Home » Public Forums » GMCnet » Inverter and converter....how about both? (Anyone using both?)
| Inverter and converter....how about both? [message #347462] |
Sat, 07 September 2019 08:18  |
6cuda6
Messages: 975
Registered: June 2019
Karma: -6
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Curious...anyone using both an inverter and a converter? So converter for 12v stuff when plugged into shore power and then the inverter to power 12v stuff when not plugged in.
My reasoning is 2 fold.....
1- can run the fridge while driving (dont want to use propane unless stopped)
2- smaller genetator needed only to charge batteries when needed or A_C ( i still think i can run A/C off inverter power given enough battery and a softstart on compressor)
I also dont really want to be driving along the highway with my generator going just to power the fridge and/or the A/C....just doesnt make sense to me when you have a 300hp generator under the hood......
Am i being realistic here or is this a totally crazy idea???
Rich Mondor,
Brockville, ON
77 Hughes 2600
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| Re: [GMCnet] Inverter and converter....how about both? [message #347465 is a reply to message #347462] |
Sat, 07 September 2019 09:33  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Rich,
I, like many others, run both a converter and an inverter, but the
inverter's only 1200 W., which is not nearly large enough to run an air
conditioner, even up there in the "cold country", much less down here in
"sub-hades". I've got two golf cart batteries, so I can run my microwave
for about 10-15 minutes, but that's about all. With lead-acid batteries,
it's not reasonable to expect to be able to run a 13,000 btu a/c AT ALL.
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
www.gmcwipersetc.com
On Sat, Sep 7, 2019 at 9:19 AM tonka6cuda6--- via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Curious...anyone using both an inverter and a converter? So converter for
> 12v stuff when plugged into shore power and then the inverter to power 12v
> stuff when not plugged in.
>
> My reasoning is 2 fold.....
>
> 1- can run the fridge while driving (dont want to use propane unless
> stopped)
>
> 2- smaller genetator needed only to charge batteries when needed or A_C (
> i still think i can run A/C off inverter power given enough battery and a
> softstart on compressor)
>
> I also dont really want to be driving along the highway with my generator
> going just to power the fridge and/or the A/C....just doesnt make sense to
> me when you have a 300hp generator under the hood......
>
> Am i being realistic here or is this a totally crazy idea???
> --
> Rich Mondor,
>
> Brockville, ON
>
> 77 Hughes 2600
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Inverter and converter....how about both? [message #347466 is a reply to message #347465] |
Sat, 07 September 2019 09:54 |
GMC.LES
Messages: 505
Registered: April 2014
Karma: -2
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Senior Member |
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Making electricity takes power, whether from your engine alternator, or from your genset. If you do a fuel consumption comparison, I bet you would have difficulty measuring the difference between the two.
Most have noted that running the Onan while driving has an impact on fuel economy of less than 1 mpg. Just changing your driving style can affect fuel consumption by more than that.
As for converter or inverter. Having both makes sense and just adds flexibility to what you can do while away from home.
Les Burt
Montreal
'75 Eleganza 26'
> On Sep 7, 2019, at 10:33 AM, Ken Henderson via Gmclist wrote:
>
> Rich,
>
> I, like many others, run both a converter and an inverter, but the
> inverter's only 1200 W., which is not nearly large enough to run an air
> conditioner, even up there in the "cold country", much less down here in
> "sub-hades". I've got two golf cart batteries, so I can run my microwave
> for about 10-15 minutes, but that's about all. With lead-acid batteries,
> it's not reasonable to expect to be able to run a 13,000 btu a/c AT ALL.
>
> Ken H.
> Americus, GA
> '76 X-Birchaven w/Cad500/Howell EFI & EBL,
> Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
> www.gmcwipersetc.com
>
>
> On Sat, Sep 7, 2019 at 9:19 AM tonka6cuda6--- via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> Curious...anyone using both an inverter and a converter? So converter for
>> 12v stuff when plugged into shore power and then the inverter to power 12v
>> stuff when not plugged in.
