bruce88123

The cheap ones are probably the REJECTS from the Voltwatch production line. They're called "floor sweepings".

Jetdesign

My Feedback: (8)

So it's o.k. to "y-off" a servo with a voltwatch? I was wondering what you do if you need all the channels in the receive for servos; I have an 8 channel receiver, and one channel is used for the battery, and I intend to (way in the future!) fill those 7 spots with servos.

Missileman

Yes, you can Y just about anything. In fact you can Y the battery in too and still use all 8 channels.

CGRetired

My Feedback: (1)

All the Y does is expand the slots in the receiver. And all the voltwatch connects to is the battery supply + and - . So, you can connect to that anywhere as long as it's in the circuit (which means NOT the charge jack because when the switch is turned on (presuming you use a switch), the charge jack is OUT of the battery circuit.

So, a Y, paired with a servo is just fine. Heck, you can also parallel up a second battery that way, again, through a second switch is best.

CGr.

TCrafty

I check with a volt meter each flight. Don't know why some are complaining about having to do that. To me, it's just like fueling the plane, just something you must do before you fly.

CGRetired

My Feedback: (1)

Nobody is complaining, just making suggestions to make it easier to do and simple to remember. That's all. Hey, if you are disciplined enough to do that then knock yer'self out.

CGr.

TCrafty

I feel that it's cheap insurance. Even at that, you're not guaranteed that something else might go wrong. I was just referring to the post a few pages back where a gentleman was saying that his club requires checking at each flight. He mentioned that luckily, they've not enforced it yet. I'm not a prude and I'm definitely not narrow minded but I could fit in there (at least in this situation) without much heartburn on my part. Not poking with sticks here, just saying that to me, that rule would be a non-issue.

CGRetired

My Feedback: (1)

Oh, no, I didn't mean to imply that. I just wanted to let you know that there are easier methods, and it simply helps people do something that should be done on every flight. I have both an ESV and use voltwatch.. as Justin Wilson (the cajun cook) says, "Always wear a belt AND suspenders!!".

Many of the posters, well, perhaps quite a few, are self taught. They have probably experienced more crashes than most of us 'formal' trained RC'ers have. Those of us that HAVE had 'formal' training, were, hopefully, introduced to the "Pre-Flight Inspection". Part of that is to check the battery (plural if more than one on the plane) before flying for the first time, then, hopefully, at least before each and every flight (I do it before AND AFTER each flight.. again, belt AND suspenders). The self taught never had that bit of information passed on to them by their instructors and are pretty much stuck with blaming inexperience on their crashes. Although not checking batteries may be included in the 'inexperience' factor, they do not understand that and attribute crashes to their lack of hand-eye coordination and the basics of flight, let alone what can happen if that battery is borderline.

And my comments were in no way intended to be disruptive. I admire someone that has the discipline to do what you do. That implies someone that is probably more organized than I am..

CGr.

waynemia

My Feedback: (2)

All the arguments about loaded and unloaded voltages are correct. If you measure the votage with with the system on and servos moving, you will see loaded voltage. The loaded meters are easier for this and usually have a go/nogo indication based on the settings of the meter.

My suggestion is to check the batteries with your load meter when you fuel the plane. Make it part of your flight preparation. You should also check linkages, etc. I am a Private Pilot and the FAA requires pilots to use a pre-flight checklist to ensure the plane is ready. RC pilots would be wise to do the same thing. Range checks, landing gear, motor mounts, battery voltages, servo throws should be done a lot more than what I typically see at the field.

A lot of people check everything at home. I do a lot of hangar work too. The transportation of the plane provides opportunities for failures and a field check it best.

Batteries are another issue all together. I have been involved in engineering battery powered equipment for a long time. The real problem with NiCads and battery testers is the discharge curve. These batteries have a very sharp knee. This means that the voltage is relatively constant with only a slight decrease in voltage for most of the charge. When they hit the dicharged level, you are typically done! When we design battery indicators, the low battery level is really unreliable be cause you just do not have enough warning between the low level and the discharged level.

If you really want to know, measure the current used by the plane during normal operation. Normal depends on the kind of flying you do. You can measure the current by placeing an ammeter inline with the battery.

