Jump to content


Photo
- - - - -

Charging Choice


  • Please log in to reply
32 replies to this topic

#1 alano

alano

    Senior Member

  • Members
  • 239 posts
  • LocationSilicon Valley

Posted 02 September 2019 - 05:31 PM

We just returned from 2 weeks in the Pacific Northwest where it was cloudy, rained a bit and campsites are often under trees. 200W of solar did what it could, but we needed the truck to do its part to keep the batteries happy - it didn't. The original separator seems to have gone wonky since we only got about 1 amp to flow to the batteries when the truck is running. (I have a current meter on the wire from the truck attached to a display mounted on the front window of the camper to monitor charging) The 1 amp was extremely constant regardless of camper battery voltage. Go figure.

 

Solution seems to be to toss out the old and replace it with... what? After research, I've narrowed my choices to two:

 

1) Renogy 40A DC to DC Battery Charger

 

2) Blue Seas 7611 Battery Link ACR

 

Factors:

 

Cost difference not an issue

 

FWC wiring and connectors from my 2010 GMC 2500 to my 2013 Hawk

 

Already have a solar controller that does a decent job of managing my AGM batteries

 

Not keen to run wires from camper to truck

 

REALLY tired of dealing with electrical issues with my camper. Want a mostly forget about it solution.

 

Thoughts?

 

Thanks,

 

Alan

 

 

 


  • 0

#2 Vic Harder

Vic Harder

    Get's a "charge" out of camping!

  • Members
  • 2,716 posts
  • LocationCalgary, Alberta

Posted 02 September 2019 - 06:05 PM

Alan, have you confirmed that the alternator can push more than 1A by bypassing your isolator and/or existing wiring?  Some jumper cables maybe directly to the camper batteries?

 

The choices you list are both reasonable.  Here are some factors to consider:

 

1) The camper batteries need about .5v more than their present voltage in order to charge.  So if they are at 12.2V, they need 12.7 to charge.

2) The higher the current flow, the greater the voltage drop across the wires from the alternator to the house batteries.

3) Typical RV 4 conductor cable is 14AWG.   Maximum free air chassis wiring for that is 32A, which maybe why FWC installs 30A breakers.  See this: https://www.powerstr...m/Wire_Size.htm

4) Wire run length is about 25'  to 30' from your alternator to the camper 

5) Assuming you get 30A from your alternator, the voltage drop is a horrendous 4.56V at 30A , leaving you with just 8V at the batteries.  The isolator knows this won't charge the batteries, and disconnects  ... https://www.calculat...es=30&x=35&y=19  

6) This is why the stock wiring sucks!

 

You can put the Renogy at camper battery end, but you are not going to get 40A of charge out of it unless you upgrade the wiring.  The losses are too big.

 

Nor is a different isolator going to help compensate for the losses just by itself.

 

To get efficient and safe charging from the alternator, you are going to have to upgrade the wires.

 

BUT, I hear people say, I DO get a charge from my alternator.  Sure you can.  The alternator may be pushing out way more voltage than 12.7.  The current flow may be way lower too.  Both together allows some charging to happen.  But certainly not 30A worth, or the promised 40A from the Renogy.


  • 0

2006 Silverado 3500 ext cab 8' bed LBZ

2012 ATC Puma Shell build - https://www.wanderth...012-puma-build/

Power considerations thread - https://www.wanderth...e-power-scotty/

 


#3 alano

alano

    Senior Member

  • Members
  • 239 posts
  • LocationSilicon Valley

Posted 02 September 2019 - 10:42 PM

Vic,

 

Thanks for your answer. I used to see 5ish amps max from the setup before. Thinking about this I realized that you are totally right about upgrading the wiring regardless of the ACR vs DC2DC debate.

 

I went out and poked around the truck and camper, did a bit more online research and have a new choice:

 

1) Replace the existing power wires with heavier (4 AWG welding cable?) wire using the existing connector between the camper and the truck with its 10 AWG pigtails.

 

OR

 

2) Add a new power plug on the right side of the camper and truck bed (or move the old one - what to do with the hole?) since both the truck battery and the camper batteries are on that side.

 

Shorter wire run with new plug - probably less than half.

 

Can use a beefier plug.

 

My Hawk has the running lights so either have to figure that out or just deal with two connectors each time camper loaded / unloaded (about once a year). Big deal.

 

Anyone know any reason why moving to the passenger side wouldn't be a good idea?

 

Thanks,

 

Alan


  • 0

#4 ClimberRob

ClimberRob

    Advanced Member

  • Members
  • PipPipPip
  • 74 posts
  • LocationTahoe

Posted 03 September 2019 - 12:57 AM

Good breakdown from Vic.

 

I ran 4 AWG pure copper welding wire, myself. Terminated at an Anderson-style connector driver side front inside the truck bed. Then replaced the stock 4WC wiring inside the camper with the same wire, leading into two Blue Sea 187-series 100A breakers/switches. At that point, 6 AWG Ancor marine + wire leads into a 30A Sterling programmable smart charger. Negative wire goes straight to a Blue Sea Power Post, which also connects to the camper battery and the main common negative bus. + wire out of Sterling charger goes to another power post, which also connects the shore power charger, solar, house, etc..

 

I highly recommend upgrading the truck to camper wire, and also highly recommend the Sterling unit. Expensive, but solid. 


  • 0

#5 Vic Harder

Vic Harder

    Get's a "charge" out of camping!