>>
>> My reasoning is 2 fold.....
>>
>> 1- can run the fridge while driving (dont want to use propane unless
>> stopped)
>>
>> 2- smaller genetator needed only to charge batteries when needed or A_C (
>> i still think i can run A/C off inverter power given enough battery and a
>> softstart on compressor)
>>
>> I also dont really want to be driving along the highway with my generator
>> going just to power the fridge and/or the A/C....just doesnt make sense to
>> me when you have a 300hp generator under the hood......
>>
>> Am i being realistic here or is this a totally crazy idea???
>> --
>> Rich Mondor,
>>
>> Brockville, ON
>>
>> 77 Hughes 2600
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: Inverter and converter....how about both? [message #347500 is a reply to message #347462] |
Sun, 08 September 2019 04:01 |
GatsbysCruise
Messages: 261
Registered: January 2017
Location: Waukegan, Illinois
Karma: 3
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Senior Member |
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6cuda6 wrote on Sat, 07 September 2019 08:18Curious...anyone using both an inverter and a converter? So converter for 12v stuff when plugged into shore power and then the inverter to power 12v stuff when not plugged in.
My reasoning is 2 fold.....
1- can run the fridge while driving (dont want to use propane unless stopped)
2- smaller genetator needed only to charge batteries when needed or A_C ( i still think i can run A/C off inverter power given enough battery and a softstart on compressor)
I also dont really want to be driving along the highway with my generator going just to power the fridge and/or the A/C....just doesnt make sense to me when you have a 300hp generator under the hood......
Am i being realistic here or is this a totally crazy idea???
--------------------------
I am getting into the Inverter (solar) side of the RV. I am at the minimum right now, a 50 watt panel on the roof to keep the batteries charged when stored. it does very well.
The inverter is interesting but don't expect a lot out of it.
for example
I have a 100 AH 12v battery. At this point in time the battery is old so I don't get a lot of power out of it.
I can run a tv 2.5Amp load for about 3 hours
I have recently installed Cobb LED lights which are incredibly low power use.
Can charge my phone and or laptop.
I can't run anything that uses a lot of power like coffee maker, micro wave, ROOF AIR CON.
I will be changing over the solar system soon to a higher capacity solar panels and increase the AH on the batteries,
but this will still not allow micro wave use or ROOF AIR.
Microwave uses about 10 amps, ROOF AIR uses 12 to 15 amps.
Let me translate that.
The converter is a power hog. It is best if you can run your items on the 12vdc circuit.
The battery must supply 120 amps of 12v dc power to the inverter to produce 12 amps at 120 v ac for the airconditioner. That is your whole battery.
The battery must supply 100 amps of 12v dc power to the inverter to procuce 10 amps at 120 v ac for the microwave. though you can get away with very short hits.
Get on You Tube and watch the solar isntallations that the RV community have been doing. To have a good system you need quite a few panels or total wattage and batteries, to add up some AH's to run that inverter.
There is a formula to crunch numbers panels vs batteries vs load. You can fudge on this a little here and there depending on how you plan to use the system.
Ok, If your GMC motor generator (engine) puts out 60 amps and you run that through the inverter, you will only get 6 amps output. You need the battery reserve.
GatsbysCruise. \
74GMC260 Former Glacier Model style. \
Waukegan, Illinois \ Keep those MiniDiscs Spinning \ MY GREYHOUND IS FASTER THAN YOUR HONOR ROLL STUDENT \ WindowsXP-Win7-Win8.1-UBUNTU STUDIO - UBUNTU VOYAGER - Berzin Auto Center
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| Re: Inverter and converter....how about both? [message #347502 is a reply to message #347462] |
Sun, 08 September 2019 07:20 |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Senior Member |
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Its not that the Inverter is a power hog, at ~90% they are pretty efficient. The issue is that 12Vdc equipment is not really that powerful compared to the power consumption of the appliances that people want to operate.
