Article-Smart Lipo Discharger Review
by Chris Bajorek
(article reprint from July 2018 Sacramento Valley Soaring Society newsletter)
Anyone who has been flying electrics for awhile has heard that your Lipo packs will last longer if you don’t leave them in a full state of charge for a long time. Lipo battery manufacturers state that you should set your packs to a storage level (~3.8v/cell) if you’re not going to use them within a few days. Here’s one of many online lipo battery care guides that explains this requirement (https://rogershobbycenter.com/lipoguide/). See the “Proper Care & Treatment: Storage” section which states that leaving lipo packs in a fully charged state for as short as a week can cause long term damage that can reduce the usable capacity of the cell.
I’ve been flying F5J electrics for 3+ years and now have a fair number of lipo packs to manage. Yes, I have been guilty of leaving packs in a fully-charged state for long periods. My excuse: too much hassle to set my charger to “storage” mode and run it on each pack. Part of the problem is that my chargers limit the discharge current so it can take a long time to discharge packs to the storage level.
Enter the ISDT FD100 Smart Discharger available from Aloft. I bought one of these a few months ago. This is a small unit with a single purpose: it will safely and quickly discharge your lipo packs for safe storage.
The Smart Discharger unit is elegantly simple: plug in your lipo battery pack (no external power supply needed), set the number of cells (2-8), set the discharge current you want to use (0.5 to 6A), and it will discharge your pack. When done it gives you a repeating beep signal. One of the big benefits of using this unit is that it can be set to discharge currents of up to 6A. The Smart Discharger uses large power resistors mounted to the thick aluminum case and a thermally-controlled fan to keep things safely cool. Many lipo chargers can’t discharge at currents this high so they take longer to do the same job. The Smart Discharger can dissipate up to 80W of continuous discharge energy whereas many chargers can only handle 5-10W.
So how smart is the Smart Discharger? I took a closer look and connected my wattmeter between a fully charged 3S 1300mAh lipo pack and the unit and watched how it ran the discharge cycle. It gradually ramped up the 4A discharge current for a minute, then ran at the set current level for 6 minutes, then it started dropping the current down in steps while monitoring the pack’s voltage. It kept doing this until the pack’s proper storage voltage level held. Then it shut down the load and signaled complete with beeps. A fully charged 3S 1300mAh pack discharged at 4A in 14 minutes. My charger would have taken 2x that time. I ran another test on one of my fully charged 3S 850mAh packs and storage-discharged it in 8.5 minutes at 5A.
The key here is simplicity: plug your packs in, push the button, and Smart Discharger does the rest. If you’re thinking this sounds like a luxury device think again. I’m here to tell you it is a major time saver and, more importantly, it completely removed the excuse I had of just leaving my packs charged because it was too much hassle to storage-cycle them.
USAGE NOTE: If you are in the habit of running your batteries way down when you use them, be advised that this discharger will not charge them back up.
This has become one of my essential battery maintenance tools. Highly recommended.
For More Information
$27.25 from Aloft Hobbies ( https://alofthobbies.com )
Smart Charger detail page: https://alofthobbies.com/isdt-fd100-smart-discharger.html