[trhoppe]

Got some advice from these forums, build threads, build sites, and a friend that does solar installs in the PNW (http://www.freedomvans.co/)

I think I have a pretty solid wiring diagram and I think I know what I'll be doing, but I have a few questions

1) How big does the wiring have to be to the DC fuse panel? Should I be using #4 ?

2) I thought about using the Xantrex Transfer Relay for shore power, but then I would still be relying on batteries for DC power. With the NOCO AC Charger, I should be able to just run everything off the batteries and keep the batteries topped up if I'm on shore power. Does that sound like a good idea?

3) With the Xantrex inverter, is it ok to just split one of the outputs into 2 AC outlets vs dealing with separate breakers here? I'll be powering a small microwave and a electric kettle (not at same time) off the inverter. Also wanted to have an outlet in the garage just in case I wanted a small air compressor or something. And lastly, I'll have a regular power strip running off the other outlet for when I need to charge the laptop or anything else.

Any other inputs/critique on what I plan on doing?

 

[MsNomer]

Your laptop may have a 12v cord option. Much more efficient than going through inverter.

 

[Gator]

it may be easier to run the second kitchen outlet directly from the first outlet, no splitter needed, also could make the first one a gfi protected outlet
be sure to put all fuses as close to power source as possible
10A shore power charger is kind of small for 300ah bank

 

[trhoppe]

Your laptop may have a 12v cord option. Much more efficient than going through inverter.

Seems the Macbook Pro options out there are pretty janky. Wonder with the new USB-C charging world if there will be a better option that pulls enough power out of a DC outlet to charge a laptop.

 

[trhoppe]

it may be easier to run the second kitchen outlet directly from the first outlet, no splitter needed, also could make the first one a gfi protected outlet
be sure to put all fuses as close to power source as possible
10A shore power charger is kind of small for 300ah bank

Ohh that's a great idea. Not sure why I didn't think of that!

Is there another shore power charger that you'd recommend? I saw some 30A ones, but they were super expensive and super gigantic. I also looked into Inverter/Chargers and for something Pure Sine what was reliable, it was not only quite a bit more money than the Xantrex inverter, but also took a lot more draw at idle.

 

[RDinNHandAZ]

Here is a MacBook 12 volt MagSafe power adapter we bought and it has been great!
https://www.amazon.com/gp/product/B0056QBQNI/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1
It says unavailable but check for the same one on eBay?

Here is a wire size chart:

 

[GaryBIS]

Here is a MacBook 12 volt MagSafe power adapter we bought and it has been great!
https://www.amazon.com/gp/product/B0056QBQNI/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1
It says unavailable but check for the same one on eBay?

Here is a wire size chart:

Hi RD,
Wondering where the wire chart comes from?

It seems like it allows currents much higher that most charts?
For example, it would allow currents up to 200 amps on short lengths of #10 wire -- this is 7 times as much current as this wire ampacity table from Cerro: http://www.cerrowire.com/ampacity-charts
Maybe I'm reading it wrong?


I use this chart for maximum current (ampacity): http://www.cerrowire.com/ampacity-charts
And, this one for keeping voltage drop down to 2%: http://www.solarseller.com/dc_wire_loss_chart___.htm


Gary

 

[GaryBIS]

Hi,
just a couple thoughts on the wiring diagram...

You might consider an Inverter/Charger rather than the seperate inverter and charger. An advantage is that the Inverter/Charger automatically handles the switchover from shore power to no shore power -- that is when you have shore power it disconnects the inverter, charges the battery, and connects your inside of van AC outlets to shore power. Then when you are not shore power connected, it automatically puts the inverter in to power the inside of van AC circuits.
This page shows the Triplite Inverter/Charger I used -- they also make a larger one, and there are other brands:
http://www.buildagreenrv.com/our-co...y-camper-van-conversion-electrical-and-solar/

The 10 amp charger seems a bit small for 300 amp-hrs of battery? If you are down to 50% SOC, its will take 15 hours at 10 amp charge rate to get back up to full charge.

