East Penn AGM Battery DOD

[svencool]

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

[ClassicCrazy]

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

[svencool]

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

[ClassicCrazy]

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

[svencool]

I have a Whizbang and a Trimetric meter but I like to validate those meters as they are just a guess..... Thanks

Mike

[ClassicCrazy]

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

[svencool]

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

[ClassicCrazy]

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 

[svencool]

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

[Highflyer]

How about a hydrometer to check Specific Gravity of the cells?  Wouldn't that give you a very good state of charge?

[Syonyk]

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.

[CDN-VT]

@Highflyer  / Brian
Topic: East Penn AGM Battery

There AGM
& the  WZBjr is the ticket , It's very close to my math also

VT