Design needs expert review

[raptor]

Hi I'm planning a system to power my gate opener and perimeter LED lights. Can you have a look at the attached jpg and comment? The goal is to maximize amp-hrs of the batteries. Thanks in advance!

 

[HRTKD]

Wire your batteries in series and you can skip the step down/up transformers.

 

[raptor]

Thanks HRTKD. Batteries in parallel gives me 430 AH instead of 215 AH. Should be able to run the load for longer. That's why I planned it that way. Transformers are only about $70 for both.

 

[HRTKD]

Waste of money, waste of battery cables. You still have the same number of watt hours.

Have you taken into account the conversion inefficiencies?

 

[raptor]

No. Didn't calc it but figured there might be some loss. Not sure how much. I better look at watt-hrs.

 

[madsci1016]

A charge controller (The victron 75|15) connected to a buck regulator negates the Victrons ability to be a charge controller. Whether you wire the batteries in series or parallel it absolutely the same amount of run time for your load. Do not put any regulators between your charge controller and load.

 

[raptor]

@HRTKD okay. watt hr =2520 regardless so I should wire batteries in series. Thanks. @madsci1016 if I wire batteries in series then I won't need the regulators. Thanks to both of you.

Where should I put a fuse?

 

[HRTKD]

The general recommendation is to have a DC circuit breaker on both sides of the solar charge controller. The breaker between the panel and the controller allows you to disconnect solar output to the controller for when you need to work on the controller or other parts of the system. You also get over current protection.

A fuse between the battery and the load is also recommended.

The load can get power from the solar charge controller alone, without ever using power from the battery, depending upon how many amps the load (LED lights and gate) consume.

 

[raptor]

Right. I will add those fuses and the DC circuit on both sides of the controller. Did not know about the load to solar charge controller circuit that bypasses the batteries. Thanks!