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Old 06-27-2016, 04:20 AM   #21
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Bob indeed comes across a little angry.

https://handybobsolar.wordpress.com/...d-up-so-angry/

There is a lot of very good information in his blog, although some of it may be outdated. The biggest concern I'd have with following his design/approach too closely is that most RVers aren't going to use their motorhomes like Bob and his wife.

Bob seems to think that people who use more power than he does don't know what they are doing. If he can live with 350 watts of solar, then why would anyone need 1,000 watts?

His comments on running generators to charge batteries, or run a 50-watt TV, are good ones. Running a generator at close to zero power load is highly inefficient.
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Old 06-27-2016, 12:00 PM   #22
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I skimmed Bob's tirades and I am not really interested in his total off grid solar living, but I was really interested in his take on converter chargers. Other info on the web seems to back up his assertion that most converter chargers (except maybe in high end Class A's) are nothing more than battery maintainers that cannot quickly recharge your coach batteries. From comments on this forum and my own experience, it looks to me that the converter charger in the Axis is one of these "low end" versions and that switching out to a three stage "smart" converter charger like the Progressive Dynamics 9200 series might be a significant improvement. I do a significant amount of dry camping and the ability to quickly (relatively) and fully charge my batteries using the generator (as well as off of shore power) is important to me.
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Old 06-27-2016, 01:24 PM   #23
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.....cut.... I do a significant amount of dry camping and the ability to quickly (relatively) and fully charge my batteries using the generator (as well as off of shore power) is important to me.
You may also enjoy reading what this couple has been doing. It appears a little more current (no pun intended) to me.

Living the Lithium Lifestyle – 3.5 Year Lithium RV Battery Update | Technomadia

In the future RVs will likely keep moving towards lithium batteries to lower weight and allow much faster charging (from engine alternator or generator) so I find their information of greater value to me.

And while it won't help those here trying to upgrade an existing system, I do agree that a 48-Volt DC system, if starting from scratch, makes more sense.

For vehicles with second engine-driven alternators dedicated to power the house, it makes little sense to me to keep a 12-Volt system.
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Old 06-27-2016, 01:47 PM   #24
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Interesting reading about the battery degradation they are seeing with Lithium batteries. Looks like they are suffering the same thing many Leaf owner's have suffered from the AZ heat.

Its funny that they mention all the studies about EV usage but then don't really make use of any of that data (which says what they are saying: Keeping a Lithium battery at 100% for an extended period of time is bad for the battery). Most of the EV world doesn't truly charge the vehicles to 100% (In the Focus Electric case it goes from 10% at empty to 90% at fully charged even when the dash reads 100%. The Chevy Volt is even more conservative when it comes to the endpoints of the batteries charge.).

Wow and no cell balancing.. They really should have looked at all the EV research...

In my case: I always had the Focus Electric programmed to charge to full overnight so that it would reach full about 30 minutes prior to leaving for work. Thus it lived most of its day with the battery between 30% and 60% full. In the 3 years I had it I had never noticed any loss of range in the car (the day I turned it in at the end of the lease it still read over 100 miles of range available at full charge). Doing the same with my C-Max.
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Old 06-27-2016, 02:56 PM   #25
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Tried to answer Chances' question on the high wattage items, keeps timing out on me. For a 1500 watt item for 15 minutes its 375 WH; typical GC-2 battery is 2700 WH. Keeping discharge to 50% is 1350 WH. The drip coffee makers I'm familiar with take about 20 to 30 minutes so figure 750 WH or half your 1350 WH of available battery.
600 watts of solar in the lab is less in real life. This may replace the coffee maker usage in about two hours in full sun. Panel output decreases as air temp goes up.

Here on the East coast it is taking from 10 AM to about 4 PM to make up for our usage over a 24 hour period which is one attic fan and an O2 Cool fan from 10 PM to 5AM plus two of the leds for about 3 hours. Water pump is around 6 amps times about 4 10 second flushes during the night.

This why a usage audit is so important. Check here for Gales' solar and battery sizing spread sheet: http://w8usa.org/club-library/documents-presentations/
This guy says the same thing as Handy Bob with out the rant: RV Electrical
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Old 06-28-2016, 07:34 PM   #26
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Tried to answer Chances' question on the high wattage items, keeps timing out on me. For a 1500 watt item for 15 minutes its 375 WH; typical GC-2 battery is 2700 WH. Keeping discharge to 50% is 1350 WH. The drip coffee makers I'm familiar with take about 20 to 30 minutes so figure 750 WH or half your 1350 WH of available battery.
....cut....
Thanks for feedback, that is a lot of energy to brew coffee.

I had measured our Keurig single-cup coffee maker before (rated 1450 watts) which takes 90 seconds per cup, but decided to test it again just to make sure.

When first turned on, it pulls 12 Amps for 40 seconds, then drops to 8 Amps for 20 seconds. For the remaining 30 seconds there is essentially no power consumption.

