Stick 40

I have read that the A123 and Life , don't respond well to an expanded scale voltmeter.

But will the VOLTWATCH give an indication of battery left to use???

thanks
sticks

scale only 4 me

My Feedback: (158)

Voltwatch just tracks Voltage,, not Capacity. They way a123s hold their voltage then drop off voltmeters won't tell you much. To determine your capacity for said plane, you'll want to fly, then recharge to determine how much MAh you use per flight

Charlie P.

The Voltwatch will check the battery under load - if you cycle the servos while watching - but is limited to 4.8v or 6.0v.  Aren't the A123 packs 6.6v or some multiple of 3.3v?  That won't work unless Voltwatch comes out with a new line for the different voltages.

tomfiorentino

voltmagic has a setting for A123 batteries. Of course, you still need to calculate mah used per flight for fl/no fly decisions, but knowing the voltage under load at the receiver is another good component to know. It is very sensitive and samples voltge 1,000 times per second...or something like that.

weighs nothing, use one on all my planes.

Tom

DadsToysBG

My Feedback: (35)

Testing A123 under load is a waist of time. They will put out 6.6 until they don't. Load testing tells you nothing about capacity of MA.
You can use this battery checker. I has tested it with my A123 and it's not accurate but it does give you some idea. Dennis
http://www3.towerhobbies.com/cgi-bin...3000%3C%2Fb%3E

scale only 4 me

My Feedback: (158)

A couple of the FMA chargers have a123/life capacity "estimating" too, if they tell me under 50% I charge. The big plus with a123 is they charge back up so fast, I typically just fly twice top them off and go again, usually no more than 10-15 min. per pack

The best way is to Charge, fly, re-Charge, fly twice re-charge,, etc,, then you'll get an idea how much you're putting back in after 1,2,3 etc. flights,, each plane and flying style will be different as to MAH consumption. after doing this a few times you'll get the feel for your plane.

good luck

DadsToysBG

My Feedback: (35)

I charge mine at 5amp. My 40% gas i can get 5 to 8 flights out of 4600ma depending on how I fly it. what really neat is if i don't fly on one week end i don't have to charge the next. Just go fly. Dennis

Stick 40

I thought the volt watch woud not help. It came with a plane I picked up at a swap meet. I can fly it and charge and get an idea of the draw, I should be able to fly several flights on the 2500 Mah as a flight pack.

thanks

sticks

tomfiorentino

Yes...in the traditional sense. I agree with that, and have said it myself!

However, there is no silver bullet with batteries and I think it's a bunch of things in combination that should be used for overall management. There are all sorts of arguments in this area.

The Voltwatch is very sensitive though. You may not be familiar with the device, but as the instructions indicate, you can "swash the sticks" before a flight and if there is a momentary dip of the voltage to within the parameters set...it will flash yellow. I can still fly on a yellow reading like this, but it just tells me where I am along the way. It is just one more piece of information that I find useful.

I can use 575 mah per flight including ignition on my 50cc bird. I'm comfortable with 4 to 5 flights before recharge. That works.

But what if, say, at the end of flight one I have something bind up, go wrong whatever and it starts hitting the battery hard. In that case the usual 4 to 5 flights might be a problem (still cushion though) and the Voltmagic may alert me to that sooner rather than later.

There is a very slight momentary dip in voltage when you slam the pack with quick amps (swash the sticks) that the Voltmagic detects. There is no downside to knowing it exists I guess is my point.

In fact, I don't have the equipment to do it, but it would be interesting to see if someone can verify at what mah discharge on those 2300 mah packs will voltage dip.

No argument here really...general statement, A123's don't need to be load tested. Its just that tiny dip that Voltwatch picks up on the 50cc and up stuff that I have found interesting. Hook an ESV up to the pack....waste of time. Agree.

Just saying.

Tom

Stick 40

"but as the instructions indicate, you can "swash the sticks" before a flight and if there is a momentary dip of the voltage to within the parameters set...it will flash yellow. I can still fly on a yellow reading like this, but it just tells me where I am "

I did not get instructions with mine, as it came with the plane. But with what you and others have said, I will check this out. It can't hurt to watch this.



sticks

tomfiorentino

http://www.voltmagic.com/instruction.htm


Tom

jester_s1

A Voltwatch is just an ESV with lights instead of a needle. It can't do anything that a regular meter can't do except stay in your plane all the time. The value of a voltwatch is not to check your battery capacity, not even with NiCd's. The value of both a voltwatch or an ESV is to make sure your battery and connections are still good for the next flight. Cycle testing, as mentioned above, is the right way to keep up with battery capacity. If you do it regularly, you'll notice if your plane suddenly starts using more battery than it used to. Fly down to 1/2 capacity based on your estimates for how much a flight uses, then recharge.

tomfiorentino

Jester,

You wont get an argument from me on cycle testing for capacity and monitoring mah per flight.

But to call a Voltwatch an ESV with lights instead of a needle is an oversimplification that invalidates the point I was trying to make. There is a big difference between plugging an ESV into a switchport and reading voltage at the battery vs monitoring voltage at the receiver during normal flight conditions and recording the average voltage experienced by the system as well as recording the Peak Low Voltage (PLV) that was experienced. You cant do the ladder with the traditional ESV. In addition, since the sensitivity and voltage sample rate of the Voltwatch is so significantly morre frequent, it "sees" voltage dips that the standard ESV won't register.

I can tell you that with a fresh A123 pack I can swash the sticks before a flight and the lights stay green (according to my pre-sets). By the fourth flight, I swash the sticks and I get a yellow. That is confirmation for me, that my power system that day for that very next flight is tracking with my expereince of what is to be expected.

I can also tell you that at the end of each flight I can see the average voltage during the last flight and the PLV as well (in fact this information is stored and shown momentarily on the very net power-up).

This, in addition to cycle testing for capacity and monitoring mah per flight on re-charge is what I use in combination.

Thanks for you comments! Some of this is nuance...I know.

Tom

jester_s1

Agreed, the voltwatch is a handy tool for knowing what voltage your system is actually getting while in use. My only point is that it is not a fuel gauge for the remaining battery capacity, which is what many want to use it for.

Myself, I don't use a voltwatch but I plug in a digital multimeter to an unused channel and flew a control surface to simulate the flight load. I don't get data logging that way, but I am able to see how much voltage the receiver gets in the real world. Flexing two servos to their stall points is more of a load that I'll ever get in flight, so if I can do that for a couple of seconds and the voltage holds up then I'm good to go.