Genasun GVB-8

[rgleason]

Sorry, I was going to add "Genasun GVB-8 Boost - Operation" the to title but CF accepted it prematurely.


Response from Ryan of Genasun.

Hi Rick,

Sorry about the delay in responding, great explanation on how the GVB-8-Pb-12V controller operates. A couple points I would like to provide a little more clarification.

1) You are correct that the 12.5V restart voltage is effective after the controller completes it's charge voltage and is in float mode, then PV input becomes not available (night), unless 12.5V or less is observed on the battery voltage it will return to float voltage once PV input becomes available. It is also the voltage that needs to be observed in order for the controller to cycle back to the bulk/ absorption voltages when actively charging at the float voltage.

2) You are correct that the time in absorption is rigid, how much time your batteries need is dependent on their state of discharge and varies form ~1-4 hours. 2 hours seems to be an industry standard for charge controllers that do not base the transition on current.

3) Since the Genasun controller are not connected to an external current shunt, when in float mode they will provide CV indefinitely (when PV input is available) at the float voltage (+/- temperature compensation). There is no way for the controller to know your batteries SOC other than basing it on voltage. It does not have a "cut off amperage" because there might be alternate loads on the batteries which the controllers are supplementing as well as the specific capacity of your battery bank.

4) The controller bring the battery to the bulk voltage initially, then immediately maintains the absorption voltage.

Regarding the PV input, the GVB-8-Pb-12V controllers have a recommend PV input range of 5-13V (Vmp) and an absolute max input amperage of 9A (Imp)

Also, you can order the GVB-8 (boost) controllers with custom Bulk, Absorption & Float voltages to match your Trojan's more precisely as desired.

Please let me know if I can be of further assistance either by replying to this email or contacting me directly at 760-208-2149.


Regards

Ryan



--
Ryan Gurin
techsupport@blueskyenergyinc.com

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On Wed, Sep 5, 2018 at 6:55 AM PDT, Frederick Gleason <fcgleason@tgp-architects.com> wrote: I have not found any description for your GVB-8 solar controller charging logic on the website.
I wish to confirm that with low voltage (Vmp=9.2v) low amp (Imp=5.51a) panels that the Genasun controller will FULLY charge the FLA batteries over multiple days, assuming the boat is on a mooring, with no drawdown loads, to the manufacturer required tailing amps (no PSoC), without damaging the batteries due to overcurrent or overvoltage.
To do that I need to know precisely what the Genasun Charging Logic is, which is not available on the website or the download documents (specs and manuals).
How to charge the FLA batteries with low voltage and amperage panels over multiple days, avoiding PSoC and overvoltage damage?
Possible Solar Controller Operation

