Rerouting Converter Connection

UPDATE:
Well, weather finally got decent enough to work on the wiring. I could not use #2 wire as #4 is the largest that will fit in the terminal strip on the converter. Total length was 14 feet for positive wire and 13 feet for negative. The positive is longer to route through the Bussman 100A circuit breaker mounted on the other side of the partition from the battery compartment. Obviously, all wire penetrations through partitions are grommeted. Wires are enclosed in 1" wire loom (that split plastic stuff). Batteries were at 12.5V when I started the voltage loss comparison. Using the original pathway, voltage measured at converter was 14.47. Voltage at batteries was 13.38. switched over to the new path and voltage at converter was 14.47 and voltage at batteries was 14.36. So I went from a 1.09V drop to a 0.11V drop. Granted, I doubt the converter was putting out 80A, but I am happy eliminating 0.98V of loss. Will see how it does when batteries have been discharged further.
If I am still not happy, I can run a second set of #4 from the converter to the battery and breaker. Hopefully that will not be needed.

Mex is right. A fuse or whatever is needed at the battery end of a direct converter to battery wire (at least in nearly all cases). The converter is internally current limited by design and generally by fuses too. The battery is not, and can easily produce enough current to be a fire hazard even with a heavy wire.

However...?

Is it not the cabling from the batteries that demands an overcurrent protection device at the battery end in cause of positive cable overcurrent fault?

I had a similar issue, but in my case, the newly installed PD 9145w/wizard could never get higher than 27.6 to the house bank. When I discovered the issue (the same way you did) and started to calculate a wire size that would fix it, that solution was impractical.

So, I just got a new 9260 (because it would fit where the 9145 would not) and mounted it almost 20 feet closer to the house bank.

Problem solved: I know this because I have now actually seen charge rates of 57+.

I am not sure about a breaker or a disconnect (I am in favor of both most places) between the PD and the bank. The PD is internally protected from over current and if it faults that badly, there are fuses in the output that will open.

Matt

LittleBill wrote:

"of course they would show lower voltage if the battery's are low, you either charge by current or voltage.

if the charger is maxed out current wise and is limiting the amperage, then the voltage will not rise until the battery's fall under the current being limited. once the voltage limit is reached, current will keep reducing. "

? The battery voltage will rise toward Vabs all the while the current is constant at the current limit of the charger. At some voltage, current will taper. Actually battery voltage appears to continue to rise a little, due to reducing voltage drop from the charger's voltage as amps taper. Only when the battery is full at no amps flow will battery voltage equal charger voltage.

I agree with SG. Just add a converter close to the battery bank. You can use both if there is sufficient shore or generator power.

Hi LittleBill,

I have to limit my charging to 108 amps out of a possible 125. I do that by limiting the input amps @ 120 volts on the Magnum 3012.

LittleBill wrote:

pianotuna wrote:
Even my Magnum charger with rather large wire and a 3 foot run shows voltage drop when the jars are low.

of course they would show lower voltage if the battery's are low, you either charge by current or voltage.

if the charger is maxed out current wise and is limiting the amperage, then the voltage will not rise until the battery's fall under the current being limited. once the voltage limit is reached, current will keep reducing.

STBRetired wrote:
We mostly stay at FHU sites, but we do probably half a dozen weekends boondocking each season.

I like to have options.

Best "option" IMO and much simpler is to just leave the existing converter as it is and invest in a stand alone charger you can connect directly to the batteries with short, heavy gauge cable that will minimize voltage loss and maximize charging those few times each season you do camp without shore power. I did just this myself with a CTEK charger, first connecting it directly then later installing it in my trailer's front pass through storage compartment where it's within feet of the battery location. Choose any one of a number of chargers that can be used for this purpose, or even another converter if that's what you prefer. K.I.S.S. :B

Yes, it is all about scenario. The abandoned wire from fuse panel to battery switch might be part of a future solar panel to controller(placed at the back) wiring job if the wire route down from the roof has to go near where the battery switch is. (Disconnected from DC panel battery lug and put on controller input instead.)

We mostly stay at FHU sites, but we do probably half a dozen weekends boondocking each season. Just like to keep the rig set up as best as possible. Did not seem right to me to run the converter output all the way to the front when the converter and the batteries are both in the back. Rewiring it will just make life simpler should we decide to go boondocking for a couple weeks at some point. I like to have options.