2015 170” DirtDevil Build

[Midwestdrifter]

Many of the questions you are asking can be answered with a little math.

For example, regarding your inverter wiring/fusing;
Magnum lists a 30 second surge capacity of 3100W for the MS2000 inverter. This would be for starting an AC motor or similar. I feel it would be foolish not to design your system for the maximum output of your inverter.
Your batteries are rated at a max continuous discharge for 50A (100A total). What is the duration of this rating? 5 minutes? 20 minutes? An hour? Since the batteries are rated at 500CCA that means they can surge to at least 500A each for the length of a starting cycle.

V=IxR 3100W@12V with 10% losses is 284Adc I would follow the manufacturer’s recommendation and use a 300A fuse.

You inverter supply wiring is 16ft total on your schematic.
2/0 wire is 0.1mOhm per foot
4/0 wire is 0.06mOhm per foot

Your voltage drop would be as follows (at least).
16x0.1mOhmx289A=0.462V
16x0.06mOhmx289A=0.277V

At 1800W your voltage drop would be .26V (2/0) and .158V (4/0).

It looks like you would be safe with 105C wire at 2/0 with a 300A fuse. Your voltage drops may be an issue due to the small battery size and wire size though. I do not have experience with lithium batteries, so I cannot predict how the battery voltage will sag under load.

All that said, I would stick with 4/0 gauge. It’s not terribly expensive compared to 2/0, and will provide for a more robust system if you decide to add higher load items in the future.

As far as busbars go they are usually rated for continuous current. The max continuous output of the MS2000 is 2100W which is about 200Adc. I don’t see any reason to require a 300A busbar in your application.

Regarding your chassis ground. Charging directly from the alternator REQUIRES the negatives be bonded. Connecting the positives together without a return path for the current will result in zero charging. If you want the grounds isolated most of the time, a high current NO relay could be added between them and triggered by the ignition. The isolator doesn’t need to be connected to the chassis; it can be connected to the negative busbar if you wish. Given that most alternators produce around 13.8-14.1V I do not see any issue with charging your lithium banks directly from the alternator given they have built in BMS. In your case a smart isolator can probably be replaced by a relay triggered from the ignition.

Your shore power plug must be rated for 30A service. If you wish to use 15A service adapters are readily available.

On your USB charging ports you may want to check the parasitic draw. I have seen some that pull 1W when not in use. If that is the case adding a switch to deactivate when not in use would be prudent.

I echo Calbikers concern that you may not have sufficient capacity for your desired usage. You probably have about 80AH usable with your current configuration. Have you done an energy budget for your average day? You may find that you need 150AH or more capacity given your large fridge and induction cooktop usage. The indction cooktop and kettle will easily use 10-15AH each. The fridge could use 50AH+ a day. That puts you are 80AH without counting other consumers.

If you check out this post it seems that the newer alternators are capable of supplying high current levels for charging etc.
https://sprinter-source.com/forums/showpost.php?p=413441&postcount=194

 

[calbiker]

Regarding your 1800W hotplate: It's pulling 1800W/12V = 150A. If that's on for 20 min, then battery is down 50AH. That's half of your total battery capacity gone in 20 min. 200W solar will supply perhaps 60AH in the summer.

The hotplate is driving your inverter size, battery capacity (capacity may be too small right now), and possibly solar size, making the hotplate design very expensive. Why not chuck the hotplate and go with a propane cooktop?

I see nothing wrong going with 4/0 12V cables. The cable design isn't dictated by maximum ampacity, but by maximum voltage drop across the cable.

I don't want to harp on the fuse issue, but to be clear, a 200A MEGA fuse will not blow at 200A, but above the rated current. At 300A, it will blow in 1 to 15 seconds. In other words, the fuse has surge current capability.

The schematic (which btw is excellent), shows a 1 AWG cable from chassis to Neg Bus. That's your alternator charging path. It should be larger. You should count on 200A charging. I'm not sure if LifePO4 batteries can handle that current. There's a big difference between LifePO4 and FLA. When charging, FLA's have a surface charge of about 1.2V. That's why the alternator is regulated to 14.3V. LifePO4's don't have that surface charge. That means you can dump a lot more current into LifePO4. I have no experience with them and don't know how they handle the relatively high charging voltage.

