Coach Electrical Upgrade

[Preese]

The ââ,¬Å"Winnie Louââ,¬Â is our first RV and bought her to use for New Yearââ,¬â,,¢s get togethers at a friend's family farmhouse plus maybe some light camping at state parks. This project involves one approach for powering the coach.  Objectives included simplifying as much as possible so no generator or propane powered appliances.   

Primary references were https://faroutride.com/electrical-system/ and https://marinehowto.com/automatic-charging-relays/ along with much perusing of CW&RV articles.

First off she did not come with dash A/C and A/C is essential for driving in the LA area (part of Florida known as Lower Alabama). The PO had changed out the 318 engine for a ââ,¬Ëœ74 Chrysler 400 with a crankshaft pulley that allowed for two belts to be connected to a new stock Powermaster 210 AMP single wire alternator.  Changed out headlights, dash and running lights to LED to lessen load. Left the original wiring from the alternator through the dash ammeter and added a 2/0 cable from the alternator to a new power bar in the battery compartment (basically a shunt setup).  The power bar is connected via 2/0 to a single 105Ah AGM coach battery and a Renogy 2000W converter/inverter.  The inverter is set to cut off if the battery gets below 50%.  Could of used #10 but had #6 so used that to run inverter AC power to the right bus (coach power side) of the original split-bus AC breaker panel.  A 20 amp breaker powers the 9200 btu (11.7 Amps) roof AC.  When driving the A/C unit is set to on, start the engine and then power on the A/C using the remote inverter on/off switch on the dash soon followed by a blissful to me ââ,¬Å"Itââ,¬â,,¢s too coldââ,¬Â coming from the lead navigator. The dash also has a Victron BMV-712 battery monitor display. 

The AGM starter battery connects to the starter relay and to the power bar via an Automatic Charge Relay (ACR).  Initially had connected the alternator to the starter battery and then to the power bar/coach battery via the ACR as per the instructions but that led to the ACR frequently disconnecting.  Finally found the ACR article link above and rerouting the wiring fixed the problem.  The DIY article above suggested a B2B setup but couldnââ,¬â,,¢t find a compelling reason to spend the extra $ for it.

For shore power, ran #6 into the AC panel left bus (shore power side) and a 30 Amp ââ,¬Å"mainââ,¬Â breaker connects to the converter/inverter and then back to the panel right bus. A 300 watt solar panel with a VictronConnect MPPT controller and disconnect switch also connects to the power bar.  DC coach power is connected to the power bar with #2 wires to a new DC fuse panel.

Wanted more room in the ââ,¬Å"trunkââ,¬Â and the old 25 gal water tank had to go somewhere.  So shortened the electronics bay to install a 22 gal tank below forward of the black water tank (not planning to be in freezing weather).  Inverter instructions stated that it could not be in the same place as lead acid batteries and maintenance are reasons for AGMs. Considered installing a thermostatic fan but there are lots of ventilation holes and heat has not been a problem...so far.  And yes replacing the starter battery in the back corner is going to be self imposed annoying.

Installed a Whale 6 gal electric water heater with an engine heat exchanger where the gas powered water heater was.  Itââ,¬â,,¢s connected to the AC panel shore power left bus with a 20 amp breaker so it canââ,¬â,,¢t be run by the inverter. While driving, the engine provides hot water through the heat exchanger.  And did change out the old air pressure water pump with a new Shurflo water pump and accumulator.

Did the inaugural trip and the 50 plus old Winnie Lou made it to the friend's country place about 100 miles away with only a couple stops to figure out what was rattling around this time.  Connected there to a 20 amp circuit.  Since the furnace didnââ,¬â,,¢t work and it was pretty cool, electric blankets and an oil filled space heater worked great.  Water heater was also on and no breakers flipped.  Did have a small water leak and the water pump went off by my head in the middle of the night and I almost shot it.

Since then the wall furnace has been yanked out with help from Mr. Sawzall to begin working on providing more bed access room.  Also the oven and 7.4 cu ft three way fridge are gone.  Plan to use plug in cookers and outdoor grilling. Hooked up a 4.5 cu ft AC only fridge which draws 0.8 amps (~96 watts) and the inverter uses 25 watts in power saver mode. Max solar power we get is ~240 watts.  Iââ,¬â,,¢ve left the shore power off and solar alone has generally been sufficient to charge the battery and run the fridge overnight with anywhere from 40% to 60% remaining. So even if ââ,¬Å"campingââ,¬Â in a hotel, in the morning there will be a cold mimosa in the RV for the wife, which makes navigation interesting. Cheers!

