Impact of wire gauge size between + battery stub and trailer

[OregonPerson]

Hello,

I have 2 Deep cycle 6 volt GC batteries serially connected on the tongue of my trailer and I'm somewhat new to RVing (1 previous season) and electrical but learning through this forum.

Recently Jayco has been dealing with a recall regarding overcurrent protection on a large number of Jayco units. Their fix includes installation of an additional 30 amp fuse box mounted on the frame between the + stub of the battery by butt splicing wire between the previous cable and the new 30 amp fuse box. The butt spliced wire includes a 12" 12 - 14 AWG wire that is spliced to the existing 8-10 gauge + lead wire feeding the trailer and 48" 12-14AWG between the new fuse box and the battery

Now I have a 48" 12-14 AWG wire from the positive stub of the battery to this 30 amp fuse box which then goes to the 12" butt spliced 12-14 AWG wire connected to the 8-10 AWG wire going into the trailer.

Why does one utilize + lead cable sizes such 0-4AWG to connect inverters and solar controllers while Jayco utilizes 12-14AWG in this fix and then connects it to a 30A fuse box mounted on the frame??

Also, I thought 12-14AWG wire only handled 20A before heating up.

[bigironcoder]

This is known as pushing the specs to the limit due to the cost of copper wire. In most cases, it works good enough but can be an issue when dry camping.

My 195RB has about 12 feet of 10 gauge between the battery and my WFCO 8735 power controller. Most any chart shows that will result in a 7% drop at 35 amps. Not a big issue except when the WFCO is trying to bulk charge the battery. It just isn't going to happen.

I'm thinking about replacing my battery to controller run with 6 or 8 gauge wire, because I do sometimes dry camp and run my battery down. Even though my WFCO is capable of bulk charging the battery, it stays in maintain mode because it thinks the battery is fully charged. I have proven this several times by loading the 12 volts at the controller end of the wire, instead of at the battery.

In looking at the cost of wire, I've actually thought of buying long 6 gauge jumper cables and cutting it up, because it's cheaper than buying just the wire.

[wabirch]

Good thinking

[Duke4857]

Originally Posted by bigironcoder

This is known as pushing the specs to the limit due to the cost of copper wire. In most cases, it works good enough but can be an issue when dry camping.

My 195RB has about 12 feet of 10 gauge between the battery and my WFCO 8735 power controller. Most any chart shows that will result in a 7% drop at 35 amps. Not a big issue except when the WFCO is trying to bulk charge the battery. It just isn't going to happen.

I'm thinking about replacing my battery to controller run with 6 or 8 gauge wire, because I do sometimes dry camp and run my battery down. Even though my WFCO is capable of bulk charging the battery, it stays in maintain mode because it thinks the battery is fully charged. I have proven this several times by loading the 12 volts at the controller end of the wire, instead of at the battery.

In looking at the cost of wire, I've actually thought of buying long 6 gauge jumper cables and cutting it up, because it's cheaper than buying just the wire.

Make sure the cheap jumper cables are not aluminum wire instead of copper. I have seen lots of aluminum jumper cables out there.

[CampNow]

Originally Posted by bigironcoder

. . . My 195RB has about 12 feet of 10 gauge between the battery and my WFCO 8735 power controller . . .

Yes, larger gauge cable is going to improve charge current; however, WFCO converters are notorious for rarely, if ever, going into bulk mode--even when batteries are severely discharged. A lot of folks replace their WFCO converters with converters such as those made by Progressive Dynamic. PD converters are programmed to go into bulk mode automatically (and always do when appropriate---unlike most WFCO's). They can also be placed into bulk mode manually using a "charge wizard" pendant.

We replaced the WFCO converters in our two previous trailers with converters made by PD. The WFCO converters (one rated at 55, the other 70 amps) would never produce more than 18-25 amps of charge current. They always remained in absorption mode---regardless how depleted the batteries were. With the replacement PD converters we were able to easily obtain a full 55-70 amps of charge current in bulk mode (automatically or manually) reducing our charge times while dry camping by nearly 1/2 to 1/3!

Fortunately, our current trailer, an '18 Jayco Eagle, came from the factory with a Progressive Dynamics converter standard.

[Duke4857]

I take my home battery charger with me. I also have 2 battery banks on the camp trailer. (2 6 volt and 2 12 volt) I will use the home charger to charge the, "out of service batteries", the online batteries can be charged by the onboard charger. Thank you for telling me about the WFCO converters.