 

[casmith32]

On the disconnect switch - Normally I guess the thought is that it goes after the fuse, however in talking with the AM Solar guys (who are great btw), they questioned the rationale and chatted with magnum energy about it; given that if you need to service the fuse/system if that fuse blows, you can't really replace the fuse w/out disconnecting the batteries first, and having to remove the seat. With it after the fuse, the thought is that you can turn the disco switch; and also in my case, open the shore power breaker, and PV disco switch and replace the fuse easily. I located both right next to the access panel on the seat pedestal in the design for that very reason. The assumption that van is not running so isolator not an issue in this case.

Does that approach not make any sense ? The likely hood of the fuse blowing is small I guess...assuming properly designed electrical sizing, etc... are there any major advantages/disadvantages to either way ?

For the solar, well it's installed already at this point nice and clean - junction box sits under the panels. junction makes it easy to add additional panels. But I had considered the poly panels but in the end went with the mono panels because they had the size (21" x 41") that worked for my roof configuration and possible future changes in placement. (maybe put in A/C unit down the road). Gives good flexibility on placement with Hein's PV panel rail setup. A larger panel wouldn't give me the option on changing the placement or splitting the PVs up, down the road if I needed/wanted to... I tend to gravitate to more modularity/flexibility approach on things .... some times at more $$ and to a fault I guess...

Quick look.

Usually the battery connection has the fuse before the disconnect switch. Reverse the positions of the fuse and disconnect?

I have a single 300 watt high voltage solar panel with two roof holes. Eliminates the connector box and makes mounting easier. I retain the panel MP4 quick disconnects that are located between the roof penetrations and the panel. Bought a 15' solar extension cable with the male and female ends that I cut in two to get the cables that run through the roof holes. Disadvantage is more potential loss from shading.

Super nice job of documenting the diagram.

 

[casmith32]

Yea - good question- I keep asking myself the same thing.

Originally I'd planned on portable versions of both; a portable dual-fuel stove that could use both propane and butane (http://www.sosproducts.com/Stansport-Dual-Fuel-Stove-p/544515.htm) with the thought that I can use it in or outside the van. And if I wanted later on, could permanently install one (https://www.corpbrothers.com/ma0502/item/7466-12031004.php) if I can find the damn thing anywhere...seems like they stopped making it. OR permanently install an induction hotplate like a bunch of upfitters are doing (outside van, RB components, etc.). Clean, simple, reasonably safe and easy; but at a cost.

I wanted the induction hotplate for quick cooking and easy setup; w/out having to bother with setting up canisters, etc in the van. Either way, the intent is to start with a clean countertop (sink excepted), using portable cooking, and if I find that having to store it, and pull it out and setup for cooking, is a pain, I can just install one in the countertop, and free up some storage...which is where I may go...

THAT was a long winded way of saying that I need to think about whether or not having the induction hotplate is really worthwhile for me or not ; and worth the cost. There is tangible benefits to having added battery bank and solar if I decide I want to be off-grid for days at a time depending on my usage (which I'll add to the post shortly)

Alternator charge path - ground to neg bus - So you think 2/0 cable for 200A ? even though the MB AUX retrofit guide uses 150A ? I was assuming that this was the "go to guide" on this; guess I can call MB and get a definitive on what the charging amps are for a 2015 Sprinter.

On the subject of fuses - you've encouraged me to dig deeper in to "why this one vs that one" for different applications, as well as the different types of fuses - definitely good to know without a doubt. So I wanted to understand your reasoning on the MEGA fuse vs the Class T-Fuse and found what seems to be a good explanation of when to use either and why.

http://www.expeditersonline.com/forums/threads/inverter-wire-and-breakers.47880/

Seems the idea is the Arc Interrupt rating (lets call it A.I.R. for short) - Class-Ts blow completely, and super high amperage; yet you still wanna fuse for the wire and also based on your battery bank CCAs. In my case CCAs = 500A - multiplied by up to 4 batteries, that's up to 2000Amps of interrupt needed. So that's way below the Class-T A.I.R. of 20K Amps, but at or close to the A.I.R. of MEGA fuses (2000-2700A) it seams from what I can find. ANLs maybe give more overhead and cheaper ? Guessing the ratings specs I'm reading can be misleading if they are for 32v vs 12v. Seeing your point...Am I off base here ?

