Please help assess my 12v system!

[Turtull]

Would really appreciate it if some folks with electrical experience could comment on my set up. I don't have an inverter or solar or anything just an isolator and aiming for a really simple setup.

I think that the fuse between the auxiliary battery and the fuse block (via the main switch) needs to be swapped out to 50 amp, because I have used 8awg wire to the fuse block?? I was going to use 4awg through out but had difficulty getting the right ring terminal sizing and connections and that's why there's different gauges in there.

Any other issues that anyone can warn me of? Thanks in advance!!

[Turtull]

87 percent to 100 percent in 20 mins highway driving? wondering what the catch is. At that rate I could charge my battery from 50 - 100 in under 2 hours highway driving. that seems a pretty good rate of charge from my alternator, much better than I expected. Wondering if I need solar as well as alternator, if away from shore power for more than a couple days...?

[Turtull]

alternator seems to charge pretty well?

[Turtull]

Doh! I just checked the charger. It has an inline fuse on the positive lead. So I guess I will just need the single bluesea terminal block fuse.

[Turtull]

Since old wizard prompted me to think ahead 🙂 I'm wondering if my on board charger will also need a fuse at the auxiliary battery? I'm thinking of getting the Bluesea terminal block fuse for the 125 amp fuse at the aux battery on the + from the isolator (as instructed by DrewE), so I'm now wondering if I should get a dual fuse block if I need to fuse from the charger also.

https://www.bluesea.com/products/2151/Dual_MRBF_Terminal_Fuse_Block_-_30_to_300A

[Turtull]

wa8yxm wrote:
IF you are using the Forum's dropbox account there are two issues.

ONE: do not use the IMAGE insert tool. Just copy and past the link as text

Two: Dropbox recently made a few changes, I do not know if that will affect the forum link or not.. But I liked it better the old way.

I appreciate the tips wa8yxm!

[Turtull]

Joe417 wrote:


To post a picture, double click your newly created shortcut "RVnetPhoto". Drag the photo you want to post to the host window and drop. It will return a link. Just copy the link and past it into the rv.net message window.

You won't see the photo until after you post the message.

You'll get the hang of it after a few posts.


http://photoposting.is-great.net/?i=1

Thank you Joe417!

[Turtull]

DrewE wrote:
You should have a 125A fuse next to the house battery on the line going to the isolator (in addition to the one next to the chassis battery). Without it, there's no safety protection against a short in that wire.

It's not a requirement that the negative returns from the loads go to the fuse panel and thence back to the battery, although that certainly is one reasonable and not uncommon way of doing things. They can just as easily go back to chassis ground as convenient, or at one or a few central bus bars. Likewise, the negative wire between the battery and the fuse panel could also just be chassis ground. If it's convenient to do so, it may well be a lower impedance path than running a wire, particularly if the battery and fuse panel or ground bus bar or whatever are not too close to each other. Again, what you show isn't wrong; I just wanted to be sure you understood that there were other possible alternatives as well.

Thank you DrewE! Good point about the extra 125 amp fuse. Will get that in there asap. As for the ground bus, I have a fuse box with an integral negative bus so that's probably actually the most convenient route.

[Turtull]

theoldwizard1 wrote:
You gave no details about lengths of specific types of batteries. If one of your goals is to recharge you deep discharge house battery bank while driving you are going to be disappointed.

Modern tow vehicles just do NOT put out enough voltage to completely recharged a deep discharge house battery bank. Period. End of discussion.

Hi there old wizard! Yes I understand this, my next step is to put in shore power with an on board charger. I have a 125 ah vmax agm auxiliary battery. I just hadn't put the shore power part in my diagram yet. Thank you for the reminder though!

[wa8yxm]

IF you are using the Forum's dropbox account there are two issues.

ONE: do not use the IMAGE insert tool. Just copy and past the link as text

Two: Dropbox recently made a few changes, I do not know if that will affect the forum link or not.. But I liked it better the old way.

[DrewE]

You should have a 125A fuse next to the house battery on the line going to the isolator (in addition to the one next to the chassis battery). Without it, there's no safety protection against a short in that wire.

It's not a requirement that the negative returns from the loads go to the fuse panel and thence back to the battery, although that certainly is one reasonable and not uncommon way of doing things. They can just as easily go back to chassis ground as convenient, or at one or a few central bus bars. Likewise, the negative wire between the battery and the fuse panel could also just be chassis ground. If it's convenient to do so, it may well be a lower impedance path than running a wire, particularly if the battery and fuse panel or ground bus bar or whatever are not too close to each other. Again, what you show isn't wrong; I just wanted to be sure you understood that there were other possible alternatives as well.

[Joe417]

Try this for pictures.

I believe it was one of the rv.net moderators that created the link below to help with posting pictures. It works great.

At your home screen, right click, select new, then shortcut. Copy the link below as the location, select next and give it a name like RVnetPhoto, then select finish. This short cut will take you to the picture hosting site quickly any time you need to post a picture.

I keep it on my home screen next to my rv.net short cut.

To post a picture, double click your newly created shortcut "RVnetPhoto". Drag the photo you want to post to the host window and drop. It will return a link. Just copy the link and past it into the rv.net message window.

You won't see the photo until after you post the message.

You'll get the hang of it after a few posts.


http://photoposting.is-great.net/?i=1

[theoldwizard1]

You gave no details about lengths of specific types of batteries. If one of your goals is to recharge you deep discharge house battery bank while driving you are going to be disappointed.

Modern tow vehicles just do NOT put out enough voltage to completely recharged a deep discharge house battery bank. Period. End of discussion.

[Turtull]

OK I have both of those, so I think I'm good 🙂 🙂 Thanks!
Regarding your comment on the standby draw on the Battery Doctor, I guess I'm stuck with it since it's already purchased and installed. I have a master switch for killing all the loads, but how to cut down on the standby draw from the isolator? I hadn't thought of this. What's it drawing from, the starter or the auxiliary? Appreciate your input on all this. It's my first time wiring a van system

[time2roll]

The #8 return is fine as it matches with the 50a fuse.
Frame ground on the aux battery needs #4