Amp limit

[boomadge]

Being fairly new with solar I am always looking for answers to help me understand how everything works. This just happens to be something that I have been thinking about.
I can push 30 amps to my battery bank through the kid, that's well beyond 10% so I have it limited to
22 amps (215 ah bank). Let's say the bank is taking all 22 amps to bulk charge then fridge turns on requiring 5 amps to run, does this pull the amps from the 22 amps that are being used to charge the batteries or does the kid utilize the 8 amps that are blocked ?

[Rain Dog]

Just out of curiosity, why limit the controller to 10% of battery capacity? What kind of batteries?

[ClassicCrazy]

I was going to ask same thing - why not let all the available amps in - when it goes to Absorb it will limit the amps to keep voltage at the absorb setpoint.

On my Classic if it was in Absorb and that was restricting charge to 10 amps and I put on a load of 20 amps it would let the available 30 amps through and try to maintain the 10 amps absorb setpoint.  You can see this if you have Whizbang because that shows system amps - what is actually getting to the battery instead of what the controller is making available .

I am guessing the Kid works same way up to it's 30 amp limit.

[Vic]

I,  too,  was going to ask why Limit the Icharge,  but,  we do not know the type of batteries in use.

AND,  we Limit Classic Output current on one system,  here.   With Version 1849   FW in the Classic,  the Classic output current Limit,  is an absolute maximum that the CC will deliver.   So if the limit is 20 A,  with light Inverter loads,  this is the nominal max current.  If a 10 A load is placed on the inverters,  the charge current into the batteries is reduced to what is left (essentially,  with a second-order effect or two).  :

See Reply #3 and #6  in this Thread regarding the implementation in the Classic
http://midnitesolar.com/Forum/index.php?topic=2208.0

Believe that this function is also still absent in the KID.

FWIW,   Vic

[boomadge]

I have 4 6v decka 215 ah flooded in series for 24 volt. I am not limiting the input from the panels I have set point in the kid to max output to 22 amps. C10 is what I was told by decka for charge rate.
I always have 8 amps doing nothing.

[Vic]

I have 4 6v decka 215 ah flooded in series for 24 volt. I am not limiting the input from the panels I have set point in the kid to max output to 22 amps. C10 is what I was told by decka for charge rate.
I always have 8 amps doing nothing.

[Vic]

I have 4 6v decka 215 ah flooded in series for 24 volt. I am not limiting the input from the panels I have set point in the kid to max output to 22 amps. C10 is what I was told by decka for charge rate.
I always have 8 amps doing nothing.

Hi boom,

Well  most of us say to follow the recommendations of the battery manufacturer.

If your average loads on the inverter are light,  then this is probably the best for your batteries.

If you had some fixed average load on the inverter,   then it might be OK to increase the output current Limit on the KID by that average  DC  load current,  until the Net Charge Current capability with the WBjr function is implemented,  IMO.
FWIW,   Vic

[Halfcrazy]

If the Fridge was running off the Kids load circuit then it would come from the extra PV power. if the fridge is AC or direct to the battery then it comes out of the 22 amps

[boomadge]

Thanks for the reply's,
System is happy never below 86 soc overnite and pretty much 100% soc by days end.
The hydrovolt numbers so far been good. Only thing dc is 24 volt pump but don't run much.
Just was curious if the 8 extra amps where able to be used for something.

I am still learning day by day, lotta good people at midnite and naws.
Thanks

[ClassicCrazy]

Here are East Penn Deka solar charging recommendations
http://www.eastpennmanufacturing.com/wp-content/uploads/Renewable-Energy-Charging-Parameters-1913.pdf

Even if you have the golf cart or other type East Penn flooded lead acid batteries the Solar ones are the same with different sticker on them - almost positive of that.

I don't know how to interpret their bulk recommendations compared to what your dealer told you . But I doubt it makes much difference if you give them all they can get in bulk because as soon as Absorb setpoint is reached it will cut back the current to maintain Absorb voltage and I doubt it would exceed the recommendations anyway . But perhaps I could be wrong - too fast a rise in bulk is bad ? Seems like they would have to be really low to get enough amps in to take full 30 amps.

[ClassicCrazy]

According to the East Penn for bulk of flooded lead acid
30% of C20

215/20  x 30% = 3.23

which seems low so if you multiply it by 4 = 12.90



The other equation they have is
6 x I/20   
I just don't get what current they refer to for  the I would be ?
Okay - just figured out the last equation
I is maximum discharge which for that battery is 75 amps so equation is
+         75.00
/         20.00
---------------
=          3.75
*          6.00
---------------
=         22.50  which is the  rate that your dealer told you

[boomadge]

Yup I was banging my head against the wall trying to figure out what settings to use as well.
So I got in touch with Lou Vondenbosch [louv@dekabatteries.com]

I was explained they are Duracell badged made by east penn and are Deka GC15 clones.
This is info he provided to me.

"These charging specs will work perfectly for 24v!"
1. BULK STAGE = 10% of Ah (C10) or 21.5 amps
26 amps (max.current) per series string.

2. ABSORPTION STAGE = 2.44 vpc (x 3 cells) = 7.32 v x the # of batteries in your strings(4)=29.28V (29.3v)

3. FLOAT STAGE = 2.34 vpc (x 3 cells) = 7.02 v x the # of batteries in your strings(4)=28.08V (28.1v)

4. EQUALIZE STAGE = 2.53 vpc (x 3 cells) = 7.59 v the # of batteries in your strings(4)=30.36V (30.4v)

This is at -3 mV / cell / °C1

So that's how I setup the kid but just noticed I could push it to 26 amps max and never changed the -5 mv to -3mv

Thanks again for looking up the info..

[ClassicCrazy]

The -3 mv setting is temperature compensation setting , but you need the temp compensation cable for that so hopefully you got one of those also . If batteries get cold you will see the voltage go higher for charging parameters.

[boomadge]

Yupper I have the MNBTS 

[SolaRevolution]

According to the East Penn for bulk of flooded lead acid
30% of C20

215/20  x 30% = 3.23

which seems low so if you multiply it by 4 = 12.90

I don't think that is the right interpretation of Deka's instructions.

Their reference to the the "Max. Current =  30% of C/20"  means that the max charge rate is 30% of the battery amp/hr rating at the 20 hour rate, so 215 x .3 = 64.5 amps.

For clarification check their glossary:  "C/20 -Battery capacity measured in Ah at the 20hr rate"

The other equation they have is
6 x I/20   
I just don't get what current they refer to for  the I would be ?

The  I/20 would be the current rate required to deliver the full capacity of the battery over 20 hours, so 215/20 = 10.75 amps
So, 6 x I/20 would be  6 x 10.75 = 64.5

Either method of calculating should come up with the same result. No?