how much voltage drop with inverter - Escape Trailer Owners Community

Go Back   Escape Trailer Owners Community > Escape Tech > Problem Solving | Owners helping each other
Click Here to Login
Reply
 
Thread Tools Display Modes
 
Old 03-23-2018, 09:36 PM   #1
Senior Member
 
Join Date: Dec 2014
Location: Milam, Texas
Trailer: 2016 ESCAPE 21
Posts: 132
how much voltage drop with inverter

I am trying to determine if I have a battery problem or a inverter problem. So, I am curious what voltage drop others experience when running the microwave from the inverter. I have new batteries and if I turn the microwave on for say 1 minute, the battery voltage drops to about 11.2 volts within 15-20 seconds and then holds there. That seems far too low to me for new batteries. What are others experiencing?
__________________

thumper-tx is offline   Reply With Quote
Old 03-23-2018, 10:17 PM   #2
Senior Member
 
Join Date: Sep 2013
Location: SLO County CA, California
Trailer: 2014 21
Posts: 3,479
What is the reading after the microwave stops? I thought I was damaging our dual 6V batteries just by making a 4 cup pot of coffee. It would go from around 13.5 down to 11.9, but then after turning off coffee pot it would jump back up.
__________________

__________________
"We gotta get as far away as we can!"
- Russell Casse, Independence Day
Rossue is offline   Reply With Quote
Old 03-23-2018, 10:25 PM   #3
Senior Member
 
Join Date: Jan 2014
Location: North Van., British Columbia
Trailer: 2014 Escape 19, sold; 2019 Escape 21, Sept. 2019
Posts: 5,178
That seems pretty normal. As long as the battery recovers then everything's OK.

On mine, given something like a 3 minute burst, the battery recovers back to the original reading. A couple of minutes more use and it might be .1 volt down.

Ron
Ron in BC is offline   Reply With Quote
Old 03-24-2018, 02:10 AM   #4
Senior Member
 
John in Santa Cruz's Avatar
 
Join Date: Dec 2017
Location: Mid Left Coast, California
Trailer: 2014 Escape 21
Posts: 1,755
a typical microwave is 600 or 700 watts when its actually nuking. lower power settings typically turn them on/off/on/off with varying duty cycles. 600 watts is 50 amps at 12V, thats a LOT of current, so yes, it draws the battery voltage down considerably.

question, is the inverter directly attached to the battery via short heavy gauge wires? are you measuring the voltage at the battery, or somewhere else in the DC system ?
John in Santa Cruz is offline   Reply With Quote
Old 03-24-2018, 08:03 AM   #5
Senior Member
 
Join Date: Dec 2014
Location: Milam, Texas
Trailer: 2016 ESCAPE 21
Posts: 132
Quote:
Originally Posted by John in Santa Cruz View Post
a typical microwave is 600 or 700 watts when its actually nuking. lower power settings typically turn them on/off/on/off with varying duty cycles. 600 watts is 50 amps at 12V, thats a LOT of current, so yes, it draws the battery voltage down considerably.

question, is the inverter directly attached to the battery via short heavy gauge wires? are you measuring the voltage at the battery, or somewhere else in the DC system ?
The wiring is standard Escape inverter wiring. I checked the voltage at the 12v outlet and at the battery with a meter, they both read the same. The engineer at Samlex says that is too much voltage drop and I tend to agree. At around 10.6-10.7v, the inverter will sht down and give a low voltage imput error code.
thumper-tx is offline   Reply With Quote
Old 03-24-2018, 08:05 AM   #6
Senior Member
 
Join Date: Dec 2014
Location: Milam, Texas
Trailer: 2016 ESCAPE 21
Posts: 132
Quote:
Originally Posted by Rossue View Post
What is the reading after the microwave stops? I thought I was damaging our dual 6V batteries just by making a 4 cup pot of coffee. It would go from around 13.5 down to 11.9, but then after turning off coffee pot it would jump back up.
The voltage returns to near normal within about 1 minute.
thumper-tx is offline   Reply With Quote
Old 03-24-2018, 08:10 AM   #7
Senior Member
 
