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


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#171 Ruffinit

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Posted 22 March 2023 - 02:07 AM

Yes, your T100’s alternator will be happier if you limit the current draw with a DC-DC. The DC-DC also provides “intelligent” charging, vs just dumping current into the battery.

Thank you Vic!


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1996 Toyota T100
2018 ATC Ocelot

#172 Vic Harder

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Posted 22 March 2023 - 02:15 AM

Thank you Vic!

Bruce, allow me add a few more details:

 

My question:

Does the ACR provide the necessary current limit for a “dumb” alternator when charging a LiFePO4 battery?

-- No.  The ACR connects the truck to the camper when it detects that charging current is available from either side.  And disconnects the two systems when it detects that the one may drain the other.

 

Can I (Should I) leave the AOPEC and add a Victron DC-DC charger to limit the current?

-- No.  Most folks replace the ACR with the DC-DC.  I say most, because I have both.  I'll add a comment to my power thread to explain.

 

My limited understanding is the AOPEC will allow 140 A (and the Blue Sea allows 500 A) >> 30 A

-- Allow?  Not really.  That is their rating.  Beyond that smoke/sparks start flying.   :D 

 

Or will the DC-DC prevent the ACR from functioning?

-- Correct.  They are not designed to work together.
 


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#173 Ruffinit

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Posted 22 March 2023 - 02:39 AM

The isolator and a DC-DC converter are; very, very roughly; parallel type components.

 

I am unsure of what you want the system to do. I'd say let's start with what you've listed above and work towards the goal of what you want the system to do.

Hi ntsqd

Thank you very much for your reply. 

My goal is just to replace my AGM with a LiFePO4 and make sure I don’t fry my alternator. 
I was concerned I might be missing something with 

“If you want to charge the truck from the camper, then you can’t use the DC-DC charger wired like this.

Thanks again 

-Bruce 


Edited by Ruffinit, 22 March 2023 - 02:44 AM.

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1996 Toyota T100
2018 ATC Ocelot

#174 Ruffinit

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Posted 22 March 2023 - 02:52 AM

Can I (Should I) leave the AOPEC and add a Victron DC-DC charger to limit the current?

-- No.  Most folks replace the ACR with the DC-DC.  I say most, because I have both.  I'll add a comment to my power thread to explain.

Yes, I thought that might be the case from your summary. You have both?


Edited by Ruffinit, 22 March 2023 - 02:52 AM.

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1996 Toyota T100
2018 ATC Ocelot

#175 Ruffinit

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Posted 22 March 2023 - 02:56 AM

My limited understanding is the AOPEC will allow 140 A (and the Blue Sea allows 500 A) >> 30 A

-- Allow?  Not really.  That is their rating.  Beyond that smoke/sparks start flying.   :D 

 

I didn’t mean allow in a good way! Just not prohibit!


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1996 Toyota T100
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#176 ArcherJim

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Posted 31 May 2023 - 09:20 PM

Vic, I've thoroughly enjoyed your threads and responses on all things electrical -- many thanks for your sage, practical advice.  Building out my ATC Puma shell system, I'm stumped with a DC grounding question, and would greatly appreciate your view, please.  
 
This camper will have DC-DC and solar charging, along with a small 500W inverter.  It will also be unloaded at camp on some trips.  Positive and negative buses with fused 4 AWG wires will connect the truck battery, DC-DC/MPPT charger, inverter and camper battery, as shown in the attached diagram.
 
I'm trying to determine how to best migrate from the factory wiring path between camper battery (front passenger corner) and DC fuse panel (driver wall mid-way).  That factory path is:
 
- 10 AWG positive wire behind the wall (18 ft run) with 30A in-line fuse
- 10 AWG negative wire through front wall at passenger corner (2 ft), then screwed to camper frame as a ground connection.  Same arrangement on driver wall from camper frame to DC fuse panel.
 
Since the wire runs from the fuse panel to load devices can be up to 20 ft, the total run from camper battery to load devices could be as long as 38 ft.  I’m considering replacing the factory path above with my own explicit 8 AWG positive and negative wires from respective buses to the fuse panel, to reduce total voltage drop and simplify troubleshooting down the road.  These explicit wires would be within a protective loom, not behind the wall.  I’d then disable the factory 10 AWG positive wire behind the wall.
 
Here’s the nagging question:  Is there any benefit (or harm) with keeping one of the 2-ft 10 AWG negative ground wires (from the negative bus to the camper frame) as a ground connection?  If the camper is unloaded at camp, I would no longer have a ground connection to the truck frame via the DC-DC charging wires.  If there is a benefit, would 10 AWG be sufficient, since larger gauge wires are used for other parts of the system?  Total simultaneous DC loads shouldn’t exceed 15A, which the factory path ampacity would have handled easily.  If a larger gauge wire is needed, I’ll need to open up the front wall to access the frame.
 
Appreciate your thoughts when you get a chance, please.
 
Thanks,
Jim
 

 

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2022 Ford F-150 HDPP with 2022 ATC Puma Shell

 


#177 ntsqd

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Posted 01 June 2023 - 12:29 AM

I'm not Vic, but I'll take a stab at this.

