Longer battery wires

[kiettyyyy]

Originally Posted by philso

Yes it does. Most teams would probably have a hard time noticing 1.7% power loss, especially if it is a transient condition.

One of the other posters had stated that a few feet of extra 6 AWG could lead to brownouts (which most teams would notice).

Absolutely. I had helped a team in San Diego that had about a 6 FT run of 6 AWG going from their main breaker to the PDP. Shortening the run solved their issue.

Battery voltage can be affected by three factors, temperature, state of charge and current. The one we're really talking about here is current. A lead acid battery has internal resistance. As you move current through the battery, the voltage changes due to its internal resistance.

Lets simplify it a little bit.

When you're charging a battery with some low current, you'll see the battery voltage increase. Charging it with a larger current, you'll really see it increase.

Same thing applies to the discharge. Discharge it with a small current, you'll see it decrease; discharge it with a large current, you'll see the battery voltage really decrease.

Now apply this same theory to having long interconnects with your battery. Say you're drawing current at some C rating that's near the limits of the battery, your voltage will likely be pretty low. Combine that with the voltage drop due to large current draw over a long run of cable.

This situation is extremely prone to causing brownout conditions.