Measured FWC power use

[DrJ]

I installed a trimetric 2030 in my Hawk earlier this summer. It is a highly useful piece of equipment for monitoring your battery useage. It provides real time data about your camper's power. I've had several other monitors and even a volt meter, but until I installed this I really didn't know for sure about my battery's actual status.

I've taken several measurements over the summer and here is what I found. I'm hopefully that this is helpful to someone else.

110 liter Compressor fridge 4.2-4.8 amps per hour
(That's the big one that FWC uses)
Heater 2.5-3 amps per hour
Water pump 2.6-3.2 amps per hour
(depending on volume of water)
Old incandescent overhead lights 2.8 amps per side or 5.6 amps for both sides
New LED overhead lights 0.4 amps per side or 0.8 amps for both sides
LED floor lights 0.1 amps
LED flood lights 2.8 amps
Porch light 0.2 amps
(Replaced with LED)
Fantastic Fan
0.2 amps at 10% fan speed
0.5 amps at 50% fan speed
1.5 amps at 100% fan speed
FWC battery sensor, IOTA IQ4 smart charger less than 0.1 amps - not measureable.

A couple of take home points for me.
LED light replacement is the best and cheapest way to decrease battery useage. The new ones use 1/7 of the power of the old ones.
Furnance uses less amp hours than I suspected.
I would have guessed 5-6 amps per hour.

 

[kmcintyre]

Nice info! Thanks! I replaced all my lighting with LEDs (and complete LED fixtures over the sink and bed; not just bulbs).

 

[ski3pin]

DrJ, great info and thanks for posting this. Can your trimetric give you information as to, in a typical summer day with the power draws you have listed, want is your daily (24 hrs) power usage in amp hours? Thanks.

 

[DrJ]

It does give you daily amp hour total.

My summer days have used 50-75 amp hours per day with camping. The average is probably 60 amps per day. My highest day was 84 amp hours.
The vast majority of that is from the fridge. On days where the outside temperature is greater than 80 degrees, the fridge probably runs 50-70% of the time.
The food is nice and cold. Ice cream stays frozen.
This also includes my kids who are always checking out the fridge for more ice cream! So you might have a more efficient setup than me.

My solar system easily charges the battery and runs the fridge during the day light hours.
I'm not sure how I could have the compressor fridge without solar.

If you are considering this setup or solar, you need to size a system that can not only run your fridge during the day but also have enough power to charge your battery before dark as well. Otherwise you still slowly drain the battery each day.

 

[orion]

DrJ, what is your solar set up like? How many watts and Ah are you pulling from it?

I have a similar set up as you, and drawing about 50-55 Ah /day average, with a 160 Ah dual battery bank, but my 100w solar can't keep up after 3-4 days. I am thinking about adding a 2nd solar plug to the exterior and having a mobile panel that I can set up in the direct sun for additional charging.

 

[ski3pin]

Thanks DrJ, good information. Our 51 litter chest fridge uses around 12 amp hours per day from my measurements with a watts up meter - 80° outside temperature. Those larger front opening units appear to use much more power. My 100W panel handles our power needs fine - mostly fridge and furnace. I want to do some data collection this winter and capture some real usage numbers for the furnace.

 

[Casa Escarlata Robles Too]

Yes thanks for the info.
My "new" up grade to 100w from 45w should keep my needs under control.
I only have a Truckfridge cooler like Ski that is using power. My lights are all LED and I don't use the water pump.
I haven't been out camping yet with the increased solar to see what my system will do.
Although I am sure I will have enough battery to not have any problems with the power usage I will need in the cold mornings. Using the heater is the important thing that I don't want to not have enough power to use.

It's nice to have an idea as to what uses the power and how much.
Thanks
Frank

 

[craig333]

I'm starting to think ski is correct about the the front opening units. Mine does seem to take more energy than I anticipated. I took but didn't use my portable panel this past weekend. No trees in the way but while it seemed to get a good charge in the day I was lower than I expected in the morning. I'm starting to think I should break down and get a meter to see whats really going on. Guessing isn't working so well.

 

[DrJ]

DrJ, what is your solar set up like? How many watts and Ah are you pulling from it?

