Easy discharge load

[AZguy]

Needed a better discharge load than what I was using and noticed one of those thermostat controlled about 12" sorta square electric skillets sitting on the fridge and thought the two great big prongs on the side where the thermostat plugs in are just connected to a great big resistor

Measure the resistance and just shy of 12Ω... perfect load for batteries up around 50+V

Put some water in the skillet as a "heat sink" and with the lid on would take likely more energy than the battery has to get rid of (I'll work some numbers, it's pretty straight forward ;-} )

Draws right about 5A... nice!

[73Eldo]

I like it. Since the 'brains' are in the cord you don't have to get all technical to try and eliminate the stuff that you don't want or would be angry with the wrong power.

[AZguy]

Exactly! The prongs just connect directly to the element and it turns out to be about the perfect size load drawing around 200-250W (~5A on 48/52V battery)

I just did a test run this morning on my monster 14s8p and it works great... took it from ~56V to ~50V in a couple of hours or so after an inadvertent charge above storage SOC - the whole reason I was noodling around the house trying to figure out a load (I rarely use this battery)

For so many reasons I wouldn't leave it unattended but with the lid on even though it gets a bit too hot to touch although not in the burn you range so pretty safe and there was almost no water loss... it doesn't even come close to reaching a simmer and the water just condenses off the lid into a nice steady very slow reflux... so no worries about water evaporating away and then overheating the skillet... my rough numbers suggest even with the lid off it would take 2-2.5hrs per liter of water to evaporate it off but I'm not going to do that...

The only thing that might be an issue is forgetting it and over-discharging but worst case the battery BMS would catch it so battery wouldn't get destroyed but I don't want to depend on that and may roll-my-own programmable LVCO...

[AZguy]

Wally world has new ones that appear to have the same size element for <$20 so not even out-of-the-question to just buy one for the shop... although if I were going to use it to cook with (I use mine!) I'd likely splurge and get the $27 dollar one

[73Eldo]

Next test would be to put 2 52v packs in series and see if you can actually cook on it.

[AZguy]

LOL - ~800-1000W? Talk about cookin'

[Dshue]

I'm going to remember this. We've got an old electric skillet that we rarely use.

[DaHose]

That's awesome ingenuity, AzGuy! I have an electric griddle that's 20+ years old, that would also be perfect as a battery load. What gauge wire did you use for the connection?

Jose

[73Eldo]

He said it comes out to about 5a on a 52v pack so it would not have to be especially large wire. 16awg or bigger should be plenty.

[AZguy]

Heck I just used some 20AWG alligator jumpers and they work fine - like 73eldo commented it's only about 5A and they don't get the least bit warm and if they drop a little voltage who cares?

[73Eldo]

Next we are going to see a trail side cook book from Azguy. He will have that griddle on the bike so he can just pull over and have a hot meal when ever he finds anything that looks like good eatin on the trail.

[AZguy]

Dunno if you want me cooking, I burn things just boiling water

[Fred]

I use my George Foreman Grill(s). I have never tried to cook a burger while discharging. I have used them directly connected and thru a 48V to 120V inverter. With the latter, it can draw more current. I normally only use these 1) to get a feel for real remaining capacity as the pack ages OR 2) to discharge to a known % charge before storing the packs for the winter.

[73Eldo]

To expand on this concept another member had the idea to go and pick one up at Goodwill. I bet they have a bunch of such things for cheap that maybe are missing the lids or cords and may or may not be a little crusty but we don't really care since we are making into a shop tool.

Next issue for those that don't have a shop full of random wires and clops and such is where do we steer those without a lot of junk laying around to get some decent alligator clip leads? I know most of the ones you get online are total garbage and even if they had more than one strand of wire in them would not hold up to the maybe 5 amps we are talking about here. For those of us dealing with something like a Wolf pack with XT-90's an alligator clip jams in there fine. Maybe even an XT60. What about shark packs? What can you jam in those?

Home depot seems to sell the raw clips but they you would have to attach your own wires which for a non electronics person would require more tools and materials. How about auto parts stores? Do they stock anything reasonably priced that could work? I'm just trying to think of something that most people in the USA could likely walk into a store and get in stock.

[DaHose]

Making your own just takes some wire, crimpers, and the alligator heads. Home Depot, Lowes, local hardware store will have what's needed. Amazon is the best buy option. Look for alligator test leads, and you get a lot of choices. If you can't/won't make your own, then buying a couple of 14 ga. pairs for higher load, and a set of light duty testers is the best combo.

Jose

[AZguy]

Cheap alligator clip leads work fine, 5A isn't much current and even 20-22AWG will handle it... I'm using cheapies I bought at Fry's

One thing is that if you connect a hot battery to the prongs it will make some pretty sparks... nothing dangerous, hard to do much welding with 5A but they are pretty =] I plugged using a simple SAE connector and that avoids the sparks... or just us the alligator and groove on the pretty sparks

I would not use a XT-90S (anti-spark)!!!

They are made to pass current for a very brief surge, not continuously and the little resistor inside of them (~5.6Ω) will fry in short order if the connector isn't inserted silly fast - Don't do it! If you have XT90S's make sure they are plugged in completely before making the last connection and don't disconnect them until something else is disconnected first!

[Fred]

Instead of using alligator clips, I built a little adapter with a female standard 120V AC plug on one end and Anderson's on the other as I have pretty much standardized on Anderson's for my battery connections. It also allows me to put my Wattmeter inline to measure current as my wattmeter has Anderson's on it as well. I know some suggest Anderson's are not the best connector out there, so one can standardize on whatever connector is suitable. For me, I have several batteries, controllers, measuring devices, etc. so I'm not about to change them all.

[AZguy]

I use Andersons a lot for indoor stuff, SAE on lower current stuff on cars and motos, but migrated most everything on the bike to XT90S's

[73Eldo]

If what you are using for a load still has any brains involved there could be issues sending them the wrong voltage and DC. That is one of the beauties of the cooker idea, the brains are in the original cord and plug so get rid of that and you just have a big load resistor. The main idea here is we are looking for things the average person can do. The mad scientists among us have no problem breaking into devices and bypassing what we need or don't need with minimal amounts of smoke released but many e bikers just don't know what they are looking at when they open something up.

[hoggdoc]

Wish I had seen this thread before buying all the bits and pieces to make a discharge unit using 50w 12v halogen bulbs.