On the wire that goes between the van battery and the house batteries, there should be a fuse or breaker near the van battery, and a 2nd fuse or breaker near the house battery. Both batteries are heavy duty current sources, and if you don't have a fuse near each of them, the wire is not protected from excessive current if there is a short to ground somewhere along the wire -- this could actually burn your van down

I think the fuse and probably the wire between the van and house batteries are larger than they need to be. I don't thing will ever see 200 amps charging current from van battery to house battery, and if you did it would be way over what the house battery manufacturer probably recommends and could damage the house battery. See what your house battery maker recommends for charging current (I'd guess about 40 amps). You don't want the batteries to be charged at much over this rate for very long.
On my setup, I have a 50 amp breaker in the van to house battery line to make sure the house batteries don't get charged at to high a rate -- it has never tripped and the highest current I've actually measured is about 38 amps. My batteries are 220 amp-hrs and are flooded lead acid.
Anyway, maybe take a look at this van to house battery connection and see what you really want there?


On the AC wires from inverter to AC loads, I don't see anything wrong with 2 outlets on one circuit and they could be wired just as the do on house circuits that have multiple AC outlets -- regular house AC outlets have terminals for AC in and AC out (going to the next outlet).
If the inverter does not have some kind of protective breaker for these circuits, there should be a breaker to protect the circuit, but the inverter probably has some kind of protection?

Be careful that the ground for the inverter is hooked up in such a way as to insure that the ground wires on the AC circuits served by the inverter are hooked to a good ground for safety.

Another alternative would be to use this pretty cost effective combined DC and AC distribution center made for RV's -- this would give you a bunch of DC circuits and up to 3 AC circuits all in one box. I used it on my Conversion and it was easy to hook up and worked fine.
http://www.bestconverter.com/PD5000-30-Amp-ACDC-Power-Control-Panel-_p_27.html#.WCSfjWsrJnI
Best Converter also carries a bunch of RV electrical stuff.



Gary

 

[Hein]

In your diagram, you show the shore charger (-) connected directly to the battery bank. That lead needs to go to the shunt along with the other charge sources. By-passing the shunt with amp-hours will throw off the state-of-charge shown on the display.

Also, best practice is to run a negative cable from the alternator chassis to the shunt as well. The alternator could be delivering close to 50A to your batteries if they are significantly discharged. Asking the OEM ground cables/connections & chassis to carry this additional load can introduce voltage drop. This can lead to insufficient charging and reduced battery life.

A 2000 watt inverter can draw significant current on the DC side. Large cables, proper fusing and careful attention to crimped ends is paramount.

Agree with Gary that an inverter/charger with built in transfer switch (complies with UL-458) would be a good option. We like Magnum Energy combined with their Battery Monitor Kit which also has a shunt based meter. So you could go to a less expensive solar controller like the ones offered with the Renogy kits and then let the BMK track the SOC from all sources.

Occasional charging on shore power with a good quality mult-stage charger is a great way to keep the batteries healthy.

 

[MsNomer]

I like having the inverter separate. It is on only when needed, never left on. Remote switch by the counter makes this easy.

I'm wondering why only 200W solar for 300Ah battery.

 

[Hein]

I like having the inverter separate. It is on only when needed, never left on. Remote switch by the counter makes this easy.QUOTE]


The Magnum (and presumably others) can be operated in that manner. The inverter can be turned on/off as needed via a remote control or it can run in 'sense' mode where it comes on when a 120V appliance is turned on. There is some Ah usage when sensing. The battery charger activates and the transfer switch is engaged only when shore power is detected. That part is automatic but the charger can be turned off manually if desired. It goes into float when/if the batteries are fully charged so no real need to turn it off.

 

[GaryBIS]

I like having the inverter separate. It is on only when needed, never left on. Remote switch by the counter makes this easy.

I'm wondering why only 200W solar for 300Ah battery.

