12V system for passenger van conversion

[mjeffrey]

I took a look last night: the plywood is 3/8". I used the foil-backed cotton on the floor; plywood held down with screws.

Cheers!
Mike.

[GreyDawg]

Originally Posted by jage

Get them to add a basic switch to your dome lights to shut them off. On top of everything else it should be an inexpensive task for them.

Good point -- thanks! There are two types of light in the celilng -- those triggered by the doors and the reading lights triggered by switches. I asked that the reading lights be put on the house battery, but yes, if they could insert a switch so I could turn off the door-triggered lights, that would be much more elegant than my plan to pull the bulbs!

I've already made notes of a couple of other things to discuss/spec, following our conversation of yesterday. The key decision will be where to place the AGM, since that will dictate whether I do the floor first (if it is inside) or second (if it is bolted under the frame, like the SMB batteries in the step of the RB-50. Does mounting there require cutting a large hole in the floor? I can't recall...

[GreyDawg]

Originally Posted by mjeffrey

I took a look last night: the plywood is 3/8". I used the foil-backed cotton on the floor; plywood held down with screws.

Cheers!
Mike.

Thanks! I assume you used sheet-metal screws through the plywood and insulation, and did not separately secure the insulation, right? Did you just lay the insulation down, or did you try to fill the ridges in the floor by cutting and laying additional strips there (ie put strips in the troughs, and then a solid piece of insulation as a blanket over those?).

Off to hunt down marmoleum or linoleum after work today -- fun!

GreyDawg

[jage]

You don't have to cut a hole in the floor. The hole in the floor allows you to access the battery from the top, whereas the starter batteries and 4D that is outside in my rig have to be dropped to access or change them.

The 4D is so heavy that I don't think it will be movable without shop tools no matter where you put it, and I don't think top access is worth a hole in the floor. You're not supposed to do maintenance beyond replacing as far as I know, and I'm managed to reach and remove both the top and cables from the 4D under the van.

That's for an emergency. To replace or pull for testing the whole frame can be unbolted- I guess that's an important thing, make sure however the battery is placed it's removable: don't let them just weld it in place.

I'm curious, does anyone have a through-the-floor access to their batteries that isn't an artifact of having to cut the side door step to create enough room for the 4D? Like one in the center somewhere, where the battery has to be dropped and lifted through the floor?

[GreyDawg]

I'm going to have follow-up conversation on Monday with the folks who will do the 12V work, so I'll push harder on exactly how/where they think they should mount the battery, and what that means for cutting the van (which I wish to avoid). I may also go over to SMB on Sunday and crawl under a van or two, and look.

Next question: I have to choose a battery. AGM of course, but my two choices are 105AH or 220AH (which I believe y'all call the 4D), the latter at 2x the cost of the former. My gut is to go with the 220AH, but the installer thinks I'd be throwing away money since I will only have a 12V system (no inverter, no 110 sockets, no shore line, no appliances ... yet).

However, quick back-of-envelope calculations show that one day not driving, sitting in a hot place and running the Fantastic Fan 12 hrs (1.86Amps on low, 2.2 on medium, so guestimate 2 amps), would eat 24AH; two days of sitting put in a beautiful, but hot, place would consume all my "available" AH in the smaller battery without running any lights, or 12 volt toys (free-standing radio, 12V plug for computer, cell phone charger, camera battery charger, rechargeable lantern).

And I might eventually tire of my marine ice chest and add a used refrigerator...

Without a solar system (yet) it seems like the smaller battery would be foolishly frugal, and that I'm better off dropping the extra $200+ for the larger. And that's just considering current 12V consumption, not future additions.

Or have I totally biffed my calculations?

(Oh, yeah: they're also worried about the weight of the bigger battery and balancing weight in the van, which is a valid concern. Since the larger battery and I weigh about the same, I'll argue that they can put it anywhere in the front half of the van on the passenger side and be balanced since I sit in the driver's seat. Is that logical? Or nuts? )

Thanks!

[LenS]

Sounds to me that your back of the envelope calculations are fairly good. You have to decide how long you want to be able to use the van w/o recharging the house batteries. That drives the battery bank size. I am using the 6xxx series Fantastic fan because it draws 50% of the current as the older design. I also like have 14 speeds. The low ones are REALLY quite and yet move air.

I don't understand the weight concern. You are talking a full size van not Mini. That is all most like saying don't walk around inside the van because you might tip it over.

[JoeyNick]

If you want the additional battery capacity, you could go with TWO of the smaller batteries, wired in parallel. And you could use the second battery to "balance" the weight of the van, left and right.

My SMB has two batteries, mounted under the rear corners in fiberglass boxes, with holes cut through the van floor for access.