[RE-wrenches] Load testing Lithium battery bank

[Larry]

I was thinking of mounting the water heat elements into an aluminum 
plate, laying the plate flat over a 55 gallon drum and filling the water 
level up to the plate. Stratified water may make the top pretty hot but 
I guess it will work.

Larry

On 3/17/15 1:07 PM, Ray Walters wrote:
> Those look like your solution.  Also water can take more heat with 
> less trouble than air heaters.  I've had air heaters start melting 
> things, etc.  You can just install those in the side of a 55 gal 
> barrel with a bulkhead fitting, or yes, weld the appropriate plumbing 
> fitting to the side of the barrel. Might even be able to install them 
> into a section of pipe with  Ts and run water through it to cool the 
> elements.
>
> R.Ray Walters
> CTO, Solarray, Inc
> Nabcep Certified PV Installer,
> Licensed Master Electrician
> Solar Design Engineer
> 303 505-8760
>
> On 3/17/2015 1:40 PM, Larry wrote:
>> Hey Ray,
>>
>> I remember seeing huge banks of light bulbs as loads back in the 
>> early 70's.
>>
>> I need to test the entire bank as one unit as the first cell of 32 to 
>> reach 2.8 volts determines the capacity for the bank. I just saw Home 
>> Depot has a 2kW 120 volt water heater for $10. Guess I need to do 
>> some welding.
>>
>> Thank you,
>>
>> Larry Crutcher
>> Starlight Solar Power Systems
>>
>> On 3/17/15 11:59 AM, Ray Walters wrote:
>>> 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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