Now look at your battery. It has a mAh rating. This is the amount of current the battery is rated for if discharged in one hour. If you have a 600mAh battery and your current is 125mA for example, you should expect the battery to be good for 4.8 hours. Now for safety, only expect to use 90% of the capacity. 4.32 hours or round down to 4 hours. This is just a for instance. Manage your battery time at the field by keeping the plane turned off when you are not using it. If you don't think you have enough time for a day at the field, you can take a charger or get a bigger (heavier) battery.

You should also have a cycler and cycle your NiCads periodically. This will reduce worries about memory issues. A lot of the chargers have this as built-in feature.

Give your batteries as much attention as you to the engine and the rest of your planes and you probably don't need to spend money on a meter for every plane.

Good Luck.

YUKONFLYR

I cycle my batteries prior to going to the field. I check the battery voltage each flight and range check at the beginning of the day. When I get home I discharge them on the cycler to see what is left. The voltmeter reading is only a guide for me in the field. If I have any doubts, I will swap out the pack with a fresh one and then check the voltage again.

kid chuckles

Well i charge my battery's on Fri. night to prepare for Sat. But have flown for a couple weeks on a 600 4.8 pulling 5 servos, all DS821'2 and had no problems. I put a Voltwatch on mine just because i think they are cool looking. Late in the evenings espesially. The little lights bilinking across when
you turn on the switch, is really bling for me but it also lets me know when i need recharging If i get down to third light i go home lol. But mine has only gotten that low once.

Campgems

The other option is a field charger. I have gotten to the point that I almost never charge my batteries at home. I get to the field 20 minutes or so before I want to fly and the first thing I do is to charge my Receiver battery. I am still flying Ni-cads in the plane and I use 1000mah packs. Usually after three flights and then setting for a couple days before the next trip to the field, the pack is usually down about three lights on the voltwatch. This is still in the safe range, but I top it off prior to flying. I get a much better charge this way as my field charger is an intellegent charger that can tell when the battery is topped off. Neither the wall wart or the Accucyle charger can tell when the battery if topped off. With the wall wart it isn't to much of an issue as the current is very low. I have blown a new Ni-Mh transmitter pack on the Accucycle topping it off overnight. It was showing great voltage at the start of my first flight and within about three minutes, the transmitter alarm was going off. One cell had "vented" as they say. The field charger recognizes when peak charge has been achieved and gives you an alarm to let you know it's finished.

One thing about the Ni-cads is that they fall off peak just setting. If you fully charge one and then check it 12 hours later, there is a noticable drop in voltage. After 24 hours, I wouldn't try to fly without topping off again.

Don

kid chuckles

Man my charger when i take it to the field and it runs off my truck batt. it takes seems like forever for it to charge anything. It takes it while to charge plugged into wall but not nearly as long as at the field. Maybe it is because I have nothing to kill time and just notice it more. Very seldom do I even take it anymore as i keep my batteries pretty much charged all the time. Most times i start charging again as soon as i get home. But there have been times i have not charged in over a week and still fly with no problems. But the Voltwatch keeps me in the know enough not to worry to much. If batteries do adapt memory mine should really never go down lol. The should remember they are charged up and stay that way rofl.

Rodney

Both NiCad and NiMh have a rather rapid (relative to PB or LI based batteries) self discharge, NiMh twice as bad as NiCad. Both increase in self discharge rate with age. Initially NiMh about 3-5% day and NiCad 1-3% per day. Note: this is in % of present charge, like a capacitor, never discharges to zero but continues to discharge a percentage of remaining capacity each day.

Campgems

Rodney, not to be argumentive, but I'm not seeing the self discharge you are stating on Ni-Mh batteries. I have two 9CAP transmitters, one is my backup and the other is flown three times a week on average. I orginally had 1000mah Ni-Cads in them and if I didn't charge overnight they wouldn't be near topped off when I went to fly, even if they had been the day before. This was a real pain as I live near the coast and fog to mid day is not uncommon, so I almost had to charge every night even if I didn't get to fly every day.