Hi MS,
The Triplite Inverter/Charger does have a "Charge Only"" position on the switch that automatically starts the charger when you hook up shore power, but does not turn on the inverter when you go off shore power.

When the same switch is in the "Auto" position it does start the inverter automatically when you go off shore power, but it seems to sense when no AC load is present and does not appear to run the inverter until an AC load is applied (but I have not actually checked the power draw when its in this no load applied mode).

Triplite also offer a remote interface (as Hein mentions), but we did not get that option.



Gary

 

[seapro]

I will add my 2 cents:

On all my boats and campers I have always used separate inverters and shore power chargers. If there is a disastrous failure only one function is lost. Simple devices are easier to understand and wire. Generally no programming and remote controls/displays are needed if the inverter is reachable to turn on and view its display, and the battery charger is the same for viewing its meter. I use a Xantrex 1000 watt pure sine wave inverter which can carry (not at the same time) my 750 watt water heater and 750 watt cooking power microwave oven which actually draws well over 1000 watts. The Xantrex inverter is rated to carry more than 1000 watts for a short few minutes. My charger is a Charles Industries 25 amp charger. Charles Industries chargers are widely used in the commercial marine industry. My 230 amp-hour AGM battery is well served by this charger because when I have shore power it is generally for overnight or more which is plenty of time to get the battery charged.

For AC to my AC circuit breaker panel I use a manual shore power / inverter transfer switch from Blue Sea. My shore battery charger is powered by a circuit breaker switch on my AC panel. I do not use any SOC metering system as I believe that they are not accurate especially as the battery ages. A simple permanently wired voltmeter works well. When battery is at rest for a few minutes 12.6 or higher is fully charged and 12.2 is about 50% charged. What more do you need?

Remember KISS -- keep it simple stupid. It will cost less, be easier to install/wire, be easier to understand, and it will be more reliable. In almost 50 years I have had only one failure -- that was a bad cell on a gel-cell battery. Today most folks use AGMs.

 

[RDinNHandAZ]

Quote from GaryBIS:
Hi RD,
Wondering where the wire chart comes from?
It seems like it allows currents much higher that most charts?
For example, it would allow currents up to 200 amps on short lengths of #10 wire -- this is 7 times as much current as this wire ampacity table from Cerro: http://www.cerrowire.com/ampacity-charts
Maybe I'm reading it wrong? End quote

Gary I can’t recall the source but can probably find it. As you know the losses in wire are a function of their length and controlled somewhat by the kind of current. AC current is dependent on the RMS (root mean square) voltage and DC is just the current given at the voltage given. The chart you posted is not length dependent and I seem to remember it work for runs of 250 (1,000?) feet in residential wiring up to 120 volts AC. The secret to pushing 200 amps through a seemingly small wire is that the power losses are proportional to the resistance and 3 feet of #10 wire has very low resistance. I don’t claim the chart nor defend it I just posted it to give builders a guide. Would I push 200 amps at 12 volts through 3 feet of #10 wire? Probably not because 3 ft of # 4AGW is probably less than a dollar and it will handle it. Now I’ll look for the chart source:

http://www.offroaders.com/tech/12-volt-wire-gauge-amps.htm

The same or similar chart is all over the net. That doesn’t make it right, just common.

 

[twicken2]

I suggest putting switches or easily resettable thermal breakers between the solar panels and the batteries and the alternator and the batteries. That way you can easily disable any charging sources you need to if working on the system, troubleshooting, etc.

Also, it is a good idea to have a battery disconnect switch on one of the leads coming off the battery bank so you can be certain everything is disconnected for storage, service, etc.

The good thermal breakers are made by bussman, and there are several marine manufacturers that make heavy duty 200A+ switches, just search for battery switch.

For the wire gauge to DC distribution panel, just add up the fuse values for all your individual DC circuits and reference a good ampacity chart. I like to use the west marine charts - http://www.westmarine.com/WestAdvisor/Marine-Wire-Size-And-Ampacity.