  • Members
  • 2,716 posts
  • LocationCalgary, Alberta

Posted 03 September 2019 - 04:57 AM

Alan,  retaining the 4 or 7 wire trailer plug for the running lights is a good idea.  As ClimberRob points out, Anderson PowerPole connectors and 4g wire are great for carrying the heavy current for charging.

 

I'd try that first, with 100A BlueSea 185 series surface mount breakers on the alternator and camper battery end of the +ve cable first, before adding in a Sterling or Renogy DC2DC converter.

 

Moving the cable to one side or another is no big deal.  Keeping the wires as short as possible is good.  

 

Plug the old hole with Butyl putty or silicone.


  • 0

2006 Silverado 3500 ext cab 8' bed LBZ

2012 ATC Puma Shell build - https://www.wanderth...012-puma-build/

Power considerations thread - https://www.wanderth...e-power-scotty/

 


#6 alano

alano

    Senior Member

  • Members
  • 239 posts
  • LocationSilicon Valley

Posted 03 September 2019 - 08:33 PM

Thanks guys. I'm drawing up a schematic and making a shopping list. After inspection, it isn't really that big a deal to run new wire through the truck and coming in through the passenger side of the camper makes that quite simple. The biggest hassle will be probably be removing and replacing the camper to mount the connector inside the bed. Probably can do the whole job in one day.

 

Alan


  • 0

#7 smlobx

smlobx

    Lost again

  • Members
  • 1,183 posts
  • LocationSmith Mt. Lake, VA and OBX, NC

Posted 03 September 2019 - 10:24 PM

Vic et. al-

I think I’m having an issue as well and not trying to hijack this thread let me ask this very basic question...

Are you suggesting running a 4 AWG wire from the alternator to the bed where my camper (7 wire)plug is located?
Is there any fuses in this?

When I looked at the wire that was run for my truck to plug in I discovered it was pigtailed off the back of the bed then up to the front of the bed where the plug is. The total distance must be over 30 feet!

Thank you.
  • 0

Eddie
KO4CPL

 

Travel light. Travel far. Travel safe.


#8 Vic Harder

Vic Harder

    Get's a "charge" out of camping!

  • Members
  • 2,716 posts
  • LocationCalgary, Alberta

Posted 04 September 2019 - 01:04 AM

Vic et. al-

I think I’m having an issue as well and not trying to hijack this thread let me ask this very basic question...

Are you suggesting running a 4 AWG wire from the alternator to the bed where my camper (7 wire)plug is located?
Is there any fuses in this?

When I looked at the wire that was run for my truck to plug in I discovered it was pigtailed off the back of the bed then up to the front of the bed where the plug is. The total distance must be over 30 feet!

Thank you.

 

I ran 2g wires (yes, two of them, one for the +ve side and one for the -ve) from the truck battery (mounted driver's front of underhood area).  

 

The +ve wire goes about 6" to a 100A Blue Sea 185 series surface mount breaker.  Then continues on (with the -ve cable) under the truck cab all the way to the bed of the truck.  It comes up into the bed via two 1/2" holes with bushings in them to prevent chafing/shorts.  It comes into the bed about 18" and terminates in an Anderson Power Pole connector.  A matching connector then takes the two cables into the camper via new holes in the wooden floor pack, sealed with Butyl rubber.  The wires go over to the battery box area, where the +ve cable again meets a 100A breaker.  The +ve then goes to a Blue Sea ML-ACR and from there to the rest of the charging electronics.


  • 0

2006 Silverado 3500 ext cab 8' bed LBZ

2012 ATC Puma Shell build - https://www.wanderth...012-puma-build/

Power considerations thread - https://www.wanderth...e-power-scotty/

 


#9 ClimberRob

ClimberRob

    Advanced Member

  • Members
  • PipPipPip
  • 74 posts
  • LocationTahoe

Posted 04 September 2019 - 01:53 AM

Alan,  retaining the 4 or 7 wire trailer plug for the running lights is a good idea.  As ClimberRob points out, Anderson PowerPole connectors and 4g wire are great for carrying the heavy current for charging.

 

I'd try that first, with 100A BlueSea 185 series surface mount breakers on the alternator and camper battery end of the +ve cable first, before adding in a Sterling or Renogy DC2DC converter.

 

Moving the cable to one side or another is no big deal.  Keeping the wires as short as possible is good.  

 

Plug the old hole with Butyl putty or silicone.

 

Vic, I think you are recommending the 285 series breakers? They are very good, as well. I like the 187 series because of the location of both studs on the bottom, as well as the fact that they are designed to be used as a switch, in addition to the breaker functionality.


  • 0

#10 ClimberRob

ClimberRob

    Advanced Member

  • Members
  • PipPipPip
  • 74 posts
  • LocationTahoe

Posted 04 September 2019 - 01:58 AM

Vic et. al-

I think I’m having an issue as well and not trying to hijack this thread let me ask this very basic question...

Are you suggesting running a 4 AWG wire from the alternator to the bed where my camper (7 wire)plug is located?
Is there any fuses in this?

When I looked at the wire that was run for my truck to plug in I discovered it was pigtailed off the back of the bed then up to the front of the bed where the plug is. The total distance must be over 30 feet!

Thank you.

 

As Vic suggests, run the cables off of the truck battery, or second truck battery if you have one. Don't run directly off of the alternator. Put a breaker or fuse on the + line, at least. Both wires is preferred. 

 

4 AWG is likely plenty, unless you are pushing a ton of amps. You probably wouldn't want to do that, unless you have several batteries in a bank in your camper. Under "normal" charging conditions of one or two batteries, 4 AWG won't cause you any issues.


  • 0




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users