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Questions regarding "So, you want to setup a good electrical system in your camper?"


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#31 ntsqd

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Posted 20 February 2021 - 01:35 AM

The contacts are silver plated, under a fair amount of contact force, and experience significant wiping during mate and de-mate. Use care with the heat shrink, easy to get it where it won't allow the contact to engage the connector body correctly or move like it should.


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#32 Tom S

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Posted 01 March 2021 - 03:54 PM

Hi everyone. So the Anderson connectors finally showed up and both the truck and camper are now fully wired.. This is what I finally ended up with:

#2 awg wire from truck to camper via 120 amp Anderson’s in the truck box.
Blue sea 50 amp breaker under the hood.
Renogy 30 amp DC to DC charger with MPPT.
#4 awg wire from charger to battery..
Blue Sea 40 amp fuse block between camper battery and DC to DC charger.
Renogy 500 ah monitor with shunt in the camper battery negative.
Stark Energy 125 amp hour AGM battery.
Pre wired for solar with a 50 amp Anderson clone (Pico) located outside on the drivers side.
Just bought 2 Renogy 100 watt solar panels.

I’m super happy with how it turned out. I could have got away with a bit smaller wire size between the dc dc charger and the camper battery but I went bigger in case I upgrade to lithium some time in the future and increase the size of the dc dc charger. Right now I’m building a folding storage box to carry the solar panels. We carry a canoe on the roof so the panels will be on the ground. My question is this. (And I probably already know the answer and don’t want to admit it to myself.) The negative terminal on my truck battery is an odd affair that the big #2 wire wouldn’t attach to easily. So I attached the the wire to the frame ground about three inches away. Toyota has a jumper between here and the battery negative but it is only I’m guessing something like a #6 wire. This bugs me. Should I upgrade this? It seems like a weak link in a pretty good system. I have two options. Put a second smaller wire between the ground and the negative terminal or cut off the terminal and replace it with one with a stud that accepts the bigger lugs. On the Toyota terminal the negative wire is crimped directly to the terminal body. I’m pretty sure I know where this is going. lol. You’re never really finished are you?
Thanks again for the help.
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#33 rando

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Posted 01 March 2021 - 04:17 PM

A few centimeters of #6 AWG wire is no issue at all, your wire is already oversized for the job, and you don't care about voltage drop anyway as you have a DC-DC charger.   

This is not at all a problem in your system as your wire is all more than sufficient, but in general it is more important that the wires between the DC-DC charger and the battery are fat (and short), as opposed to the wires between the truck and the DC-DC charger.   The charger will compensate for voltage drop on the wires to the truck, but not between the charger and battery.


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#34 Wallowa

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Posted 03 March 2021 - 07:58 PM

Brian G.,

 

My recent saga is on the forum but my 2x75 amp AGMs ['16 Hawk] faded on me during cold temps with very minor load.

 

Ironically I also have an appointment with SixGun for about what you are doing:  100Ah BB LiFePo4; DC 2 DC; Victron 110/30 Controller [replacing Zamp Controller]; re-wiring my 170 & 160 W Zamps from parallel to series new roof connector.  I already have a Victron 712 w/temp.  My appointment is June 4th, 0900-1600hrs.  They rewire and install.

 

Brian when are you having your work done?

 

* Question:  I have read the differences in putting solar panels in parallel vs series.  Does anyone have first hand experience with the functional difference in terms of battery charging and SOC maintenance?

 

Thanks...Phil


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#35 Machinebuilder

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Posted 03 March 2021 - 08:20 PM

* Question:  I have read the differences in putting solar panels in parallel vs series.  Does anyone have first hand experience with the functional difference in terms of battery charging and SOC maintenance?

 

 

When I added a second panel I wired them in series.

 

My reasoning is when you look at the Victron manual the voltage from the panels needs to XX volts over the Battery voltage to start charging. When you put them in series it hits the voltage difference in much lower light, ie earlier am or on a cloudy day.