Make sure you pay attention to voltage drop on long DC runs. Keep all your wire stranded if possible, it does better with automotive vibration, etc. I used stranded duplex and triplex wire throughout.. the Ancor Marine stuff is really nice, but you can find generic stuff much cheaper on ebay. There are also several vendors on ebay that will do custom lengths and lug sizes on thick battery cables, it is a pain and requires special tools to assemble those cables yourself.

I used the same AC/DC distribution panel Gary linked, it is nice! Also I have a Magnum pure sine inverter/charger combo and it has been great.

 

[Winston]

Let's see, 3 feet of #10 is 0.003 ohms. Not much, but when one considers "I squared R", at 200 amps, that's 120 watts being generated in that 3' of wire . . . not trivial.

On a related point, in our CaRV (to be replaced, we hope, with a real RV conversion), we deliberately picked a fairly low gauge wire, #10 , so that the 30 feet (15' x 2) of wiring between the car battery/alternator and the 250AH coach battery in the trunk would be self-current limiting. Even with a rather discharged coach battery, it never charges at more than 35 amperes . . .

 

[RDinNHandAZ]

Thanks for the calculation above. Clearly we need to go a wire size or two bigger from the common chart. I did that and more! As for the charge rate of the coach battery I have it connected with 4 feet of #4AGW and have it fused at 80 amps. It has never blown but I take the precaution to allow the auto circuit to only close when the van is at idle. Normally I let the solar charge the battery and have only needed to allow the auto switch to close 4 or 5 times on rainy days following long dark nights with the refrigerator working with the lights, etc. I have the auto switch on a manual switch normally open! Internal resistance in the battery once it has begun to charge seems to keep the current to a reasonable level. Your loss in that 30 feet is 40 watts, not a problem but if it is at 35 amps for a while it must get warm?? I know I don’t want to charge my similar sized batteries at near 80 Amps and until recently I had no way to measure it. I do now so next time I am in a discharge and switch it in I will check. For those who wonder the calculation we are using is: Power (lost to heat in watts) is equal to the square of the current (in amps) multiplied by the resistance (in Ohms- from a wire chart usually) [P=(IXI)XR]

 

[seapro]

Re post 16 & 17 above:
I have also used reduced wire size to cause voltage drop at high current to temper the initial surge when charging from the engine. Within a couple of minutes the current is reduced and the wire does not overheat enough to be a hazard. When the battery is very low I also let the connection only close when the engine is at idle so the alternator output is low. These things work. After an initial very few minutes charging current will be below 30 amps.

All wiring, both AC and DC, in a boat or vehicle should absolutely be stranded. Solid wire is prone to fatigue cracking due to vibration.

 

[trhoppe]

Thanks for all the feedback.

Regarding the inverter vs inverter/charger, I was told do get the separate setup by a friend that does lots of van installs. I was just sort of going with his advice. It also seems like it's not a bad plan to just always run off the batteries and if I am in a place that has shore power, to just plug in the charger while everything is happening so they stay topped off.

Price was also a thought. While I found the AIMS 2000W Pure Sine Inverter/Charger for $600, I've seen some negative reviews of it. I found an open box Xantrex PROWatt 2000 on Amazon for $300. That one seems to be used by quite a few people and is reliable.

It seems that if I go for a nice 20+ amp secondary charger, I'm in for $150 for that, so then I'm a lot closer to the $600 and I might as well just go that route

-Tom

 

[softseds]

trhoppe, I have the Xantrex PROWatt 2000 inverter. I purchased it online and it was dead out of the box. Stinky electronic burn smell. Since I bought it from some online marine supply company I went through the Xantrex Warranty procedure. I gave them a short description of my issue and they quickly took care of me and FEDEX me a replacement within 3 days. By their standards the 2000W unit is rather small and they don't rebuild them. So they didn't require it to be returned. It gave me great confidence that they stand behind their products.

I have the distribution panel that GaryBIS and Tyler Wick have, as stated in other posts, if your are interested in purchasing it. It didn't fit my space in the end. It's new.