[ClydesdaleKevin]

That looks great!  I love nice and neat installations, especially when it comes to electrical components.  Feel free to share more pictures!


Kev

[Rickf1985]

Question, The AC unit draws 11.7 amps which is just about dead on 100 amp draw on the inverter direct math but with efficiency loss through the inverter it will be closer to 110 amp. The startup current will be closer to 14 amps so 24 amps added for that equals 134 amp draw at startup. Now, a 210 amp alternator will handle that, for a little while but I think you are going to find that it is going to overheat on you eventually. Those Powermaster alternators are famous for being over rated. Producing power generates heat which has to be shed somehow and that is the biggest problem with these high amp alternators. Enough about the alternator. What are you using for a ac/dc converter for shore power that is giving you 150 amps DC power to the coach? If you are pushing this across the batteries and using the batteries as the buffer they are not going to last long at all. I am only pointing all of this out because people have been looking for a way to do this for 30 years and none have been consistently successful yet. Forgive me but I am just a very curious person.

[Preese]

Did some testing to check power calculations.  The alternator is advertised to put out 150A at idle, 190A at cruise and actually 220A max.  These are measurements from the Battery Monitory System mounted on the house negative side.  Before start, house battery was at 60%, so 80% of total capacity at 12.75V.  The ACR was off so only measuring current from the house battery, not shared with the starter battery.  At idle (~850 rpm), saw 40.3A charge @ 14.02V.  Turned A/C on full cool and the peak discharge I saw was -44A and then promptly settled down to .3A to 1.4A charge, 13.06V still at idle.  Turned A/C off and charging went to 36.4A @ 13.07V.  Doesn't really show how much alternator is putting out other than can run the A/C at idle given everything else is off.

However the inverter display was showing 121V at 76% capacity.  So 2000W x .76/121V x .90 efficiency = 11.3Amps AC.  Also ran the A/C on battery only and saw peak discharge of -133A and then it went to -116.5A discharge @ 11.5V (11.1A AC).  Bottom line, figuring keeping the alternator load below 80% max capacity (210 x .8 = 168A) with the A/C on leaves roughly 50 Amps for inverter losses, fridge, running lights etc so should be good provided no prolonged idling.  The A/C documentation says starting amps could be as high as 29Amps AC but no indication of getting anything like that.

Second, there is no converter setup like the original.  It's actually an inverter charger.  Hard to see in the picture but the shore and AC out wires run under the inverter charger and connect in the front behind the cover.  DC connections are in the back.  One note is that the inverter has to be on to get shore power to the rig.

Not claiming success yet as have only tested on short rides, 20 mins or so.  Need to do a long trip but been busy with other stuff.

[Rickf1985]

All I have to say is be VERY careful because you are playing with fire, almost literally. That alternator will be red hot. I have dealt with these things on off road vehicles with winches and after a long winching session or a vehicle equipped with an onboard welder I have seen those alternators go up in flames. They simply cannot get enough cooling. All they are is standard CS or SI style alternators that have been rewired for the higher output but still have the fans designed for 75-100 amp output. In a Jeep or pickup truck you will see this right away since it is out in front of you but in an RV you usually find out when someone pulls up next to you screaming you are on fire!

[Preese]

Fire bad.  Called Powermaster and they said the alternator will be fine for what all I am running.  Sadly, I'll have to be on shore power to power up the 5,000 watt amplifier I use to play Barry Manilow albums.

[Rickf1985]

Of coarse they said it would be fine, but ask them to give you that in writing so you are covered in case it is NOT alright! I will bet my next pension check they will not. And your insurance will not cover it because it is a modification that is not certified. It's your unit and your choice. If you were only running the alternator at 50% I would say yea, go for it but you are pushing 75% plus.

[Oz]

Barry Manilow....
Damn, we're getting old...

[Mlw]

Her name was Lola... She was a showgirl  :)rotflmao

Yep, feeling the vibe baby, so yes, were getting old, and glad too. But I like "The time of my life" too!   O Wait....

I'm feeling so sorry for the 18 till 21 year old in this sick Covid world.

But how did this story ends, or is it so quit because Rick was right after all