I have a similar set up as you, and drawing about 50-55 Ah /day average, with a 160 Ah dual battery bank, but my 100w solar can't keep up after 3-4 days. I am thinking about adding a 2nd solar plug to the exterior and having a mobile panel that I can set up in the direct sun for additional charging.

I have 340 watts of solar and a 200 amp hour battery bank.
That is probably more solar than most people would ever need. I sometimes camp using a 63 quart ARB fridge in addition to my 110 litter fridge. Those two use quite a bit of power and need a lot of solar to make it all work.

I think if you are using the larger compressor fridge you need 150 watts of solar to make it work. 200 watts would be about right. Or you would need to recharge more with a generator, driving, etc. It may not be a problem at all if you drive around and don't stay in one spot for very long.

When you drive your truck can charge up to 30 amps per hour, at least by my measurements. So driving a couple of hours to your next destination does make a big difference.

If you have the smaller fridge, you can obviously get by with much less battery and solar.

 

[Smokecreek1]

Wow, we need to keep doing this stuff--, been trying figure out what my new set up produces (100 w panel/30 amp comptroller and 2 blue top batteries(110 ah) produces) and my system needs. Been up in the sun at the lake(Eagle) and all the gages say things, but the other night-watching the Giants on my tv, the comptroller reads 12.1 to 11.9-and the gage reads yellow, the converter changes tone and the comptroller reads 12.1 again and the gauge goes to green and 15 minutes later the system shuts the tv and vcr off and will not let me re boot the game-but the gages read good. Okay, i'm up there to figure out how to use this set up so i can watch my 49ers while out and about. In the morning turned on the stuff , no work, started the truck up, all systems go. Its sort of learning how to add and subtract all over again. Anyway i can watch tv in the day time on solar, think i may need another 100wt solar pane to do it all the time-just learning and reading the books. more old dogs learning new trips on my learning curve. If i was a full time camper i guess i could add lots of things to make things go, but not there yet. Thanks keep up the info

Smoke

 

[DrJ]

Smoke,
What things are you using that consume power?
Is your tv 12 volt and any idea how much power (amps) it uses?

 

[Smokecreek1]

DJ-still adding up my list of things that use power. i have several lists and what each thing uses but its like, i think the inverter uses more power than all he rest combined, I don't use allot of things-still a back packer at heart, so it's the tv, the vcr, the sat dish when i want to watch the 49ers,, the other things-hot water heater, compressor frig-now that. uses allot of power, i spend allot of times turning it up and down from 4.5 and making sure i don't park the truck with the rear in the sun. It's all new to me, and if i didn't have the cp frig/freezer, i think i got the power to watch when i want too. I really don't use allot of things except when i try to watch a game-a failing on my part-been doing this now for 9 years and learning this new power grid and what works and not - a new learning curve-probably didn't answer your question, but trying-if i didn't want to watch my niners would have more power than i need. ! just learning 1

Smoke

 

[DrJ]

You could always just start your truck or carry a small generator with you. Even 1-2 hours of just letting your truck idle while you are watching the game could recharge 30-50 amp hours. Plus then you don't miss the game!
It's obviously not the most economical way to go, but it would definetly work.

I was packing a bunch of food for a week long scout camp earlier this summer and had several days of rain and poor sunlight.
Between my ARB and Waeco compressor fridges, I was running out of battery power in a hurry. Just idling my truck for 1-2 hours made all the difference. Next day the sun returned and we were in business.

There are a lot of things that can mess up even a well planned solar and battery system. It's always good to have a back up.

 

[Smokecreek1]

Thanks-more thinking is needed-and yep i have a Waeco 110 and that thing seems to have a mind of its own-not like my old 3 way frig-more leaning curve and thanks, idling has always been my back up and seems to help now. will i ever reach solar "wonderfulness" ? Down the road maybe another 100 wt panel may be in order, one can always wish all tings will work.

smoke

 

[Ethergore]

DrJ- since you have solar you may not be able to answer but I was wondering if you can provide any numbers on how well your battery bank is charged with just the alternator.

It may put out 30-50 amps as someone said on this thread however the voltage is usually quite low and takes a long time for the batteries to accept the charge.

Really what I'm trying to figure out is how many hours of driving it takes to get to what percentage of charge. This will help those of us with remote, non-permanent solar setups.

