New Lithium-based Sprinter Build

[Backcountryguy]

TomH,

If we assume our alternator will be the Nations 290XP we should be fine. I think that is what Sportmobile uses since it's the specific alternator listed by Nations for our Sprinter.

The Balmar wiring guide shows 2/0 wire for a 275 AMP alternator with a 15' round trip distance. Pretty close.

You could make an argument for 3/0 based on distance and alternator sizing but as you pointed out and as I thought we're going to have 2/0 and that is that.

[TomH]

2/0 is thicker than 3/0 and thus offers less resistance. It's like hypodermic needles, and fraction denominators: the bigger the number, the smaller the size. So 2 is better than 3.

https://www.tedpella.com/company_htm...uge-vs-dia.htm

Using that table, I get 0.00023445 ohms of impedance on a 15' run of 2 gauge cable.

[Backcountryguy]

I think 2/0 means OO wire and 3/0 is OOO, therefore thicker? Did I read that incorrectly? I looked at the common wire size showing 2/0 vs. 4/0 in table below. However, I'm not an electrician.

AWG
Diameter
Ohm/1Kft
†

†

Area/ft
† 2
2/0
0.47" –
0.53"
0.0779
0.78V
78W
18 in2
4.3 W/in2
4/0
0.60" –
0.66"
0.0490
0.49V
49W
24.1 in2
2 W/in2

†

[Backcountryguy]

Well that table didn't cut/paste very well! At any rate it shows 2/0 wire as fairly substantial.

I think the thing I have to keep in mind with all this is that we are all probably somewhat type A OCD people and we like to get our fingers in the mix. However, Sportmobile does build a really quality product and despite some of my wish list items not getting done my wife Alison and I are going to be really happy with the finished product., and we'll do some add-ons after that will make it perfect. I mention this because the wiring is very good from what I saw on my first visit. I'm talking about how it's neatly bundled, correct fuse bars/isolators/surge protector used, all very meticulous work.

[Backcountryguy]

This probably should go in another thread. It occurs to me we are hijacking Wrinkledpants build thread. My apologies. Hopefully the information is of use to him in his build. But it's still good information for all. I think the main point is the 2/0 will be fine for us.

[Wrinkledpants]

I have a few followup questions to Brian - specifically about the wiring from the alternator to the battery box spec'd for a larger battery. Will answer the other questions posted up once we finalize our order (hopefully today or tomorrow).

[Backcountryguy]

Would you mind sharing your build layout with final positions of invertor, battery, water tank, etc. once finalized? I believe the aft 1/2 of our design will mirror yours.

If SMB provides an electrical schematic such as that provided by Nations Alternators I believe that would be of interest as well.

[Wrinkledpants]

Yeah - I'll post that stuff after it's finalized. There isn't any electrical schematics involved, and the build layout is essentially a mockup (not to scale). Their final build plans use the same software the SMB website has for the DIY build - just with extra notes about things. It's fairly low-tech compared to some of the other upfitters who use CAD drawings for this stuff. I have no idea where water lines, wiring harnesses, or other utilities will actually be routed. I can tell you that one side of the dinette will have the 23 gallon tank and other water utilities. The air handler will be in the bottom of a cabinet. The other side of the dinette will have the inverter and batteries. Our dinette is 48" wide.

[TomH]

Ahhhh, o.k., if 2/0=00 and 3/0=000, then you are absolutely right. My apologies. As I look back over Brian's last email, he said the wiring was 2/0. If that is 00, then we're in really good shape.

I told Brian he had my permission to discuss my build with either of you. If either or both of you feel that you can do likewise, that would be greatly appreciated. That way we could benefit from each other's ideas. My thanks to both of you, as well as Fitz, as your knowledge and insights have been invaluable.

[TomH]

BCG, Take a look at this post by Fitz. He thinks his deep locker would be fine for battery location with the skid plate in place.

http://www.sportsmobileforum.com/for...tml#post210408