I don't really want to spend $200 dollars on the 4 or more I really should have. The better ones are quite expensive and involve a lot of electronics. Some of the commercial back-up units look quite good. I too have had success with a dedicated airborne pack, but the added weight and space requirements, and maintenance of yet another critical battery while still having only one power source didn't seem like the best option for me. I actually had just received the final parts to build this system the day before my crash, but hadn't installed it yet. They are cheap, so periodic replacement is probably a good idea in any case.Īfter a recent disaster, I no longer trust the motor LiPo as the sole source of power for my airborne systems. In any case, I have tested my 1S back-up cells after being fully charged for a year (topped up every 3 or 4 months), and they seem as good as new. Multi-cell LiPo batteries are definitely harmed by being left fully charged, but I think that is because imbalances between the cells in the packs cause current flows that damage them. The 1S cells do not seem to suffer any issues being left fully charged for years.
#Back up battery pack how to#
There are lots of explanations on how to test diodes on the internet. You can test whether the diodes work correctly with most multimeters in the diode setting. One builder discovered there are some bad Schottky diodes out there, with only one leg that worked. A 380mAh will give 20 minutes of back-up with most airborne systems Just search eBay for "1545 Schottky diode T0-220". It is impossible to keep up to date links for the Schottky diodes and 1S cells. The original dual Schottky device works just as it always did, and is very simple and low cost. Or Randy's nice implementation of the two zero drop TI device set-up: If I was going to use it in a HV set-up, I would use a small 2S LiFe for back-up.Ĭhris's set-up with the voltage booster to maintain 5V with a 1S cell is very nice: Keep in mind the servos will be slower and less powerful on 1S voltage, so careful use of the big flaps on an F5J plane will be required.
I tested my big glider airborne systems down below 3.5V, and with the zero drop device in the 1S back-up path, that gives me lots of time (20 minutes+) to finish a task and make a safe landing even after telemetry notifies me of the voltage drop on to the 1S back-up. The system I use now is with one of the TI zero forward voltage drop devices (TI SM74611KTTR) for the 1S path and a surface mount Schottky for the BEC path, with a 380mAh Tatu 1S (Amazon) for the back-up battery. While the Zepsus dual battery system system is very nice, I use back-up systems in many airplanes and the cost gets a bit out of hand. There are several excellent versions in here for excellent home-made battery back-up systems. The back-up systems have saved a few airplanes since I fist posted this, which is nice. I'll try to simplify finding relevant information by adding some explanation and links to relevant posts in this first post. Update: This thread has gone on much longer and become much larger than I ever thought it would.
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