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Coach batteries voltage low… HUMPH!!!

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For the last couple weeks  i have sleeping out in my coach ,The 1st week i took myself out to a local camp site and was plugged into a 30 amp box. Because of the cold weather i found to save the propane heater from running so much, i use a electric heater, which keeps the whole rig comfie an warm with a temperature of 68 to 70 degrees, its quiet and according to the EMS read out and my surge protector it uses 13 amps. So now the project is compleated, i go to a different location and there im pluged into a 15 amp service. I found that the electric heater still worked fine, last night as i went into the rv to go to bed i discovered i had left the electric heater on. That is not normally my plan due to safety as well as costly, so be it note to self to be more aware, so as im getting ready for bed i hear my propane heater cycle on as its done before, however it sounds “different” like the motor is slow. I open my cabnit to view the EMS and the battery voltage i see the battery statis at 11.5 volts??? Thinking the worst that i may have a issue with my inverter / charger i look at the amperage usage and its showing 14 amps, i figure im close to my limits so i figured turn off the electric heater an see what happens. Now the EMS read out changes from 14 to 7 amps and almost instantly my battery voltage starts climbing, at that moment i realised a couple things, one is dont leave the electric heater on when not there to watch it, (Duh) the other is when the inverter / charger is battling for line voltage it deferes to taking a smaller amount rather than overloading the incoming circuit total, something i had no idea it was capable of doing. So having left the electric heater off all night now the EMS readout is at 5 amps which is still 3 amps higher than where it normally runs, battery voltage is at 13.8 and as soon as the batteries finish there soak charge im hoping to see the Ampreage return to its normal 2 to 3 amp draw, i kinda figure that lesson was a early Christmas present.

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http:// https://www.youtube.com/watch?v=8_H6fv0Jb7Y


Looks like you are "reverse engineering" the system. That is, you are finding out how it works versus having a manual and moving forward.

It appears you have an EMS system. A management system that does exactly as you are suggesting. Or pretty close for discussion.

On 30 amps or less shoreline the management can get very sophisticated. I rarely run the water heater on electric if on 30 amp or less. IF you can program your charger output to 10-20 percent after the batteries are fully charged that will help keep your loads down.

Changing to LED bulbs throughout will save a tremendous amount of DC current. They can draw a couple of amps each. I think I have at least 25 of them in my rv. Do the math.

Be sure your electric heater is NOT plugged into an outlet that is fed by the Inverter/Charger. 



Edited by myrontruex
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Yes….one learns.  BUT…what you did not state was what brand of inverter as well as the “set up” parameters.  Now….for the MAGNUM, you should have gone to the SHORE button and reduced the amperage from 30, which is the rating of the circuit breaker feeding the inverter, to FIFTEEN….ot 15.  That is the max amps you have available.  That is a “MUST DO”.  If you have a XANTREX/TRACE….read the manual.  

in addition, since you are wanting full amperage to run the space heater, you really should have gone into the SETUP button and reduced the charging rate to maybe 10%….otherwise you are overloading.  The space heater will work on low voltage.  What you don’t know is the INTERNAL LINE VOLTAGE.  ODDS ARE…it was low. Your surge protector is measuring the receptacle voltage….it should go down under load, but will be lower at the point of use.

Folks that understand the above NEVER run a space heater on less than 30 amps.  Most will run a HD (15 AMP RATED) cord from a second receptacle on the pedestal or from an adjacent one.  You risk having your inverter go into a low AC fault (not good) as well as damaging things like a TV.  Never run the space heater and microwave on 15 amps…..bad and unsafe practice….

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1 hour ago, Rikadoo said:

turn off the electric heater an see what happens. Now the EMS read out changes from 14 to 7 amps and almost instantly my battery voltage starts climbing,

It sounds to me like you were running the electric heater on an inverter outlet.... and as far as I know... (correct me if I'm wrong...) I do not believe your inverter can not output AC power to the outlets and charge the batteries at the same time.... (unless on shore power (30 or higher amp)). 

OR... the inverter 'load sheds' battery charging when it has "limited" AC amperage input.....


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