Caution about using the capacitor with an ECU. the slow brown out when you shut down can cause funky things to happen to the ECU.

I have been running the Dcup since the first prototypes. Put a separate switch on the DCup so that you can shut it off just before shutting off the jet, so that when you kill power, the jet shuts off now. I nearly lost an aircraft because of an unexplained failsafe, and i troubleshot it down to a couple things, with the repeated brown outs when I shut down power being the thought of the main issue.

Its no problem on a receiver because it simply resets, but the combo of it trying to reset and the low voltage on the ECU caused some condition we cannot explain.

So again, if you are running turbines with the DCup capacitor, put it on a standard switch so you can lock it out when its time to shut it down. Its a wonderful product, it really smooths out transients.

PM me if you need to discuss further..

My observations, and several discussions with Mike and Kurt of Fromeco:

If you run two straight packs into the RX, the cross charging is really negligble because the higher voltage will cause current flow mostly into the RX until it drops down to some nominal value. Its kinda like two cars going down the road at the same speed approximately... they both get there nearly the same time. the difference is not important unless racing..

Add regulators to the mix and things change dramatically:
IF you have two Batts and two regs wired directly into a common bus with no battery sharing circuitry, almost every time, one regulator will be at a slightly higher voltage. That battery provides most of the power except during high demand points. I have done it over and over in bench and flying. My nano has twin regs. I cannot get them closer than .1 volts together, so one battery drains 75% before the other really gets draining. Moral: you must check both batteries. You should learn the characteristics of each setup you do or it will eventually bite you.

If you have some sharing circuitry, it will normally allow the batteries to draw down together. Enter the wolverine, the smartfly, the weatronics..... PB switch...etc... THis gives another level of insurance if that is what you like. My preference is this setup. I use wolverines, or receivers with sharing technology built in. such as JR batt safe rx.

Batteries:
Lions internal resistance allow you to pull them down with less load, thus the 7volt/1amp Rule of thumb. This does not work for any other chemistry. Andy Low has come up with an A123 checker, but before that we checked them unloaded. 6.2 was my minimum, and that was really min.. The only true answer was to know how much the plane used in MAH and never push it past 50% usage. I still live by that rule. the one time I pushed it, I lost a plane because I did infact have a bad cell. If you run A123's you must balance them...there are hundreds of posts as to why, just do it... they actually are more prone to unbalancing than lipos are when used in a very low current setup (receiver packs). Finally Lipos. Like A123's, they have low cell resistance but higher overall voltage, so the ION rules dont apply to them. Jack is right on with the statement about less than 50% remains if you use a ION checker with them. the problem is that its really east to overtax them at low charge state, and with regulator losses factored in, I can see fadeouts happening, so oversizing them is good since they dont weigh alot. I think battery sharing circuitry is the most important running a Lipo.

With todays balancing chargers, you have to learn what each setup uses and how your packs act in each setup. So fly twice, charge....fly twice...charge... see how much you put back. round up to the nearest 100Mah, and then never go past 50% capacity MAH used..

I know some of that info is repeated here but .. thats my 2c for what its worth...

It goes up from there, but that is the basics in my opinion on managing power

Good to bring this point up re: servos stopping at higher voltages than receivers. And a nice catch on the LiIon vs. LiPo ... most of us would not check that unless we used a computer-driven device to plot the discharge curves of our batteries.

The problem with servo drop-out was first noted here on RCU six or so months ago when the junior achievement technical team at JR/Horizon posted a video supposedly showing a Futaba RX stopping working at low voltage. I went looking for the thread so I could link it here but could not find it. I sure hope I recall it correctly... did someone else see it too?

The thread pointed out that if you watch the video closely, the servo (it was a JR of course) stopped responding to stick movements on the TX as the voltage to the Futaba RX (a 607 or 617 as I recall) was lowered ... BUT ... the green light was still on ... the RX was still working. Duh.

I got curious and checked a bunch of Futaba and JR digitals I had in the shop and it was pretty much the same for all .. they stopped close to (but below) 4V and the RX held on much lower.

So, Jack is doing us all a great service in his thorough troubleshooting to remind us if a critical system failure point. And many thanks to the JR/Horizon team for unintentionally bringing attention to the matter in a failed attempt to make a "gotcha video". Perhaps they should hire more engineers and fewer ad copy writers :-)

Dave

Lately I have purchased this item

http://cgi.ebay.co.uk/NEW-BATTERY-IM...ht_2644wt_1139

off EBAY.

Following this great threads from Oliver I am now pretty confident that I know what the health of the heart of my planes (my batteries) is like.

I have also purchased this great charger http://www.hobbyking.com/hobbyking/s...dProduct=10327 which has also a very nice function called "STORAGE" and when I know that I'm not going to use my batteries (LiPo) for more than 2 weeks I discharge them to 7.6V for storage.

At the same time I always keep track of the voltage drop during flight through the Royal screen were there is illustration of current voltage level as well as minimum achieved during flight (dotted line in the picture).

So from now on I keep some basic rules to monitor the power source of my planes and try to protect my investment as much as possible.

1. Once batteries are new I record their impedance (check this out every 3-6 months, once impedance is doubled the battery is near its end of its life)
2. Monitor the capacity of the battery, cycle them every 3-6 months to check their capacity and if its decayed
3. Discharge my batteries to 7.6V (for 2S Lipo) if I'm not going to use them for longer than 2 weeks period
4. Monitor the max voltage the batteries can achieve (usually 8.4V)
5. Monitor the voltage drop after every flight, especially towards the end of the day
6. Charge my batteries after every use to check what was "burnt" in mAh
7. Always DISCONNECT and REMOVE the batteries from the planes

I would like to say a big THANKS to Oli for his great thread and his private support through PMs.

This is what RCU is all about.

Thank you

Tassos

Once again, you're more than welcome Tassos.