NEW wiring sketch

[Scott3569]

Well since my last sketch was confusing people.. 

Here is a new sketch.. 

as I stated in the other thread.

I may add a fuse panel, but I believe that would be after the house battery.

 

[MrAlvinDude]

You might be aware of the placement of the big fuses, but just for clarity, I have added placement of the big fuses, that will protect your main wires, to your drawing.



The principle is, to place a fuse close to the Plus of any power source.

 

[Scott3569]

You might be aware of the placement of the big fuses, but just for clarity, I have added placement of the big fuses, that will protect your main wires, to your drawing.



The principle is, to place a fuse close to the Plus of any power source.

Well then, that brings the question to what size fuses do I need.. 

Sooo.. this is exactly what I have so far..

Wiring 4g positive
Starter battery - battery Isolator 

4g negative (ground)

House battery compartment- chassis 

NO FUSE AT THE MOMENT 

I do not have wiring for anything else.. 

I don't believe I need 4g to complete the rest of the hook up.. and the controller I think can handle 10g. 

So do I need 4g 
Isolator- house and what fuse is needed for 4g?

If I use 10g for the rest what fuse do i need?

 

[B and C]

Here is a good page to help with wire sizes and fuses: https://www.bluesea.com/resources/1437

 

[MrAlvinDude]

Well then, that brings the question to what size fuses do I need.. 

According to this chart,
https://www.powerstream.com/Wire_Size.htm
then 135 Amp is what one can safely expect to continuously draw over a 4AWG wire.

So a max of a 135 amp fuse is probably a good idea.


How many AmpHour are your batteries?
And are they Lead Acid batteries?


The only situation when you might experience above 100 amp, in the wires between a lead acid starter battery and a lead acid house battery, is if the house battery has been drained quite a bit. As in: it is close to being flat.  Then there might be a current of 100 amp (or more) for a few seconds, or possibly for up to a minute or so.

For most charging scenarios, you will typically not be supplying even close to 100 amp into a lead acid house battery. 
The internal resistance of a lead acid battery is simply too high, for such high charging rates to happen for any prolonged time.

If your house battery is lithium, then it is a very different story, and an active type of DC-DC controller should always be used. 


It is good that you use the same awg size wire for the plus and the minus
You only need a fuse on the plus wire.


For the controller 10 AWG sounds fine.

A max fuse of 55Amp for a 10 AWG wire is suggested in the chart:
https://www.powerstream.com/Wire_Size.htm

So a 50 Amp fuse will be fine.
One can always use a fuse that is smaller, than the recommended max, for any wire size.

 

[Weight]

I try to use the larger fuse appropriate to the wire AWG to reduce voltage drop.

In most cases there is no need for a fuse between solar panels and charge controller. The exception would be in larger parallel array.
The other would be if you decide to use wire to small to handle the ampere from the panels. But don't do that.

 

[highdesertranger]

Another reason to have a fuse/breaker between the solar panel and the controller is to disconnect the panel from the system for testing or servicing. Remember always disconnect the panel first and reconnect it last. Highdesertranger

 

[Weight]

HDR is correct.
I prefer a hd switch as there is less voltage drop across the switch than a breaker. I have a Blue Sea dpst battery disconnect that switches the battery and the solar panels with one turn. It has worked well with my 400W panels and MorningStar controller.
I use this switch. https://www.bluesea.com/products/6010/m-Series_Mini_Dual_Circuit_Battery_Switch_-_Red
Searching I have found them for less than $30.
Using 4 parallel panels, I route the positive wires through a fuse block then to the controller. https://www.bluesea.com/products/5045/ST_Blade_Compact_Fuse_Blocks_-_4_Circuits

 

[Scott3569]

Hello guys, as you can see in the photo, I have all of the components minus the battery and solar panel

the space I have to mount things is not that large. 
Aprox 14"L and 9"H

So, I am wondering of maybe  I could also mount a positive and negative Buss bar. 

If I can do the above

Then I could run the Isolator and Solar controller right here on this panel.. and only have the two cables from the isolator to the battery 
If that makes since..

 

[Weight]

Do you have fuses at the house battery positive terminal? At the starter battery positive terminal?

