Jump to content
Sign in to follow this  
FIVE

50 Amps Is Not Really 50 Amps

Recommended Posts

For nearly a month we have been out and about in our MH.  As all know, it’s been rather brisk to say the least.  We saw temps in the teens and traveled in the low 20s.  When “camped,” and I use that term loosely, in these temps, in an all electric coach, we needed all the “amps” available.  We all know that 50 amps really means two 50 amp lines. 

However, American Coach (don’t know about other manufacturers) wires their coaches so all electric appliances on Line 1 go through the inverter, all those on Line 2 do not.  As a result of that wiring, Line 1 can handle only 30 amps, even if the inverter is not on.  Any attempt to add more than 30 amps to Line 1 will result in the inverter circuit breaker tripping.  So, I don’t really have two 50 amp lines, in actuality, I have a 30 amp line and a 50 amp line.   

What can I do in the way of changing the system, either rewiring or added a circuit breaker, to give me back the 20 amps I’m losing to the manner in which the coach is wired?

Share this post


Link to post
Share on other sites

Gee, "All American Coaches"?  Mines not, and I'm all electric.  L1 & L2 goes into it's own inverter and I get 45A on each leg!

Share this post


Link to post
Share on other sites

Two possible solutions:

Install a sub-panel with only those things you want to be able to run off the inverter on the sub-panel (both hots and neutrals). Wire 120 VAC "out" side of inverter to the sub-panel. This assumes (properly I hope) that you never plan to exceed 30 amps from the inverter/sub-panel.

Then 30 amp breaker from main panel to the 120 VAC "in" side of the inverter.

L1 and L2 to main panel, and move anything you don't want to run off the inverter to a breaker on the main panel.

 

Other option used by some manufacturers (Foretravel for one):  Use a second 50 ATS with one "in" from main breaker box, the other from the inverter "out".  Be sure to wire shore power as primary.

Share this post


Link to post
Share on other sites

I agree with the thought of a sub panel. That gives you the most flexibility to decide what gets to draw from the inverter and what goes directly from each of the lines.

One question though...If your inverter suddenly gets a full load applied to it (starting an a/c, for example) does it momentarily draw more than 30 amps? If so, perhaps that's why it's on a line by itself?

Share this post


Link to post
Share on other sites

Carl, I'd love to get 45 amps out of L1 that goes through the inverter.  On this recent trip, we tripped the inverter circuit breaker twice on the same day until we got in the habit of monitoring the amps on L1 on the Power Control System Monitor before turning on anything else on that line....toaster, coffee pot, Lasko heater, etc.

Rich, the electrical system consists of:

-  8 each 6 volt AGM batteries.

-  One pure sine wave inverter/charger (2,800 watts)....the normal AC set up is like Carl's...two separate sets of 4 each 6 Volt AGMs each with a PSW inv/charger.

-  A Magnum Energy Remote Control, 2812.

-  Power Control System, Central Monitor Pane.

-  Solar power charge panel, 95 watts.

Share this post


Link to post
Share on other sites

Like Brett's description, except just a little different, I used a 50 amp breaker box, from which, both air conditioners are each on 15 amp breakers, electric water heater on a 15 amp, then a 30 amp breaker for most other items in the coach. The second breaker box is 30 amp with more breakers inside to feed everything else in the coach. The 30 amp breaker in the main box is wired to a 30 amp ATS as primary power to the second breaker box, the inverter feeds the side marked generator. If shorepower fails or generator is not running, the inverter now kicks in and powers the 30 amp box.

Share this post


Link to post
Share on other sites

The MS2812 is a 23 amp continuous current box - it can provide 3900 watts  (~30 amps) momentary.  Toaster, Heater, Coffee pot could present an overload condition in any event. You may need to find a non-inverted outlet to run the Lasko heater which by itself it is close to half available (12 amps) on your inverter.  Such is RV life.

I'm a little confused when you say you have 2 inverters:  "...the normal AC set up is like Carl's...two separate sets of 4 each 6 Volt AGMs each with a PSW inv/charger" << Is this what you have?  It likely is what you want and move half your inverted outlets to inverter #2.

