BajaNomad

Best way to disconnect solar from batteries?

Doug/Vamonos - 12-15-2015 at 08:45 AM

Hi. I'm away from Baja for several months at a time. And the electrolyte in my batteries gets low. I have 6 6-volt GC batteries set up for 12-volts. I have two sets of panels that charge through 2 charge controllers. My idea is to disconnect the more powerful set and only leave the lesser panels connected to the smaller charge controller to limit the charge to the batteries. Hope that made sense. My question is can I simply disconnect the + and - cables that come out of the charge controller? Or is there a better way to separate the panels/charge controller from the batteries? I don't want to do this via programming the charge controllers. Keep it simple. Somewhere I heard not to leave the panels in the sun and connected to nothing. Thanks.

willardguy - 12-15-2015 at 11:00 AM

I get what you're after but even with two charge controllers stacked a day after you leave they'll be at float, remove one and it'll still be a the same float voltage.
for disconnects or combiners use quality marine battery switches (off-1-2-both)

[Edited on 12-15-2015 by willardguy]

small tip

captkw - 12-15-2015 at 11:34 AM

car,truck,boat, RV, solar always disconnect the neg side first and hook up last at the battery :light:

[Edited on 12-15-2015 by captkw]

rts551 - 12-15-2015 at 12:35 PM

Willard has it. the voltage will be the same. You can disconnect the panels without damage to them. Just make sure they (the wires) do not short out. (Nothing will be going into your batteries then).

Bob and Susan - 12-15-2015 at 01:41 PM

actually you should have a 250A breaker from you solar panels to each charge controller...

just flip the breaker on one

you should have another 250a breaker from the inverter to the batteries too...flip that also

don't disconnect the batteries and don't use marine battery switches...your house is not a boat

larryC - 12-15-2015 at 01:53 PM

Quote: Originally posted by Bob and Susan  
actually you should have a 250A breaker from you solar panels to each charge controller...

just flip the breaker on one

you should have another 250a breaker from the inverter to the batteries too...flip that also

don't disconnect the batteries and don't use marine battery switches...your house is not a boat


A 250 amp breaker between the solar panels and the controller is a little large. Circuit breakers are designed to protect the wiring so if he had 12 gage wire from the panels to the controller then a 25 amp breaker should do it. That is for each panel to the controller. Between the controller and batteries he should have a breaker large enough to allow all the current from the controller to pass into the batteries but not so large to allow the wire to burn up in case of a malfunction. So wire size is also important.
To answer the OP question, he could either install a switch, circuit breaker or do it the old fashioned way and disconnect one or both of the wires. The end result will be the same.
Larry

[Edited on 12-15-2015 by larryC]

Bob and Susan - 12-15-2015 at 02:24 PM

Quote: Originally posted by lencho  
Quote: Originally posted by captkw  
car,truck,boat, RV, solar always disconnect the neg side first and hook up last at the battery

Why?



that is actually true...the "snap" when removing the positive first can fry electronics

it is weird but true

Bob and Susan - 12-15-2015 at 02:27 PM

Quote: Originally posted by larryC  
Quote: Originally posted by Bob and Susan  
actually you should have a 250A breaker from you solar panels to each charge controller...

just flip the breaker on one

you should have another 250a breaker from the inverter to the batteries too...flip that also

don't disconnect the batteries and don't use marine battery switches...your house is not a boat


A 250 amp breaker between the solar panels and the controller is a little large. Circuit breakers are designed to protect the wiring so if he had 12 gage wire from the panels to the controller then a 25 amp breaker should do it. That is for each panel to the controller. Between the controller and batteries he should have a breaker large enough to allow all the current from the controller to pass into the batteries but not so large to allow the wire to burn up in case of a malfunction. So wire size is also important.
To answer the OP question, he could either install a switch, circuit breaker or do it the old fashioned way and disconnect one or both of the wires. The end result will be the same.
Larry

[Edited on 12-15-2015 by larryC]


25A too small...

monoloco - 12-15-2015 at 04:44 PM

Quote: Originally posted by Bob and Susan  
Quote: Originally posted by larryC  
Quote: Originally posted by Bob and Susan  
actually you should have a 250A breaker from you solar panels to each charge controller...

just flip the breaker on one

you should have another 250a breaker from the inverter to the batteries too...flip that also

don't disconnect the batteries and don't use marine battery switches...your house is not a boat


A 250 amp breaker between the solar panels and the controller is a little large. Circuit breakers are designed to protect the wiring so if he had 12 gage wire from the panels to the controller then a 25 amp breaker should do it. That is for each panel to the controller. Between the controller and batteries he should have a breaker large enough to allow all the current from the controller to pass into the batteries but not so large to allow the wire to burn up in case of a malfunction. So wire size is also important.
To answer the OP question, he could either install a switch, circuit breaker or do it the old fashioned way and disconnect one or both of the wires. The end result will be the same.
Larry

[Edited on 12-15-2015 by larryC]


