Truck camper system review

[memilanuk]

Okay... I've spent a bit of time going over this, looking at various different configurations of chargers, panels, etc. as well as doing some 'exploratory' partial disassembly of my truck camper (2017 Adventurer 910 DB) to see where I actually have room to fit things. I've been using various online calculators (@ explorist.life) as well as reviewing a number of the resource documents from this site. Pretty sure it's not too far off, but I'm sure it could benefit from another set of eyeballs - and opinions.

Thanks!

 

[rmaddy]

I would think the generator should be wired to the Lynx, not directly to the batteries.

What 12V DC loads do you expect to have? 10AWG is only good for 30A.

The wire between the 150/85 SCC is too small. That SCC can output up to 85A (that's the second number). You want 4AWG wire for that.

The 250V 63A dual-pole breaker between the panels and the 150/85 SCC is too big. With an Isc of 5.83A at 2P that's only 11.66A. You only need a 15A breaker. 10AWG wire should never be fused more than 60A. So the 63A breaker is not safe for the 10AWG wire and it's way more than the 15A you need. If you want a breaker that allows for more panels in the future then something bigger than 15A is fine but 63A is getting unsafe.

 

[memilanuk]

I would think the generator should be wired to the Lynx, not directly to the batteries.

FWIW, the camper as received (2nd owner) was wired (presumably by the dealer) with the factory pre-wired generator leads landed directly on the battery terminals. The limited feedback I've gotten to inquiries on this and other (RV-specific) forums indicates that this is considered 'normal'.

What 12V DC loads do you expect to have? 10AWG is only good for 30A.

Again, going off the factory wiring here. Although I may be adding an extra 12v receptacle or two - mainly because the sole existing one is in an inconvenient location.

The wire between the 150/85 SCC is too small. That SCC can output up to 85A (that's the second number). You want 4AWG wire for that.

Okay... that was one of the things I wasn't 100% certain about - I've been going thru multiple iterations of this (dual 100/30, then dual 100/50, finally one 150/85), and some of the logic/justifications started to overlap from one to the next, unfortunately. According to the Blue Sea 'Circuit Wizard', it looks like #6 would carry the current, but the voltage drop might be an issue - hence the #4. Does that sound about right?

The 250V 63A dual-pole breaker between the panels and the 150/85 SCC is too big.

The breaker was selected solely as a means of disconnecting both PV conductors at the same time. As such, it is not sized for over-current protection per se. Whether the panel config warrants fusing or other OC protection is something I'm open to suggestions about.

 

[rmaddy]

FWIW, the camper as received (2nd owner) was wired (presumably by the dealer) with the factory pre-wired generator leads landed directly on the battery terminals. The limited feedback I've gotten to inquiries on this and other (RV-specific) forums indicates that this is considered 'normal'.

But having the generator on the wrong side of the shunt makes the shunt mostly useless, at least when the generator is in use.

Again, going off the factory wiring here. Although I may be adding an extra 12v receptacle or two - mainly because the sole existing one is in an inconvenient location.

But I was asking what your DC loads will be. You need to make sure you will never have more than 30A running at once due to the 10AWG wire. If your DC loads can be more than 30A (which is quite likely) then you need bigger wire between the Lynx and the DC fuse box.

According to the Blue Sea 'Circuit Wizard', it looks like #6 would carry the current, but the voltage drop might be an issue - hence the #4. Does that sound about right?

Using the Blue Sea Circuit Wizard app I see it recommend 4AWG for the ampacity (85A) and 6AWG for the voltage drop (I assumed 10' roundtrip). Either way, 4AWG would be best for the 150/85.

The breaker was selected solely as a means of disconnecting both PV conductors at the same time. As such, it is not sized for over-current protection per se. Whether the panel config warrants fusing or other OC protection is something I'm open to suggestions about.

I'm using a breaker as a disconnect as well. But it just seems wrong to choose a breaker larger than what is safe for the wire.

 

[memilanuk]

But having the generator on the wrong side of the shunt makes the shunt mostly useless, at least when the generator is in use.

Those leads are there solely to supply the generator starter when the button is pressed. Once the unit is running, there's nothing for the shunt to see anyway.

