Please review my wiring diagram

gaffa

New member
Hi, I'm helping a friend with his Sprinter conversion. I've done plenty of AC house wiring, but not a DC guy at all - other than helping him with an earlier car project. He's using a pair of solar panels, a Xantrex 1800 inverter, a C-Tek 25000 battery charger, the C-Tek D250S and Smartpass combination and a pair of 6 volt AGMs in series.

Could you much more knowledgeable folks review my drawing? I've made it editable. Where should I have fuses, breakers, shunt, etc? Is my basic diagram workable?

Thanks so much!
 

DAWg134

DaleW
The wiring diagram appears to be correct, based upon my interpretation of the D250S DUAL, SMARTPASS, and MULTI US 25000 User/Installation Manuals. However, you currently have all of your DC goverened by the SMARTPASS and may want to consider connecting critical DC functions (e.g., key lighting fixtures) directly to the battery, otherwise, ALL DC consumers will drop offline if the battery voltage decreases below the threshold.

I've also modified your drawing to indicate (using callouts) where I would install fuses and/or circuit breakers - basically, I would place them as close to the producer as possible in case of a chaffed wire shorting to chassis. My preference is to use circuit breakers whenever possible, but for heavy amperages, those can get expensive and in the case of ensuring close proximity to the solar array... simply not practical.

I also added in the alternator... just for the sake of completeness. My apologies for my crude modifications to your drawing, but I'm not used to Google's graphic editor.
 

gaffa

New member
Thanks for your response and contributions!

The AC Breaker/DC Fuse panel has one 30 amp input, one 20 amp and 3 15 amp branches and a dozen DC fuse locations.

All this equipment, other than the two batteries, solar panels (obviously) and the starter battery/alternator will be installed on a single piece of 3/4" plywood underneath the bed (with a cooling fan). I'll have Anderson plugs for each battery and the solar panels, as well as the feed from the alternator, and a Hubbell 30 amp twist-lock connector to the breaker. I want to be able to wire this whole system on the bench in the warmth (it is February), plugging it into the Sprinter when done.

I have one other piece of equipment that I forgot to add: a Bogart Engineering Trimetric, which I have been told should be between the negative side of the battery and the shunt.

The solar panels come through the roof via a rubber compression connector, and are protected with split loom from the source to the panel.
 
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nugget

Member
I'm in the process of a sprinter conversion purchasing many items to start upon the arrival of my van in May. I would like to see a picture of your A/C- D/C panel and also the brand and source. I'm trying to find the most compact panel to save space. Your help would be appreciated. Also anyone else out there I'm open to suggestions to other panels and sources.
 

gaffa

New member
I'm in the process of a sprinter conversion purchasing many items to start upon the arrival of my van in May. I would like to see a picture of your A/C- D/C panel and also the brand and source. I'm trying to find the most compact panel to save space. Your help would be appreciated. Also anyone else out there I'm open to suggestions to other panels and sources.
This is the one we're using. The dimensions are: 13.78"L x 4.25"D x 7.3"H
 

calbiker

Well-known member
You don't need a fuse next to the solar panel. Other than a possible disconnect, it serves no purpose.

I wouldn't use the D250S. Max voltage of this charge controller is only 20V. That's extremely low! What type of panels are you using?

I would use a Blue Sky or Morningstar controller. But, you don't even need MPPT. There's very little performance gained over PWM.
 

OrioN

2008 2500 170" EXT
You don't need a fuse next to the solar panel. Other than a possible disconnect, it serves no purpose.

I wouldn't use the D250S. Max voltage of this charge controller is only 20V. That's extremely low! What type of panels are you using?

I would use a Blue Sky or Morningstar controller. But, you don't even need MPPT. There's very little performance gained over PWM.
You don't need a fuse next to the solar panel. Other than a possible disconnect, it serves no purpose.
A fuse is very good practice, place after any source of current and to protect wires from starting fires. In my case, my panels are wired in series and output 63V / 7A, and there is no way I will have these wires unprotected.

I wouldn't use the D250S. Max voltage of this charge controller is only 20V. That's extremely low! What type of panels are you using?

I would use a Blue Sky or Morningstar controller. But, you don't even need MPPT. There's very little performance gained over PWM.
There is an abundance of performance gain with MPPT, close to 30% for most setups. Results are Very well documented on Solar forums, review and manufacturers' sites. The question is whether one see's a return in the extra cost... in my case, work/living off solar, the cost of the MPPT was covered by me using less propane/genset in under 2 years.
 
