2108DS Lithium install: installing the batteries

[thataway4]

Yes, I would fuse both batteries with one fuse at the max draw you expect. In your case it may be only30 to 40 amps. There are DC circuit breakers which can be mounted on the surface with terminals in back or terminals on the face. You may design a panel on the box where you have the batteries. With the lower current you can also use the circuit breaker as a disconnect.

Look at the Blue Seas 285 or 187 series, and the C panel mounts, with toggle switch. I use both of these. The C series where there may be multiple circuits. The Blue Seas Web site is the best place to compare. Be careful of Chinese imitators.

This breaker should be as close to the battery as possible. You are fusing to protect the wire--if the wire draws over XX amount of current, you want that flow interrupted before the wire becomes a hot glowing heat element (and that can happen rapidly in a full short)

I have much higher current potential draw--the Victron Inverter also will boost current and voltage, so there can be sudden surge loads on it. Thus a larger fuse, rather than a breaker.

I understand your concern about the box. I prefer plastic junction boxes. There are many outdoor type of plastic boxes at Home Depot or Lowes, where you can make water tight connections, which will serve you much better in an out of body type of mount--be in under or over, or in a compartment where there is risk of water intrusion.

Another concern with a metal box and potential issues with wire insulation failure, is that the metal box may be grounded--and the positive wire short to that box. The grounding may be where the box bolts or screws onto the frame of the vehicle.

You are thinking and looking forward to make the installation as safe as possible. That is excellent.

[tinglett]

Bob, thanks for the update and the pointer to Blue Seas. Looks like good stuff there! I'll probably put a 50A fuse between the batteries and the positive bus bar, and I'll use the battery disconnect switch I have (leaving it mounted in the same place) between the fuse holder and bus bar if I can. I may have to change to heavier gauge wire to the switch.

Do you have a recommendation as to what type of fuse is "best" for this application? One where replacement fuses are available at a home center might be best for me, but I could get spares. Hopefully it won't get used up, though!

I have to say this has been an interesting and enlightening experience. I've learned a TON about my TT, and I've owned it over a year already. Nothing like some mods like this to force a bit of learning.

It'll be a bit before I get to this stuff as it's snowing now. Gotta love Minnesota!

[thataway4]

If you want to go with readily available fuses, I would go the automotive type spade connector. They are reasonably weather resistant, and easy to get. You should have an assortment on board your tow vehicle already, just in case.

You would be best served with a fuse holder which has as large wiring as possible--and that is where the use of a circuit breaker may be better vs a fuse. The circuit breaker is easily re-setable and will turn off the circuit. It also has terminals which allow the use of ring terminals for any size wire.

If you stick with #6 wire you will have to use what is called a Maxi fuse. The Maxi fuse is larger than the standard ATO/ATC car fuse (there are also smaller "mini" fuses, but the holders will have even thinner wire leads). The maximum size fuse for the ATO/or mini fuse is 40 amps. The ATO/ATC fuse holders seem to have about #10 wire as the maximum size; this would be difficult to make a butt connector between #6 and #10 wire (It can be done, either by folding over the smaller wire, cutting strands out of a #6 wire to be the diameter of a #10 or trying to find a reducing #10 to #6 butt connector. The latter is the only acceptable way to do the connection)

Look up Maxi Fuse holder #6 wire--there are a number of suppliers. These are available in sizes from 15 to 120 amps. I use the Maxi fuse 30 amps for both ends of my 30 amp charging circuit for the Li batteries. In your case I would tend to be conservative and keep the fuse at 40 amps max, because of the wire size. If you go up in wire size, then you can go up in fuse size. The fuse is there to protect the wire from overheating in case of a short circuit or major overload.

[al1florida]

I use Blue Circuit Breakers/on-off switches when I put together my system almost 5 years ago. These are very compact and easy to turn on and off.

Here is a link to the 100amp version. There are many other amp ratings available as well.

https://www.amazon.com/s?k=blue+sea+...b_sb_ss_i_3_11