Isn't there also the issue of voltage drop through the different sized fuses ? bigger = less drop for the load in my case ? I'm sure there is a point of diminishing returns on this though...meaning I don't wanna be right 2000A but have a fuse that maybe has 2500+ ? But maybe not a Class-T necessarily...

In any case - I already have the fuse, inverter, and shunt; and since this is my first rodeo on the van - I'm inclined to go with the manufacturers recommendations. But I do see your points! And can see if there is significant reason to swap out equipment here... And I will put more thought into fuse choices and costs in the future for sure. But here is the page from the manual on circuit protection -

View attachment MS2000-protection.png.pdf

Regarding your 1800W hotplate: It's pulling 1800W/12V = 150A. If that's on for 20 min, then battery is down 50AH. That's half of your total battery capacity gone in 20 min. 200W solar will supply perhaps 60AH in the summer.

The hotplate is driving your inverter size, battery capacity (capacity may be too small right now), and possibly solar size, making the hotplate design very expensive. Why not chuck the hotplate and go with a propane cooktop?

I see nothing wrong going with 4/0 12V cables. The cable design isn't dictated by maximum ampacity, but by maximum voltage drop across the cable.

I don't want to harp on the fuse issue, but to be clear, a 200A MEGA fuse will not blow at 200A, but above the rated current. At 300A, it will blow in 1 to 15 seconds. In other words, the fuse has surge current capability.

The schematic (which btw is excellent), shows a 1 AWG cable from chassis to Neg Bus. That's your alternator charging path. It should be larger. You should count on 200A charging. I'm not sure if LifePO4 batteries can handle that current. There's a big difference between LifePO4 and FLA. When charging, FLA's have a surface charge of about 1.2V. That's why the alternator is regulated to 14.3V. LifePO4's don't have that surface charge. That means you can dump a lot more current into LifePO4. I have no experience with them and don't know how they handle the relatively high charging voltage.

 

[calbiker]

This should work for cooking.

A 2.6 gal tank should fit under the chassis. If I did the math correctly, this bottle is equivalent to ~2300 AH of battery usage. Perhaps 50 cooking sessions.

 

[GeorgeRa]

Calbiker brings up a good point of the cost of infrastructure required to run high power appliances. We decided to have battery powered small microwave and picked the minimally sized Magnum 1000W inverter/charger. The actual usage cannot justify additional cost and work. I would be better off with just 300W inverter and a charger. So I ended up with 2, a mistake.

Our cooking is primarily done in the typical camping style, outside. For very cold or rainy days we have electric stove to be used with the shore power available or the alcohol one without. We had a very good experience with none pressurized alcohol stoves from our boating times so picking an alcohol stove was very natural for us.

George.

 

[calbiker]

I didn't mean to lead you astray with the MEGA fuse. The Class T fuse is the correct fuse for your application. I should have pulled up the T fuse spec instead of the MEGA when stating how much current it takes to blow it.

From the Class T fuse spec: A rated 200A fuse will blow at 300A in 100 seconds.

The previous argument against using a 200A fuse was due to possible surge currents blowing it prematurely. I would argue there's plenty of headroom for surge currents.

There are different philosophies in sizing a fuse. There's the brute force crowd that wants to fuse the wire. Look up the ampacity, and there's your answer. I don't like that approach and I don't think that's how the Sprinter is fused. I would look at each load to determine maximum current and then add a margin above that. Not all shorts are zero ohms, resulting in extreme currents. If you have a big fuse you may not catch some faults that can still start a fire.

So I wanted to understand your reasoning on the MEGA fuse vs the Class T-Fuse and found what seems to be a good explanation of when to use either and why.