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calbiker

Well-known member
We're not talking about your system. The OP's system operates on 12V panels. There is absolutely no need for a fuse! What size fuse would you use anyways? It's virtually impossible to size.

Claims of 30% MPPT gain is hogwash. I bet average gain when charging battery from 60% to 80% SOC (in boost mode) is only 5% - 7%. There is no gain when in absorption or float.

Cal
 

OrioN

2008 2500 170" EXT
We're not talking about your system. The OP's system operates on 12V panels. There is absolutely no need for a fuse! What size fuse would you use anyways? It's virtually impossible to size.

Claims of 30% MPPT gain is hogwash. I bet average gain when charging battery from 60% to 80% SOC (in boost mode) is only 5% - 7%. There is no gain when in absorption or float.

Cal
OH...MY...

Really? No need? 12V? ... then explain why every 12v circuit in an van and rv conversion is fused, even as low as 3A? I use BlueSea System breakers. ***Not to mention, the fuse acts a second level of protection for short damage to the panel (assuming there's a primary fuse, as some China's seem to not have any).

As for MPPT... again, real side by side array comparisons have shown REAL GAINS and UP TO 30%... while I'm too lazy to fetch these (again), they exist (so this is the end of any argument or pissing contest). And, if anyone is under a load draw scenario (which you haven't thought to consider), and the battery bank is in a state that would required a float charge, an MPPT controller will still output as such. So the net gains are substantial in that one can recover their bank faster. I know this as mine does, as verified by my Morningstar serial port/monitoring software that is running on my pc's. Plus... I can harvest more current under low light conditions with the MPPT process as my unit is very efficient with low V's as much as it's with +12 V's.


.
 
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Oldfartt

Active member
Hi Gaffa,
You have it right, with the addition of fuses as suggested by DWG134. I am putting nearly the same equipment into my conversion. The D250S Duel is a very smart, sophisticated device as it combines the functions of of a number of devices. It saves you having a separate voltage dependent relay to connect the house battery and the engine battery, It has desulphation , and pulse maintenance for the batteries. These features offset the price differential for separate items.
The Maximum voltage input is 22v, not as Calbiker indicates.
It is designed for solar panels wired in parallel, not series. The battery arrangement, 6v wired in series is the best configuration as the charging current is identical through both batteries.
If you have not already purchased the fuse holders, consider Maxi fuses for the heavy current devices, batteries and solar. Place these close to the source of current. If you have a NCV3 then there is a spare terminal on the DC distribution panel attached to the +ve battery terminal. Purchase an 80Amp strip fuse from any auto electrical supplier. The Maxi fuses are capable of taking high current reliably but are there to protect the wiring if something fails.
The low voltage cut off is designed to protect the battery and also protect those devices which may fail due to low voltage i.e 12 Dc fridges (which may/may not have built in low voltage protection) Only wire critical services like radio telephones and the odd light directly to the battery.

Let us know the finished system and provide some pictures.

Cheers

Ross
 

NBB

Well-known member
You need a big fuse near the battery.

The inverter needs to have a direct connection to the above fuse via a very fat and short wire. Read the manual.

The "DC + Barrier Strip" should be replaced with a proper 12v fuse box. See "My Climbing Rig" for details on how I used OEM parts to add fuses to the OEM fuses under the driver's seat.

There really is a ton of information missing from your diagram - fuses and wire diameters being the most important. You also have no accessories shown.
 
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calbiker

Well-known member
You didn't answer the question. What size fuse should the OP use, and what size fuse are you using.

Again, under normal operating conditions:

Boost mode (Vbat = 13.0V to 14.5V)
Panel temperature 50C

average gain is well under 10%.

It is possible to get 30% gain. But that would be transient, not sustainable. The panel would have to be extremely cold and the battery voltage extremely low.

BTW, I define gain as the ratio: I_mppt / I_pwm. This is only valid for 12V (or 36-cell) panels.

Cal
 

calbiker

Well-known member
Thanks for the correction. Typo error.

22V is still extremely low. Panel voltage shouldn't come anywhere near this limit. A Kyrocera 135W panel has a open circuit voltage of 22.1V. This controller is poorly designed. It shouldn't be used.

The Maximum voltage input is 22v, not as Calbiker indicates.
 