You need to look at the Wattage of the appliances, not the Amps. Watts = volts X Amps so at 12V you need approximately 10 times the current to produce the same power + about 10% more for losses in the inverter.
At the maximum rating, your 12V engine alternator can produce only 80Amp X 12V (nominal) = 960 watts. That's not enough to run most appliances (coffee maker, small microwave, toaster etc each consume approx 1200 watts), so your battery needs to make up the difference.
But a 100AmpHr battery should not be discharged beyond 50% so its really only a 50AmpHr battery. And that 50AmpHr rating is only if you discharge it at a rate of 5 Amps. If you want to make morning coffee and a piece of toast, That would be say 10 minutes for the coffee makers and 5 minutes for the toaster = 15 minutes at 1200 watts (1200/12V = 100Amps + 10% = 110Amps)
110Amps for 15 minutes or 1/4 of an hour = 27.5AmpHrs or about 1/2 of your batteries usable charge. BUT at high current levels the capacity of the battery goes way down, so really to make your toast and coffee you have actually used all your batteries USABLE charge.
Now lead-acid batteries should be recharged immediately and you should not charge it faster than a 5C rate (100/5 = 20 Amps). So at a rate of 20Amps, its going to take 2 hours to recharge, BUT your battery wont charge continuously at 20Amps, it will quickly taper down, so more like 4-5 hours before its fully charged. Since you are using your battery for this, I assume you have no shore power and you will now need to run your generator for several hours.
So you have a 100 watt solar cell with the coach parked away from trees and its a bright sunny day. With your PWM solar controller you might get 60 watts of charging so that's 5 Amps max (which will taper off). So its going to take likely 6-8 hours to fully recharge the battery from your toast and coffee from your solar panel.
So... until we get higher capacity batteries (LiFePO4 etc) and charging systems, for high power appliances you are better to run the generator for 10 minutes for your toast and coffee (you can run both appliances at the same time) than try to run it off your battery. Use the batteries for long term low current applications like LED lighting, entertainment devices etc.
The above calculations were rounded off, back of the hand, off the cuff, closer to real world than using absolute specifications.
Just my 2 cents.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| Re: [GMCnet] Inverter and converter....how about both? [message #347506 is a reply to message #347502] |
Sun, 08 September 2019 07:54 |
Olly Schmidt
Messages: 1265
Registered: February 2014
Location: Germany and Scottsville, ...
Karma: 8
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Senior Member |
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I run a Victron Energy Multiplus with 2000W continuous/ 3000W Spike connected to 200Ah LiFePo4 battery. Coffeemaker is a Nespresso machine which runs for less than a minute from turn on to off, plus a watermaker for tea, which probably runs about 2minutes. Microwave/convection oven runs 10 minutes for a pizza. I can stay off-grid for two-three days. Charging is fairly fast officially at 80amp from the charger, no idea how fast the battery really is until full again. I do run the AC, but only when connected to any kind of shore power, even if it is just 5amo/240v. The inverter takes care of the additional liad. Very helpful. And the most expensive items I have on my GMC in Europe
--
Regards
P O Schmidt
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Best regards
Olly Schmidt
PGP Key ID: 0x18a9 3a1f 4196 bf22
'76a Eleganza II, VA
'73 Sequoia, SH, Germany
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| Re: Inverter and converter....how about both? [message #347508 is a reply to message #347462] |
Sun, 08 September 2019 08:38 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Bruce H., great synopsis. Back to original post, best bet for running refrigerator down the road is 3 way on DC mode. You chill it on AC shore power before trip, and go down road on DC to maintain temps. At fuel stops I simply hit OFF to not have the alternator have to play catch-up recharging house and running frig and coach once driving again Frig maintains cool fine on 20 min stop. If we stop for a while at a rest area for lunch and don't need generator due to nice weather, simple switch to Propane. You can go a looong time on propane parked or dry camping.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Inverter and converter....how about both? [message #347531 is a reply to message #347508] |
Sun, 08 September 2019 23:43 |
Vern Crawford
Messages: 81
Registered: August 2016
Karma: -1
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On our '77 Palm Beach I completed the install of our solar system just over
two years ago. During those two years we have traveled over 25,000 miles,
*never* plugging into shore power or firing up the Onan. In the past two
Summers we have enjoyed boon-docking in fixed locations twice for 15+ days
in Oregon with our solar panels in full shade until after 10:00 a.m., and
twice for 30+ days in Texas with panels in shade until 9:00 a.m., and again
shaded by 6:00 p.m in the evening.
