Grape Solar 40A PWM controller

[RDMueller]

Hi all,

Decided it's time to get into solar! Got a Grape Solar 40A PWM controller and a single 100W panel for starters. My batteries are 2 Trojan T105s.

Have some questions about setting up the controller. It doesn't come with a user manual, just a little one page leaflet with some basic info. There is also an app that you can use to set it up, but I can't find any documentation on how to use the app.

I took these screen shots of the app:





Here's the charging profile I've been using (recommended by Trojan):



There are quite a few fields in the app that I'm not sure what they mean or what to plug in. For example:

Boost Char Return Volt
Over Disc Reture Volt
Temperature Compensation

Also, not totally sure what to plug into some of the other fields to get the desired profile. For example, I've been doing manual absorption charging using a Drok buck booster. I charge at a fixed 14.8V until charge amperage drops to a constant value (usually about 2.5A). Then raise it to 16.2V for a finish voltage at a constant amperage and shut it off when the voltage stops rising.

I have no idea how to set up the Grape to achieve a similar profile. The app doesn't even have any mention of absorption charging.

I know there are at least a few here that are using this controller. I'd love to hear how you set it up and how it's working out for you.

[grizzzman]

RDMueller wrote:
OP here with another question about this controller, specifically using the iOS app. Hopefully someone with this same controller can help.

For some reason I can't get the settings to change. For example:

1. Open the app and connect it via Bluetooth
2. Select "Settings"
3. Change the value in the "Boost Charge Volt" field from 14.6 to 14.8
4. Press the "Set" button
5. App displays message "Set successfully"

You would think that would be it. Done. Well, not so fast... Leave the settings page and when you come back, it's right back at the default value, 14.6!

"have you logged in as the administrator? The plus on the right upper corner will need a code that came with the software."


Then I though that maybe all those values are the default for a flooded battery. So, I went to the top and changed "flooded" to "user." Leave the page and when you come back, right back to flooded again. Won't stay on user.

So I called tech support. The good news - they answer the phone immediately. No phone tree, no waiting on hold. A real live human immediately! The bad news - they weren't sure why I was having that problem. Talked to two reps and the second guy especially seemed very knowledgeable, but was not very familiar with the iOS app. He tried it with his android while I was on the phone and he was able to change the values. But he was baffled by why I couldn't get it to work with the iOS app. He also hadn't heard of anyone else having an issue.

So, anyone here using this Grape controller with the iOS APP? If so, are you able to change the boost voltage? TIA!

[RDMueller]

OP here with another question about this controller, specifically using the iOS app. Hopefully someone with this same controller can help.

For some reason I can't get the settings to change. For example:

1. Open the app and connect it via Bluetooth
2. Select "Settings"
3. Change the value in the "Boost Charge Volt" field from 14.6 to 14.8
4. Press the "Set" button
5. App displays message "Set successfully"

You would think that would be it. Done. Well, not so fast... Leave the settings page and when you come back, it's right back at the default value, 14.6!

Then I though that maybe all those values are the default for a flooded battery. So, I went to the top and changed "flooded" to "user." Leave the page and when you come back, right back to flooded again. Won't stay on user.

So I called tech support. The good news - they answer the phone immediately. No phone tree, no waiting on hold. A real live human immediately! The bad news - they weren't sure why I was having that problem. Talked to two reps and the second guy especially seemed very knowledgeable, but was not very familiar with the iOS app. He tried it with his android while I was on the phone and he was able to change the values. But he was baffled by why I couldn't get it to work with the iOS app. He also hadn't heard of anyone else having an issue.

So, anyone here using this Grape controller with the iOS APP? If so, are you able to change the boost voltage? TIA!

[RDMueller]

That makes sense. The lack of the negative was throwing me off. Anyway, a 5, that's all I needed to know. Thanks!

[red31]

temp compensation is negative 3 even though it shows as non negative.
page 9 of the manual shows it is -3.0mV/degreeC/2v(cell)

http://www.grapesolar.com/docs/GS-PWM-40BT%20manual.pdf

"Trojan recommends using the following: For every 1º F below 77º F add 0.0028 volts per cell or for every 1 C below 25º C add 0.005 volts per cell to the charger voltage setting."
For every 1º F above 77º F subtract 0.0028 volts per cell or for every 1º C above 25º C subtract 0.005 volts per cell to the charger voltage setting.

based on that the correct setting is 5

[RDMueller]

I agree, they have good customer support. I called to get the Bluetooth app and had it emailed to me within 10 minutes. I'm sure they'll be able to answer any remaining questions I have. Frankly though, I have a pretty good understanding now from the replies I got to this thread.

[jplante4]

FWIW, I got a quick answer from customer support at Grape. There's a bluetooth app that they will send a link for. Allows you to view the history stored in the controller's memory.

[RDMueller]

Thanks for the replies. I basically understand most of the fields now, really does make sense. Still unsure about temperature compensation though. The default value is a 3, but no mention of what units or what the range is.

[MrWizard]

i set my charge 'boost' 14.8v
set time for 4 hrs aka 240 minutes
return to charge if voltage is below 13.4v

i have NO loads thru the controller, so LV shut off doesn't count

we full time, so i want max solar everyday i can get it

and i want max solar to come back on, when the generator is turned off
so if voltage drops below float because the fridge came on or i used the MW
i want the solar to kick back into high gear and goto 14.8v

[red31]

here is how the controller profile works using the 'terms' of the controller.

solar charge the battery until the batt = boost charge volt(v)
Maintain boost charge volt(v) for the boost charge tim(min)
Maintain float charge volt(v)
on the 28th of each month, after boost charge time(min) do the equalz(v) for equal time(min).

While in float mode, return to boost (start over) anytime the batt v drops to boost char return(v).

so set boost to 14.8 and on a normal usage day determine if 2hrs is short, if so increase 120 to something bigger. Set eaual to whatever you like that will not damage your equipment, default is every 30 days for 60 min. Not sure if you could set it to daily (every 1 day) to match your charge profile.

you would also need to set the first 2 parameters higher for your equal v.

[jplante4]

Same as my controller. The charging cutoff voltage should be no more that 15V. Boost is fine, but be aware that the controller will bump into boost mode everyday as soon as the sun is high enough to provide that voltage. You won't get the same boost amps off the solar panels as you would off shore power or the genny, so the panels will really only maintain a top off charge.

Unless you're running the DC loads through the controller, the low voltage cutoffs and over discharge settings don't matter.