25, 2004

3d-aholic said:
What's to keep us from using a 3 cell lipo to power our tx's?

Click to expand...

Why do it? There is no reason....for the added expense. Normally, you use LiPoly's to save weight...but weight is really of no real significance on a TX. I'd get NiMH and fly for a month without charging.

I was thinking pretty much the same....but without the admition that you don't fly much!! :lol: Most of us with the 1600 mAh NiMh get a weeks worth, for me that's 3 to 5 trips to the field, 4 or 5 flights a trip (more on weekends)

I too don't see the need for the LiPos, but it would be interesting to see it....

ChuckAuger

· #7 · Oct 25, 2004

Yep, Radical RC has a 2100 Mah NiMh TX pack! And I thought the 1650 was bad ass

2100mah 9.6V NIMH Square TX Pack $32 + connector

Sanyo HR-AA-2100 Flat Pack. Ultimate capacity if you are sick of your TX running down. Yes, it's the same size as your current Square "AA" pack. About 3x the capacity of most factory packs! This is absolutly the finest computer TX pack money can buy. Fits all the Futaba and JR radios requiring Square pack. If you have a clip pack, get the apapter kit to go with this pack. Clip packs are corrosion prone and any modeler at this level needs to make this update before you get bit. Why did they sell you that fine high end radio only to give you a palty little pack with it? Fix that factory ignorance with this pack. Don't let the shadow in this picture fool you, this pack is about 3 15/16 long. A "AA" is a "AA" is a "AA". It's the same size as your current SQ AA pack. This is Sanyo's latest high capacity AA. Unlike their other NiMH cells, these ultra high capacity cells should never be charged above C/2 or or about 1.1 amps on NiMH rated fast chargers. Of course standard C/10 or lower overnight charging is A-ok.

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glowbum

Discussion Starter · #8 · Oct 25, 2004

I was contemplating the Lipo because of the low self-discharge rate, and because I had a spare 3 cell lying around. Doesn't Nimh have a high self discharge rate? One last thing - what does the Futaba 9C come with? The standard 600mah Sanyo?

ChuckAuger

· #9 · Oct 25, 2004

Not sure about the 9C, but the 8UHPS had about a 600 in it. As for the self discharge, I don't really notice it. It's not like it'll be dead next time you go out or anything that severe. Say I charge mine, fly a few times then don't get it out for a couple of weeks, it's still gonna be plenty for a whole weekend.

RayJ

· #10 · Oct 25, 2004

the 9c has a 700mah pack

Wind Junkie

· #11 · Oct 25, 2004

ChuckAuger said:
Yep, Radical RC has a 2100 Mah NiMh TX pack! And I thought the 1650 was bad ass

2100mah 9.6V NIMH Square TX Pack $32 + connector

Sanyo HR-AA-2100 Flat Pack. Ultimate capacity if you are sick of your TX running down. Yes, it's the same size as your current Square "AA" pack.

Something doesn't add up here. That's pretty amazing you can get a 2100 size NiMH pack to fit where 8 AA's did before.

I've tried NiMH cells in a TX before, but they didn't stand up to my style of usage. I only fast charge, and I do a lot of flying when the batteries are cold (ie 40 degrees F). They didn't even last a season this way. I got my first set of NiMH cells (I think they were about 1200 size, if memory serves) from tower hobbies about 5 years ago. The first few weeks of use were great, I was getting about 4 or 5 hours of continuous flight times on a MP8000 AM TX. But then over the next few months I could barely get 2 hours from a fresh slow charge, and a LOT less from a fast charge. In cold weather the batteries crapped out way too fast and I was running back to the car to charge again every 45 minutes.

I've been really hoping that the Duralite packs would increase their specs. According to this page, they're only up to 1300 mAH now:

http://www.duralitebatteries.com/batteries-ion.html

I don't really want to trust lipos in a TX charging unattended without "charge safe" circuitry or equivalent.

Still, for me, cold weather flying would still be a problem. Nicads don't like cold either, but Lipos are probably the worst for cold capacity.

As you said, weight isn't the issue for the TX, but I thought the capacity would at least be comparable. It looks like the Radical RC NiMH cells are still superior in energy per unit volume, which surprises me.

Gordo

· #12 · Oct 26, 2004

I can't imagine a "style of flying" that would bother NiMh. It's not like you can get too high a discharge in a tx, and I figure I get 6 or 8 hours of use and never get down very low, and charge in one hour. Now my cells are rated for c1, but if I had those 2100s I can't see how anyone wouldn't be able to charge them overnite when required.

