Lightbulb Discharger

Batteries, Chargers, and Battery Management Systems.
Post Reply
xenodius   1 kW

1 kW
Posts: 488
Joined: Sep 03 2012 6:55pm
Location: Spokane, WA

Lightbulb Discharger

Post by xenodius » Sep 24 2013 12:27pm

I got a Cellman pack a little while ago and I don't have a bike to discharge it on yet. This was bought "new", set at full charge for one year, but I got a good deal with a charger. Don't know what the capacity losses are for 1 year at roughly full SOC, room temp... only 2% at 50% charge. Maybe 5%? More? If anyone know's I'd appreciate the info.

The 24s pack will be paired with a Cromotor, 60t chainring/16t freewheel, Thun BB, and Sabvoton controller on a KMX trike full of panniers. I can use the throttle if I want to go faster than 30mph, but I think the torque-sensing setup is the way to go-- beats using a Schlumpf HSD that's inefficient at "60 teeth" and doesn't integrate with the motor or tell you what calories you're burning, and costs three times as much.

But I digress.

I needed a way to discharge the pack but I don't have any power resistors. Then I had a lightbulb moment, pun intended, and I realized the answer was right in front of me. Currently discharging ~108 watts into the 150 watt bulb, should reach 50% SOC in about 7 hours.

It cost me 6 inches of electrical tape and two zipties.

http://imgur.com/a/8slQK

Yes, I used welding gloves to connect the tail for the first time because I know a short could produce a hell of spark with these cells... even with a fuse...

A search of the forum didn't yield anyone else doing this, but I'm sure someone has thought of it too. Either way, anyone out there who needs a cheap way to discharge a pack for storage... use a lamp! =)

dnmun   100 GW

100 GW
Posts: 16190
Joined: Jun 09 2008 1:32pm
Location: portland, or and loveland, co

Re: Lightbulb Discharger

Post by dnmun » Sep 24 2013 1:38pm

i use electric heaters for the load. i have 6 heaters i can plug into my duplex outlet x three outlet plugs to make up the load. i use the oil filled radiators for heaters.
Attachments
DSC01678.JPG
DSC01678.JPG (156.18 KiB) Viewed 901 times
DSC01677.JPG
DSC01677.JPG (140.22 KiB) Viewed 901 times

migueralliart   10 kW

10 kW
Posts: 887
Joined: Apr 08 2011 7:32pm
Location: West Palm Beach , FL
Contact:

Re: Lightbulb Discharger

Post by migueralliart » Sep 24 2013 4:09pm

I made a discharging unit following the instructions over on rcgroups. I used 24V spot light bulbs from ebay and a cell log with datalogging to discharge lipo packs quicker.
Last edited by migueralliart on Sep 24 2013 7:40pm, edited 1 time in total.

xenodius   1 kW

1 kW
Posts: 488
Joined: Sep 03 2012 6:55pm
Location: Spokane, WA

Re: Lightbulb Discharger

Post by xenodius » Sep 24 2013 7:08pm

My pack only ran the 150w bulb @ 79.2v = 99 watts, 6 hours and 20 minutes... that's barely over 600wh. More disconcertingly, the 6amp charger only charged it up for an hour.

I don't have a cellog or CA to measure discharge, but... one 150w bulb at 79.2v... is that conclusive enough to question the health of this battery?

EDIT: Haha. I'm an idiot. My wife turned the lamp off. LOL.

dmwahl   10 kW

10 kW
Posts: 611
Joined: May 06 2009 9:41am
Location: Madison, WI

Re: Lightbulb Discharger

Post by dmwahl » Sep 26 2013 8:48am

I've used a 200W halogen bulb countless times, why spend $$$ on power resistors when you can get the same result for far less and probably safer since the bulb has a built in fuse. Just get one of those porcelain bulb fixtures, screw it down to a piece of scrap, and you're good to go.

User avatar
Ypedal   100 GW

100 GW
Posts: 12523
Joined: Dec 27 2006 12:55pm
Location: Moncton NB, Canada
Contact:

Re: Lightbulb Discharger

Post by Ypedal » Sep 26 2013 8:58am

ES site status page:
http://www.ypedal.com/ES/ES.htm
----------------
http://www.ypedal.com

User avatar
amberwolf   100 GW

100 GW
Posts: 29017
Joined: Aug 17 2009 6:43am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: Lightbulb Discharger

Post by amberwolf » Sep 26 2013 11:37am

Auraslip also built an LBD; it's documented somewhere here on ES, possibly even the wiki.

User avatar
agniusm   10 MW

10 MW
Posts: 2393
Joined: Apr 16 2011 3:06pm
Location: Lithuania, Zarasai
Contact:

Re: Lightbulb Discharger

Post by agniusm » Sep 29 2013 2:37am

Or something like this:
Image
Image
1 to 6kW :)

JEB   100 W

100 W
Posts: 287
Joined: Jul 19 2007 5:47pm
Location: Santa Barbara Ca

Re: Lightbulb Discharger

Post by JEB » Sep 29 2013 7:57pm

Light bulbs are great , in the right combination (wattage/voltage) one can build a fair constant current discharge source, as the light bulb dims it's current load stays somewhat the same (resistance goes up).

"Selected voltage turn off", (12v voltage regulator, 36v or below in, or voltage divider for above volts + reg) one could use a comparator, but I used a inverter (Schmidt trigger cmos), voltage divider pot (hysteresis around 6v in, cmos) and a power mosfet to unlatch a relay for load turn off, in the same circuit one of those cheap clocks, with voltage divider (to 1.5v) (clockkit) that stops with relay turn off. shows the hours/minutes to turn off (re-set, finger rotate the hands back to 12:00).

Also to check capacity of rechargeable nmh single battery cells, clock in parallel with light bulbs selected for current load, clock stops around 1 volt.

For led's I use small Christmas bulbs in series parallel as current limiters, using a non regulated power supply in the 100ma, or above range.

dmwahl   10 kW

10 kW
Posts: 611
Joined: May 06 2009 9:41am
Location: Madison, WI

Re: Lightbulb Discharger

Post by dmwahl » Oct 02 2013 10:24pm

I like your setup agnasium, kind of steampunk-ish

dnmun   100 GW

100 GW
Posts: 16190
Joined: Jun 09 2008 1:32pm
Location: portland, or and loveland, co

Re: Lightbulb Discharger

Post by dnmun » Oct 02 2013 11:13pm

i especially liked it because those huge bulbs were made in east germany. for someone stuck over here who never sees stuff from east germany it is like the rare pearl. fat pearls with frosting on top.

Post Reply