Inverter charger setup question

[RCpilot]

Everyone, I will try my best to supply as much information as I have for this question. I have searched the board and haven't found a post that really answers this for me. This question is mainly because I can't find good information for the forklift battery I have yet. In the Xantrex Prosine 2.0 inverter, I have to set up the charger using custom settings since my battery is not one listed in it's internal charts for charging. Being new to all this I don't quite understand all the settings. What I need to know is your recommendation for the various settings for Bulk, Absorption, Float, Overcharge and Equalize. I have included text from the manual as well. First, the battery: GNB 24V 750Ah Forklift battery converted to 12V 1500Ah. The SG on this battery has always been low: 1.250 after charging at 15A for several days. But, I was using a car charger. I only got two charge cycles on the battery with the previous inverter before it failed and it wasn't set right either. All cells SG is equal, all cell voltages are equal while charging or just sitting. I don't have enough free energy yet to properly charge this battery so for now, I will be using the Prosine's charger to: one, to charge it up and two, to try to desulfate it since the SG is low even after charging it once or twice with the inverter charger. This week, I finally made contact with a gentleman named John from http://www.arconequipment.com that took the time to give me some numbers for the battery. He was pulling the info he gave me out of his head but assured me he knew forklift batteries well. He said run a couple of equalize charges on it with as much as the charger will put out, watching the SG to see if it comes up a little each time, run it down to 80% then regular charge the battery with as much as the charger will put out (Prosine is rated for 100A but I don't want to run it at max right now, I just replaced it, the previous unit lasted two weeks and blew. So, I'm thinking around 80A) until the voltage per cell reaches 2.37 X 6 = 14.22 then allow it to go into absorption mode. While in absorption mode, hold that voltage and allow the current to drop down to around 30A then go into float mode. He said then to go about three hours more while floating. So, Here are the available settings as they appear in the menus of the inverter and below them are the manual's explanation of what each setting is. I know it's a long post, if a question like this is too much to ask then it's ok by me to delete this post. If I knew more information about my battery I would just call Xantrex. Also, in the battery setup, there is one more setting I don't know what to set, it is: Battery temperature coefficient. It's currently on -15.00mV/Fahrenheit it has a fairly fine setting for the values. Any help for these settings would be greatly appreciated. The following settings are as they appear on the inverter menus. The prosine's manual is in my files section.




Kelly




Bulk Charge Settings:

Max Voltage = I don't know what to set this to compared to the Threshold Voltage

Max Current = %C  5% = 75 A  10%=150A  Since my battery is 1500 AH and the Inverter maxes at 100 A  I am going to set this a bit lower for now so it don't fry again. I was also thinking of lowering the setting for the Battery Ah so the percentages could be tweaked better, what do you think?

Threshold Timeout = 3min  Default, I understand this setting as how long before the battery switches modes

Threshold Voltage = 14.2 I set this myself according to what John said




Absorption Charge Settings

Max Voltage = I don't know what to set this to.

Max Current = %C  5% = 75 A  10%=150A  The percentage of the Max Current goes from 5-10% with nothing in between.

Max Timeout = 12 hours  Default, I understand this setting as how long before the battery switches modes

Threshold Current = 2% = 30A I set this myself. This percentage can be set with .1 divisions

Threshold Timeout = 3min Default, I understand this setting as how long before the battery switches modes




Overcharge Mode Settings  - I don't understand what the difference is between this and Equalize

Max Voltage = I set this to 14.6 but not sure what to set it to.

Max Current = %C  5% I set this

Max Timeout = 0min  Default, Not sure about this




Float Charge Settings

Max Voltage = 13.8 Default, this might be close?

Max Current = %C  5% = 75A I set this, again to keep the inverter from hitting 100A

Max Timeout = 21 Days Default  I guess the charger will shut down after this?

Threshold Voltage = 12.5 Default when voltage drops below this, goes back to bulk mode.

Threshold Timeout =  15min Default When Voltage drops and remains for this time, goes to bulk mode.




Equalize Charge Settings

Max Voltage = 16.5 I set this according to an average of the other presets in the inverter tables

Max Current = %C 10% I set this, will max out the charge rate to 100%

Max Timeout = 4 hours, I set this, not sure

Threshold Change: 0.0v  Default

Threshold Timeout 0min Default




From the Manual:

Bulk Charge Mode Settings

Max Voltage

This is the maximum available charging voltage for the Bulk charging stage.

Max Current (%C)

The maximum available charging current (in A) as a percentage of battery

capacity (in Ah) for the Bulk charging stage.

Threshold Voltage and Timeout

When the battery voltage goes above this value for the Threshold Timeout

specified, the unit goes into Absorption charging stage.




Absorption Mode Settings

Max Voltage

This is the maximum charging voltage for the Absorption charging stage.

Typically, the battery will be at this voltage for the duration of this stage.

Max Current (%C)

The maximum available charging current (in A) as a percentage of battery

capacity (in Ah) for the Absorption charging stage.

Max Timeout

This is the maximum amount of time that the unit will stay in the Absorption

stage.

Threshold Current (%C) and Timeout

When battery current goes below this value (A as % of battery capacity in Ah)

for the Threshold Timeout, the unit goes into the next charging stage.




Overcharge Mode Settings

Max Voltage

This is the maximum charging voltage for the Overcharge charging stage.

Typically the battery will be at this voltage for the duration of this stage.

Max Current (%C)

The maximum available charging current (in A) as a percentage of battery

capacity (in Ah) for the Overcharge charging stage.

Max Timeout

The amount of time that the Overcharge stage will run.