I switched over to 2300Mah Ni-Mh batterys and now, I can leave the transmitter in the trunk for a week or more and still be good for flying all day. The standby transmitter hasn't been charged in near four months and it is showing 10.1V this morning. It has no flight time on it so it is all self discharge time. My other hasn't been charged in over four weeks and has maybe eight flights on it. It is also showing 10.1V.

I did a little Excel work and if the discharge rate was 0.1% of the previous days charge, starting with a 11V charge, it would take 85 days to drop to the 10.1V stage. At 1%, it would be there in 10 days. I am guessing as I don't remember the exact day I charged the standby, but it looks as if the self discharge rate is close to 0.075% a day. That would put me at the 10.1V at 115 days of shelf life and still have a couple day flying avaible. Aint bad

Don

kid chuckles

That is good to know Camp, but i will still try and charge my Transmitter before going to fly, if going to be flying awhile and a couple diff., planes. I still think the Voltwatch dealy is cool though. Here is mine on a tinted canopy.

HighPlains

My Feedback: (1)

Although many on this thread seem to have an almost religious fervor on the subject of the Voltwatch, I don’t think it’s worth any more than a warm bucket of spit. It is completely uncalibrated, nor does it have a realistic load applied to the battery. You might as well look at moss growing on the north side of a tree to get an idea of the condition of your flight pack.

You are much better taking actual data (voltage measured by a digital voltmeter to at least 0.01 Volts) with a fixed load (just a simple power resistor), based on the size of the model, type of servos, and battery pack size. On top of making these spot measurements at the field before every flight, you need to test the pack from a fully charged state to its discharged state. Unlike so many posts on RCU where the poster states the battery is used up at 1.2 volts per cell, they actually continue to do useful work all the way down to 1.07 volts per cell. That is the typical voltage of the knee that has been mentioned. But since you can not depend on the cells to be completely balanced in capacity, it is a good idea to never go past the 1.12 V – 1.15V or about 4.5 to 4.6 Volts for a 4.8 Volt pack.

To find out how many flights a pack is good for, test the pack under your load and plot the voltage vs. time to below 4.40 volts. Charge up and go fly what you consider a safe number of flights. When you return home, continue to discharge the pack with your load resistor to see how much time is left to the 4.40 volts. This will tell you if you are safe or on the edge. Most of you will be surprised to find out that the pack has several more safe flights left in it and another one or two on the edge. Since you have already taken the data with the load resistor, you can always determine where you are in the battery pack’s discharged cycle, based on your discharge plot.

The other thing about the Voltwatch. It’s always discharging your battery while in flight. The specifications indicate that it could be using as much as 34 mA, which is a considerable discharge and wasted battery capacity.

But this is just my opinion, based on 37+ years of flying RC and a degree in Electrical Engineering.

Missileman

Never mind, not worth arguing over.
I will just go pray to my voltwatch and fly my plane until my bucket of spit runs over.

hungryandbroke

I AGREE 100%

Just another product for the manufactures to make more money off of.

I've been flying for 35 years and never found a need for one!

Campgems

Kid, I use the volt watches on all my planes. The issue with charging is that it is easy to overcharge. I've blown a couple packs doing that. The Ni-Mh comes with a warning to not leave it on the trickle charge as it will over charge. I look at my fleet of chargers and the only one that claims to peak charge without over charge is my field charger. My plane is usually at about 3/4 or more when I get home, so if I'm going out to the field again in the next couple days, I just wait until I get out there and top it off with the field charger. I'm currently running 1000mah Ni-Cad packs and with my field charger, it is only a maner of 10 minutes or so to get it back on top. The transmitter though is a different deal. The battery is like the bunny add, it just keeps on going. With the Ni-cad that was in it, I couldn't get it to hold over 10.4V going from the charger to the field. This was with a new battery. The Orginal 600mah got side tracked after a few months. With the Ni-mh I'm not using, I can't see a need to cycle it because it still has almost the full charge the Ni-cad had after a number of fly days. I don't dare top it as that may over charge it. I'll waith until I get down around 9.5V or so and then cycle it back up. I guess I could get another field charger and do both the receiver and transmitter at the same time, but what I'm doing now works well.