OrioN

2008 2500 170" EXT
You didn't answer the question. What size fuse should the OP use, and what size fuse are you using.

Again, under normal operating conditions:

Boost mode (Vbat = 13.0V to 14.5V)
Panel temperature 50C

average gain is well under 10%.

It is possible to get 30% gain. But that would be transient, not sustainable. The panel would have to be extremely cold and the battery voltage extremely low.

BTW, I define gain as the ratio: I_mppt / I_pwm. This is only valid for 12V (or 36-cell) panels.

Cal
OP fuse? Depends on his panel Watts. Mine: Each of my two 63V / 7.5A arrays has a 10A breaker on the wires, (wire sized accordingly).

My output is sustainable, and not just for the conditions you describe at all... give me 2 months to prove it (I NEED MORE SUN!!!) with my logs/graphs. No joke!
In the meantime... look at these screenshots (from last summer)... full sun, +20c ambient temp, bank at 80% and running a 20A dc load... I can explain the meat & potatoes if you can't decipher...
 

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calbiker

Well-known member
As I understand it, you have an array that outputs 7.5A. You fuse it with 10A. A 10A fuse does not open at 10A. It may take 10 minutes to open at 135%, or at 13.5A. Your array has a short current current about 10% greater than Imp. That means in your case short circuit current is 8.25A.

So you see, a short will generate 8.25A. The fuse won't blow till 13.5A. It serves no purpose. It will never blow.

Cal
 

gaffa

New member
Hi Gaffa,
You have it right, with the addition of fuses as suggested by DWG134. I am putting nearly the same equipment into my conversion. The D250S Duel is a very smart, sophisticated device as it combines the functions of of a number of devices. It saves you having a separate voltage dependent relay to connect the house battery and the engine battery, It has desulphation , and pulse maintenance for the batteries. These features offset the price differential for separate items.
I'm the person wiring, my friend did the component selection, but his choice was based on excellent reviews of the C-Tek products - especially ones from Australia and New Zealand, where the brand is much more popular.

The Maximum voltage input is 22v, not as Calbiker indicates.
It is designed for solar panels wired in parallel, not series. The battery arrangement, 6v wired in series is the best configuration as the charging current is identical through both batteries.
The panels are two Kyocera KD135GX panels wired in parallel.

The batteries are Lifeline GPL-L16T 6 volt, 400 amp. The house batteries and all the converters are in one area, one on each side, beside the rear wheel-wells. We should only need something like four feet of wire from each battery to the system. There will be a fairly long run from the starter battery/alternator.

If you have not already purchased the fuse holders, consider Maxi fuses for the heavy current devices, batteries and solar. Place these close to the source of current. If you have a NCV3 then there is a spare terminal on the DC distribution panel attached to the +ve battery terminal. Purchase an 80Amp strip fuse from any auto electrical supplier. The Maxi fuses are capable of taking high current reliably but are there to protect the wiring if something fails.
Do you have a link for them?

The low voltage cut off is designed to protect the battery and also protect those devices which may fail due to low voltage i.e 12 Dc fridges (which may/may not have built in low voltage protection) Only wire critical services like radio telephones and the odd light directly to the battery.
The fridge is a Novakool RFU8220, which I understand has built-in under-voltage protection, and pulls a max of 4.5 amps.

Let us know the finished system and provide some pictures.
Will do!

You need a big fuse near the battery.
Will do.
The inverter needs to have a direct connection to the above fuse via a very fat and short wire. Read the manual.
Based on the above information, suggested gauge?

The "DC + Barrier Strip" should be replaced with a proper 12v fuse box. See "My Climbing Rig" for details on how I used OEM parts to add fuses to the OEM fuses under the driver's seat.
All the stuff in the drawing is in the back. I am mounting most of the stuff on a removable panel that I'll wire on the bench. The batteries, solar panel and AC input, and AC and DC output will all have their own connectors on the edge of the panel.

There really is a ton of information missing from your diagram - fuses and wire diameters being the most important. You also have no accessories shown.
I just put a rough sketch together to make sure I hadn't made any huge mistakes and get feedback from more experienced builders. I'll make a much more professional and complete based on the replies in this thread.
 

