Wondering about going to a 6V system in my new plane.  
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All Forums >> Radios, Batteries, Clubhouse and more >> Batteries & Chargers >> Wondering about going to a 6V system in my new plane.
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Wondering about going to a 6V system in my new plane. - 12/17/2002 4:49:11 AM   
Frankenthumb



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I ordered a NiMh 1500mA battery for my new project, and it turned out to be 6V when I was expecting 4.8V. Instead of returning it right away I thought I would look in to setting up this plane with a 6 volt system. I have a couple of questions to get started, and the answers will surely lead to more questions.

First off, it's a 120 size Sukhoi, and I'm putting HS5925MG's on the rudder and elevator halves. I'll put 625s on the ailerons.

1. Can I charge the 6V battery with the wall warts I use to charge my 4.8V packs? (OK, I know that wall warts will eventually get me into trouble, but I mitigate the risk by cycling the packs every few months.) If not, is there a cheap way to charge?

2. How important is a regulator, and if needed, how much are they?

3. How much flying time am I going to lose with 6V?

Thanks in advance,
Frank
       Post #: 1

Re: Wondering about going to a 6V system in my new plane. - 12/17/2002 6:18:24 AM   
sfaust



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[QUOTE]Originally posted by Frankenthumb
I ordered a NiMh 1500mA battery for my new project, and it turned out to be 6V when I was expecting 4.8V. Instead of returning it right away I thought I would look in to setting up this plane with a 6 volt system. I have a couple of questions to get started, and the answers will surely lead to more questions.

First off, it's a 120 size Sukhoi, and I'm putting HS5925MG's on the rudder and elevator halves. I'll put 625s on the ailerons.

1. Can I charge the 6V battery with the wall warts I use to charge my 4.8V packs? (OK, I know that wall warts will eventually get me into trouble, but I mitigate the risk by cycling the packs every few months.) If not, is there a cheap way to charge?

2. How important is a regulator, and if needed, how much are they?

3. How much flying time am I going to lose with 6V?

Thanks in advance,
Frank
[/QUOTE]

1. Some do, but I wouldn't use it. It will take much longer to charge your packs for one. However, if you follow the right procedures, it's not going to hurt anything. Just adjust your procedures accordingly.

2. A regulator isn't required, but can be a nice addition. The servos are designed to run on 4.8 to 6.0v per the manufacturers, however, a fully charged 6v pack has a higher voltage. JR and Futaba have been quoted as saying they are fine on a freshly charged 6v pack. When fully charged, the servos may jitter for the first minute or so, but it hasn't appeared to be a problem for anyone I know over the years. And most of them are running unregulated packs. In fact, most of the TOC competitors run unregulated packs.

Running a 6v pack, and using a voltage higher then 4.8v either regulated or unregulated, will give you an increase in speed and torque. Basically, the servos will perform better on a 6v pack than a 4.8v pack. There is also a voltage loss when using long leads, so having a 6v pack can help keep the voltage higher to the servos out on the ends of long leads. Thus instead of starting with 4.8v and dropping at it reaches the servo, you start with a higher voltage, and will end up with a higher voltage at the servo. Less than 6v, but more than 4.8v.

Adding a regulator between the battery and receiver adds two more connections which add their own failure rates, and the electrical components themselves. Basically, the reliability of the battery to supply power to the receiver is reduced. Not by a lot, but certainly a little. This is a trade off between overall reliability of the power system, vs reliability of the servos themselves, which will take more wear and stress with a 6v system.

3. You will loose approximately 20% of your flight time for the same capacity pack.

_____________________________

Stephen
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Wondering about going to a 6V system in my new plane. - 12/17/2002 6:31:19 AM   
Frankenthumb



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Wow, I was fearing that it would be much more complicated than that. Sounds like it's basically "plug and fly".

If you wouldn't recommend using the same wall wart that I use to charge my 4.8V packs, what would you recommend? Am I likely to find a suitable wart at My LHS?

How about checking my battery at the field, anything different with the 6V packs? I assume that I would want to charge when I get to 1.1V per cell. Is that still a good rule of thumb?

Thanks for the help,
Frank

(in reply to Frankenthumb)
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Wondering about going to a 6V system in my new plane. - 12/17/2002 7:10:22 AM   
midget racer



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I run 6v packs in all my 1.20 size planes, no regulators or junk like that. 2 years and not a single glitch or anything, i am using all jr equipment by the way , never tried anything else.

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Deadstick !!!!!!!!!!!!!!

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Wondering about going to a 6V system in my new plane. - 12/17/2002 7:12:29 AM   
sfaust



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[QUOTE]Originally posted by Frankenthumb
Wow, I was fearing that it would be much more complicated than that. Sounds like it's basically "plug and fly".

If you wouldn't recommend using the same wall wart that I use to charge my 4.8V packs, what would you recommend? Am I likely to find a suitable wart at My LHS?

How about checking my battery at the field, anything different with the 6V packs? I assume that I would want to charge when I get to 1.1V per cell. Is that still a good rule of thumb?

Thanks for the help,
Frank
[/QUOTE]

The reason I wouldn't use a wall wart is basically that it goes against the way I manage my batteries. I like to know the capacity that goes in, comes out, and charge at either a C/10, and/or occasionally at a fast charge rate. I just don't like to rely on a black box without any indications on whats happening (one of the reasons I didn't like the Duralite chargers either). But, that said, one could develop a reliable method with a timed charge with the wall wart, and ESV readings at the field.

