Ah setting on charge controller

[HOASUNBuster]

Hi all, I have an EPSolar 40A tracer and although the manual tells you how to set things, it does not tell you what to set things at. For instance, I have 4 230Ah Deka 6V GC batteries 2X2 for 12 volts to run my inverter. The settings on the controller range from 10Ah to 900Ah and I don't know how to figure what I should set this at. Where and how do amp hours add in this situation. Are the 2 - 6V 230 in parallel still 230Ah and if I add another pair, does that make it 460Ah or is it still 230Ah? Been looking at the battery threads and others but haven't seen any titles that might direct me to an answer. Google does not seem to be my friend here. Any insight would be appreciated as I don't want to under or over charge my battery bank with an improper setting.

[Sunking]

I will try to help. You have a 12 volt 460 AH battery.

Not quite sure where you are seeing to set the controller to AH because it is not needed nor serves any real purpose. The Manual I see makes no mention of AH just Bulk, Boost, Float and Equalization voltage stetting like every charge controller. Current is controlled by panel wattage and battery state of charge. With a 12 volt 460 AH battery at a minimum you need a full 500 watts input to supply the battery with 40 amp charge current.

[HOASUNBuster]

I will try to help. You have a 12 volt 460 AH battery.

Not quite sure where you are seeing to set the controller to AH because it is not needed nor serves any real purpose. The Manual I see makes no mention of AH just Bulk, Boost, Float and Equalization voltage stetting like every charge controller. Current is controlled by panel wattage and battery state of charge. With a 12 volt 460 AH battery at a minimum you need a full 500 watts input to supply the battery with 40 amp charge current.

The amp hour setting from the manual states the below. I was just not familiar with how to add AH capacities in serial and in parallel.

http://www.epsolarpv.com/en/index.php/Product/pro_content/id/363/am_id/139Date

"Battery capacity modify: capacity modify range from 10AH to 900AH, the default value is 200AH. The modify data should be near or equal to the real capacity. While display battery capacity and temp., press K1 into setting mode, modify the data through K2, K3. Battery capacity will be up/down 10AH, press K1 for saving data and back to the reading status. Or press K4 for back to reading status without saving. The capacity remain the same."

So, if I understand correctly, 2, 6 volt 230Ah batteries in series make a 230Ah 12V battery and 2, 12V 230Ah batteries in parallel makes a 460Ah battery so I should be setting my controller to 460Ah which is within range.

[inetdog]

The amp hour setting from the manual states the below. I was just not familiar with how to add AH capacities in serial and in parallel.

http://www.epsolarpv.com/en/index.php/Product/pro_content/id/363/am_id/139Date

"Battery capacity modify: capacity modify range from 10AH to 900AH, the default value is 200AH. The modify data should be near or equal to the real capacity. While display battery capacity and temp., press K1 into setting mode, modify the data through K2, K3. Battery capacity will be up/down 10AH, press K1 for saving data and back to the reading status. Or press K4 for back to reading status without saving. The capacity remain the same."

So, if I understand correctly, 2, 6 volt 230Ah batteries in series make a 230Ah 12V battery and 2, 12V 230Ah batteries in parallel makes a 460Ah battery so I should be setting my controller to 460Ah which is within range.

My first suspicion after not finding the AH parameter mentioned in the CC manual itself was that it was related to the remote display, but I did not follow through on that.
With no more information than is found in the display manual, I can only give a guess:

One of the things that the remote display can show is State Of Charge (SOC). This function is not described in the manual, but is implied by the "SOC" icon on the sample display picture.
Since there is no external battery shunt involved with either the CC or the display, we know that the SOC indication has to be based entirely on the measured battery voltage.
Simple voltage to SOC conversions for a particular battery type are only accurate with a rested (no load or charge for four hours) battery. The chances of seeing that in a working system are small to none, and certainly cannot be expected during the working day.
It is possible to make a better estimate of the SOC based on voltage if you know the current going into or out of the battery, and for a given battery type (FLA, AGM, (shudder GEL)), the voltage offset during charging will be roughly dependent on the relative current, that is the current as a function of capacity, C.
So, since the controller knows the battery type and knows (well assumes to know) the net charging current (when in fact it knows only the gross output of the CC itself), it can use the current combined with the entered C value to correct its SOC indication.

