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 VoltOver Disc Reture VoltTemperature CompensationAlso, 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.

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.

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.

i set my charge 'boost' 14.8vset time for 4 hrs aka 240 minutesreturn to charge if voltage is below 13.4vi have NO loads thru the controller, so LV shut off doesn't countwe full time, so i want max solar everyday i can get itand i want max solar to come back on, when the generator is turned offso if voltage drops below float because the fridge came on or i used the MWi want the solar to kick back into high gear and goto 14.8v

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.

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.

Grape Solar 40A PWM controller | Good Sam Community

RDMueller
Explorer
Aug 21, 2017
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
Moderator
Aug 21, 2017
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
Explorer
Aug 20, 2017
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
Explorer II
Aug 20, 2017
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.

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