Measured FWC power use

RC Pilot Jim said:
When I viewed Bill Harrs "Trimetric" video yesterday the presenter showed the -Uni-Solar - peel-N- stick flex panel or panels glued to his roof plus a very elaborate controller running everything.

Overkill for us , however shows that gluing them down poses no problem .As I have done research on flex panels over the last year I have seen many of these panels directly affixed to roofs of motorhomes and travel trailers with no adverse affects connecting them that way.

For me I have the one-piece roof. If I glue the panel down....and a panel lasts - say 10 years? ...That means me or the next owner will be scraping or dissolving glue to replace the panel..... If I get a regular panel...I remove 4-6 bolts and just swap it out in 10 years. ...Course Flex panel weighs less than 3 pounds and the 100 watt weighs 25 pounds = harder to lift the roof....Always trade-offs.....
Click to expand...
Jim, I started with a 100 watt panel on the roof. I later added a 150 watt for total of 250. After seeing the Renogy 100watt flexible panel, I purchase one. I remove the 100 watt panel and kept the 150 watt on the roof. I will plug in the flexible panel when stationary and locate for best sun exposure. Seems like a easy way to get maximum charge with less weight on the roof. The old 100 watt panel is now in my backyard serving as a charge source for a 12v gel battery for my ham radio stuff. Harv
 
Harv,
Thanks for the shunt info. That is the shunt that came with the Trimetric (as an option) . Trimetrics dealer in L.A. charged me $31 for the same shunt (The Shunt 500 - Deltec 500 amp/50 mililmeter - $27.00)


DrJ recommended the Renology 100 watt flexible for my application (correction TWO circuits). Our top loading Refer only draws an average of 1.5 amps per hour. The 100 watt puts out 5.5 amps giving me 3-4 amps per hour to charge the battery.

We will have the Trimetric at the fall Rally as well as the 60 watt portable panel. It will be good to be able to monitor the refer usage and charging amps...no more guessing. Based on that experience will give me the data I need to decide whether I NEED not SHOULD buy the panel for the roof.
 
RC Pilot Jim said:
Harv,
Thanks for the shunt info. That is the shunt that came with the Trimetric (as an option) . Trimetrics dealer in L.A. charged me $31 for the same shunt (The Shunt 500 - Deltec 500 amp/50 mililmeter - $27.00)


DrJ recommended the Renology 100 watt flexible for my application (4 circuits). Our top loading Refer only draws an average of 1.5 amps per hour. The 100 watt puts out 5.5 amps giving me 3-4 amps per hour to charge the battery.

We will have the Trimetric at the fall Rally as well as the 60 watt portable panel. It will be good to be able to monitor the refer usage and charging amps...no more guessing. Based on that experience will give me the data I need to decide whether I NEED not SHOULD buy the panel for the roof.
Click to expand...
I appears that a 100 watt panel should do it for you. My biggest draw is the Dometic at 4.5 amps. With a 100 watt panel, it just barely kept up with the Dometic, particularly in the hot desert sun. Now with 250 watts, I get both batteries charged up by the end of day. Here is my Trimetric installed next to the FWC battery indicator and the shunt installed next to the MPPT controller and batteries.


full



full
 
My 2014 Hawk has the Sure Power Model 1314 voltage sensing battery separator. The data sheet from the FWC web site has the following information.

http://www.fourwheelcampers.com/batteryseparator1315.pdf

"MODEL 1314
This unit will activate only when the Main Battery System exceeds 13.2-13.5 volts"

"If the drain on the charging system by the auxiliary or main battery bank reduces the system voltage below 12.4-12.9 volts, the BATTERY SEPARATOR will disconnect the battery banks from each other"

"Wire Length Wire Gauge if not using Auxiliary Start
Up to 10 feet 8 gauge
10 to 20 feet 6 gauge"


I'd speculate that the 10 gauge wire as installed is not optimal for charging the camper batteries from the truck alternator. Replacing the entire wire run with 6, or even 4, gauge would seem to be recommended. Remember that the wire run length is different from the distance between the batteries. Include the length from the battery down to the frame and from the frame up to the connector in the truck bed. This is why DrJ's measurements are so useful. He can directly measure the voltage at the battery while running.

DrJ, if you have a GoPro Hero camera, you could set it up to capture a time lapse of the Trimetric display while running on an extended trip to record voltage or current. Could be interesting to see how the truck voltage regulator affected the camper charging as the truck battery got fully charged after starting the engine.

Paul
 
Here's decent resource about charging voltages.... you need that higher voltage for the health and longevity of your batteries.
http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery
DrJ said:
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.
Click to expand...
 