Whether or not it really does that, as well as whether or not it is possible to do a good enough job to make the reading at all useful, is an open question, but the logic fits.

[HOASUNBuster]

My first suspicion after not finding the AH parameter mentioned in the CC manual itself was that it was related to the remote display, but I did not follow through on that.
With no more information than is found in the display manual, I can only give a guess:

One of the things that the remote display can show is State Of Charge (SOC). This function is not described in the manual, but is implied by the "SOC" icon on the sample display picture.
Since there is no external battery shunt involved with either the CC or the display, we know that the SOC indication has to be based entirely on the measured battery voltage.
Simple voltage to SOC conversions for a particular battery type are only accurate with a rested (no load or charge for four hours) battery. The chances of seeing that in a working system are small to none, and certainly cannot be expected during the working day.
It is possible to make a better estimate of the SOC based on voltage if you know the current going into or out of the battery, and for a given battery type (FLA, AGM, (shudder GEL)), the voltage offset during charging will be roughly dependent on the relative current, that is the current as a function of capacity, C.
So, since the controller knows the battery type and knows (well assumes to know) the net charging current (when in fact it knows only the gross output of the CC itself), it can use the current combined with the entered C value to correct its SOC indication.

Whether or not it really does that, as well as whether or not it is possible to do a good enough job to make the reading at all useful, is an open question, but the logic fits.

Thanks inetdog. Seeing it is one of the lower cost MPPT devices, you have to wonder if it actually does anything really well but I want to give it all the chance of properly maintaining my batteries with proper settings. I have corrected the setting to 460Ah and will let it run a day or so and check the SOC with my hydrometer after an adequate rest. I may eventually replace it with a Midnite Solar classic 150 to be able to get more out of my panels to the batteries but I am still limited by a 12V bank and my 12V inverter. Again, thanks for responding.

[Sunking]

OK I read the manual, all 4 pages of it. The Battery AH metering is pretty much worthless as all it does is make a guess on what capacity is left based on SOC voltages. Well SOC voltages as anyone knows is worthless information on a working system.

[paulcheung]

I think the AH selection is for the charge controller to determine the time it stay on absorb mode before it change to float.

[Sunking]

I think the AH selection is for the charge controller to determine the time it stay on absorb mode before it change to float.

Read the manual Paul. It is only a turd of an SOC meter in disguise. Absorb mode on all solar charge controllers is a fixed time of usually 2 hours.

[paulcheung]

M My bad, I thought it use it to calculate the absorb hours. instead it use it for the lousy ampere capacity meter with 5 bars.

[Sunking]

M My bad, I thought it use it to calculate the absorb hours. instead it use it for the lousy ampere capacity meter with 5 bars.

Yep here we call them Idiot Lights. Like old cars with a Hot Light. Completely useless.

[PNjunction]

Don't sweat it too much. The Ah setting is also in my inexpensive little pwm controller from Renogy (rebadged EPsolar). Not that I put much faith in it.

[HOASUNBuster]

Yep here we call them Idiot Lights. Like old cars with a Hot Light. Completely useless.

I hate idiot lights. Maybe I should get a better CC with a proper manual when I can afford it

[notyoung]

I'm aware that this is an old thread, but I have an answer.

On the Tracer A Series controllers I have (two 3210A 30amp, and one 4210A 40amp, all MPPT), the SOC only shows 100% when the battery is at float voltage or above. The manufacturer specs the AGM batteries I use at 100% SOC at 12.72 to 12.84 volts after 24 hours rest (six 12HX330 for 540AH at their 20 hour rating). The EPSolar monitor software is currently telling me that the battery voltage is 12.93 volts and the SOC is 55%. Obviously, this SOC value does not match the battery specs so I just ignore the SOC display and watch the battery voltage.

If you want an accurate SOC display, you either spend $$$ or you build something - probably based on an Arduino and some current sensor chips (sensors rated to at least 100 amps are available).