Safely discharge to storage voltage

[wacked215]

Folks,

Let’s say you charge up past 86V to go fly but then don’t end up flying. How do you safely discharge your battery back down to storage voltage? Obviously flying is the most desirable option but it is not always possible.

[Jackal (Marius Suciu)]

Inverter working great with my half hour batteries!

I finally had to use the inverter for real. Three days ago the conditions looked ok for a spin but when I arrived at the site, the parking lot gates were closed and a sign read “Closed for dune erosion”. Bummer! We had a nasty storm last weekend here on Long Island. I drove back home with a fully charged battery. The weather did not improve. Rain and higher wind speeds are in the forecast. So, I connected the inverter to the half hour battery and turned the ceramic heater ON at the lowest setti…

SP140 battery discharge for storage/transport

Any suggestions on the best method to discharge the SP140 battery for storage, if unable to fly or run the motor? I was thinking of building a discharge load with several power resistors, but open to suggestions. Don’t require quick discharge times, I am fine letting it drain over a day.

[Voltair (Phil)]

Hi Marius, I have been using this model. Just make sure to choose the correct AC voltage depending on the country you live in (110 or 220V) Pure Sine Wave Power Inverter 1500W 96V DC to AC 120V 220V Solar System Off Grid | eBay
With the old 1/2 hour battery I plugged my office LED lights for a couple days - about 9 hours per day or my small ceramic heater on the low setting. It did the job in less than an hour with the heater. Need to keep an eye on the inverter screen. I usually dropped the voltage to 85V because it went back up a bit after unplugging the battery. I kept my battery at 86V. for storage.
Have not done it yet with the new half size battery but Paul told me to keep each cell between 3.2 to 3.8V for long term storage.

[Jackal (Marius Suciu)]

Thanks Phil, I use an infrared heater myself, just posted these thread links for wacked215.

[hortoni (Brian)]

I looked at going the inverter route but it was pricey and required careful babysitting to be sure I didn’t overshoot the target voltage, I ended up buying a KP184 DC Electronic Load from Amazon. I wired in a plug to connect directly to the battery and I can use the discharge mode to enter a target voltage. It will discharge at about 400 watts and automatically shutoff when the target voltage is reached. The price was right around $100.00. An inverter would be quicker but more expensive, more complicated and riskier. It discharged my battery from full to storage level in a few hours.