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Question about discharging lipos
Serious question that just came to me... Let me set up a scenario:
Two Hitec X4 multi chargers are discharging 8 total 4S lipos at 3A. Where does the energy go? From battery, to charger, to power supply, then where? I could be using that energy to charge other batteries... |
Its usually burned off thru resistors. Thats why your charger gets really warm while it discharges.
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Most chargers just dump the discharged energy off as heat. The only exceptions I can think of offhand are iChargers and PowerLabs that have a regenerative discharge feature. They can dump the energy back into a lead acid battery used as a power source.
I doubt the X4 can discharge a 4S at 3 amps. Believe it is limited to 5 watts per port of discharge power, or around 0.3 to 0.4 amps on a 4S lipo. |
Hitec X4's are hooked up to 25A power supplies. So you're saying the discharge energy dissipates within the charger? Show me a link to evidence and I'll believe you. ;)
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Whats not to beleive? Thats how its been done for a long time now. Set up one X4 to charge 4 batts, and the other to discharge 4 batt and feel the heatsinks. I garuntee the discharging one will be much hotter. Thats because it sends the current through a bank of ceramic resistors connected to your heatsink. If you wanna regain that energy make an adaptor to hook your charger inputs to your battery. It wont last long tho.
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It's not that complex. The power from the cells are passed through resisters which are attached to heatsinks which dissipated the heat. That's all. Back in the day of Nimh or Nicad, we used automotive lightbulbs wired in series to discharge batteries. That method can still be used but you need to monitor voltage so you don't go below 3.0 volts per cell.
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I have the venom pro chargers and I tried one time(I don't discharge ever cause it don't seem good for battery or charger) to see what it would do, and the charger gets so hot that I could smell it, so I shut it off but it def does get hot!!!
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Originally Posted by matt_is_superco
(Post 12316141)
Hitec X4's are hooked up to 25A power supplies. So you're saying the discharge energy dissipates within the charger? Show me a link to evidence and I'll believe you. ;)
A couple clips from the iCharger 106B+ manual (with my highlighting): Maximum discharge power capacity: 20W Maximum regenerative discharge power capacity: 250W Up to 250w unique regenerative discharge capability. Regenerative discharge takes most of the output battery‘s energy and puts it back into the input battery, which is not the same with the traditional methods of discharge to deplete that energy in the form of heat across a transistor. That is, when you discharge your LiPo for storage, you will be re-charging your Lead Acid input battery. The amount of current and voltage that your input battery can accept limit the total amount of power that you can achieve, or 250W, whichever is lower. A clip from the PowerLab 8 manual (with my highlighting): Selectable discharge: • Internal discharge 10mA to 10A, 100W max. • Regenerative discharge 10mA to 40A, 1344W maximum when powering the PowerLab 8 from a Lead Acid battery. Regenerative discharge takes most of that energy and puts it back into the input battery. For example, when you discharge a LiPo pack for storage, you will be recharging your Lead Acid input battery. |
Discharging is perfectly safe if the voltage is monitored. Why else would manufacturers put the function there. Really good chargers have fans to cool the heatsinks/ resistors.
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+1 on discharging/storage charge...wouldn't recommend leaving LiPo's at full charge longer than a few days, as it can quickly shorten lifespan and cause cell damage.
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