 

[casmith32]

okay, I've given it some thought and have decided on one of two routes. I'm going to add another 100W of solar regardless; for multiple reasons. I'm going to stick with my original plan of combined use of a butane stove and induction hotplate, as well as my other appliances like the hot water tea kettle, etc...

option1: stick with 100Ah battery bank, and "see how it goes" ; fairly easy to add additional batteries under the seat if I decide to...

option 2: bite the bullet and up the battery bank to 200Ah LifePo4 ! Given what I wanna do with this rig and my anticipated adventures, I'm willing to invest in the infrastructure a bit more. Some people buy condos in the mountains, I'm building a roaming condo more overhead to accommodate future loads, and maybe better support adding 12v A/C unit in future if I feel the need with the pup in the van. (but I presume I'd upgrade the battery bank further if that happens; or go with a small A/C unit with portable gennie.)

My gut is telling me to do option 2 , as I'm probably briefly postponing the inevitable; and would rather not revisit this so quickly in the future...And 200Ah seems to be a good general capacity. And not have to come back and rewire things, even though it shouldn't be that much.

Updated diagram attached with edits based on feedback.

- Added another 100Ah lifepo4 batteries - 200Ah total; all under passenger seat
- updated 120v outlet wiring to be 12 AWG with 20A breaker; to accommodate high wattage items.
- updated Neg bus to Chassis ground to 2/0 AWG - to accommodate 200A charging
- Added 100w solar panel
- Wiring - Given max 200A cont. draw from battery bank, can the wiring be 2/0 or 3/0 vs 4/0 ? to enable smaller wiring ? such a nominal difference not worth it vs the decreased resistance ?
- Alternator charging device TBD - considering options...

View attachment Sprinter-ElecSys-v4.pdf

 

[Goldenraf]

I'm starting to import these batteries and I will also use them in my project RV
My batteries are telecom grade, much better than RV grade.
My estimated landed cost in North America will be much lower than the RV dealers
I will have from 60 to 200 Amps at 12V. I also have solar panels, inverters and so on.
Send me a message if you need any help with this, I have over 40 years experience with power equipment. www.itenclosuresystems.com

 

[calbiker]

That's going to be one awesome camper! I was going to remind you that the main priority is to keep the beer cold. I think you'll be meeting that goal with the added batteries and solar.

I took a look at the battery spec. They are pretty cool. Only weigh 15 lbs each. Max charging voltage is 14.6V. The alternator shouldn't pose any problems.

You changed the chassis ground to 2/0 AWG. The same should be done to the positive side which is 1 AWG.

The 4 batteries could pull 200A from the alternator. If it's not much trouble, I would change the 150A fuse to 200A.

The 4/0 cable can be changed to 3/0.

You have a Truck Fridge 130? Average consumption = 24W/hr = 48 AH/day. 300W solar should produce 90AH/day. That may give you close to 20 min cooking time on the hotplate.

 

[casmith32]

Thanks for all input from everyone! Kinda like crowd sourcing my design !! In any case yes beer will be stocked continuously of course! Few follow ups -

Battery - yea SmartBattery isn't the easiest to deal with - but I'm already in half way - and they are the only batteries I've found that will allow me to get a full 200Ah under the passenger seat... hoping it's not a bad decision; the company has had some issues that they tell me was due to the distributor they've since booted... we'll see. I've since found much better sources for Lifepo4 batteries at way better price points for the capacities.

Noted on the positive battery side for the charge relay/isolator and increased fuse to 200A - will update diagram.

Don't have a fridge yet, but that's the one I was looking at - way cheaper than the "branded" marine one - but seems to be the same OEM almost. They market to truckers who won't pay a premium on these I guess. But I'm assuming at 2a/h that it won't be a full 48Ah given a duty cycle, yes ? I'm thinking 30%-50% duty cycle - nevertheless always ok to plan on max use though for worst case...