 

[Scott3569]

Do you have fuses at the house battery positive terminal? At the starter battery positive terminal?

if you look just above the Isolator, that is a fuse box for a 100amp fuse.. NOT PERMENANTLY IN PLACE ( I can put that one closer to the Starter Battery if need be)

I have 1 more 100amp fuse and I know I need a 3rd.. I have no idea why I only ordered 2. 

I created another post about this.. I didn't think anyone would see this..

 

[Weight]

You must have every cable from the positive battery post fused. Fuse as close to the battery post as possible. On each battery. If your wires are sized to exceed the maximum short circuit amperes of the panels, you do not need a fuse between the panels and the controller. You do need a switch. I prefer a switch rather than a circuit breaker as charging circuits need very low voltage drop.

 

[Scott3569]

You must have every cable from the positive battery post fused. Fuse as close to the battery post as possible. On each battery. If your wires are sized to exceed the maximum short circuit amperes of the panels, you do not need a fuse between the panels and the controller. You do need a switch. I prefer a switch rather than a circuit breaker as charging circuits need very low voltage drop.

ok, so if I am understanding correctly it should look like this

Starter Bat Positive-----Fuse---Bus bar---Isolator
Negative-- Grounded Bus bar with 4g cable

House Bat Positive----fuse---bus bar with 4 g cable
House Neg-----Neg bus bar

Charge controller Positive ----Bus bar---Fuse---Controller 10g wire
Char controller neg---- Negative Bus bar 10 gage 

Fuse box positive-----Bus bar----fuse---fuse panel 10 gauge
Fuse box Neg ----Bus bar

the way things are working out.. the controller, Isolator bus bars, and fuse Box, will have wires no longer than 6 Inches...

I am currently trying to find bus bars.. But it seems like I will need to order them.. And I am looking at the one below

https://www.amazon.com/Recoil-BB212...ds=electrical+bus+bars&qid=1626542636&sr=8-11

 

[bullfrog]

Starter battery positive---fuse---positive inlet post of the Isolator---outlet post of the Isolator---positive bus bar. The point of having an Isolator is to prevent having the house battery and the starter battery connected when the vehicle is not charging them. Connecting the starter battery to the bus bar without going through the Isolator connects them at all times.

 

[Scott3569]

Omg I was thinking the Isolator needed to go to ground.. But I suppose ground would only be for the ignition connection..

 

[izifaddag]

You do not need an isolator. You need a current limiter. That will act as an isolator and stop your alternator overheating and being destroyed. 
If you have upgraded your alternator to the level of a sherman tank you'll be fine. Otherwise there is a direct correlation between the heat generated in the windings of an alternator and the current drawn. There are many videos demonstrating this principle showing the destruction point. 
The current being drawn from the alternator to charge the house battery needs to be regulated down to a bit more than trickle or float. The gadget you need is 

https://www.amazon.com/dp/B07Q5VYPC...olid=1ZBMI2J4P4KI6&psc=1&ref_=lv_ov_lig_dp_it

I really wouldn't worry too much about fuses etc until you have got your head around this problem first. 
In my case I have 2 x 50 amp resets attached to my controller I do not recommend fuses of any kind. They are wasteful and annoying. 1 is for the incoming solar PV and the other is for the connection to the batteries. They are handy. Very occasionally the controller needs resetting. Very simple using the resets. Always disconnect the solar first and connect it last.

 

[Scott3569]

Well I have the Isolator.  Never heard of what your talking about..

 

[izifaddag]

Then I strongly suggest you find out.
My expertise in electrical engineering goes back to 1972, 4 years of college and many years of experience, but what would I know.
An isolator is a very cheap and dirty solution. Anybody who uses that system and has not burned up an alternator has had good luck. Good for them. The link I provided is the real answer. 
That is what I am talking about.

 

[bullfrog]

^^^I agree with you izifaddag. Using a vehicle's alternator to bulk charge is a bad idea in my opinion. One of the reasons I recommend a small generator is so batteries can be bulk charged easily. I also recommend having a large enough battery bank as not to deplete them to a point a heavy bulk charge is required. I think maybe that using the vehicle to "help maintain the battery" after it is bulk charged would be okay but a DC to DC charger would insure that is all the vehicle's alternator does. If you are going to use the vehicles alternator to charge house batteries and no DC to DC charger the isolation switch will at least insure you do not drain the starting battery over night.

 

[Scott3569]

Ok Great what size????