 

The main purpose of the larger gauge wire/cable between the truck and the camper is to reduce the voltage drop as much as is reasonable. A DC-DC converter largely, but not totally, negates this need. I feel that 4 ga. is excessive for 30A. I used 6 ga. without a converter for an estimated 80A peak and I'm well under 3% at normal charging amps. With a 30A converter I would expect that 8 ga. would work well and 6 ga. would be appropriate overkill.

 

Consider using a breaker at the truck batteries too. One that allows a manual disconnect like 285 Series from Eaton but sold by most everyone. While the Anderson connector will make/break under load I never do that and the breaker under the hood is the easiest for me to get to in order to open the circuit. It is also nice to be able to turn off the circuit between the breaker and the Anderson Connector to work on that section of cable.

 

I would operate under the assumption that ATC sized the ground wires appropriately until proven otherwise. That said, I'm not a fan of multiple ground or hot wires connected to the battery. When I rewired our first camper I considered the fuse panel & ground buss to be the consumer of the power supplied to it and sized the main hot and ground wires appropriately for their length and the max possible draw that the fuses would allow - offset with a small dose of reality i.e. not everything is likely to be all running at the same time. It was a short bed camper with the panel at one end and the battery at the other, but as I recall 10 ga. was the largest wire size that I used inside the camper.

 

I would leave the ATC installed ground cable between the ground buss and the frame in place. Unless you plan to turn the frame into the only ground buss I would only make one connection to it. Sometimes having a ground loop, that is a circular path within the ground system, doesn't matter, other times it will drive you knucking futz. Just what comprises a "ground loop" can get contentious. I define them as multiple paths to ground from any consumer of power. Better to just avoid them.


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#178 craig333

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Posted 01 June 2023 - 02:24 AM

I left the entire FWC 10ga wiring in place when I ran my 6ga wires. Has caused 0 issues for me.


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Craig K6JGV_________________________ 2004 2500 CTD 4X4 FWC HAWK 1960 CJ5


#179 Vic Harder

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Posted 01 June 2023 - 09:51 PM

+1 to Thom's suggestion of a breaker at each end of the run between truck and camper.  Handy, as well as safer to fuse that fat wire on both ends.

 

Thanks for reading my posts! 

 

I'm not sure which brand mppt you are using, but Victron gear can only accept up to 6AWG, so I run that from my bus bars to the Victron gear.  

 

6AWG minimum seems to work best for the camper to DCDC run, at least in my experience and KP has mentioned the same.

 

Ground loops suck, so keep grounding points to a minimum.  Worst case scenario is if your primary ground is disconnected somehow and everything has to go to ground through some small left over ground wire hidden in the walls.  That wire might be undersized and melt! So, knowing where those grounds are is important.

 

Think of your camper as an independent unit from the truck, meaning GROUND in the camper is just that... camper ground.  When plugged into the anderson connector, there is an intentional (and thick) wire running to the truck so that you now share a ground.  It is not really ground (since you are running on rubber tires!).

 

Thanks again for the kind words!


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#180 ArcherJim

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Posted 03 June 2023 - 04:58 PM

Appreciate everyone’s responses – that’s what makes the WTW forums so great.  Camper frame grounding has always been a puzzle to me, and I suspect to a few other folks as well.  A few follow-ups to clarify:
 
- Thom, the additional breaker at the truck end of the DC-DC charging circuit makes good sense, thank you.  It will also allow the truck bed connection to be de-energized when the camper is unloaded, a good thing.
 
- Vic, my DC-DC/MPPT charger is the Renogy model RBC30D1S, with M8 (5/16”) terminal posts, so I can crimp matching rings to any gauge wire.  Seems like nice flexibility.
 
- Agree that 6 AWG wire would be sufficient for the 30A DC-DC run to the truck battery, and may offer easier connector type options at the truck bed wall.  I’ll also need to figure out how to best run a 16 AWG positive ignition sensing wire through the same (or additional) connector and forward to an ignition fuse tap.  I’ll check that out, but all suggestions are welcome.
 
- Craig, your comment “left the entire FWC 10ga wiring in place” made we wonder if you had both the 10ga and 6ga wire pairs energized to the fuse panel.  Am I understanding correctly?
 
- I did a quick test to verify that no factory 12V load device depends on the frame for a ground connection.  Disconnected the factory wires from the fuse panel, and temporarily replaced them with [fused positive] and negative wires from their respective buses.  All load devices operated properly (LP/CO monitor, inside lights, exterior patio lights, roof vent fans, furnace).
 
- Vic, the camper grounding question appears to be relevant only if the camper is unloaded from the truck, correct?  That is, when unplugged from the Anderson connector that is already grounded to the truck frame?  For the unloaded case, it seems like my options are:  
 
1. No changes, use the existing factory 10 AWG wires and frame ground.  Deal with larger voltage drop than desired to more sensitive device demands such as furnace, fridge and tablet/phone chargers.
 
2. Keep the existing 10 AWG frame ground wire, but only from the negative bus (disable the frame ground wire to the fuse panel).  Run explicit 8 AWG positive and negative wires to the fuse panel.
 
3. Option 2, but replace the 10 AWG frame ground wire with larger (__ AWG) wire.  Requires opening up the front wall to access the frame.
 
4. Disable the existing frame ground wire.  Deal with loss of ground connection when unloaded from truck in some other manner.
 
All thoughts welcome!
 

 


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2022 Ford F-150 HDPP with 2022 ATC Puma Shell

 





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