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Topic: Amp hours used vs volts in batteries after use (Read 586 times) previous topic - next topic

Amp hours used vs volts in batteries after use

I think this is good but with enough feedback from other users I can confirm my initial thoughts.

177 amp hours used overnight and my link 2000 showed the battery voltage at 12.35. 

Three fresh deka gel 8D's

Charger off on purpose but all 110 stuff off of a 50amp pedestal.

Any thoughts or comments?

Bob
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Amp hours used vs volts in batteries after use

Reply #1 –
With the inverter off and running 110 volt devices on shore power, sounds like a lot of DC usage to me.  You might want to turn various DC stuff on & off watching the amps and understand your usage.  Re amp-hours used and battery voltage:  plotting these numbers for various situations would be interesting.
Audrey & Harvey Nelson
2000 U-320, 40' towing 2014 Jeep Grand Cherokee
nelsonah@ieee.org

Re: Amp hours used vs volts in batteries after use

Reply #2 –
 This is a subject that someone like Wyatt should jump in on , but as Harvey said I agree that this is a lot of battery use.
I can run all night the fridge (residential on its own PSine inverter)and till bedtime the lights and pump etc and wake up before solar kicks in and use around 100 amph from the 3 8d AGMs. Some very low use of Micro on main inverter too.
Plus not be connected to shore.
John H
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: Amp hours used vs volts in batteries after use

Reply #3 –
My coach had pantom loads on the 12 volt crcuits of 6.5 amps when I first bought it so about 100 amphours was used overnight when solar power was not available (4pm - 9am).

I have reduced the phantom load to less then half an amp, so when I am not using the coach about 8 amphours is used overnight. When I am boondocking, 20 - 60 amphours is used overnight. I have 1200 watts of solar which will provide 40 amps for 6 hours, so about 240 amphours on a sunny day.

It is not possible to tell what  that 12.35 volt reading means without information about how many amps were being drawn for how long when the reading was taken. I assume that you used some of those 177 amphours after dark before going to bed. I would guess that your phantom load is 8 or more amps. This 177 amphours is a little high. If you decide to boondock, it would be better for you if you turned off some of that phantom load. For example, maybe there is a closet light or cargo bay light which has been left on.




Wyatt
96 U320 40 WTFE, build 4943
84 Toyota Supra towd
2015 Jeep Wrangler towd
Victoria, BC, Canada

Re: Amp hours used vs volts in batteries after use

Reply #4 –
Ok, so my 1200 watts on the roof has delivered 500 watts to the FT so far today here in sunny El Centro, CA (back from Cancun). For 12v systems that's 500/12= ~42amps

But now I'm not sure how to go the rest of the way to get from watts to amp-hrs. 10hrs at 4.2amps is tempting but I have no reason to do the calc that-a-way.

What is the correct answer?

best, paul
1999 U320 40' 1200 watts on roof. 12cf AC/DC Cold plate fridge/freezer. VMS 240 CL Honda Element

Re: Amp hours used vs volts in batteries after use

Reply #5 –
Amp-hours is that simple, amps times hours so long as the amps are constant.

So  a constant 4.2 Amps for 10 hours is 42 Amp-hours.

Tom Lang K6PG (originally  KC6UEC)
and Diane Lang
2003 38 U295 build 6209
2016 Jeep Grand Cherokee Summit Ecodiesel
still have tow-ready 2006 Acura MDX 
Temple City, California
Motorcade 16681 California Chapter President
SKP 16663 member of SKP Park of the Sierra, Coarsegold California
FMCA F071251
Retired electrical and electronic engineer

Re: Amp hours used vs volts in batteries after use

Reply #6 –
You guys are as good as I thought. I was using the 110 volt aqua hot heating element only overnight.  Temp went down to 49.  Front and rear zones set to low 70's.  Zone three bath heater set similarly.  Extended run times on the fans because of the btu shortage.  Front living room fans probably ran all night.  Bedroom was slightly chilly as my DW snuggled closer.  Turned on the diesel at 7am to add to the electric element and in 30 minutes the whole coach warmed up and adding the charger to bring the voltage up
Increased the fan speed noticeably.  Normal overnight was around 120 amp hours so the extended pump and fan run times added that much more draw it seems.