Our owner-installed system consists of:
7 panels of various sizes from various manufacturers rated 960 watts total
input.
2 identical Zamp ZS-30 amp charge controllers (front one controlling the 3
panels 470 watts, the rear one for 4 rear panels 490 watts).
5x100 amp Battle Born LiFePo4 lithium batteries (at 31 pounds each
weighing155 pounds total weight).
Victron BMV-700 with dongle for smart phone/tablet for remote battery
monitoring.
Zamp 2000PS 2000/4000 watt pure sine wave inverter.
All wiring and marine switches are one or more gauges heavier than
recommended, with fuses on all circuits.
As we never have had occasion to use our Onan generator, we passed it on to
another GMC owner at the recent Tallahassee GMC Rally, gaining a nice
"basement" storage compartment, while loosing two heavy lead acid batteries
in that same bay. If I refrain from filling that space with anvils, then
we have reduced the total GVW a net hundred pounds or more!
How is the system working out for us?
No, we don't even consider turning on the air conditioner! That is why we
have six Alcoas with good tread on the ground, and one on the spare rack,
so we can head to more moderate climates during the hot Texas Summers,
As half-time RVers for the past two+ years we do have around 400 days and
nights of experience inside our coach. Much of the time 2 or 3 of our
FanTastic Fans are circulating air throughout the coach as appropriate.
Our Norcold 12/120v compressor fridge keeps the ice cream firmly frozen at
a maximum of around 12-15 degrees, but usually around the zero mark (+/- a
couple of degrees), while drawing around 4 Ah when operating (about 60% of
the time). Almost all of our lighting has been converted to LED, so that
is not much of a burden on the system.
Both Lenore and I are somewhat dependent on modern technology to keep up
with all of our outside obligations that seem to follow us around in
"retirement." Lenore's laptop and large monitor, my 27 inch iMac desktop,
iPads and iPhones to keep our internet hot-spots humming, plus backup hard
drives spinning.
Most days we are traveling we will stop at a highly recommended eatery, and
our propane stovetop or oven is occasionally put to use. However we almost
always finish the day utilizing the 700 watt Black+Decker microwave to warm
up leftovers, reheat a few cups of coffee, grind fresh coffee beans to set
up Mr. Coffee for the following day, and such.
When we retire for the night, we usually have fans on (or possibly an
electric blanket if it is clod outside), the fridge running, electronics
devices and tools charging, etc cetera.
First one up in the morning usually flips on the Mr. Coffee maker using 900
watts, after the coffee is finished the microwave usually gets an
assignment or two, and often the toaster will crisp up some homemade bread,
electronic gadgets have been monitored for our daily dose of news from the
outside world, etc cetera.
By the time all of these morning activities are completed, checking the
status of the batteries will typically reveal that we are down to somewhere
between 85-90% of our reserve capacity remaining. Typically our battery
bank has fully recovered by 10;00 a.m., or if it is overcast or we are in a
particularly shady parking spot it might be noon or later before we hit
100%. It is very unusual to not fully recover, but there have been a few
times that everything (unusually unbroken cloudiness plus heavy electrical
demands over several consecutive days), all working against us have caused
us to get down to near 50%, but that has been the lowest we have depleted
our system, which quickly recovered as soon as the situation changed.
All of these comments about our experience with our system as installed are
based not on technical data of what should, or should not, be possible.