Oldfartt

Active member
Hi Gaffa,

The Kyocera panels produce an open circuit voltage of 22.1V at standard test conditons in which the insolation is 1000w /m squared. These conditions are not normally found in real life mounted flat on the top of a sprinter. The panels connected to a circuit will not achieve the 22.1V open circuit voltage, but is in the range of 16 to 20V.
The fuse holders I am using are these http://bepmarine.com/home-mainmenu-8/product-696/702-mfh-maxi-fuse-holder
The maximum fuse size recommended for the solar panels is 15amp.
The Maxi fuse for the house battery should be at least 60A, preferably 80A.
The Novakool fridge uses a Danfoss compressor which does have an under voltage cut out. It can be programmed for various voltages by changing the value of a resistor on the control board. The normal setting is OK for your batteries.
The cable from the batteries to the Ctek D250S and to the inverter should be the largest that your pocket can afford! The rule of thumb for voltage drop is no more than 0.3Volts drop from source to load. So work out the maximum current for each circuit and apply a suitable cable. Remember to include the negative return lead in the resistance calculations.

Cheers

Ross
 

gaffa

New member
Hi Gaffa,

The Kyocera panels produce an open circuit voltage of 22.1V at standard test conditons in which the insolation is 1000w /m squared. These conditions are not normally found in real life mounted flat on the top of a sprinter.
"Real life", in this case, will be on the notoriously overcast sea coast of places like British Columbia, Canada. That's one of the reasons why my friend chose this particular configuration.

The panels connected to a circuit will not achieve the 22.1V open circuit voltage, but is in the range of 16 to 20V.
OK.

The fuse holders I am using are these http://bepmarine.com/home-mainmenu-8/product-696/702-mfh-maxi-fuse-holder
The maximum fuse size recommended for the solar panels is 15amp.
The Maxi fuse for the house battery should be at least 60A, preferably 80A.
The Novakool fridge uses a Danfoss compressor which does have an under voltage cut out. It can be programmed for various voltages by changing the value of a resistor on the control board. The normal setting is OK for your batteries.
Thanks.

The cable from the batteries to the Ctek D250S and to the inverter should be the largest that your pocket can afford! The rule of thumb for voltage drop is no more than 0.3Volts drop from source to load. So work out the maximum current for each circuit and apply a suitable cable. Remember to include the negative return lead in the resistance calculations.
Is there an on-line calculator? I'm planning to use a pair of Anderson connectors for each battery, (as well as the solar panels) so I'll see what the largest cable I can fit into the connector.


Thanks so much for your help, and the help of everyone in this thread. I'll post pictures. I plan to make this installation a thing of beauty.
 

OrioN

2008 2500 170" EXT
As I understand it, you have an array that outputs 7.5A. You fuse it with 10A. A 10A fuse does not open at 10A. It may take 10 minutes to open at 135%, or at 13.5A. Your array has a short current current about 10% greater than Imp. That means in your case short circuit current is 8.25A.

So you see, a short will generate 8.25A. The fuse won't blow till 13.5A. It serves no purpose. It will never blow.

Cal
So here's the scoop....

I will explain the reasons for the need to fuse the wire between PV's and Charge Controller. There are 2.

Attached is a picture of my home-grown combiner box which used to accommodate 4 breakers for 4 PV's in parallel, and conveniently made into an illustration (I hope).

*Illustration Notes:

RED Wires/Arrows/Labels: Pos. Current Flowing Under Normal Conditions
RED & Black Arrows/Labels: Pos. Current Flowing Under Shorted Conditions

Reason 1: 3 or More PV's in Parallel - One PV shorts

If one of the PV's (PV #1 in our case) shorts, the 2 other PV's will supply a 10A current (back-feed) through the PV #1 wires. These wires may now be undersized and it and the PV will fry.


Reason 2: Charge Controller Shorts

If the charge controller fails and shorts, the 20A current from the battery will flow towards the PV's. The wires after the combiner and Pv's are rated for 5A, so again things can fry.

*From the Manufacturers: A PWM controller has the ability to have current flow in reverse under failure/short in some scenarios. An MPPT controller apparently cannot (but this is not definitive).



.
REBUTTALS:

I erred in me previous postings... I have 5A breakers (not 10A) protecting each PV that is Isc: 5.85A or Ipm: 5.45A, but under normal operating, the max. range is 4.33A -ish.

BUT, as you can see, I now run 2 PV's (each with 3 panel's wired in series @ 36v), SO I no longer have or need protection for Reason #1, but since the fuse is under the PV's Isc: 5.85A, it does add another layer of protection (Reason 3?)

.
 

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