On the battery/inverter wiring - for my own education, Based on the max surge of the magnum inverter of 275ADC, I did some calcs on wire sizes/lengths. Used the BlueSea calculator for reference.The one thing that confuses me is references to wire length. This Blue Sea calculator says the length should be the len of the supply wire + the return wire. Not understanding that one; would think the ampacity of a wire is that single length of wire?

Calcs assuming a single wire's length as the input to the calculator:
275A @ 7ft; 2% voltage drop = 0 AWG with wire capacity for 285A
275A @ 7ft; 1% voltage drop = 3/0 AWG with wire capacity for 385A

275A @ 8ft; 2% voltage drop = 0 AWG with wire capacity for 330A
275A @ 8ft; 1% voltage drop = 4/0 AWG with wire capacity for 445A

275A @ 10ft; 2% voltage drop = 2/0 AWG with wire capacity for 330A
275A @ 10ft; 1% voltage drop = beyond 4/0


Calcs assuming double the wire's length as the input to the calculator:

275A @ 7ft(14ft); 2% voltage drop = 3/0 AWG with wire capacity for 385A
275A @ 7ft; 1% voltage drop = Larger than 4/0

275A @ 8ft(16ft); 2% voltage drop = 4/0 AWG with wire capacity for 445A
275A @ 8ft; 1% voltage drop = Larger than 4/0

275A @ 10ft(20ft); 3% voltage drop = 3/0 AWG with wire capacity for 385A
275A @ 10ft; 1% voltage drop = Larger than 4/0

My anticipated total len will be approx 5-7 ft from passenger seat to just behind the driver seat. So depending on which of these calculations are best to use, 2/0 should be sufficient I'd think.

275A @ 7ft; 2% voltage drop = 0 AWG with wire capacity for 285A
275A @ 7ft; 1% voltage drop = 3/0 AWG with wire capacity for 385A
275A @ 7ft(14ft); 2% voltage drop = 3/0 AWG with wire capacity for 385A

Another calculator (http://www.bulkwire.com/wireresistance.asp) suggests that I can use the following on a 7ft run:

2/0 AWG cable @ 1.283% drop
3/0 AWG @ 1.0% drop
4/0 AWG @ .8% drop

at this point it seems like I could run 2/0 AWG, which magnum says is okay for <5 ft, and it's <2% drop; or 3/0 for more overhead/less drop; but at a capacity of 330A for 2/0 AWG, wouldn't that suffice ?

looking for some enlightenment....thoughts ?

thanks!

That's going to be one awesome camper! I was going to remind you that the main priority is to keep the beer cold. I think you'll be meeting that goal with the added batteries and solar.

I took a look at the battery spec. They are pretty cool. Only weigh 15 lbs each. Max charging voltage is 14.6V. The alternator shouldn't pose any problems.

You changed the chassis ground to 2/0 AWG. The same should be done to the positive side which is 1 AWG.

The 4 batteries could pull 200A from the alternator. If it's not much trouble, I would change the 150A fuse to 200A.

The 4/0 cable can be changed to 3/0.

You have a Truck Fridge 130? Average consumption = 24W/hr = 48 AH/day. 300W solar should produce 90AH/day. That may give you close to 20 min cooking time on the hotplate.

 

[Graphite Dave]

Don't have a fridge yet, but that's the one I was looking at - way cheaper than the "branded" marine one - but seems to be the same OEM almost. They market to truckers who won't pay a premium on these I guess. But I'm assuming at 2a/h that it won't be a full 48Ah given a duty cycle, yes ? I'm thinking 30%-50% duty cycle - nevertheless always ok to plan on max use though for worst case...

Your duty cycle is in the right area.

You will notice that none of the manufacturers have thick insulated walls. I built cabinet so I could add 1 1/2" of rigid polyiso around the refrigerator. Also put a hole in the van floor behind refrigerator so I could get air flow up past the coil. These help to reduce the run time.

I just bought a 85 liter Vitrifigo refrigerator for the Transit build. Had a Dometic 80 liter in the sold Sprinter. Did not like the Dometic door design but otherwise it worked well. The Vitrifrigo has the compressor mounted at bottom back instead of like most that have it mounted top back. The bottom location makes a major difference in the freezer capacity. The door has 3 shelves instead of 2 and the door design is much better. The reason for this info is the coil is not mounted on the back like the Dometic. It is a small coil with fan mounted low on the left side. I will have to add a vent opening in my cabinet to allow good air flow. The point is pay attention to getting airflow for the refrigerator.

