Individual power wiring or large wire and relays

[transmitterdan]

All voltage drop calculations must be made using twice the wire distance because the negative return path has the same voltage drop as the positive cable.

[Sailor 99]

Originally Posted by transmitterdan

All voltage drop calculations must be made using twice the wire distance because the negative return path has the same voltage drop as the positive cable.

Depends on the app and the charts. I would expect both to be clear about how they got to their calculations

[Sailor 99]

Originally Posted by transmitterdan

Be sure to look at the solar charger specifications. Many models can be destroyed by disconnecting the battery while the solar panels are connected. Without the battery the internal electronics do not have power. Then the solar panel voltage rises because there is no place for the current to go (no battery) and this excess voltage damages the solar charger electronics. Many solar chargers require disconnecting the solar panels before disconnecting the battery.

I can understand that. Much like disconnecting the batteries from the alternator while the engine is running. Usually fatal for the alternator.

[transmitterdan]

Originally Posted by Dark Horse

Depends on the app and the charts. I would expect both to be clear about how they got to their calculations

I don’t trust apps. But I do trust Ohm’s law. And to use that you have to know the diameter and length of the positive and return cables.

[john61ct]

Blue Sea's Circuit Wizard is very trustworthy.

Takes all the variables into account, which a paper table cannot

[hellosailor]

Also consider that relays throw spikes. You might want to install a diode clamp across each relay to eliminate those.

[Sailor 99]

Originally Posted by hellosailor

Also consider that relays throw spikes. You might want to install a diode clamp across each relay to eliminate those.

Thanks,,, I did not know that.

[Sailor 99]

Originally Posted by john61ct

Blue Sea's Circuit Wizard is very trustworthy.

Takes all the variables into account, which a paper table cannot

But does not give the actual backing data.



I am using the one below. I choose the cable size and it tells me what the drop is in real number and percentage.



https://www.calculator.net/voltage-d...s=15&x=74&y=19

[transmitterdan]

Originally Posted by hellosailor

Also consider that relays throw spikes. You might want to install a diode clamp across each relay to eliminate those.

Most relays don’t “throw spikes”. If you want to know how to deal with transients post an example and we can discuss.

Spikes in a system with relays mainly come from the device the relay is controlling. The same spike happens with plain switches too. So it’s not the relay that causes the spikes.

The actuating coil of the relay can cause a minor spike but it isn’t usually significant.