Don

CGRetired

My Feedback: (1)

HighPlains and hungryandbroke

I think you are missing the point here. If proper care is taken with your battery pack, then there is no need for anything. But, most of us do what we can to fly and keep our batteries charged. I take pains to make sure that they are charged enough to fly. The voltwatch does that very nicely. It gives me a visual indication of what is going on before and after each flight, so it gives me a good feeling for what happened during flight.

The specs for voltwatch say 4 - 34 ma current draw. That's a range of current draw with the minimum being least active and the most current is with all LED's lit. Come on, don't be a politician and give the worse condition as a typical operation example. Normal operation is probably in the range of 10 to 20 ma. And that's probably an over estimation. Rarely (if ever) are all the LED's lit. And you know that they have to list the worse condition even though it will most likely never happen.

For a healthy receiver system, and a properly charged battery if sufficient capacity, (standard shipiment is around 700 mah with new transmitters.. I use a 1200ma NiMh 5 cell pack, on some aircraft, two of these) there is plenty of available current without even considering voltwatch. Even at 20 ma/hour, that would take 14 hours to fully drain a 700 mah battery. I don't see people flying continuously for even 5 hours, giving lots of room for the voltwatch current draw.

Of course it's not calibrated. Who cares. It's for an indication, not a precise measurement of battery voltage. If it goes to the yellow or red, it's time to recharge before flying again. What needs to be calibrated with that type of display? Come on. And of course it's connected to a load, and a proper load. What are servo's and a receiver considered? If not a load, then what? Do they put a demand on the battery? Mine do.

Don't over-exaggerate just to try to prove a point. The current draw is minimal and you know it. The use of voltwatch is a good practice, and the device is a good product.

CGr.

kid chuckles

Well ain't it cool though HighPlains? And good post there CG. I knew i had a good reason just besides i like the way they look under the canopys. I have been using them almost since i started flying about a yr ago and a month or two. Sorry they did not have them earlier so you could have enjoyed them more HighPlains. Man a bucket of spit that is nasty rofl. (stay on topic lol) and spit is not the topic. Anyway good debate some of us like them I more for the apperance. Some get peace of mind and weather they work for intended use or not Peace of mind is a very good thing flying. I have found out that at times i get the shakes and when i do I land quickly and try to calm down. Peace of mind helps in that regard. I know very seldom do get the shakes and even when i am in trouble i stay calm and usually fly out of it and it is the VOLTWATCH that keeps me calm and cool, knowing even if i crash my battery was not the reason rofl. Also when you use the Voltwatch it actually gives you more Horsepower and aids in making all landings smooth and easy. It attracts women and makes you smell better also. So many positives how could you not use it. J/K guys. (really does not help much with smell) lol.

-pkh-

My Feedback: (2)

I've seen at least two guys loose planes with this method of flying. What is a safe number of flights for your pack one month, may not be a safe number of flights the next. Check it before each flight, with a loaded ESV or a Voltwatch.

WILDCRASHWILLY

I have a volt watch on most of my planes. I do not believe it should take the place of a volt meter at all. I check the voltwatch immediately upon landing to get a summary impression of my battery's health. That being said, I use the voltwatch in conjunction with the analog volt meter. Every third flight I use the meter as added checks prior to flying. However there have been times I have used a voltmeter on the second flight if the volt watch displayed anything that I'm not used to seeing or peaked my interest for some reason for that particular plane. Because of the volt watch I more readily recognize trends such as, I've noticed on extremely hot days the batteries on some of my planes exhibit a little more power drain than on mild days. Nothing alarming and have had to take no corrective action but not sure I would have picked up on it with the volt meter alone as it is usually several minutes after a flight before I connect a meter. The voltwatch does help me to be more aware and causes me to pick up the meter more readily.

Missileman

HighPlains,
I have to ask. Why exactly was a 34ma load a concern? Even if the Voltwatch is maxed out throughout the entire time of use, which it isn't, a ten minute flight would result in it chewing up a whopping 5.6mah out of my battery pack, even with a measly 600mah pack that is less than 1%. Just a drop in that bucket of spit.