Thanks

 

[Ethergore]

I'm starting to think ski is correct about the the front opening units. Mine does seem to take more energy than I anticipated. I took but didn't use my portable panel this past weekend. No trees in the way but while it seemed to get a good charge in the day I was lower than I expected in the morning. I'm starting to think I should break down and get a meter to see whats really going on. Guessing isn't working so well.

What kind of charge controller do you have and how many volts is it sending to your battery? Also what size solar setup do you have?

If you have enough solar to cover your needs with enough to charge your battery left over, then you may just need to change your charging voltage.

 

[craig333]

I was thinking I want to camp with Smoke to watch the Niners, but preseason has me thinking being cutoff from tv might not be a bad idea.

 

[DrJ]

DrJ- since you have solar you may not be able to answer but I was wondering if you can provide any numbers on how well your battery bank is charged with just the alternator.

It may put out 30-50 amps as someone said on this thread however the voltage is usually quite low and takes a long time for the batteries to accept the charge.

Really what I'm trying to figure out is how many hours of driving it takes to get to what percentage of charge. This will help those of us with remote, non-permanent solar setups.

Thanks

My understanding of battery charging has always been that it does take a higher voltage like 14.2 or higher to completely charge your battery to 100%.

When you have a fairly discharged battery like 20% or more, it will initially accept a lower voltage and higher amps. But as it approaches 90-95% of capacity it would take a higher voltage to get those last few amp hours back in.

I'm not exactly sure how this works with a truck alternator. But I would suspect it could take a few hours of driving to go from 60% to 90% of charge. Then that last 10% is pretty hard to get in unless your truck alternator runs above 14 volts and the voltage loss isn't too big from your truck to camper. If it only ran 13.5 volts it might never reach 100%. Even at 14.2 volts or more, it would probably take a few hours.

I have the IQ4 smart charger addition to the IOTA in my 2013 Hawk. I've noticed when I'm plugged in to 110 volts it does take several hours to float charge that last 5-10%.

I have to assume our truck charging system would be the same.

I should disconnect the solar, discharge the batteries to 50-60% and then see what happens when I have to drive around. That would be an interesting experiment. But if I had to guess, I bet you could recharge to 85-90% fairly easily and that last 10% would be tough.

 

[Ethergore]

My understanding of battery charging has always been that it does take a higher voltage like 14.2 or higher to completely charge your battery to 100%.

When you have a fairly discharged battery like 20% or more, it will initially accept a lower voltage and higher amps. But as it approaches 90-95% of capacity it would take a higher voltage to get those last few amp hours back in.

I'm not exactly sure how this works with a truck alternator. But I would suspect it could take a few hours of driving to go from 60% to 90% of charge. Then that last 10% is pretty hard to get in unless your truck alternator runs above 14 volts and the voltage loss isn't too big from your truck to camper. If it only ran 13.5 volts it might never reach 100%. Even at 14.2 volts or more, it would probably take a few hours.

I have the IQ4 smart charger addition to the IOTA in my 2013 Hawk. I've noticed when I'm plugged in to 110 volts it does take several hours to float charge that last 5-10%.

I have to assume our truck charging system would be the same.

I should disconnect the solar, discharge the batteries to 50-60% and then see what happens when I have to drive around. That would be an interesting experiment. But if I had to guess, I bet you could recharge to 85-90% fairly easily and that last 10% would be tough.

It would be really interesting! I have read in various places people stating anywhere from 80-100% charge is possible so it would be nice to know for certain. Im also thinking that those of us with the stock FWC wiring that it may be lower than we expect since it is 10 gauge wire and pretty long. I have a pretty significant voltage drop in my current setup and cant even see 13 volts at the aux battery when the truck is running.

 

[Cayuse]

With only having the built in FWC meter currently I can only present ancillary evidence based on my experience but since I put in my Isotherm 65 a 2-3 hour drive with the fridge running only brings the charge up to 4 lights most of the time. If I drive 5 hours with the fridge running it will bring the batteries to all the way full. Doesn't seem to matter what level the batteries were at when I started.

Hopefully this is all going to change soon as 200W of solar is scheduled to be delivered next week!