Join Date: Dec 2014
Location: Milam, Texas
Trailer: 2016 ESCAPE 21
Posts: 132
What I failed to mention is that when voltage reaches 11.2, the inverter starts giving off a continuous shrill beeeeeep. On the old batteries, when the voltage reached 10.8, the beep would then become a rapid series of beeps just before the inverter shut down from low voltage imput.
thumper-tx is offline   Reply With Quote
Old 03-24-2018, 10:23 AM   #8
Senior Member
 
phalaney's Avatar
 
Join Date: Jul 2016
Location: St Louis, Missouri
Trailer: 2017 5.0TA
Posts: 249
Quote:
Originally Posted by thumper-tx View Post
What I failed to mention is that when voltage reaches 11.2, the inverter starts giving off a continuous shrill beeeeeep. On the old batteries, when the voltage reached 10.8, the beep would then become a rapid series of beeps just before the inverter shut down from low voltage imput.
What was your no load voltage? I reviewed your posts and missed any mention of it. Based on what I remember as the volt drop on our new 6*2 volt battery pack, when loaded with the ~276 watts required by our 3 way fridge (a short experiment), I think the ~1.6 volt drop referenced earlier from the coffee pot (probably kind of close to your load) in the thread is from a healthy system. I.e., you probably can't expect less without more battery power.
__________________
Peg and Bob
phalaney is offline   Reply With Quote
Old 03-24-2018, 01:48 PM   #9
Senior Member
 
tdf-texas's Avatar
 
Join Date: Nov 2015
Location: Baytown, Texas
Trailer: 2017 21' Escape - since 1/9/2017
Posts: 1,558
Quote:
Originally Posted by thumper-tx View Post
What are others experiencing?
I ran my 950w microwave full power (1200w to the inverter) and the voltage dropped to 11.7 volts at the inverter. The voltage prior to the test was 13.3 volts. The inverter didn't beep or seem unhappy and the battery voltage recovered shortly after I turned off the microwave.
__________________
If It Isnít Perfect, It Isnít Finished
tdf-texas is offline   Reply With Quote
Old 03-24-2018, 01:55 PM   #10
Senior Member
 
Vermilye's Avatar
 
Join Date: Feb 2010
Location: Oswego, New York
Trailer: 2017 Escape 21, 2018 Ford F150
Posts: 3,578
Quote:
Originally Posted by John in Santa Cruz View Post
a typical microwave is 600 or 700 watts when its actually nuking. lower power settings typically turn them on/off/on/off with varying duty cycles. 600 watts is 50 amps at 12V, thats a LOT of current, so yes, it draws the battery voltage down considerably.

question, is the inverter directly attached to the battery via short heavy gauge wires? are you measuring the voltage at the battery, or somewhere else in the DC system ?
The actual wattage of most microwaves is higher than the labeled wattage, i.e. my 700 watt RCA microwave supplied by Escape actually draws 95 amps at full power (1140 watts at 12V).

As John said, this will definitely pull your batteries down due to their internal resistance. Too long or too small wiring will cause voltage drop, which will show at the input terminals of the inverter, but not at the batteries. If the voltage drop is caused by the internal resistance of the batteries, (i.e. the same voltage measurement at both the batteries & the inverter) larger wiring will not help. One expensive & heavy solution is to add another pair of 6V batteries, or switch to a pair of paralleled 12V batteries (with the same total amp hours), which will decrease the internal battery resistance losses.

I have the 2 6V batteries & the RCA 700 watt microwave, and the Escape installed wiring, and have not had the inverter alarm, although I generally have fully charged batteries - 320 watts of solar.
__________________
Jon Vermilye My Travel Blog
Travel and Photo Web Page ... My Collection of RV Blogs 2018 F150 3.5EB, 2017 21
Vermilye is offline   Reply With Quote
Old 03-24-2018, 03:07 PM   #11
Senior Member
 
Join Date: Jan 2014
Location: North Van., British Columbia
Trailer: 2014 Escape 19, sold; 2019 Escape 21, Sept. 2019
Posts: 5,178
Quote:
Originally Posted by Vermilye View Post
or switch to a pair of paralleled 12V batteries (with the same total amp hours), which will decrease the internal battery resistance losses.

have not had the inverter alarm,
Yes, works for me although I seem to be the only one with a paralleled 12V set-up. Both for microwaving, 1 or the other for normal house use. I think that my total amp hours work out to be a little less than two 6's but I've never had an inverter alarm.

My own self imposed guideline is no microwaving if the batteries aren't pretty close to fully charged.

