Montana Owners Club - Keystone Montana 5th Wheel Forum - View Single Post

Gkerlin · 03-02-2013, 07:09 AM

Sorry about giving you the heart attack.

I just downloaded the specs for the 128s

If you go with the last set up... the 3 36v strings. (actually looks like 49.5v each string - 33v + 16.5v) It looks like You will want an 8amp dc fuse or circuit breaker on the positive lead of each string. (3 8 amp fuses)

If you look at the spec sheet for your panels you'll see a spec "Max Series Fuse Rating - 10 amps" for the pvl-68 but 8 amps for the pvl-128 This is the fuse I'm talking about.

Again - if you had a short in a panel - one or two strings cant produce enough current. But 3 or more could produce enough current to start a fire in the shorted panel so the 10a fuse protects against that.

I noticed that the screen shot that you posted showed that the Tristar was in MPPT mode. That is bulk charging. Your battery voltage was 13.something.

Bear in mind that when your battery gets up to about 14.7 isn (depending upon your settings and the temperature) the controller will go into absorb mode. You'll see the watts drop off. That's because now the controller is just maintaining a constant voltage to finish topping off the batteries - not trying to give them all its got.

I've found out here boon docking - at the later part of the day when my batteries are almost done charging and I am in absorption - that's a good time to take advantage of the extra panel power that is not being used to do stuff like charge computers, and any other stuff that can utilize the power now rather than later on at night when it will be coming out of the batteries instead.

In absorption I might be just showing say 150watts. But then I turn on the inverter and start charging up the computers, phones, iPads and all that stuff and the meter might show the panels putting out 300w and we are still in absorption.

In MPPT mode the panels are giving you all they got.

03-02-2013, 07:09 AM	#19
Gkerlin Montana Master Join Date: Feb 2012 Location: Beaufort Posts: 545 M.O.C. #12221	Sorry about giving you the heart attack. I just downloaded the specs for the 128s If you go with the last set up... the 3 36v strings. (actually looks like 49.5v each string - 33v + 16.5v) It looks like You will want an 8amp dc fuse or circuit breaker on the positive lead of each string. (3 8 amp fuses) If you look at the spec sheet for your panels you'll see a spec "Max Series Fuse Rating - 10 amps" for the pvl-68 but 8 amps for the pvl-128 This is the fuse I'm talking about. Again - if you had a short in a panel - one or two strings cant produce enough current. But 3 or more could produce enough current to start a fire in the shorted panel so the 10a fuse protects against that. I noticed that the screen shot that you posted showed that the Tristar was in MPPT mode. That is bulk charging. Your battery voltage was 13.something. Bear in mind that when your battery gets up to about 14.7 isn (depending upon your settings and the temperature) the controller will go into absorb mode. You'll see the watts drop off. That's because now the controller is just maintaining a constant voltage to finish topping off the batteries - not trying to give them all its got. I've found out here boon docking - at the later part of the day when my batteries are almost done charging and I am in absorption - that's a good time to take advantage of the extra panel power that is not being used to do stuff like charge computers, and any other stuff that can utilize the power now rather than later on at night when it will be coming out of the batteries instead. In absorption I might be just showing say 150watts. But then I turn on the inverter and start charging up the computers, phones, iPads and all that stuff and the meter might show the panels putting out 300w and we are still in absorption. In MPPT mode the panels are giving you all they got.