My 9C came with 600 or so NiCads and within 6 months they wouldn't last more than 3 flights, and that IS due to flying style. I will oftem fly dawn to dark in the summer at least one day a week, that meant 2 to 3 fast charges in a day, NiCads didn't like that. :x

Anyway, I'm so totally thrilled with my 1600+ that I barely even think about TX power anymore. Basically, once or so a week, when the charger isn't busy with something else, I stick it in the tx and fill her up. just never think about it. OH, and I paid more than that Radical price for 500 MaHr less. But that's OK, I'm still happy.

Spaz

· #13 · Oct 26, 2004

Ok, thanks guys, i guess i'm going to radicalrc

you talked me out of it

Wind Junkie

· #14 · Oct 26, 2004

Wow, that's exactly OPPOSITE of what I've experienced and heard regarding NiMH vs Nicad reliability.

When I use that MP8000 radio, it's for slope soaring, and I often only get a few hours notice when the wind starts to pick up, so I NEED to fast charge in the car on the way to the hill. And once I'm there, I fly all day. That's about an hour each flight, for many hours. The TX doesn't get more than a few minutes rest, but I bring many planes.

I'll ask around at work again, but I'm pretty sure the general opinion is that Nicads still rule when it comes to reliability. We've specifically avoided other battery chemistries (li, lead acid, nimh) sacrificing weight for "abuseability". Nearly everyone agrees Nicads are still champs for amps, but I thought it was assumed they were also the easiest to charge and AND maintain.

You're right that the AMPS are low in my TX though. But I couldn't explain why the NimH went bad so fast. Maybe the newer generation cells are better.

That's wierd that your 600 cells went bad that quickly. Were they the yellow label with red lettering AA sanyo cells?

Gordo said:
I can't imagine a "style of flying" that would bother NiMh. It's not like you can get too high a discharge in a tx, and I figure I get 6 or 8 hours of use and never get down very low, and charge in one hour. Now my cells are rated for c1, but if I had those 2100s I can't see how anyone wouldn't be able to charge them overnite when required.

My 9C came with 600 or so NiCads and within 6 months they wouldn't last more than 3 flights, and that IS due to flying style. I will oftem fly dawn to dark in the summer at least one day a week, that meant 2 to 3 fast charges in a day, NiCads didn't like that. :x

Anyway, I'm so totally thrilled with my 1600+ that I barely even think about TX power anymore. Basically, once or so a week, when the charger isn't busy with something else, I stick it in the tx and fill her up. just never think about it. OH, and I paid more than that Radical price for 500 MaHr less. But that's OK, I'm still happy.

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ChuckAuger

· #15 · Oct 26, 2004

My 1650 NiMh TX packs are a couple of years old, and still do pretty dang good..

Wind Junkie

· #16 · Oct 26, 2004

Chuck, Do you fast charge your TX often?

RayJ

· #17 · Oct 26, 2004

Nicads build a memory which is why you are supposed to cycle them to get rid of the memory. NiMh are not supposed to create a memory of charges and therefore are supposed to be better than NiCads. That is just what I have read and experienced.

Gordo

· #18 · Oct 26, 2004

Memory is the big drawback of the NiCds, and that is why my stock pack went bad. If 600 only gets you part way through the day, you have to fast charge to keep flying. Since you don't have the luxury of waiting until the NiCds are totally down, you end up charging them when they are not low enough, viola! Memory.

NiMh I just charge when I feel like it, Never letting it get so low it won't support a day at the field. It won't develoope a memory, so I don't have to worry about it. Cycling isn't an issue, I do it once in a great while just to check pack condition. After this whole season, I cycled my tx pack last week and it gained about 15 MaHr. That may not be totally accurate because I didn't write down the settings of when I cycled it new for break in.

I don't even have any NiCds in planes anymore. I haven't heard anyone with reliability issues or temp issues, all last winter I had them in my planes. 1800 MaHr in a pack the same size as a 700 NiCd, I get two trips to the field on those too :lol: Or in some planes I have 700 NiMh that weigh half the NiCds.

Anyway, fly what you like and trust. God knows I flew NiCds for YEARS and many were many years old. They were fine. I'm guessing Nicd technology will be frozen now, and soon even the cheap tX will come with NiMh. The power density is so far superior and the demand so high I think it will just get better and better. Unless LiPos just take over the world....but that's annother thread!! 8)

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Gordo

· #19 · Oct 27, 2004

Hey, I just got this link, it's to the Japanese web site for Futaba. Just cruising the little english on the site, I see the batteries are Lipos, gues that blows my thoughts out eh? Will they skip NiMh all together and go LiPo stock?

http://www.rc.futaba.co.jp/hobby/new001.html

The email with the link said it costs $2k and is 14 channels!!

Spaz

· #20 · Oct 27, 2004

it makes sense to go strait to lipo, look at every other handheld device that uses alot of power...my new dell laptop batt is 4000mAh and weighs alittle more than a stock TX pack, not that u need that much time, well maybe....dont forget the newer computer radios will use more and more power with color lcd's forget about it!! :shock:

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