Share this post


Link to post
Share on other sites

But, I don't see a "proper way" with Five's OE wiring.

Either one roof A/C going through the inverter (so one on L1 and the other on L2) OR both A/C's are on L1.

Again, two recognized options are sub-panel for inverter powered items (my preference) OR second ATS.  The reason I lean toward the sub-panel is that I do not want a roof A/C to run off the inverter if shore or generator power were to go out with the A/C running.

Share this post


Link to post
Share on other sites
6 hours ago, wajames said:

The MS2812 is a 23 amp continuous current box - it can provide 3900 watts  (~30 amps) momentary.  Toaster, Heater, Coffee pot could present an overload condition in any event. You may need to find a non-inverted outlet to run the Lasko heater which by itself it is close to half available (12 amps) on your inverter.  Such is RV life.

I'm a little confused when you say you have 2 inverters:  "...the normal AC set up is like Carl's...two separate sets of 4 each 6 Volt AGMs each with a PSW inv/charger" << Is this what you have?  It likely is what you want and move half your inverted outlets to inverter #2.

Sorry for the confusion....I don't have two inverters, I have 8 each 6 volt AGMs and one PSW inv/charger.  Most Amer Coaches, have two separate sets of 4 each 6 volt AGMs each with a PSW inv/charger.

Brett.....the ACs are wired with #1 on L1 and #2 and #3 on L2.

Share this post


Link to post
Share on other sites

What FIVE is saying.  I have 2 PSW 2800 inverters, 4 AGM 6V on each. 

Brett, I can not run AC off of inverter.  I do have the generator set to come on automatically in the event of Shore power loss or when batteries hit 11.8V  (it reads 2 together), when on inverter.  Mine is a Tradition, FIVE's is 4 years never than mine and it's a Eagle & why his is wired that far from mine, is above my pay scale! :wacko:

Share this post


Link to post
Share on other sites

Five,

I think your 30 amp limit is due to your invertor.  I have much the same with my rig.  I DO get more than 30 amps (and I suspect you do also) from both L1 and L2.  I have three outlet circuits in my coach each on its own breaker.  All three of these are supplied by either shore power, invertor or generator via a sub-panel.  ALL go through the inverter/charger which limits total draw for these three circuits to 30 amps.  Do these three circuits come from L1 or L2 - I do not know and don't care.  There are also other items items (hot water heater, frig, heat pump, etc.) that DO NOT go via the invertor and are not subject to the 30 amp limit.  If/when all of these other items are drawing power I am sure I am drawing much more than 30 amps on both L1 and L2.  Thus, I believe your statement "50 amps is not really 50 amps" is not true.  I would guess your rig is capable of much closer to 45 and 45 on each leg.

I do, however, feel your frustration.  I have the same problem if I try to run too much.  Not fun running outside to push a breaker button on the invertor when it is COLD outside and your trying to heat the coach AND brew a pot of coffee.  This winter I had the need to run two portable heaters and all was fine until 7:00am when the coffee pot turned itself on.  No more heat (or coffee).

I solved the problem by switching one of the three outlet circuits to a breaker in the main panel (versus the sub-panel).  I used the breaker for the washer/dryer which we never use at night so now I can run both heaters AND make coffee AND run the microwave at the same time.

Lenp

Share this post


Link to post
Share on other sites
lenp...

Read my first post.  There is no doubt the inverter on L1 is the limiting factor.  I know what AC outlet is on what line and what line each built in appliance is on.  I can watch my Power Control System, Central Monitor Panel, and see the amps on each line change when an AC appliance comes on or goes off by itself (AH electric element) or I turn on or shut off an appliance (coffee pot/toaster).  Line 1 trips the circuit breaker any time 30 amps are exceeded, I don't see how you think I can exceed 30 amps on that line...any suggestions would be appreciated.  Line two is good for 50 amps.  Many of the high draw electrical appliances are on L2, such as the AH heat, heat pump, one floor heater, air conditioners two and three, and engine pre heat. This is only a problem in the winter.