1. Assume Alternator has completed the Trojan FLA (C20=225ah) Bulk (Constant Charge) equal to 10-13% of C20 (22.5-29.5 amps) up to 14.82 volts followed by some time in Absorption (Constant Voltage) with amperage falling. Assume alternator charging stops at 85%SoC, with resting voltage (with no loads) at 12.55-12.6v.
2. The next morning, with good sun, the solar PV controller will "Bulk" charge up to 14.4v, then has time to run part way through the 2hr absorption 14.2v routine.
3. The controller will not Bulk charge again until after battery voltage has dropped to 12.5v when Bulk stage will be reset.
4. Late evening/ nightime occurs, no PV power, batteries are not fully charged and the Solar Controller has not completed all cycles (Absorption in particular).
5. The next day, when PV power is available, the controller knows that Absorption has not been completed, and will automatically charge to the bulk/ absorption voltage (14.4v, then drop to 14.2v) and hold the Absorption time for 2 hours (timer is reset). This is a CV or constant voltage routine. Trojan requires a CV between 14.1-14.7v completing when the current falls to the finish current of 2.25 amps. The controller simply stops after 2 hours and this is not adjustable, so the batteries will not be FULL at 100%SoC, because the Trojan charging routine has not been met.
6. Assuming the Controller changes to CV Float stage (13.8v) after 2 hours, using the amps produced by the PV and we do not know how or if this ends. Trojan Float requirements are CC equal to 1-3% of C20 applied as voltage increases (2.25-6.75 amps) with trailing amps of .005C (1.125amps). I use 1 amp to stop float stage. The Genasun Controller Float stage does not appear to follow the manufacturer Float routine. How do we know this will produce a "Full" battery bank?
7. To reset the Controller, cycle battery power to the controller (disconnect-off/on, not PV input), if PV power is present, the Controller will automatically charge to the bulk/ absorption voltage and hold the absorption time for 2 hours, then float.
8. If there is a dark cloud, or solar eclipse without PV input, the controller will commence again (when PV power is available) at the stage that was not fully completed, provided battery voltage has not dropped below 12.5v.
9. If the charge cycle is completed before "nighttime" and is in "Float", the Controller will go back to "Float" the next day, provided battery voltage has not dropped below 12.5v.
10. Float Stage: Once the controller has completed bulk and absorption and the controller is holding the float voltage, if battery power remains constant while PV power is not present, the controller will return to the float voltage, when PV input becomes available (unless the controller observes a battery voltage of 12.5V or less).
11. If 12.5v or less is observed by the controller while no PV input is present, the controller will cycle to the bulk/ absorption voltages once PV input becomes available. This is to prevent unnecessary time at the absorption voltage with fully charged batteries.

Is the above description correct with respect to the Genasun GVB-8 Solar Controller?
If not, please correct me.
Thank you
Rick Gleason

[rgleason]

Ryan clarified below several questions I had.

1. The part I am trying to understand more completely is the Absorption Mode logic to determine if there will be adequate multi-day charging:
2. If the 2 hour "absorption" period is Not completed before nightfall, exactly what happens the next morning?

I believe that multi-day charging of the batteries is feasible. Since these controllers can have settings programmed at the factory, for the particular batteries, the settings would need to be determined.
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Hi Rick,

If the controller does not complete the time in absorption (and begin to maintain the float voltage), the next day it will attempt to achieve the absorption voltage and hold if for the full two hours.

Ryan
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Hi Rick,

I'm sorry if I confused you.

You said "From your response, it appears that if the 2 hour "absorption" period is not completed before nightfall, the controller will roll immediately into "float" mode the next morning, rather than restarting the 2 hour absorption period or restarting the absorption period to complete the 2hr period". It's the other way around.

If the two hour absorption time is completed and the controller is holding the float voltage, that is when the restart voltage comes into play. To put more simply, after any time the charge controller reaches Float mode, it will always return to the float voltage (day or night) unless the battery voltage drops at or below the restart voltage, at which point the controller will begin the charge cycle anew, providing Constant Current (CC) until the absorption voltage is achieved where it will provide Constant Voltage (CV) at either the abortion or float voltage.

It is true that the Genasun controller focuses on harvesting every watt possible and this mentality results in less "bells & whistles" compared to other chargers. Blue Sky Energy (www.BlueSkyEnergyInc.com) is Genasun's sister company and also manufacturers excellent charge controllers that can incorporate external current shunts so that the transition from absorption to float can be based on current vs time.

Given your lower Vmp, you would need to connect 2x-4x of the panels (in series) to a SB1524iX charge controller. I understand this may not be ideal depending on the anticipated partial shading of your array. The IPN ProRemote Display incorporates the aforementioned external current shunt. The BSE controllers can be configures in a Master/ Slave relationship so that up to eight controllers and operate as one, but you would need a minimum of two of the Soliban panels (in series) to have sufficient input voltage.

http://www.blueskyenergyinc.com/uploads/pdf/SB1524iX_Datasheet_(2017).pdf

http://www.blueskyenergyinc.com/uploads/pdf/IPN_ProRemote_(-S)_Datasheet_(2017)_1.pdf

Also there is a video on our website on "How to program IPNPRO" which gives further insight towards it's capabilities.

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