These are our actual experience using our system in the real RVing world.
With the benefit of the Victron instrumentation and its graphing ability I
can back up all of the experiences I've reported here. Did I over engineer
our system? Some would argue that I did, but it has provided for our
electrical energy needs, and has met all of our expectations. That was my
goal. Thus far it has met that goal with maintenance free energy for our
reasonable and conservative needs.
When I put the system specs out for bid by AM Solar of Springfield, Oregon,
their quote was over $21,000 to build a comparable system. Our actual cost
was within a few dollars of $7,000 total, plus a bit of sweat equity. The
most important of those dollars was for the $200 Victron battery monitoring
system!
If I were outfitting another GMC would I duplicate the same system? No
way, as I've learned so much in the process, while actually using the
system for the past two years. I'd make many improvements to get even more
useful energy for the buck. But we continue to enjoy our solar system
every day.
I so delight in handing an icy cold Shiner Bock to a fellow GMC owner
looking over my setup, and remind them that the frosty drink they are
holding in their hands is provided "compliments of the sun!"
Hugs,
Vern, Lenore, and Knibbles D. Kat
P.S. It is interesting and should be noted that the advertised wattage,
both on the attached decal and packaging of a microwave, is the "output"
wattage that heats the food, while the actual wattage used for operating it
is listed in the more complete manufacturers specification sheet as "input"
wattage. Thus as in our case for the smallest readily available microwave
it actually uses 1050 watts.
On Sun, Sep 8, 2019 at 8:39 AM John R. Lebetski via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Bruce H., great synopsis. Back to original post, best bet for running
> refrigerator down the road is 3 way on DC mode. You chill it on AC shore
> power
> before trip, and go down road on DC to maintain temps. At fuel stops I
> simply hit OFF to not have the alternator have to play catch-up recharging
> house and running frig and coach once driving again Frig maintains cool
> fine on 20 min stop. If we stop for a while at a rest area for lunch and
> don't need generator due to nice weather, simple switch to Propane. You
> can go a looong time on propane parked or dry camping.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Vern Crawford (and Lenore Langsdorf)
155 JJ Lane
Center Point, TX 78010
(618) 203-8296 Vern's cell
(830) 928-5550 Lenore's cell
VernCrawford@GMail.Com
LenoreLangsdorf@GMail.Com
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| Re: [GMCnet] Inverter and converter....how about both? [message #347532 is a reply to message #347531] |
Mon, 09 September 2019 01:03 |
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ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
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Senior Member |
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Vern, Lenore, and Knibbles,
Please don’t leave us hanging! What would you do NOW?
I have no expectation to be living the RV life for some time yet, but I am interested in solar for the coach. At this point it would mostly just be to keep the house bank (flooded lead acid golf cart) charged while in storage.
If you had it to do again, today, what would you do?
If money weren’t nearly as scarce, what would you do?
What bit of improvement are you waiting for?
I loved reading your post (and I can’t wait to hear what Jerry Work has to say) and just am greedy for more.
Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, CA
Howell EFI + EBL + Electronic Distributor
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Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
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| Re: Inverter and converter....how about both? [message #347536 is a reply to message #347462] |
Mon, 09 September 2019 06:55 |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Senior Member |
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LiFePO4 batteries are the way to go for sure...
You can discharge them down to 10-20% and recharge them at a much higher rate. They have a much lower self-discharge rate and are happy if they don't get recharged all the way to 100%. One 100 Amp-hr LiFePO4 battery has the useful capacity of the popular two golf cart battery configuration at 1/2 the size and 1/4 the weight. Plus they will last 4+ times longer. They are cheaper in the long run.
I was hoping to wait a couple more years before taking the plunge at ~$1,000+ Cdn each for Rich and I north of the border. I haven't checked the pricing lately, but with China being the major source of Lithium as a raw material and also the major source of Lithium cells I'm sure the trade war has pushed prices much higher.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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