But I was asking what your DC loads will be. You need to make sure you will never have more than 30A running at once due to the 10AWG wire. If your DC loads can be more than 30A (which is quite likely) then you need bigger wire between the Lynx and the DC fuse box.

Understood. That said, nothing in this 'upgrade' affects or changes anything into or out of that panel - so the 'house' part of the DC system should be fine as is, for now.

 

[rmaddy]

Understood. That said, nothing in this 'upgrade' affects or changes anything into or out of that panel - so the 'house' part of the DC system should be fine as is, for now.

So the current DC panel is supplied by 10AWG wire? And you have never had more than 30A of DC loads going at any one time? That's seems really unlikely.

 

[mikefitz]

Those leads are there solely to supply the generator starter when the button is pressed.

Put a fuse in the positive at the battery end, and should the connection be after the isolator switch?

Mike

 

[memilanuk]

Put a fuse in the positive at the battery end, and should the connection be after the isolator switch?

What size would you suggest? Typically fusing is there to protect the wiring... but any fusing for #2 AWG would be well below the levels seen during start. I've measured (multiple times) 350-375A starting current on those #2 AWG gauge, using a good quality Fluke clamp-on ammeter - even though some people have tried to tell me that it's not possible to have that kind of starting current.

Again, the factory setup on this camper is with the wires landed directly on the battery terminals. I asked here, and got almost zero response. Asked elsewhere, and the general consensus was that that's a fairly 'normal' configuration for generator starter leads. If you have some reference source that states otherwise, I'd love to see it.

 

[memilanuk]

So the current DC panel is supplied by 10AWG wire? And you have never had more than 30A of DC loads going at any one time? That's seems really unlikely.

Dunno what to tell you. There are exactly four wires coming out of the battery compartment in the original configuration. Two of them are the #2 AWG leads that are labeled 'GEN START' and go directly to the generator starter. Two of them are #10 AWG labeled 'BATT +' and 'BATT -'.

In it's stock config, there just aren't a lot of DC loads on at any one time. Just sitting there 'steady state' running nothing but the DC control board for the fridge and small parasitic loads like the CO detector, it's maybe 1.5-2A draw. Obviously a little more if running the roof fans or charging something from the 12v outlet. See the attached PDF for the factory supplied load center drawing.

I suppose in theory someone could attempt to extend the slide *and* the awning *and* raise the camper on the jacks, all at the same time, whilst also running the furnace blower, the water pump and both roof exhaust fans... but you'd have to be pretty talented to manage all that. Kind of like you could, in theory, run the air conditioner at the same time as the microwave and a toaster plugged in on the counter, on the AC end of things. It probably wouldn't work very well for very long, even on '30A' shore power.

 

[memilanuk]

Drawing updated to reflect #4 AWG from the Victron 150/85 SCC to the Lynx distributor, and changed the 300A main fuse on the battery from ANL to a class T fuse.

 

[mikefitz]

. I've measured (multiple times) 350-375A starting current on those #2 AWG gauge

seems possible, can the batteries and BMS tolerate that?

As for a fuse try a CAL 1 automotive fuse, used in starter and alternator circuits.

factory setup on this camper is with the wires landed directly on the battery terminals.

Factory setup in the RV industry may not follow the best electrical practice .

You have designed a great system with every connection to the DC power source correctly protected against circuit fault currents. Why take a risk with a possible long cable run to the generator?

some reference source that states otherwise,

You don.t need a specific reference for a situation that is covered by normal electrical working practice. I am in Europe and the standards we have for RVs state that each connection to the low voltage power source, the battery, needs overcurrent protection suitable to protect the cable.

Rather than feed the generator from the lithium pack why not fit a dedicated AGM battery, would provide a degree of redundancy in the system.

Mike

 

[memilanuk]

seems possible, can the batteries and BMS tolerate that?

In parallel, pretty sure. Individually.... probably. Specs for the BMS cite overcurrent trip @ 160A for 10 seconds, or 890A instantaneous. Given that the measured peak current was for about a second or so... well, fingers crossed.

Rather than feed the generator from the lithium pack why not fit a dedicated AGM battery, would provide a degree of redundancy in the system.

Did ya miss the part where this is a truck camper?

I had to compromise a bit on the size of the setup I wanted just to make this fit. There absolutely is not any extra room for another LA battery.