25A too small...
It all depends on the size of the array. To protect your equipment, the breaker should be sized just slightly higher than the maximum output amperage of the panels. With a modern MPPT controller and panels wired in series, the amperage can be quite low due to the higher output voltage, which also allows for the use of smaller gauge cabling to the charge controller.

weebray - 12-15-2015 at 05:31 PM

Negative terminal off first and on last - cuz - if your wrench happens to touch ground (a very real possibility) and you're working on the positive terminal with the ground still attached the system goes in to "weld" mode.

willardguy - 12-15-2015 at 06:05 PM

look, dougs original question was simply "can I disconnect one of my solar arrays to lessen the current to my battery bank to slow the need for watering". the answer is no.
now we have susan telling him to install 250amp breakers between panels and controller. really? :rolleyes:

OMG !!

captkw - 12-15-2015 at 06:25 PM

Being I do this for a living and a specialist in electrical systems,,I am staying out of this...BUT,, did BOB just agree with me ??? raise the flags and get the trumpets blarring !! LOL:lol:Since I had to edit the word "and" I will throw this in; a 250 Amp fuse/circuit breaker ??????????? WTF ???:?:

[Edited on 12-16-2015 by captkw]

mtgoat666 - 12-15-2015 at 08:59 PM

Quote: Originally posted by Bob and Susan  
Quote: Originally posted by larryC  
Quote: Originally posted by Bob and Susan  
actually you should have a 250A breaker from you solar panels to each charge controller...

just flip the breaker on one

you should have another 250a breaker from the inverter to the batteries too...flip that also

don't disconnect the batteries and don't use marine battery switches...your house is not a boat


A 250 amp breaker between the solar panels and the controller is a little large. Circuit breakers are designed to protect the wiring so if he had 12 gage wire from the panels to the controller then a 25 amp breaker should do it. That is for each panel to the controller. Between the controller and batteries he should have a breaker large enough to allow all the current from the controller to pass into the batteries but not so large to allow the wire to burn up in case of a malfunction. So wire size is also important.
To answer the OP question, he could either install a switch, circuit breaker or do it the old fashioned way and disconnect one or both of the wires. The end result will be the same.
Larry

[Edited on 12-15-2015 by larryC]


25A too small...


you guys dont know how many panels and the panel rating. you dont know if he has string inverters or a single inverter. you guys got no flocking idea if he needs a 10, 20, 40 or 80 amp breaker!
the way he asked his question, i suspect he doesn't have any breakers :lol::lol:

all he needs do is clip the wire, then rewire and wrap with duct tape when he comes back :lol::lol:

if he's gone 6 months of the year, the panels would last longer if he took them out of the sun :light::light::light:

willardguy - 12-16-2015 at 02:48 PM

Quote: Originally posted by lencho  
Quote: Originally posted by soulpatch  

I've seen your array... unless you've added to it.
A 20A breaker would do it on the negative side.
Which brings up a question; do standard household circuit breakers behave the same on DC?


few are designed for DC use, and are clearly marked as such. the issue is arcing,DC switches and breakers use a Knife type switch to prevent this.

healthdetective - 12-16-2015 at 04:29 PM

You can use Square D breakers but ONLY QO series as they are DC rated (not their Homeline series)

Here is a video (not mine) that goes into it:
https://www.youtube.com/watch?v=ZkSk4Go2ACo

I recently hooked up a wind generator this way with great success

GRrr

captkw - 12-16-2015 at 06:44 PM

switchs are always on the positive side and if you want to be ahead of the game use:" Blue sea marine" parts..no its not a boat but we have been using solar stuff in/on boats long before houses...FACT and marine grade is the way to go if your any where near the coast (DUH)...Hey Billy bob,, just twist those wires together......NOT !!

mtgoat666 - 12-16-2015 at 07:08 PM

Quote: Originally posted by captkw  
switchs are always on the positive side and if you want to be ahead of the game use:" Blue sea marine" parts..no its not a boat but we have been using solar stuff in/on boats long before houses...FACT and marine grade is the way to go if your any where near the coast (DUH)...Hey Billy bob,, just twist those wires together......NOT !!


Cappy, this is Mexico, anything that works is fine! Twisting wire accomplishes same thing as a switch!

Yo Goat

captkw - 12-16-2015 at 07:26 PM

Ya,, your right,,BUT. in a normal little room with controller and batts that are "gassing" while being charged// I would use marine parts as they will hold up in the long run with almost no failures and are ignition protected,, aka no spark to go Boom,Boom...Cant tell how many propane tanks that I have seen hooked up with car fuel line and hose clamps...just not the way I roll

Doug/Vamonos - 12-16-2015 at 08:26 PM

You guys kill me! Too funny. Didn't mean to start all this! :-)

Pescador - 12-17-2015 at 09:42 AM

Yeah, I read through the whole thing and figure if I ever need some solar help, I will use Bob Frambes cause he runs his whole place on Solar. Now as far as the Cappy is concerned, I suspect he was filtering a little too much Sterno through bread slices in his younger days.