[RE-wrenches] Load testing Lithium battery bank

Ray Walters ray at solarray.com
Tue Mar 17 11:59:01 PDT 2015


Hi Larry,

I think you hit on the best load already: water heater elements rated 
for 120 v.  We have also used dump loads for wind turbines like the air 
heating elements from Bergey, but they are only about 1 kW each.  
Another possible source are the resistor banks for old golf carts 
(before they had controllers, they used resistor banks to operate at 
slow speeds)
A very long time ago, an inverter company had a demonstration that used 
a large bank of incandescent light bulbs.  They used to make a 300 watt 
bulb for mining, so 33 of those would work.  (maybe a few more bulbs, 
since your voltage is bit lower than 120 v)  Cheap electric space 
heaters would work too.  You also might look around at an electronics 
surplus store.
Whatever you do, it sounds like a lot of time and work to set up. Any 
chance of doing a smaller load test for subsets of the total bank?  You 
might be able to use a standard 12 v battery load tester then.

Good Luck.

R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760

On 3/17/2015 12:41 PM, Larry wrote:
> I am repairing and restoring a pair of poorly designed lithium-ion 
> battery bank that suffered over discharge, damaging many cells. After 
> cell replacement I need to perform a discharge test with a 10kW load 
> to verify the remaining capacity. The battery voltage is 105 volts @ 
> 100% SoC and 89.6 volts @ 0%
>
> I would like advice on how I can create an economical 10kW load. Water 
> heating element? Wire wound resistors? Are there any GT inverters that 
> will operate at these voltages?
>
> Thanks.
>




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