I have 4 of these 12v batteries wired in series for 24v. Where can I find a chart showing DOD values for a 24v system at lets say 80%? I've tried to find it on the manf web site with no luck.
Mike
Quote from: svencool on July 13, 2017, 07:24:52 PM
I have 4 of these 12v batteries wired in series for 24v. Where can I find a chart showing DOD values for a 24v system at lets say 80%? I've tried to find it on the manf web site with no luck.
Mike
Not sure what you mean 80% DOD ?
This shows all the specs for East Penn Deka batteries.
http://www.eastpennmanufacturing.com/wp-content/uploads/Renewable-Energy-Charging-Parameters-1913.pdf
Larry
DOD = Depth of Discharge was just asking on AGM's what would the resting battery voltage be lets say your batteries were topped off and if you pulled 20% out of your 24v battery bank? What would or should they read?
Mike
Quote from: svencool on July 14, 2017, 04:19:31 AM
DOD = Depth of Discharge was just asking on AGM's what would the resting battery voltage be lets say your batteries were topped off and if you pulled 20% out of your 24v battery bank? What would or should they read?
Mike
You can't tell the battery state of charge by looking at the voltage . That is why you need something like the Whizbang to count what goes in and out of the battery to calculate the SOC.
Larry
I have a Whizbang and a Trimetric meter but I like to validate those meters as they are just a guess..... Thanks
Mike
Quote from: svencool on July 14, 2017, 05:55:16 PM
I have a Whizbang and a Trimetric meter but I like to validate those meters as they are just a guess..... Thanks
Mike
The Whizbang and Trimetric will always be a better guess than trying to figure it out from voltage. There isn't a way to do that. When I first started in solar there were some curves for flooded lead acid and depending on what the load or charge amps were you could take a guess but the graph was not linear and of course everything was temperature dependent. I have never seen anything for resting voltages. AGM's there is no way to verify like you can with flooded by taking specific gravity. And from what I have seen on some AGM they can show a good resting voltage when they are dead for capacity.
Larry
Well I've noticed that if they read lets say 24.6v while in use. After disconnecting the load they go up to 24.9 or so afterwards. I have a 200ah battery bank at 24v. If watching the whizbang it usually ends up being around 188ah or so. So if I used 20% it should read 160ah right? As I'm trying to get the most milage out of my batteries :)
Mike
The Classic / Whizbang compensates battery capacity based on temperature of the battery pack too.
To get the most life out of batteries you keep them cool , try to only discharge no more than 20% of capacity, and make sure that any parallel batteries wiring is balanced so the loads and charge are the same across all of them.
At least that is what I have gathered from all available info .
Yeah your calculations sound right .
Larry
Thanks Larry! and Yes 2 sets of batteries in series only to be connected in Parallel via a buss bar. I've measured each line and made sure I would get them as close as possible to the same length and resistance level....
Mike
How about a hydrometer to check Specific Gravity of the cells? Wouldn't that give you a very good state of charge?
Quote from: Highflyer on September 16, 2017, 07:37:23 PM
How about a hydrometer to check Specific Gravity of the cells? Wouldn't that give you a very good state of charge?
It would give you a great state of charge indicator. But the batteries in question are AGM, so you can't do that.
@Highflyer / Brian
Topic: East Penn AGM Battery
There AGM
& the WZBjr is the ticket , It's very close to my math also
VT