 

[casmith32]

Awesome! thanks for the suggestion - I'll look into those - seems like a better design to me !! can't argue with a little more freezer space! Whats a good source for these ? I see them at suremarine.com.

The units with the external compressor are interesting - gives a bit more fridge space if I can find a good location for the compressor. you see any huge caveats with going that way ?

Your duty cycle is in the right area.

You will notice that none of the manufacturers have thick insulated walls. I built cabinet so I could add 1 1/2" of rigid polyiso around the refrigerator. Also put a hole in the van floor behind refrigerator so I could get air flow up past the coil. These help to reduce the run time.

I just bought a 85 liter Vitrifigo refrigerator for the Transit build. Had a Dometic 80 liter in the sold Sprinter. Did not like the Dometic door design but otherwise it worked well. The Vitrifrigo has the compressor mounted at bottom back instead of like most that have it mounted top back. The bottom location makes a major difference in the freezer capacity. The door has 3 shelves instead of 2 and the door design is much better. The reason for this info is the coil is not mounted on the back like the Dometic. It is a small coil with fan mounted low on the left side. I will have to add a vent opening in my cabinet to allow good air flow. The point is pay attention to getting airflow for the refrigerator.

 

[Graphite Dave]

Awesome! thanks for the suggestion - I'll look into those - seems like a better design to me !! can't argue with a little more freezer space! Whats a good source for these ?

I am sure the Vitrifrigo at $744.25 plus $142.36 shipping is a lot more expensive than a truck fridge.
My point was to pay attention to air flow and added insulation no matter what refrigerator you buy.

 

[calbiker]

I don't use cable calculators. They're too complicated. ;-)

Get a wire gauge table and look up wire resistance at 1000 ft.
http://www.powerstream.com/Wire_Size.htm

1/0 AWG = 0.0938 mohm/ft
2/0 AWG = 0.0779 mohm/ft
3/0 AWG = 0.0618 mohm/ft
4/0 AWG = 0.0490 mohm/ft

You have 7 ft one way or 14 ft round trip.

Voltage drop is calculated:

Vdrop = R(ohms/ft) * length * I

V(1/0 AWG) = 0.0938 mohm/ft * 14 ft * 275A = 361 mV
V(2/0 AWG) = 0.0779 mohm/ft * 14 ft * 275A = 300 mV
V(3/0 AWG) = 0.0618 mohm/ft * 14 ft * 275A = 238 mV
V(4/0 AWG) = 0.0490 mohm/ft * 14 ft * 275A = 189 mV

At 12.8V, percent voltage drop is: 2.8%, 2.3%, 1.9%, 1.5%

BTW, the fridge has an average power consumption of 48 AH/day. This is not max.

The Magnum MS2000 has a no load AC power consumption of 25W, or 2 AH, or 48 AH/day. That's huge, as much as the fridge! Your electric hot plate is driving this. You won't be able to keep this inverter on all the time. It's too power hungry. You'll probably need a 150 - 300W inverter for general purpose use.

My anticipated total len will be approx 5-7 ft from passenger seat to just behind the driver seat. So depending on which of these calculations are best to use, 2/0 should be sufficient I'd think.

275A @ 7ft; 2% voltage drop = 0 AWG with wire capacity for 285A
275A @ 7ft; 1% voltage drop = 3/0 AWG with wire capacity for 385A
275A @ 7ft(14ft); 2% voltage drop = 3/0 AWG with wire capacity for 385A

 

[Graphite Dave]

The Magnum MS2000 has a no load AC power consumption of 25W, or 2 AH, or 48 AH/day. That's huge, as much as the fridge! Your electric hot plate is driving this. You won't be able to keep this inverter on all the time. It's too power hungry. You'll probably need a 150 - 300W inverter for general purpose use.