Another reason, is that the 1.1v cutoff can be misleading. To try this, discharge your battery, then put it on the charger for an hour. Check it with an ESV. You will think you have more capacity than you really have. And if you were unaware that the battery didn't get a full charge (ie, power failure during the night), you could be mislead and fly much longer than the battery would hold out. For the most part thought, if it charges all night, an ESV reading should be fairly close. But, if you have a discharger and know your capacity is good, you know who many flights you can get while still leaving an adequate reserve, you can use the ESV meter to backup what you know with confidence.

What I would recommend is just about any charger will will charge from 1 to 8 cell packs, go into trickle mode after a timed or peak charge, and allow you to cycle and measure capacity. It doesn't have to be complicated or expensive. Look for a used charger on e-Bay, or at RC auctions, that fits the above parameters, and you might be able to pick one up for a reasonable price. While it is an expense you didn't expect to incur, it is one that could save you much more in the long run.

_____________________________

Stephen
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Wondering about going to a 6V system in my new plane. - 12/17/2002 7:37:42 AM   
Frankenthumb



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sfaust-

I have an Accucycle (no groans please) that meets the timed charge period then trickle charge criteria that you mentioned. That will probably suffice for the time being, until I step up and buy a better battery maintenance system.

midget-
That's good to know. I guess I'll keep this battery and try something new!!

Frank

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Wondering about going to a 6V system in my new plane. - 12/17/2002 8:04:15 AM   
sfaust



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[QUOTE]Originally posted by Frankenthumb
sfaust-

I have an Accucycle (no groans please) that meets the timed charge period then trickle charge criteria that you mentioned. That will probably suffice for the time being, until I step up and buy a better battery maintenance system.

midget-
That's good to know. I guess I'll keep this battery and try something new!!

Frank
[/QUOTE]

Yes, the accucyle will be much better than using the wall wart. However, no reason why you can't use both as you see fit. Once you have a way to cappacity check, almost any charging method will work as long as you stay within the parameters of the battery.

No reason to groan about the Accu-Cycle. It does the job, and doesn't cost an arm and a leg.

I think you'll like the performance increase on the 6v batts. Let us know.

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Stephen
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Wondering about going to a 6V system in my new plane. - 12/17/2002 7:52:38 PM   
sfaust



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I just added an excellent summary and the complete response from Simon Van Leeuwen in regard to my question on the power sharing and isolator issue. But, he also covers issues related to 6v vs 4.8v systems, and why the 6v setup is better than 4.8v when you get into the larger airplanes (basically voltage depression). There is good info on wiring, regulators, etc. Worth the read time.

Elec Issues-Dual RX, dual batts, isolators, 6v, voltage depression, redundancy,etc

http://www.rcuniverse.com/forum/tm.asp?m=424119]

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Stephen
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Wondering about going to a 6V system in my new plane. - 12/17/2002 8:00:09 PM   
sfaust



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[SIZE=3]OUCH!!! IMPORTANT PLEASE READ!!! [/SIZE]

Frankenthumb mentioned 1.1v as the cutoff voltage. I was obviously asleep here. 1.1v per cell is 5.5v. THIS IS VERY BAD!!!! Don't fly down to 1.1v per cell.

The lowest no-fly voltage, if you use that method to determine when to stop flying, is the same as on a 4.8V pack. Basically, its 1.2v per cell, or the cells rated voltage. Ie, 4.8v for 4.8v packs, and 6.0v for 6.0v packs.

1.2v per cell will leave you in the flat portion of the discharge curve before it falls off the end. Its a Conservative number, and should be safe for batterys that are in good condition and of an appropriate capacity.

DONT use 1.1V as the cutoff, unless you know you batteries extremely well!!

(I still laugh evertime I see the frankenthumb. wish I thought of it first )

Sorry I didn't catch that in my first reply,but I am glad that I caught it either way.

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Stephen
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Wondering about going to a 6V system in my new plane. - 12/17/2002 9:41:28 PM   
MHawker



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I assumed he meant a discharged rate of 1.1 volts for cycling purposes. The batteries should be discharged to 1.1 volts during the cycling process to be effectively cycled.

I'm glad you brought it up. That whole "assume" thing. You'd think I'd learn by now.

Mike

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Mike

Anyone know any good blonde jokes? I'll start- "There was this blonde customer service rep..... "

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Re: Re: Wondering about going to a 6V system in my new ... - 12/18/2002 2:23:01 AM   
Gary Retterbush



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[QUOTE]Originally posted by sfaust
(big snip)
3. You will loose approximately 20% of your flight time for the same capacity pack.
[/QUOTE]

For what it's worth, I have done quite a few tests and I have never had over a 12% loss. The whole thing is a bit more complicated than it first appears. YMMV

BTW, sfaust, your web URL under "WWW" in your profile doesn't work.

Gary

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Re: Re: Re: Wondering about going to a 6V system in my ... - 12/18/2002 3:04:33 AM   
sfaust



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[QUOTE]Originally posted by Gary Retterbush


BTW, sfaust, your web URL under "WWW" in your profile doesn't work.

Gary
[/QUOTE]
I just checked, and you are right. It doesn't work because it appears that RUC is putting [url]www.RCUniverse.com[/url] in front of the data I enter in the www profile. It appears that other peoples links work, but for some reason, this one doesn't.

In either case, you can get there by entering [url]www.GiantScaleRC.com[/url] in any browser.

Thanks.

_____________________________

Stephen
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Wondering about going to a 6V system in my new plane. - 12/18/2002 4:32:41 AM   
Gary Retterbush



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Stephan,
Thanks for the info. Glad I mentioned it as it was well worth the trip to your site. Very nice!!
Gary

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       Post #: 13