High Amperage 12 volt runs ???

[pjc]

I am about done with upgrading the battery box and battery capacity on my 06 Kibbi Renegade. I went from three, Series 29 wet batteries to three, 4D AGM batteries. I had to build a bigger battery box in the process.

I am also adding a Bogart Engineering Meter and Shunt to get a true handle on power consumption before I add solar panels.

So far so good.

In the process of identifying the actual, 12 volt positive runs from the batteries to the various points on the coach, I have:

1 * Coach batteries to chassis batteries Isolator and bridge relay to chassis batteries and engine alternator. (not fused)
2 * Coach batteries to Genset (not fused)
3 * Coach batteries to Coach 12v power, breaker panel (not fused)
4 * Coach batteries to Inverter (fused)

The runs for #1-3 are pretty darn long. Should these be individually fused? Consider that #2 also supplies cranking power to a 3-cylinder, Kubota Diesel for the genset.

Also, there is a big 12 volt manual, switch right off the coach batteries that feeds #1-4 above. The entire bank can be completely removed from load. Same for the Chassis batteries.

[Bob E]

Yup, . . .fuse (or install a breaker) on everything (where practical) as you never know where those little electrical gremlins are going to appear - or when. All it takes is a mis-placed staple or screw to cause a short, or worse, a fire.

Battery isolators are ok however a relay has some advantages.
An isolator is basically a diode which will not allow your engine alternator to fully charge the motorhome batteries. Most diodes are maybe 88 to 92% efficient.

A relay can be wired to the ignition circuit so it closes any time the engine is running, therefore providing a full (nominal) 13.8 volts to your motorhome batt's.

[pjc]

Originally Posted by Bob E

Yup, . . .fuse (or install a breaker) on everything (where practical) as you never know where those little electrical gremlins are going to appear - or when. All it takes is a mis-placed staple or screw to cause a short, or worse, a fire.

The long run to the genset and the 12v panel have me particularly worried. Why would Kibbi not fuse these yet they have a huge fuse on the Inverter lead???

I figure a 100amp fuse is fine for the 12v panel but what size for the Genset? Remember, this is lead serves as both a charge and cranking lead.

[Bob E]

The generator starter shouldn't pull over 100Amps. Charge amprage from the 12V generator alternator will likely be in the 20 to 25 Amp range (max).
You can get an induction amp meter Alter Systems On-line Shop
that you can temporarily hold on top of the wire while the gen is cranking, to get an idea of amprage draw.
Some auto parts stores carry these also.

[Bob86ZZ4]

I think United Specialties wired my generator to the chassis batteries. Not to the coach batteries. That way I can use my house/coach batteries down to nothing and still start up the generator. Then when I start the generator it powers a recepticle in the storage bay that powers the charger/convertor and charges up the house batteries. There is a large rotary switch in that bay that allows me to use only the house batteries, or only the chassis batteries, or both sets if I want. My truck chassis has 3 truck batteries. The coach/house batteries are two 12v deep cycle ones. When I'm boondocking I set the switch to only use the house batteries. That way I can run them down and not risk draining the chassis batteries and not be able to start the generator or motor. When I'm under power or hooked up to shore power I switch the two battery systems together so the alternator or the charger/converter will charge up all batteries. Works pretty good that way I think. I wonder why they wired up your generator to the house/coach batteries?

[pjc]

So far so good.. I am almost done. I just need to mount the Bogart Systems meter inside and verify the genset pull during start at the meter. I found some great fuses that stem off of the battery lugs or, in my case off of the big boat switch right off the batteries. I now have the main 12v fuse panel in the coach fused at this switch at 100 amps. You can get the fuses up to 200 amps.

Pictures to follow.