I found the same thing with my 1000 watt Magnum. Left it on overnight once without a load connected and it used 7% of my 255 amp-hr battery capacity. Lesson learned. Now only turn it on when I need 120 volt power.

 

[casmith32]

I found the same thing with my 1000 watt Magnum. Left it on overnight once without a load connected and it used 7% of my 255 amp-hr battery capacity. Lesson learned. Now only turn it on when I need 120 volt power.

I was thinking about that - Was going to turn the unit off when not needing it. Easy enough. But now I'm guessing that the remote won't be usable if the unit is off ? so I'd not be able to do basic battery monitoring w/out the inverter on ? I bought the magnum BMK kit.

 

[GeorgeRa]

I was thinking about that - Was going to turn the unit off when not needing it. Easy enough. But now I'm guessing that the remote won't be usable if the unit is off ? so I'd not be able to do basic battery monitoring w/out the inverter on ? I bought the magnum BMK kit.

Just turn the inverter function off with the remote. If you disconnect the battery than you need to reprogram the remote.

George.

 

[casmith32]

I don't use cable calculators. They're too complicated. ;-)

Get a wire gauge table and look up wire resistance at 1000 ft.
http://www.powerstream.com/Wire_Size.htm

1/0 AWG = 0.0938 mohm/ft
2/0 AWG = 0.0779 mohm/ft
3/0 AWG = 0.0618 mohm/ft
4/0 AWG = 0.0490 mohm/ft

You have 7 ft one way or 14 ft round trip.

Voltage drop is calculated:

Vdrop = R(ohms/ft) * length * I

V(1/0 AWG) = 0.0938 mohm/ft * 14 ft * 275A = 361 mV
V(2/0 AWG) = 0.0779 mohm/ft * 14 ft * 275A = 300 mV
V(3/0 AWG) = 0.0618 mohm/ft * 14 ft * 275A = 238 mV
V(4/0 AWG) = 0.0490 mohm/ft * 14 ft * 275A = 189 mV

At 12.8V, percent voltage drop is: 2.8%, 2.3%, 1.9%, 1.5%

BTW, the fridge has an average power consumption of 48 AH/day. This is not max.

The Magnum MS2000 has a no load AC power consumption of 25W, or 2 AH, or 48 AH/day. That's huge, as much as the fridge! Your electric hot plate is driving this. You won't be able to keep this inverter on all the time. It's too power hungry. You'll probably need a 150 - 300W inverter for general purpose use.

Yea - I was going to turn the inverter off when not needed anyways - however I'm wondering since I have the battery monitoring kit tied into the magnum remote, once I turn off the inverter, do does the remote - hence no battery monitoring...may think about separate battery monitor if thats the case... man - parasitic loads are a pain .... thanks for the heads up on that!!

thanks for the info on the wiring - so the general consensus is to do wire calcs with lengths as round trip then it seems ?

 

[Midwestdrifter]

Awesome! thanks for the suggestion - I'll look into those - seems like a better design to me !! can't argue with a little more freezer space! Whats a good source for these ? I see them at suremarine.com.

The units with the external compressor are interesting - gives a bit more fridge space if I can find a good location for the compressor. you see any huge caveats with going that way ?

I ordered my Vitrifrigo C115 from here. Price was $750 plus 150$ shipping to Oklahoma. Karl can get you any of the Vitrifrigo fridge line. He was great to deal with.

The freezer is truly massive for a single door fridge. Quality of the interior is an improvement over the TF-65 I had in my previous conversion. The Truckfridge units are every bit as reliable as the more expensive units. They do have much cheaper finish though. You can't go wrong with either one.

Edit: remote compressors are useful on boats and the like due to space/ventilation constraints. In an RV where you may need to remove cabinets for repairs a remote compressor is a liability in my opinion. I would stick with the fridge mounted compressor. a 100+liter fridge is a lot more than many ppl need, so the space saved by remote mounting is not that important. IIRC you can easily put 48 beer cans in a TF65.

If you go with the truckfridge drop me a PM and I can give you some advice about improving noise and performance prior to installation. There are some easy fixes/tricks.