Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
RV Trip Planning Discussions

Go Back   iRV2 Forums > RV SYSTEMS AND TECHNOLOGIES FORUMS > RV Systems & Appliances
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
Thread Tools Search this Thread Display Modes
Old 05-21-2022, 01:25 PM   #1
Senior Member
Join Date: Sep 2018
Posts: 138
dual solar controllers question

So I see lots of threads about using more than one controller, but I have yet to find an answer to this question of mine.

I currently have 300 watts roof mounted. So I know when I am on shore power, the controller "behaves" differently, moaning it does not push as much power to the batteries since the convertor is working, especially when it is in boost.

So, how do multiple controllers work together if one see the higher voltage of the other, does it not step down? They are not communicating so can only register the current voltage, and if one is putting out 13.8 volts, the other would shut down right?

Or is it that one set, say the roof mounted, is not producing enough so the other senses the lower voltage and produces to its potential?
2014 Ram 2500 4x4 quad cab
2007 Denali 26RLS
300 watts solar, 40 amp MPPT
rbTN is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free! RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 05-21-2022, 02:01 PM   #2
Senior Member
Join Date: Apr 2020
Posts: 596
Different charging sources, chargers, alternators and solar controllers have slightly different charging parameters, but they will all adjust to one common voltage at the battery. Then each will supply current based on that voltage, some reduced, some not and all will coexist fine.

DavidEM is offline   Reply With Quote
Old 05-21-2022, 02:31 PM   #3
Senior Member
Join Date: Sep 2018
Posts: 138
ok, so you will not actually increase the charging capacity by adding one source to the other, but one may produce more in the absence of the other, and therefore working together to charge
2014 Ram 2500 4x4 quad cab
2007 Denali 26RLS
300 watts solar, 40 amp MPPT
rbTN is offline   Reply With Quote
Old 05-21-2022, 03:04 PM   #4
Senior Member
paul65k's Avatar

Alpine Owners Club
Join Date: Nov 2015
Location: Lake Havasu City, AZ
Posts: 2,636
Typically multiple charge controllers are combined at a bus bar or power distributor (eg Victron Lynx) and then connected to the battery bank.

All power sources are fused accordingly prior to this distribution block.
Paul & Jean
2001 Alpine 36FDDS (74291)-1600W Solar, 13,440Wh (525Ah @24V) LiFePO4
2019 Jeep Grand Cherokee Trailhawk (Hemi)
2006 Alpenlite 32RL - Sold
paul65k is offline   Reply With Quote
Old 05-21-2022, 05:16 PM   #5
Senior Member
corn18's Avatar

Join Date: Sep 2020
Posts: 538
I have two solar charge controllers rated 50A each. I have seen each one pushing 35A to the batteries. That's about the best my solar panels can do. If I had more panels, they might push more amps. They just see voltage. When one turns on and starts charging, it tries to put out 14.6V but if the battery needs charging, the actual voltage at the battery might be 13.4V. The other charge controller sees that and also starts pushing amps. If the battery is really hungry, then the voltage will still sit around 13.4V. Once the voltage starts rising as the battery charges, both controllers will see that and throttle their charge per the charge profile. Mine is set to absorb @ 14.4 and float @ 13.4. Once the battery hits 14.4V, the controllers will switch to float. Once the BMS says "enough", it will cut off the charge and the controllers will show 0 amps.

If I have the inverter/charger running, it works the same way. They all seem to contribute something until the voltage hits 14.4V and then all go to float until the BMS has had enough.

The key is to make sure all your charging sources are set to the same voltages. I also have a DC-DC smart charger connected to the truck. That is also set to 14.4V and 13.4V. If I set any of them to different voltages, they would contribute differently.

I hope that makes sense.
2015 Chevy 2500HD 6.0 4x4 CC SB
2021 Salem Hemisphere 290RL
Andersen Ultimate
1200W Solar > 412 aH LiFePO4 > Victron MultiPlus II
corn18 is offline   Reply With Quote
Old 05-22-2022, 09:38 AM   #6
Senior Member
Join Date: Nov 2018
Location: Beaver Dam, Wisconsin
Posts: 3,285
Over thinking

It is complicated, but you do not need to over think it.

Multiple controllers connected to a battery bank will usually work fine together. Some may contribute more than others for electrical reasons. Overall, the battery bank will be the primary control on current.

Controllers are usually in voltage regulation mode. Deeply discharged batteries will take more current than nearly fully charged batteries.

The only time you will get full current from a controller is when the batteries will take more than the controllers can deliver. If a controller is idling it is because the battery bank is not absorbing more.
Paul Bristol
Kodiak Cub 176RD
Nissan Pathfinder 2015
Persistent is offline   Reply With Quote

controller, solar

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Dual input charge controllers rarebear.nm Class C Motorhome Discussions 6 02-06-2020 03:09 PM
Solar panel controllers Magic-carpet Entegra Owner's Forum 21 12-03-2016 11:42 AM
Beware of cheap MPPT Solar Charge Controllers powercat_ras RV Systems & Appliances 2 04-18-2016 03:39 PM
Hitches, Brake Controllers, Airbags, Air Shocks, Sway Controllers-Oh My?? TXDIANIMAL 5th Wheel Discussion 10 07-09-2014 06:46 PM
solar panel controllers in storage jstreiff Country Coach Owners Forum 3 12-29-2012 01:19 AM

» Featured Campgrounds

Reviews provided by

All times are GMT -6. The time now is 04:06 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2022, vBulletin Solutions, Inc.