Homebrew electrical layout and shopping list

[wlbaker3]

Originally Posted by Scalf77

Actually, for your project, have you thought of a DC to DC battery charger instead of the traditional ACR that most of use. I know a couple of people that have installed the KISAE DMT1230 Abso 30A DC-DC Battery Charger. This also is a MPPT solar charger, so when you add in the future cost of a solar charger, it is a cost efficient solution. It does not give you a jumpstart option of the 7622, but tat is a feature you are not looking for anyway. Not planing a shore charger, this will give you a true multi-stage charger when using alternator and solar.


-greg

Greg,

I’ve been reading tons of these threads, as I’m preparing to install my house electrical system. Lots of great info from you and others.

I really like the looks of this Kisae device. If one were to install a setup like this, what gauge wire would you spec between the starter battery and the DMT1230? I’d expect a max of 30amps on the output side, would it be the same on the input side of the device as well?

Thanks for your insight.

Bill

[Scalf77]

The gauge you choose will be mostly driven by voltage drop an not current. Also for a 30 Amp output you would need more than 30 Amps in as there is some cost of conversion. In their manual they use 50 Amps and say (6 to 16 mm2 )or 10 to 6 awg up to 5 meters. Or (16 to 35 mm2 ) 6 to 2 awg for over 5 meters. You can fuse for 50 Amps (protects their box and cover 10 awg and larger.

feel free to PM if you have questions. On a couple I've installed we ran larger awg to support an emergency battery switch for jump start solutions or backup if it fails.

-greg

oh, and by larger i mean actual wire size not awg

[arctictraveller]

Originally Posted by wlbaker3

I’d expect a max of 30amps on the output side, would it be the same on the input side of the device as well?Bill

The published specifications don't seem to mention the maximum input current, so as always, I would contact the manufacturer for that information. It's probably not much more that 30A though, as I don't see anything that makes me think they increase current beyond the max output of 30A. What ever size wire you use, if you fuse it properly, there should be no danger of overheating the wire. If your run is very long, using a slightly larger gauge will reduce voltage drop and increase efficiency.

[wlbaker3]

Thanks for your insights. I'm working on a drawing for my system, and I'll start a new thread with it once it's ready. Thanks.

[Scalf77]

If you expect 30 Amps out at bulk/absorption level 14.6 for AGM than you would be 30 x 14.6 or 438 watts. Divide 438 by the low voltage cutoff (from battery side) of 10.5 and you get 41.7 amps, Additional derating factors such as temperature 0 C gives you bulk/absorption of 15.78, this gives us 473.4 watts or 45 amps at the input, add 10% conversion cost 4.5 amps and we are at 49.5 amps, this calculation is in line with the specified input fuse of 50 amps.

-greg

[wlbaker3]

I'm really glad there are people who are this good at math ... and are willing to share what they know!