12v + 24v

[jp.beauchemin71]

My son came up and asked me what is the simplest way for him to add solar to his electrical system. His boat is small (weekender) and has very little demand. Just lights, music (12v) and a trolling motor for fishing. But that requires both a 12v and 24v system. I asked him what he already had and he said 3 batteries (2 for 24volt and one for his 12volt). I figure I still have a couple old PWMs from before I switched to MPPT than he can have. All he has space for is just two solar panels. So I came up with something like this but I'm a amateur. I thought I would ask on here if anyone knew if this would work or any better ideas. I'm sorry I did this quickly and hope it makes sense.

[Teknishn]

12-VDC battery circuit looks good. The circuit charging for the 24-VDC system appears to show that you are trying to charge 2 batteries wired in series for 24-VDC with a 12-VDC solar panel. You have the output from the Charge Controller connected at each end of the battery circuit....Won't do much charging that way. You might want to only charge one battery of the 24-VDC system with the Charge Controller and then that battery with "naturally" charge the second battery through an equalization process.

An alternative circuit would be to wire all 3 batteries in series for a complete 24-VDC system, connect each of the PWM's to individual batteries, and then tap off of one battery for the 12-VDC equipment since they are light loads. Granted, the trolling motor may cause interference with the sound system, lights, VHF, etc. during operation depending on the current draw of the motor. Advantage of this circuit is that you now have two solar panels charging you 24-VDC battery bank which results in a theoretical 66% charge rate over a 50% charge charge rate using only one solar panel to charge two batteries while leaving 3 batteries to equalize their charges when the trolling motor is not in use, providing a lot of battery amps leftover for the 12-VDC systems.

FWIW, from my experience working with local "Marine Electricians" here in Egypt for the past 20-years, you and your drawing would qualify you as an Electrical Engineer by local standards here in Egypt! You understand electricity AND can read a drawing! (33 DTG till I'm outta this sandbox!)

Good Luck!

[john61ct]

​Yandina "trollbridge" 12 / 24v combiners

​http://www.yandina.com/troll2400info.htm

​http://www.yandina.com/troll24info.htm

Ann-Marie Foster, Yandina Ltd. tech@yandina.com, well-respected marine electrics engineer, invented the ACR in 1993

[smac999]

No....

2 panels. One to a 12v controller to 12v battery. and one 24v controller to 24v battery. (Yours probably isn't 24v output...) If you can't find a ~30v panel they make boosting controllers.