Float Mode Settings

Max Voltage

This is the maximum available charging voltage for the Float charging stage.

Typically the battery will be at this voltage for the duration of this stage.

Max Current (%C)

The maximum available charging current (in A) as a percentage of battery

capacity (in Ah) for the Float charging stage.

Max Timeout

This is the maximum amount of time that the charger will be in Float stage.

Threshold Voltage and Timeout

When the battery voltage goes below this value for the Threshold Timeout

specified, the unit goes into Bulk charging mode.




Equalize Mode Settings

Max Voltage

This is the maximum available charging voltage for the Equalize charging

stage.

Max Current (%C)

This is the maximum available charging current (in A) as % of battery

capacity in (Ah) for the Equalize charging stage.

Max Timeout

This is the maximum amount of time that the unit will stay in Equalize stage.

Threshold Change and Timeout

When the battery voltage changes by less than the change value over the

Threshold Timeout specified, the unit goes to Float charging.

[Volvo farmer]

I must be bored this morning. :-)

I looked at the online manual for this thing. It is rather confusing.  I think Overcharge is the same thing as Absorbtion, not Equalize. (see 4-16)

This charger seems a lot more complicated than my Outback. I just ignore current, and use voltage and time to get things fully charged. So for an equalize cycle, I bring the battery to 16 volts or so and hold it there for 2-3 hours.

I'd go a little higher on your absorb voltage, maybe 14.4. I float a little lower than 13.8, like 13.6.

Lastly, you might consider splitting your battery in half to equalize it. I think it's going to take some time to get that voltage up over 16V @ 1500Ahr, and it might be a little easier on your charger if it wasn't running near full rated current for such a long period of time.

[RCpilot]

Volvo, thanks for the comments and taking the time to look at the manual, Having never seen another unit I just figured they were all like this. As you probably saw, there are separate settings for Absorption and Overcharge. That confused me because I can't figure out where in any of the cycles overcharge comes into play. As the unit is charging, it shows what charge mode it's in and all I have seen is: Bulk, Absorption & Float.  I will continue my quest for the actual numbers for my battery, I am one of those that must have a manual for everything. You said go higher for the absorption voltage, which one? There are two voltage settings for each mode. Maybe just make them the same? The Max Timeout setting is how long the battery remains in absorption mode. Is this setting something that needs to be calculated per battery capacity X current being applied with some extra? Or, will the unit decide when it needs to leave absorption mode and go into float? Good idea about equalize, It's easy enough to disconnect a paralleling cable to halve the battery. I am leary of running it at max amps since the other one blew while doing so. I also am considering lowering the setting for "Battery Size" from 1500Ah to maybe 800-1000Ah as this will allow any of the charge percentage settings to be finer and more tunable. For instance now, going from 5% to 10% on the %C setting, the charge current goes from 75A to 150A. At 800Ah it would end up being 5%=40A, 10%=80A and 80 amps is a bit higher. Am I thinking wrong here? Anyway enough for now, I am hoping others that use Forklift batteries will take a look at this as well.




Question about your homemade panels: What were your cell ratings and what are you actually getting out of them? Mine are the Siemens Powermax 6" round 6A rated cells. Each panels' open voltage is 20V and shorted is around 5.5A on a really good day. Out of the BZ500, I never see more than 7.5A, panels are in series. Just wondering..

Kelly

[RP]

Kelly, I wonder if the cummulative resistance of the "tabs" in the string is limiting your current.  There's probably a significant length in each panel.  Any idea what the equivalent wire gauge would be?

[RCpilot]

RP, I thought about this and at the charge controller, 80' away, I can short the panels and measure the current and it's equal to the shorted current at the panels. I did that to make sure I had no loss. I know the charge current cannot be the same as the shorted current because the shorted current is sort of at 0 voltage. I wonder sometimes if the charge control is "holding back" for whatever reason. I suppose a test would be to connect the panels directly to the battery and see what kind of current I get then. Maybe I will try that today.

Kelly

[Volvo farmer]

Maybe a call to Xantrex would sort out the "overcharge" thing.

I only see one voltage setting for each mode.

To me "bulk" is when you put as many amps as you can (in your case 80), into the battery until it reaches 14.4V. Absorbtion is where you hold the voltage at 14.4 volts for two hours. During those two hours, current will gradually decrease from 80A to something less than that, I have no idea what your final figure would be. Then float is where you hold the battery at 13.6V, in my case, until the sun goes down, in your case, until you turn off the charger, I suppose.

I don't know how to make your charger do what I just explained. Maybe, when you have a day off, put some values into it that you think are right, then sit around and watch it with a meter on the battery and see if it does the right thing.

I think my panels Voc were about 37-38V and my Isc was in the 3A range. I wired them for 24V. I have four of them out there and I have never seen more than 10A out of them.

However, they are tilted up for maximum winter gain. Also, it's difficult for me to ever see them at their maximum, because I'm into absorb well before solar noon almost every day. Maybe this December, I'll turn off my other panels around noon and see what the homebrew array would max out at.

[RCpilot]

Thanks Volvo, I agree with your bulk explanation. Where do you come up with the two hours for absorption? Bank size? I am going to try to call Xantrex today and see if they can shed any light on the various settings. Once I figure out what they do, I will report back so than the board can maybe help me to get them dialed in properly for this battery. Thanks for the info about your panels, you are getting 10A out of all of them I take it right? Mine are VERY sensitive to aiming and even 10degrees makes quite a difference on output. Maybe another tracker is needed for yours as well?  

Kelly