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Idea to discharge??

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Old 01-14-2013, 07:09 PM
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rcfan450
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Default Idea to discharge??

Usually I discharge my lipos by putting them in some other rc toy - like my Traxxas Revos. But I have some lipos stuck in planes that I can't get out, got any ideas of ways to discharge them. I would just leave the plane on and watch the voltage but they're also hooked to the electronic ignition and I don't want that thing running forever unused. I hate storing them at 4.xx volts/cell when they should be at 3.8ish.

I know, I need to just buy a charger that can discharge them... but until I can do that, got any ingenious ideas?
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Old 01-14-2013, 07:15 PM
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Default RE: Idea to discharge??

I may have just found my own solution. found an old brushed motor that I don't care about, going to hook it up and watch the voltage fall....
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Old 01-15-2013, 02:49 AM
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Default RE: Idea to discharge??

a lamp. [link=https://sites.google.com/site/tjinguytech/charging-how-tos/light-bulb-load] click[/link]
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Old 01-15-2013, 07:16 AM
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Default RE: Idea to discharge??

Thanks. I like that better than my .5A load motor that takes forever to discharge and makes all kinds of noise while doing it. I did it to one battery last night, I have 4 more to do. The light idea will go much quicker...and light up my man-cave at the same time!
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Old 01-15-2013, 07:44 AM
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Default RE: Idea to discharge??

Two lights would do it twice as fast!
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Old 01-15-2013, 07:51 AM
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rcfan450
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Default RE: Idea to discharge??

It was $9 bucks for a pack of 10 or $12 for a pack of 25. I got 25 12v 20w bulbs. 4 will do the trick for what I want though. ha ha
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Old 01-15-2013, 09:21 AM
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Default RE: Idea to discharge??

Start off with one and time it. Then add a second make a log, you don't want to discharge too quickly.
I wouldn't go no more than 7C, Be careful of the wires getting hot when adding more lamps.
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Old 01-16-2013, 03:38 PM
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Default RE: Idea to discharge??

I know it's preaching, but leaving Lipos installed is asking for trouble, as is charging them installed. I store mine in an old microwave in the basement, during the summer they're left in an old grille.
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Old 01-17-2013, 03:33 AM
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Default RE: Idea to discharge??

if it's too much load, it's asking for trouble, Thats why 7C is the highest I'd go, even if the pack has a discharge rate of 40C,
Using a junk charger is trouble, but people save a few dollars to buy better packs. A bad charger will wreck any pack.
Lipos have the potential to be dangerous, but people give them that potential.
Aren't microwaves nearly fully sealed with a glass front. This is potentially dangerous.
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Old 01-18-2013, 01:14 AM
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Default RE: Idea to discharge??

yeah,I did it to one battery lastnight, I have 4 more to do. The light idea will go much quicker.thank you[img]http://www.*****.us/imax/images/9.gif[/img]
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Old 01-18-2013, 01:44 AM
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Cool, do you have an alarm/monitor plugged into the balance connector to keep check of the lipo and to warn you when it's nearly at the voltage you want it at.
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Old 01-29-2013, 02:32 PM
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Default RE: Idea to discharge??

Quote:
ORIGINAL: trax de max

a lamp. [link=https://sites.google.com/site/tjinguytech/charging-how-tos/light-bulb-load] click[/link]
Thanks for this link. I copied you. Didn't do two different circuits (one for 12v and 24v, just 12v), just made one with several a few different lines of lights. So the further to the right I plug the banana plug in, the higher amount of lights will be pulling watts... if that makes sense. See video
[youtube][link=http://youtu.be/Aaxp4LCeHMw]http://youtu.be/Aaxp4LCeHMw[/link][/youtube]

I hate it when the "YouTube" link doesn't work and put the video here, copy and paste if needed. (or tell me the trick to do it right)
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Old 01-29-2013, 04:28 PM
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Default RE: Idea to discharge??

Cool, nice idea on using the psu case and fan with the lights. yea i get the 4 rows of lights, one row for each banana plug on the case , plug 1, 4 lamps, Plug 2, 8 lamps and so on. What size lamps did you decide to use.
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Old 01-29-2013, 06:33 PM
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Default RE: Idea to discharge??

You could convert the energy stored in Lipos into 110v AC via a suitable inverter. If you have some spare lipos that are in "empty" state (say @ 25%), you could charge them to 50% with the dumped energy.

This [link=http://www.ebay.com/itm/300w-grid-tie-power-inverter-14V-28V-DC-solar-system-charge-18v-DC-solar-panel-/370530308695?pt=US_Power_Inverters_&hash=item564553d257]300w grid tie power inverter (14V-28V DC,solar system,charge 18v DC solar panel)[/link] can even push the energy directly to your home grid.
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Old 01-29-2013, 07:00 PM
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Default RE: Idea to discharge??

Quote:
ORIGINAL: trax de max

Cool, nice idea on using the psu case and fan with the lights. yea i get the 4 rows of lights, one row for each banana plug on the case , plug 1, 4 lamps, Plug 2, 8 lamps and so on. What size lamps did you decide to use.
I used what the link said, 12v 20w bulbs. I found a pack of 25 on Amazon for $12. I have 5 left over. I found that they work great as a quick and easy (and hot) flashlight if you stab them into a small 3S pack with a jst plug on it too. They fit right in. And they're stinkin bright! You just have to use a glove to pull them back out cause they get hot.

So ya, I have 4 rows each containing 5 bulbs. I found that on some of my smaller batteries that even 5 bulbs was a little much (amp wise) for draining them. So I may go back and de-solder one or two on the first couple rows.

Fun little project, I've been lighting the basement up today discharging lipos!
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Old 03-01-2013, 03:18 AM
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Default RE: Idea to discharge??

There is a lot of misinformation about these subjects out there, and it changes periodically too - so make sure you are reading current information. For CURRENT (late 2010) HIGH QUALITY batteries, it can be stored fully charged up to a few weeks. For old batteries or budget types, hard to say - but I don't think it's a big deal. I have stored them fully charged for months at a time. For storage, the manufacturers mostly recommend running them down to the 3.7V per cell - if you don't have a way of setting that voltage, I would say taking a guess is probably worse than storing it fully charged.
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Old 03-01-2013, 07:04 AM
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Default RE: Idea to discharge??

there is no set voltage for storage, the reason the say 50% is because storing at full voltage and at low voltage has proved it has caused issues and 50% gives a good range for tolerance. My charger default setting is 3.85V per cell, some chargers go 3.7 and some 4V. Lipo's are built better now, but it's best to use something that made old packs safe, than to store the newer good packs nowadays at full or drained.
storing fully charged reduces battery life and could cause swelling the internal resistance also goes up more doing this.
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Old 03-07-2013, 06:58 PM
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Default RE: Idea to discharge??

I built a discharger about 10 years ago using automotive light bulbs and just modified this evening with a banana plug adaptor to dischage my LiPo battery packs.    I plugged in my Battery Balancer stuck my LiPo battery into a Fire Proof Battery Charge Bag with 4 Automotive brake lights than discharged them down to about 3.8 Volts per cell.
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