Will report the resting voltage at dark tonight. 
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Amp hours used vs volts in batteries after use

Reply #7 –
Quote from: Caflashbob –
You guys are as good as I thought. I was using the 110 volt aqua hot heating element only overnight.  Temp went down to 49.  Front and rear zones set to low 70's.  Zone three bath heater set similarly.  Extended run times on the fans because of the btu shortage.  Front living room fans probably ran all night.  Bedroom was slightly chilly as my DW snuggled closer.  Turned on the diesel at 7am to add to the electric element and in 30 minutes the whole coach warmed up and adding the charger to bring the voltage up
Increased the fan speed noticeably.  Normal overnight was around 120 amp hours so the extended pump and fan run times added that much more draw it seems.

Will report the resting voltage at dark tonight. 


Bob,

Please clarify.  Not sure I understand.  Are you dry camping or on shore power.  Running the electric heating element from an inverter while dry camping will run the battery bank down VERY quickly.  That is what diesel is for.

And if plugged into shore power, the 120 VAC electric element is just fine, and our inverter/charger should keep the batteries fully charged.


Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Amp hours used vs volts in batteries after use

Reply #8 –
Quote from: wolfe10 –
Bob,

Please clarify.  Not sure I understand.  Are you dry camping or on shore power.  Running the electric heating element from an inverter while dry camping will run the battery bank down VERY quickly.  That is what diesel is for.

And if plugged into shore power, the 120 VAC electric element is just fine, and our inverter/charger should keep the batteries fully charged.

Sorry for the mystery.  Intentionally not charging the batteries plugged in.  Testing everything as we do dry camp. 
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Amp hours used vs volts in batteries after use

Reply #9 –
Watt, which is amps*volts, is a measurement of power and so is horse power. Watts and horsepower do have conversion ratios but do not involve time.

An amphour is a measure of amps over time and is not a measure of power. It is not possible to convert watts (a measure of power) to amphours. If you measure watts over time so watt hours, then it can be converted to amphours.

Your 1200 watts can provide up to 72 amps, on a sunny day when your panels are focused on the sun, which requires moving them every 5 minutes. You can get this amperage for about 5 hours in a day which provides 360 amphours or about 4300 watt hours.

Wyatt

Quote

Ok, so my 1200 watts on the roof has delivered 500 watts to the FT so far today here in sunny El Centro, CA (back from Cancun). For 12v systems that's 500/12= ~42amps

But now I'm not sure how to go the rest of the way to get from watts to amp-hrs. 10hrs at 4.2amps is tempting but I have no reason to do the calc that-a-way.

What is the correct answer?

best, paul
Wyatt
96 U320 40 WTFE, build 4943
84 Toyota Supra towd
2015 Jeep Wrangler towd
Victoria, BC, Canada

Re: Amp hours used vs volts in batteries after use

Reply #10 –
Thanks, Wyatt.

best, paul
1999 U320 40' 1200 watts on roof. 12cf AC/DC Cold plate fridge/freezer. VMS 240 CL Honda Element
 

Re: Amp hours used vs volts in batteries after use

Reply #11 –
104 amp hours consumed overnight. Aqua hot Diesel burner was on versus the previous night.

Two new Winnebago owners I know both consumed 240 hours overnight.  They both had 6 group 31 gel batteries I think rated at 100 amp hours each.

They both had non led lighting and household refers. 

I mentioned to both they might need another six batteries.  "But where?" Separate problem I said. 

Seems like I am using about 15% of capacity overnight depending on the actual battery  ratings where they are using 40%.  Aqua hot system seems fairly good on power consumption. 

The three MK deka's 8D's I am running seem to have more capacity than the rated 225 amp hours each?

Bob


"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4