Need 24V 200A load

[vile]

Hello everyone!
here I have already found lots of good information and advice, so I ask you again

I am looking for an electric load to test a 8s1p A123 20Ah lifepo4 at high currents. That means ~200A @25V. My intention is to analyse if I need any active cooling for a 112s1p battery pack (I've written about the temperatures in another thread before and found interesting posts).
I'm going to check that with an ir camera I can use at my university using different types of discharging (continuous high and lower currents, currents for shorter times with pauses etc).

The problem is I don't know how to get these discharge currents with simple methods. I thought about using several 250W 24V halogen bulbs or a long piece of copper wire (120 milliohm) that lies in distilled water. Normal high power resistors are to expensive for this one test and I haven't got yet the motor controller.

All in all, I need some kind of cheap resistor enabling 200A at 25V and being able to stand the 5000W dissipation.

If you can give me advice, I can post the test results. Might be interesting.

Vile

 

[dogman dan]

Go to goodwill and get a hot plate? Or stove element?

500w halogens would work, but you'd need about 6 of them. But a hot plate or coffee pot should draw aobut 1500w of 110 ac. Not sure what one would draw on 24v DC. Likely more than a halogen bulb at least.

 

[vile]

This could be difficult, 1/4 of the voltage does 1/16 power with constant resistance.
But thanks for your answer

 

[jonescg]

Use some galvanised fencing wire coiled up and plunged into a bucket of water. Less strain on the eyes than a string of lightbulbs too.

 

[major]

All in all, I need some kind of cheap resistor enabling 200A at 25V and being able to stand the 5000W dissipation.

If you can give me advice, I can post the test results. Might be interesting.

Vile

Hi Vile,

I have a few extra of these. About 0.15 Ohms and 1-1.2 kW rated but I have used them at 4 or 5 kW for like 10 minutes at a time and they don't even turn red. Put a fan on it and it'll take the load. You can tap in on the coil to get lower resistance as show. Might weigh about 10 pounds. If interested, send a PM.

 

[knighty]

just use a long solid bar or steel ? (stainless is even better)

guessing you want to do 200amps constant for a while if you're checking for heat build up in the cells... so to keep it cool, do it in the garden and hose it down when it gets hot

 

[major]

Yep, a piece of steel rod or channel or pipe or section of fence or wrench in a bucket of water will work. Using a braking resistor offers a pretty constant resistance over a wide temperature range. Therefore the current is proportional to the voltage across the resistor. May be a bit easier to collect your data. And it can be a compact and a repeatable test in case you want to recheck it a month. All depends on your personal preferences.