Variable load for battery testing

Thread Starter

BatteryTony

Joined Jul 3, 2022
2
Hello friends,
I´m new at this forum. Tried to look for some post in this topic, but didn´t find my solution. If I missed it, sorry for that.

I´m trying to build my own Li-Ion batteries. I would like to measure, what current can the nickel strips handle. I know there are some tables available on the internet, but you know, these strips vary pretty much in quality, especially in the content of Ni. Therefore I would like to test my available & future strips. My idea was to put a variable load in the circuit which is at a point connected with the nickel strip & see at which point it will blow off. I´m looking for some easy, quick & cheap solution. Best would be to order a ready to use unit from Aliexpress. I was trying to search something like this, but these variable loads were available only for something like 60W. My intention would be to use 7,4V battery as a supply & run like 15-20A through the strip. Unfortunately I don´t have a laboratory supply available, which can adjust the output current.
Many thanks.
 

Irving

Joined Jan 30, 2016
2,769
What physical size are your strips? An e-load at that current is non-trivial - your control MOSFET(s) will be dissipating 150+ watts - that's a big fan cooled heat-sink - and very few lab supplies will do that anyway. You can get 250W e-loads but they are more expensive.

This one claims 150W.... though for how long is questionable

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Thread Starter

BatteryTony

Joined Jul 3, 2022
2
What physical size are your strips? An e-load at that current is non-trivial - your control MOSFET(s) will be dissipating 150+ watts - that's a big fan cooled heat-sink - and very few lab supplies will do that anyway. You can get 250W e-loads but they are more expensive.

This one claims 150W.... though for how long is questionable

View attachment 270632
Thanks for the reply Irving. The strips to be tested are in the range 5x0,1mm to 10x0,20 mm. Maybe the suggested equipment would do the task. However, I´m just wondering if it´s worth the price.
 

Ian0

Joined Aug 7, 2020
5,504
What’s wrong with the good old fashioned lamp-board?
Fix a dozen lampholders on a piece of wood, and plug in as many lamps as required.
For a 7.4V battery you can test with 12V lamps, and you can still get them in GLS types with E27 and B22 bases.
Still my preferred method for loads too small to require the 3-phase dummy load
 

metermannd

Joined Oct 25, 2020
309
The older editions of the Meterman's Handbook had examples of resistances used to test the DC watthour meters of that era, which included carbon compression rheostats (stacked pancakes of carbon that could be compressed to give varying resistances) and water rheostats (non-conductive buckets with special hardware for conducting the current through the bucket).
 

dendad

Joined Feb 20, 2016
4,168
I remember years ago at a research place I was at for a short time during my training, (in fact, we watched the moon landing there, so it was quite a while ago!) they had a large battery test load.
It was made up of steel (possibly stainless steel) tube that had water running through it for cooling. This was testing large telephone exchange batteries so quite a lot of power. Sliding clamps were the current adjustments.
 

Ian0

Joined Aug 7, 2020
5,504
At work I have a 200kW dummy load. Inside it looks like a forest of immersion heater elements (which are switched by a series of contactors), and a big fan (about 2' diameter). We try to avoid having to use it during warm weather.
 
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