What size shunt do we need - do we need the 500A, or is the 100A enough for our systems and loads? The manual says you can use the 100 if your system uses less than 70 amps max charging or discharging. We don't use that much do we? They're close to the same price, so that's not an issue. Just thinking the 100 being smaller might be easier to put is small spaces - but maybe that's not really an issue.

Thoughts? Thanks!
-Rick
 
PaulT said:
My 2014 Hawk has the Sure Power Model 1314 voltage sensing battery separator. The data sheet from the FWC web site has the following information.

http://www.fourwheelcampers.com/batteryseparator1315.pdf

"MODEL 1314
This unit will activate only when the Main Battery System exceeds 13.2-13.5 volts"

"If the drain on the charging system by the auxiliary or main battery bank reduces the system voltage below 12.4-12.9 volts, the BATTERY SEPARATOR will disconnect the battery banks from each other"

"Wire Length Wire Gauge if not using Auxiliary Start
Up to 10 feet 8 gauge
10 to 20 feet 6 gauge"


I'd speculate that the 10 gauge wire as installed is not optimal for charging the camper batteries from the truck alternator. Replacing the entire wire run with 6, or even 4, gauge would seem to be recommended. Remember that the wire run length is different from the distance between the batteries. Include the length from the battery down to the frame and from the frame up to the connector in the truck bed. This is why DrJ's measurements are so useful. He can directly measure the voltage at the battery while running.

DrJ, if you have a GoPro Hero camera, you could set it up to capture a time lapse of the Trimetric display while running on an extended trip to record voltage or current. Could be interesting to see how the truck voltage regulator affected the camper charging as the truck battery got fully charged after starting the engine.

Paul
Click to expand...
Paul,

I ran the engine today to test out idling for truck truck charging and found this exact problem.

The voltage was at 12.2 volts when I started the truck. The compressor fridge was running.
I could get it to charge up to 12-14 amps but then the battery separator would click and the charging would stop completely. This happened repeatedly at 15-20 second intervals.
Once I turned off the fridge, it worked just fine. It never turned off.

You are correct about the newer battery separators. If your voltage gets too low, the system won't allow it to charge. 12.2-12.4 volts sounds like the cutoff.

Idling had essentially the same voltage and amps as driving. This is great if you need to charge your batteries but don't want to leave camp. Probably won't make a big difference. It does take about 5 minutes of idling before any power at all made it to my batteries.

It does appear that the truck voltage will increase as it gets closer to full. I made it up to 13.4 volts and amps were down to around 5 amps when the monitor showed 85% full.

I'm hoping to post some explanation of the trimetric setup including shunt. There has already been one great picture posted already.
 
Thanx Harv for the Shunt picture. The visual helped. I have just enough room to install it above the battery if I move and install the wires from the roof solar plug. Go to do that anyway so will do that tomorrow.
 
RC Pilot Jim said:
"Idling the truck for 1 hour increases voltage from 12.3 to 12.9 volts"

I always thought idling for long periods of time was bad??
Click to expand...
 
I was reading one description where the guy used double stick tape and put the shunt on top of the battery. I just ordered the meter, shunt, and wire, so I guess I'll get to figure it all out next weekend :)

Thanks to all for the great info here. I've had a 100w panel and a 68L Nova Kool DC fridge for a couple of years and am tired of guessing. Overall works very well, but looking forward to the extra information to decrease anxiety. I got all the stuff for $204 including shipping from John Drake Services:

http://www.solarseller.com/trimetric_battery_monitor_and_flexcharge_voltage_monitor_amp_hour_.htm#trimetric_wiring_harness

Cheapest prices I could find. I have used him before and all was fine.

Thanks again :)
-Rick
 
Ethergore said:
I wish you would have had a few more hours of driving. I have a feeling the charging rate would stay slowing down pretty quickly once the battery was at a higher state of charge and really needed the voltage. I would also like to know what voltage you are getting at your aux battery when your battery is 50% or more discharged. At that point my separator will cycle on and off as my truck battery dumps everything it has in to the aux battery.

Thanks for your time and input.
Click to expand...
Ethergore - This might answer some of your questions:
I did notice a few things during my second trip studying truck charging of the camper battery.

On my trip back home, the camper battery bank was at around 94% to start the journey. I had used the solar to get my battery closer to full.
The truck charging setup actually did a nice job topping it off.
On my trip home, 2.5 hours later, my voltage was up to 14.2 volts and the amps were less than 1. The trimetric showed 100% of charge.