I don't have the exact voltage in my memory or available right now.

 

I have not tested this completely as part of the reason for me to upgrade is I killed my AGM battery by over discharging it.

I have a 100AH Battleborn LifePO coming this week.


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#36 Wallowa

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Posted 03 March 2021 - 09:22 PM

hanks MachineBuilder,

 

My ignorance again...I thought the voltage even during shading did not vary, or did not change much, just the amps delivered did...my concept was that higher voltage could more effectively 'push' amps and develop watts..as I remember my panels are about 19volts each...and around 9.4 amps each ...at best.  I looked at the Vic Controller and it recommended 5V over battery voltage...17V?

 

Wish all this would pop in place and make sense to me....still feeling like I am basically clueless!  Even claims that MPPT can deliver 30% more power than a  PWM gets lost with me...hype or real difference...

 

Phil


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#37 Jack

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Posted 03 March 2021 - 11:29 PM

The short answer: if your panels are the same type/brand (or same wattage and very similar Vmax), connect in series up to what your MPPT controller can handle. I have four 100W 19Vmax panels - 76V - on my 100/30 Vic, which can handle up to 100V input. Some controllers are limited to 30V or 50V.

 

Your panel voltage will vary by about 2V to 4V depending on how much sun and how much current you are asking the panel to supply.

 

The higher voltage from two panels in series does not pull more current out of the panels - but the higher voltage (38V instead of 19V - it varies by a few volts) means that the voltage is always more than 5V above your battery voltage and the MPPT controller will always be adjusting the voltage (up and down) to get the most watts (current X voltage). The MPPT controller actually sets the output voltage of the panels to get the maximum watts.

 

You can see this with your AGM batteries. Charged and with almost no load, they should be about 12.6V. Now add load by turning on the overhead fan and the furnace (about 7A) and watch the battery voltage drop. The amount of current drawn out of the batteries changes the battery voltage. The MPPT, by controlling the current drawn out of the panels changes the panel voltage. What's different about solar panels is that the change is non linear. Lets say, for the same amount of sun, your two panels in series are producing 40V at 5A. That's 200W charging your battery at 14V X 14.29A. (The MPPT takes in whatever voltage and current the panels supply and outputs what is needed for the battery.) But if the MPPT finds (generally by trial and error with small changes) that if it lets 5.4A flow from your panel, the panel voltage will drop to 39V. 39V X 5.4A is 210.6W. Your MPPT just got you an additional 10.6W so your battery will now charge a bit faster at 14V and 15.04A. As the amount of energy from the sun coming into your panels changes, this sweet spot changes. Your MPPT is always hunting for it when the panel voltage is 5V more than what is needed to charge the battery or meet your load.


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#38 Vic Harder

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Posted 04 March 2021 - 12:24 AM

Nice explanation Jack. 

 

In comparison, a PWM controller can't do the fancy juggling of varying power and current to maximize the power output.  All it can do is reduce the voltage if it is too high.  So, 20V in at 5A = 100W, but the battery only needs 13V, so it cuts the voltage down to 13V.  That 100W panel is now only producing 13*5 = 65W.  Oops.  In the same scenario, the MPPT is still getting 100W out of the panel.


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#39 BrianG

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Posted 04 March 2021 - 12:30 AM

Wallowa, my appt is April 19. 


Edited by BrianG, 04 March 2021 - 12:30 AM.

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#40 A.Smith

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Posted 04 March 2021 - 02:05 AM

How are you guys getting #4 wire into an Orion-Tr Smart 12/12-30 Dc/Dc charger ?
Try as I might, a number of strands are not making it into the opening.
#6 fits fine, but..

I am going to run #4 from the truck battery to the Anderson Connector, but what gauge from the Connector to the charger and what gauge from the charger to the battery ?
Charger will be close to the BB LiFePO4, but wire garage is important, so do I worry about a few strands of #4, or use #6 ?

Thanks,
Fred
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