A Forum run by Enthusiasts of MidNite Solar

Charge Controllers and Clippers => The "Classic" charge controller => Topic started by: Gearjam on September 05, 2017, 10:07:59 PM

Title: battery capacity
Post by: Gearjam on September 05, 2017, 10:07:59 PM
Just trying to figure out how I can tell when my batteries are at about 50%. I have the classic 100 or 200, can't remember right now. Equipment is at another location. is there a menu I could pull up or do I have to purchase something? Seems to me it would show on screen somewhere. Thanks.
Title: Re: battery capacity
Post by: ClassicCrazy on September 05, 2017, 11:34:14 PM
Quote from: Gearjam on September 05, 2017, 10:07:59 PM
Just trying to figure out how I can tell when my batteries are at about 50%. I have the classic 100 or 200, can't remember right now. Equipment is at another location. is there a menu I could pull up or do I have to purchase something? Seems to me it would show on screen somewhere. Thanks.

You need to have a Whizbang and shunt installed in your system and then have the correct data for your batteries capacity programmed in to the Classic ( battery capacity, efficiency )  and then you can get a reasonable approximation  of your battery % state of charge (SOC).

The way that works is after your batteries are full, the Whizbang will know exactly how many amps are going into and out of the battery and find the difference which compared to the programmed in capacity and efficiency ( and compensated for temperature ) will give you SOC figure which can be fairly accurate once you fine tune the settings.

If you have the Whizbang and shunt installed and programmed in there  are screens on the MNGP or info in Local Status app that will show you the SOC and capacities as well as system amps ( exactly how many amps are going into or out of battery ) .

Larry
Title: Re: battery capacity
Post by: boB on September 07, 2017, 12:50:09 AM
What Larry said...

And you can measure the capacity of your batteries with the WB. Jr. or another decent A-Hour measuring meter...

Charge them up... Just complete a bulk/Absorb cycle until the Absorb time is up OR measure the specific
gravity of the electrolyte until it reads what the manufacturer says is 100%.

Then, run them down to wherever...  Not too fast...  Maybe C/5 or C/10 or whatever the manufacturer
specifies.  Then, by measuring the battery voltage or stopping and measuring the SG again you can
get an idea of what the state of charge is and how many amp-hours you removed.

You might even be able to tell when you are close to 50% capacity and double that for the capacity you
enter into the meter or WB Jr screen.

I don't necessarily believe the label rating of the battery capacity, especially if they have been used
for a while.  They might be higher than they are rated too.

Ralph at Bogart Engineering also has a good description of measuring your battery capacity in one of his manuals.

I would love to hear what some people have found after they measured their battery's capacity and how
they measured it.

boB