With the truck running still, I measured the truck battery and the truck's aux battery. They both tested 14.4 volts. Inside the camper we stayed at 14.2 volts. Only a 0.2 volt drop was significantly better than I would have guessed on my first trip (however this is at really low amps so you'd expect voltage drop not to be too much).
Once enough battery % had been recovered, the setup if given enough time can provide enough voltage to get to 100%.

I'm sure adding a higher gauge wire or dual alternators would really speed this up by letting more power being sent to the camper, but it's much better than I first thought.

There have been some good links here about battery charging. I'm certainly no expert but my understanding is that as batteries are heavily discharged they accept more amps at a lower voltage. As the approach full charge they need higher voltage as the amps decrease to complete the charge cycle. The truck charging setup does a decent job of doing just that.

Anyway, here's my summary of charging the camper by amps:
IOTA with 4 stage - up to 27-30 amps/hour
Truck with FWC setup - up to 14-17 amps/hour
Solar (depending on setup, sunlight, etc) - 4-6 amps/hour per 100 watts of solar

Hope that answers some questions so many of us have had with charging.
 
photohc said:
It really depends on how you've connected the panels. If in "series", then blocking the sun on one panel will seriously deteriorate the total output as the panel out of the sun will hinder the output of both. If in parallel, then blocking on one panel, should not deter the other from pushing out it's maximum output. The advantage of connecting in series is that both panels connected in this manner produces a higher voltage and lower current to reduce any voltage losses due to wire size and length. In parallel, current is higher and voltage drop is more as this is determined by the wire size and length. The advantage of parallel connections is to eliminate power drops due to one panel being in a shadow. Setting up your solar panels, like other things in life, is a trade off in features.

Parallel connection:
Pros
1. Reduces effects of one panel in shadow affecting total output of 2 or more panels.
Cons
1. Requires larger wire size due to larger current flow.

Series connection:
Pros
1. All panels add in voltage and current flow is smaller (best to have MPPT controller in this instance)
2. Smaller and longer wire runs will not affect voltage loss as much.
Cons
1. Any one panel in shadow will severely affect the total output.
Click to expand...
Thanks .I will try the series wiring.
Frank
 
As long as we don't resist going way out into the weeds, there is another instrument that will test your batteries. The West Mountain Computerized Battery Analyzer that mostly hams use. It can determine what the true capacity of your battery system really is.

http://www.westmountainradio.com/cba.php

Another device that could compensate for the voltage drop from the truck is this one:
http://stores.tgelectronics.org/the-new-n8xjk-boost-regulator/. Or, this one:
http://www.mfjenterprises.com/Product.php?productid=MFJ-4416B

Hams use this device to maintain battery voltage to their transmitter. Don't know how well it might work to boost the voltage from the truck at the camper battery separator. However, it might be worth talking to the manufacturer for their recommendation.

I have not used either of these in the camper setting, but thought it might be worth discussion.
Paul
 
DrJ,

Excellent discussion and testing. The charging rates with ITOA/truck/solar is helping me to figure out what I'll be doing with my set up. I thought maybe the truck would do a better job of charging the camper battery. It's probably enough if you're load is small. I've got dual alts with the camper package but it sounds like the separator may be a bit of a hinderance. Hate to say it but I think a generator is in my future. Thanks for the good work.
 
I'm sitting in our 2013 Hawk on the Mogollon Rim outside of Payson, AZ while typing this. I will do a complete post regarding our Hawk and the power issues I have had but here are some initial thoughts;

We just had 4 gauge wire with an Anderson connector added to make vehicle charging better. With 2 days of rain it has really helped. I replaced the Exide group 27 batteries with Sun Extenders. People more knowledgeable than I can detail the reasons but these are meant to store more amperage for steady release. The Exide's and others are meant to push a lot of amps to start something.

I have 2 Global Solar flexible panels and like them. I also upgraded the IOTA charger to the IQ4. Changed the Global Solar charge controller to a Morningstar and it knows how to charge AGM cells.

We have an 85 liter 2 way Dometic. Adventure Trailers, (New Arizona FWC Dealer) is the best group of make it bullet proof and good looking did the battery to camper wire add and put 2 exterior grills and an additional fan to keep the fridge cool.

I cannot single out one fix that made things work well. We had hot fridge, poor charging issues, I just hit all problems at once. Stays charged well now.

I appreciate the usage and charge numbers shared. I'm getting similar results. No matter what you have, nothing beats being plugged in. I always connect to shore power 24 hours before leaving, fire up the fridge and load it with water bottles to get some mass cooling. We also have one of those little blue fans that circulates air. Reduces cold and hot spots and the thermostat can be set to a lower number.
 
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