Chinook RV

I am going to upgrade to a lithium battery system in our RV (More on that later in the project thread – going to install the lithium batteries underneath the couch – It’s going to be fun!).

I have been checking the current battery cable system in the RV and have found to my dismay that the cables from the Onan generator and the Ford starter battery via the isolator (A previous owner had replaced the “Smart” Solenoid with what appears to be a Continuous Duty Solenoid) to the coach battery bank are these: 2 GA SAE J1127 Type SGX cables and not AWG cables. Humm. Has anyone else seen this setup on their Chinooks? Further, there are no fuses on these cables in the connections to the respective batteries. There is supposed to be an 80-amp fuse on the Onan connection, at least I cannot find it, and I am under the impression that there was never a fuse to the smart solenoid for some unexplained reason.

I cannot tell from the lettering what type of 8-gauge wire there is for the converter/charger, but that is not a concern because when I install the lithium batteries inside under the couch, I am going run a new wire from the batteries to the brown box along the couch frame and not use the existing 8-gauge wire that runs up the pillar back to the rear of the RV to the brown box via voltage drop land!

I do not want to have to replace the current 2-gauge SAE cables with AWG wires, but I don’t know what fuses should be there. According to Blue Sea Systems: “SAE conductors are smaller than AWG by 5% to 12% with current capacity typically less by 7%. So, a #2 AWG with a temperature rating of 105 degrees C insulation in the engine compartment requires 179-amp fuse or lower, if I read the Blue Sea Systems Ampacity chart correctly. Then, with the SAE wire would the corresponding fuse requirement be 7% less, or roughly 166 amps, or lower? That would be my guess…

That sounds about right. I'd fuse them both at 150 Amps, as that is safe and neither wire should ever be carrying anywhere near that amount.

Testing my Onan startup a few times it had a maximum draw of almost 80 Amps for a few seconds one time, but mostly around 60-70 Amps for a few seconds the other times. My Concourse had all AWG when I got it, though did not have fusing on either the wire to the generator or the engine starter battery (and there was no indications anywhere that it ever did).

Make sure if you ever need to cut those SAE wires to use SAE lugs on them. They are close enough it is easy to accidently use AWG lugs, but they may not get tightened properly even if they feel tight.

Bob,

Thanks! 150 amp fuses for both. Also thanks for the advice on the SAE lugs.

Jon

I did not know there is even such a thing as SAE lug. learn something new everyday from you guys.

I have the 2000 Concourse, and so far, I have not even able to find the wiring going to the genset. I also look all over the place for the breaker/fuse, and to no avail (if I see the genset fuse, I would find the wire!). If anyone do find the fuse to the genset, I am all ear. I guess I can just follow the wiring from the generator and figure it out myself.

If you do install the lithium, are you keeping the smart solenoid that allow the charging of the chassis battery? You may need to make sure the lithium battery voltage is proper for the function, otherwise, it may be bad news for the lead acid battery.

Hi Chin,

In our Chinook, the conductor run to the generator from the current battery bank runs underneath the chassis back to the generator. The run to the starter battery is also underneath the chassis. Here are a couple of photos of the wiring setup:

The first shows the wires going into the battery bank compartment as well as the 8-guage Converter/Charger wire and the 14 guage red “Sense” wire that run out of the battery bank to the auto reset breakers and then to the LVD.
This second photo again shows the three wires running under the chassis to their respective points:


I am still researching how best arrange all of the components that are to go under the couch, but without going to detail in this thread (I am saving all of the details of this for the project thread of the Forum), I will be removing the LVD (good riddance!), replacing the continuous duty solenoid in the engine compartment with a Battery Isolation Manager specific for lithium batteries, the current lead acid batteries with 2, 100 Ah lithium batteries, the Magnatek converter/charger with a PD4645LI, and replacing the 50 watt solar panel and charge controller with 400 Watts of panels and an MPPT controller, among other things. Stay tuned…

Jon
PS Do you want my LVD? I will gladly send it once I remove it. My project is on hold right now because of the lead time to get the lithium batteries as well as a long-earned, 3-week vacation to Hawaii. We leave for Hawaii March 7th and return March 28th.