Share this post


Link to post
Share on other sites

Do as I used to do, run an extension cord out the window to run a heater.  A small towel in the sliding window will seal the gap.  Now... I just move to a warmer climate.

Share this post


Link to post
Share on other sites
17 hours ago, wajames said:

Do as I used to do, run an extension cord out the window to run a heater.  A small towel in the sliding window will seal the gap.  Now... I just move to a warmer climate.

That's a good idea, I run my Laskos like that when I can.  This year, even the "warmer climate" was cold!:(

Share this post


Link to post
Share on other sites

Five,

All I am saying is there is more then the invertor connected to L1.  I suspect at least one of your AC units (and maybe some other "appliance") also runs on L1 it is not going via the invertor.  

If/when your connected to 30 amp service, a whole new scenario presents when your EMS takes over and load shedding starts.  But that is not the subject here. 

If yours is like mine, all of your invertor supplied circuits are run via a sub panel. But the main panel has a few other circuits such as a washer/dryer or ??? that is ran direct from shore power or generator.  These would ADD to the 30 amps your invertor is drawing.  Yours may be different than mine (and probably is) but I still suspect your capable of more like 45 on each leg but limited on the invertor controlled circuits.

Lenp

 

Share this post


Link to post
Share on other sites
On 2/1/2018 at 8:57 PM, FIVE said:
lenp...

Read my first post.  There is no doubt the inverter on L1 is the limiting factor.  I know what AC outlet is on what line and what line each built in appliance is on.  I can watch my Power Control System, Central Monitor Panel, and see the amps on each line change when an AC appliance comes on or goes off by itself (AH electric element) or I turn on or shut off an appliance (coffee pot/toaster).  Line 1 trips the circuit breaker any time 30 amps are exceeded, I don't see how you think I can exceed 30 amps on that line...any suggestions would be appreciated.  Line two is good for 50 amps.  Many of the high draw electrical appliances are on L2, such as the AH heat, heat pump, one floor heater, air conditioners two and three, and engine pre heat. This is only a problem in the winter.

Do you have a wiring diagram for your coach? This might help you track down exactly how things are put together. If you don't have one, I'd call the manufacturer and see if you can get one. Even if it costs a few bucks, I'd consider an accurate wiring diagram a valuable tool for the tool box in general, and specifically for things like the problem you're having. You may be surprised what else is on L1 that you're not aware of.

I'm not certain from your description, but are you saying that L1 goes directly to your inverter? Or does it go to the load center (circuit breaker panel) and then feed the inverter through a breaker? If it feeds through a breaker, then you should be able to connect the dots to see what else is being fed from L1. If it's being fed directly from L1 (which I doubt) than you have your answer as well.

Also, have you done the math to calculate how many amps your inverter/charger is using on its own? Battery chargers can easily draw 12-20 amps, so perhaps the reason your is set up with everything on L1 limited to 30 amps and running through the inverter is to leave the rest of the capacity on L1 to power the inverter/charger itself?

Share this post


Link to post
Share on other sites

Then again, when your on Shore Power, turn your inverter on L1, off.  That should tell you what your getting and not getting to run on that leg.  Since we both have a non propane coach, I assume we have the same residential stuff in there.

Stackable washer & dryer, dishwasher, microwave/convection, 3 burner elect. stove, fridge, heated tile floors, separate elect. wall heather in bath room, heat pump and 3 AC's!  Am I missing something? 

Share this post


Link to post
Share on other sites
Richard...I do have a wiring diagram, I'll have to check it out.
 
Carl...pretty close, no dishwasher, 2 burner induction cooktop, we also have an Insta Hot Water dispenser (which stays unplugged when cutting it close on L1 amps)...and of course the AH electric element on L2 and the engine pre heat on L1.

Share this post


Link to post
Share on other sites
On 2/2/2018 at 1:03 PM, FIVE said:

That's a good idea, I run my Laskos like that when I can.  This year, even the "warmer climate" was cold!:(

 

85 deg F here in So Cal today.  Might get down to 53 tonight.  Just sayin'

Share this post


Link to post
Share on other sites

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now
Sign in to follow this  

×
×
  • Create New...