20 hour test in 2 parts?

[Davidasailor26]

Im planning to do a 20 hour battery capacity test with a constant C/20 load as Maine Sail has described. I'd like to know if doing the test in two 10 hour segments, separated by 8 hours is still accurate. That would let me keep the current constant by adjusting the load without worrying about it changing overnight.

 

[Ned Ludd]

The short answer is NO. Stopping the draw on a load test gives the battery bank recovery time which will give you an inaccurate test result.

 

[jssailem]

David. Why not video your test. Would give you the 20 hour result while you do other things like eat and sleep.

 

[Davidasailor26]

David. Why not video your test. Would give you the 20 hour result while you do other things like eat and sleep.

I thought about that, but I'm using an amp meter that's not really rated for continuous use. I'm using a switch to switch between the amp meter leads to measure the current and a direct lead. The load is a light bulb with a dimmer to keep the draw at 5A as V changes. Each hour or so I'm going to switch to the amp meter and adjust the load to keep at 5A, then switch back to the direct lead.

 

[jssailem]

You have one long day ahead of you. Coffee is recommended. A cold beer, or stronger after all the testing is done.

 

[Maine Sail]

Im planning to do a 20 hour battery capacity test with a constant C/20 load as Maine Sail has described. I'd like to know if doing the test in two 10 hour segments, separated by 8 hours is still accurate. That would let me keep the current constant by adjusting the load without worrying about it changing overnight.

No it s not going to be accurate. You'll get a ball park but your real 20 hour capacity, as compared to the actual, will be higher with a pause...

 

[Davidasailor26]

Thanks for the responses. I guess I'll plan on making some continuous adjustments.