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Jan 11, 2012, 03:49 PM
Registered User
DontTMACajun's Avatar
Discussion

Lipo "fuel gauge", worth it?


So I've stumbled across the "lipo fuel gauge"....generally a small circuit board with color-coded LEDs which (when plugged into the charging port of your lipo battery) gives you an indication of the remaining charge.

http://www.stormerhobbies.com/cgi-bi...pn=CSRFGAUGE14

There are more on Ebay, Amazon, and a half-dozen other sites...some waaaay overpriced, some priced just about right.

My question is - can it be used in-flight, or is it strictly for on-the-ground? I was thinking (which normally isn't a good thing, but in this case I might have a good idea!) "maybe I'll attach one of those fuel gauges to the outside of my airplane, plug it in, and go fly. A quick fly-by would tell me how much juice is left in my pack". Can it be done like that? Anyone have any experience with these things?

Thanks in advance
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Jan 11, 2012, 03:56 PM
Stress Be Gone
GBR2's Avatar
I like the Electrodynamic EDR-207. There is also a generic version of the same device that is less expensive. Then there is the Lipo gauge that NQRC/ PL Daniels Electronics, makes that uses a digital readout to tell you how many milliamps you have used.
Jan 11, 2012, 04:02 PM
Go Hawks!
cryhavoc38's Avatar
simplest method is to time your flights where you have approx 20% left in your lipo's.
You can get this number by flying for a set number of minutes, land, charge your pack and see how many mAh it takes to get your pack to full charge.

Do this a few times until you need to put back approx 80% of the packs capacity. Then you know what your safe flight times should be.

A better alternative to the led readout is the handy Quanum telemetry unit that Hobbyking sells, or of course, any of the newer radio systems that have telemetry modules/abilities.
Jan 11, 2012, 04:05 PM
Registered User
Hobbyking has a great cell checker for about 16$. I have one and find it to be a valuable piece of electronics and so do all my flying buddies who use it after every flight.
Jan 11, 2012, 04:10 PM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
I've got one with an alarm, you can set the alarm at any voltage and it sounds when any of the cells reaches that pre-set voltage. You could set it just a little higher than your ESC LVC which would give you suitable warning when it was time to come down without the danger of actually hitting the LVC. It's pretty loud so you can hear it in flight.
In practice though I just tend to use it to check my lipo's on the ground and fly to a timer, as suggested above..

Steve

Edit.. this is the one I have: http://www.brchobbies.co.uk/?page=shop&item=183
Jan 11, 2012, 07:15 PM
Cajun-American
Boogie_'s Avatar
Alright!! a fellow coon-ass. ...how 'bout dem Tigers!

A volt meter to monitor your battery levels after a flight is a great idea. ...almost a must to determine your flight times.

Any number of hobby sites have them for less than $5 bucks:

http://www.hobbyking.com/hobbyking/s...itor_2_6S.html

They're usually not super accurate but will get you in the ball park keeping you from harming your batts.
Jan 11, 2012, 08:19 PM
Not failing=Not trying enough
Wehrdo's Avatar
I got one from hobbypartz for $3. It matches my multimeter exactly, and gives readings to two decimal places. It's the best $3 I've spent in this hobby. Before I usually came in between 60 and 70 percent of my battery. I now consistently drain it to around 45%(Pretty full, but I still get 15 minutes of flight time, and it's easy on my batteries)

Like mentioned, if you want the best you can, get a telemetry system that shows your voltage. I think the Turnigy 9x can do telemetry with a certain module and Rx. I could be wrong though.
Jan 12, 2012, 02:51 AM
Registered User
Time yout flights, you get used to how long to stay in the air with each different plane. I always end up bringing my pacs in at 3.8 let per cell. Very close every time and I haven't ran to LVC since I have been timing.
Jan 12, 2012, 06:21 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Quote:
Originally Posted by Tony K
Time yout flights, you get used to how long to stay in the air with each different plane. I always end up bringing my pacs in at 3.8 let per cell. Very close every time and I haven't ran to LVC since I have been timing.
I time my flights too but I can still see a potential use a low battery alarm. Batteries loose performance over time, you might fly for (say) ten minutes now but maybe in a few flights time your battery might start losing performance and before you know it you hit LVC. Then there is the possibility of user error and putting in a part charged battery or forgetting to start the timer (lost count of how often I've done that). Or maybe you just gain confidence with a plane and fly harder.

The failing battery issue happened to me only this weekend. Luckily it was no big deal and I managed to land ok but I'd been doing low level aerobatics at the time it could have ended in tears. I’ve just ordered a couple more of these alarms so i can have one in each plane.. cheap insurance!

Steve
Jan 12, 2012, 06:59 AM
Registered User
Andy W's Avatar
I use mine (a model that Hobby Lobby introduced years ago) just about every time I touch a LiPo - before and after flights and before and after charging. It will instantly warn you if there is any cell imbalance, and of course knowing you are putting a full-charged battery into the model is important.

The only exception is if I am using a balancing charger, as the balancer itself (I use the TP ones with the external balancers) indicate balance state - so I know those are good when I take them off the charger.
..a
Jan 12, 2012, 11:12 AM
3D, 1D at a time!
Park_aviator's Avatar
Quote:
Originally Posted by Andy W
I use mine (a model that Hobby Lobby introduced years ago) just about every time I touch a LiPo - before and after flights and before and after charging. It will instantly warn you if there is any cell imbalance, and of course knowing you are putting a full-charged battery into the model is important.

The only exception is if I am using a balancing charger, as the balancer itself (I use the TP ones with the external balancers) indicate balance state - so I know those are good when I take them off the charger.
..a
Same. I use this one. http://www.hobbyking.com/hobbyking/s...System_6S.html

Works great!
Jan 12, 2012, 02:53 PM
miniture aircraft pilot
rcshirt's Avatar
i use one , to quickly see the power taken out on a flight. however i noticed if left plugged in .. it can show you out of power as the voltage drops under load. this can be on a near fresh battery. it is also hard to see individual cells at any distance. great pocket tool for checking all batteries. etheir one is fine. but the colors translate to the newer/or nitro flyers. as they don't know what a full or discarged lipo voltage should run.
Sep 20, 2012, 02:47 PM
we can take off without that
green_flyer's Avatar
Exactly! My mini edf jet knocks the 3s fresh packs down to 10.5V from the start, so a Low Voltage counter/buzzer is pretty useless during the flight. What I really want is a very light coulomb counter which will monitor the charge state (not voltage) of the battery, and be programmable so it gives a waring when a pre-programmed number of mAh have been used up.
Sep 22, 2012, 12:32 AM
Arizona Fun

Have two...


I have two of them, never used them. Seemed like a great idea when I bought them but having gotten used to using a timer and having LVC as a fail safe I never had the inspiration to hook them up. Would have to mount them outside the plane so you can see the LED lights while flying, seems cool to see those pretty lights but figured I'd spend too much time doing low passes looking at the lights to see my current battery state. I'd give them to you if I could. After writing this it may provoke me to hook one up and give it a try. I agree with the others that using a timer is the best. I get digital kitchen timers from Target for $6 and attach them to my radio, very handy...
Sep 23, 2012, 10:57 AM
we can take off without that
green_flyer's Avatar
I use a timer too (on the transmitter) but find that my flights are so variable, sometimes I go round full throttle all the way, sometimes I cruise around slowly. With a EDF this makes a hugedifference, I have seen my batteries come down from 10.9V to 11.5V. So a really light coulomb counter with a byzzer, or a single warning LED on a long wire would have been really usefull.


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