Ron
Ron in BC is offline   Reply With Quote
Old 03-24-2018, 05:04 PM   #12
Senior Member
 
John in Santa Cruz's Avatar
 
Join Date: Dec 2017
Location: Mid Left Coast, California
Trailer: 2014 Escape 21
Posts: 1,755
note to you guys reading 13.x V before running the load, thats charger float voltage. batteries will stay at that upper voltage for awhile after being taken off a charger (either solar or the AC converter), but generally an hour or so later, you'd see the 'real' voltage of a fully charged battery, which is 12.6-12.7V typical. 12.1V at rest is 50% discharged, and is my normal lower threshold for wanting to recharge the batts ASAP... under any sort of heavy current load, you'll always read less, but a few minutes after switching off the load, it should return to the rest voltage.
John in Santa Cruz is offline   Reply With Quote
Old 03-24-2018, 07:40 PM   #13
Senior Member
 
Join Date: Dec 2014
Location: Milam, Texas
Trailer: 2016 ESCAPE 21
Posts: 132
As a footnote as I didn't mention it, I was going into these test with the new batteries at 12.6V.

I found an additional issue after one of the load test when I noticed the cable joining the two 6V batteries together was rather warm! but none of the other cables were. The nuts on the cable were very tight but one of the crimps had very slight movement when I pulled on it. After correcting it. the cable no longer got warm under load and with a full three minute microwave run, voltage only dropped to 11.6 . I believe the lose crimp was costing me some amps and thus causing my other problems.

Dang, why are the simple solutions so hard to find.
thumper-tx is offline   Reply With Quote
Old 03-24-2018, 09:26 PM   #14
Senior Member
 
Join Date: Oct 2017
Location: Smithers, BC, British Columbia
Trailer: Escape 21, July 2018 delivery
Posts: 239
Quote:
Originally Posted by Vermilye View Post
One expensive & heavy solution is to add another pair of 6V batteries, or switch to a pair of paralleled 12V batteries (with the same total amp hours), which will decrease the internal battery resistance losses.
or get a pair of 6 volt AGM's. Also expensive, but lower internal resistance, which also speeds up charging, all else being equal. Once our trailer is wired up with our AGM's later this summer, I will be able to report performance with our microwave, but it should be better than with flooded batteries.
AllanEdie is offline   Reply With Quote
Old 03-25-2018, 03:34 AM   #15
Senior Member
 
Join Date: Dec 2012
Location: Edmonton, Alberta
Trailer: 1979 Boler B1700
Posts: 12,208
Quote:
Originally Posted by Vermilye View Post
The actual wattage of most microwaves is higher than the labeled wattage, i.e. my 700 watt RCA microwave supplied by Escape actually draws 95 amps at full power (1140 watts at 12V).
Yes, the wattage used in the description of a microwave oven is the power output (of microwave energy into the food), so the input electrical power to the appliance is always significantly higher. In addition to imperfect efficiency of the microwave generator, there is a fan and light and controls to operate. The input electrical power is listed on the usual appliance information label, which may be on the back panel but is often in front, visible when the door is opened. In the traditional type which cycles on and off, the power draw when on is always that listed maximum.
Brian B-P is offline   Reply With Quote
Old 03-25-2018, 03:39 AM   #16
Senior Member
 
Join Date: Dec 2012
Location: Edmonton, Alberta
Trailer: 1979 Boler B1700
Posts: 12,208
Quote:
Originally Posted by thumper-tx View Post
I found an additional issue after one of the load test when I noticed the cable joining the two 6V batteries together was rather warm! but none of the other cables were. The nuts on the cable were very tight but one of the crimps had very slight movement when I pulled on it. After correcting it. the cable no longer got warm under load and with a full three minute microwave run, voltage only dropped to 11.6 .
Good troubleshooting.

Quote:
Originally Posted by thumper-tx View Post
I believe the lose crimp was costing me some amps and thus causing my other problems.
It was adding resistance, which would reduce current through a fixed-resistance load, but wouldn't reduce the current taken by the inverter. It would certainly reduce the voltage across the battery bank for any given voltage... which would actually slightly increase the current the inverter would need to take to meet a particular output power requirement.
__________________

Brian B-P is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off






» Featured Campgrounds

Reviews provided by

Disclaimer:

This website is not affiliated with or endorsed by Escape Trailer Industries or any of its affiliates. This is an independent, unofficial site.


All times are GMT -5. The time now is 05:06 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Copyright 2012 Social Knowledge, LLC All Rights Reserved.
×