We each drink 2 cups in the morning, so total energy for our 4 cups is 85 watt-hours. Allowing for inverter and wiring inefficiency, I expect 120 watt-hours from batteries, or 10 Amp-hours (based on 12-Volt system) should easily cover our morning coffee. As Bob stated somewhere, being more efficient is often easier than adding more capacity.

What I would really like to have (i.e. -- need) is the ability to run a small air conditioner off batteries at night. Just wish it wasn't so expensive and/or heavy.
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Old 06-28-2016, 08:18 PM   #27
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Only talked with one person that claimed to run his A/C for 3 and 1/2 hours.
Didn't see his battery bank but his solar array was two 6 by 8 feet arrays that were tiltable. That much solar foot print wouldn't fit on an Axis.
I think without climbing up there maybe enough room for 4 150 watt panels.
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Old 06-28-2016, 09:08 PM   #28
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Only talked with one person that claimed to run his A/C for 3 and 1/2 hours.
Didn't see his battery bank but his solar array was two 6 by 8 feet arrays that were tiltable. That much solar foot print wouldn't fit on an Axis.
I think without climbing up there maybe enough room for 4 150 watt panels.
Sorry to mislead. And also to drift somewhat off topic (although energy storage and efficiency is a very big part of solar).

We are "travelers" more than "campers", rarely staying in one place for long, so getting batteries charged back up wouldn't necessarily have to be from solar. We do spend many nights without shore power, many of them where running a generator isn't allowed, or a good idea for other reasons. That's why battery-powered AC sounds so appealing.

It just doesn't seem practical and or affordable yet. I estimate 8 Trojan T105s (or equivalent) could do the job using an efficient small 5,000 BTU/hr AC, but that's 500 pounds of batteries. Not only is the weight an issue, they require access to check water. And going with AGM or lithium batteries because they are maintenance free just makes it more expensive. While I know I can technically do it, I can't justify the cost yet.

My question about making coffee or microwave off inverter/batteries was generic. We would NEVER boondock like Bob and his wife in the middle of the desert living off solar power. We've driven through Death Valley a few times and my wife couldn't wait to get to civilization.
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Old 06-29-2016, 12:40 PM   #29
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solar rule of thumb

Currently the rule of thumb on solar is 100 watts per 100 Ah of battery.
Our experience is it takes closer to 140 watts.

For 120 volt ac devices divide the wattage by 120 and multiply by 10 to get an approximate DC current. This ignores inverter efficiency.

The most accurate way is measure the AC devices with a Kill-a-Watt and DC with a clamp on DC ammeter. Lowes and Home Depot for the Kill-a-Watt and watch Sears to put their AC/DC clamp on meter on sale. Sometimes you can find a Radio Shack that is still in business that has a similar clamp on. Both are about $60.
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Old 06-29-2016, 05:19 PM   #30
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....cut....

For 120 volt ac devices divide the wattage by 120 and multiply by 10 to get an approximate DC current. This ignores inverter efficiency.

....cut....
For 12-Volt system, a quick estimate one can do in their head is taking wattage and divide by 10, which is the same but makes an allowance for inverter efficiency. That works out to around an 83% inverter efficiency, which is in right ballpark.

As an example, an air conditioner that requires 450 watts, pulls 3.75 at 120 Volts. Then at 12-volts it's 37.5 Amps. Using 83% efficiency batteries have to supply 45 Amps.

Instead of all the math, I can divide 450 watts by 10 in my head to get to the 45 Amps directly.

Obviously that's a rough approximation, and either way ONLY works with 12-Volt systems.

Anyway, we can easily see that running a 1500 watt microwave or coffee maker will require about 150 Amps from 12-volt battery bank, which is a lot even if comming from 2 typical RV batteries.

I think one of the factors that gets overlooked is that many owners do not adjust available battery Amp-hours (rated at a very slow 20-hour discharge rate) to much faster discharge rates that can't even be supported for an hour. Not only is this hard on batteries, it also throws the numbers for energy storage and production off. It may be tedious to estimate, but when using high-power devices (microwave, Keurig, air conditioner) we need to go beyond simply adding up Amp-hours.
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Old 11-20-2016, 10:39 PM   #31
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Hi Oneilkeys
My 2016 Vegas has a WFCO8955 Charger/converter. It does not charge my two house batteries higher than 12.55v which according to HandyBob is about 90% and is typical of a low quality unit. The most mentioned upgrade that fits right in is the Progressive Dynamics PD4655V which is a smart charger. I intend to do this in the spring when I get my unit out of storage.
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Old 11-21-2016, 12:09 AM   #32
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Hi Oneilkeys
My 2016 Vegas has a WFCO8955 Charger/converter. It does not charge my two house batteries higher than 12.55v which according to HandyBob is about 90% and is typical of a low quality unit. The most mentioned upgrade that fits right in is the Progressive Dynamics PD4655V which is a smart charger. I intend to do this in the spring when I get my unit out of storage.
I don't pay much attention the WFCO, if solar isn't doing the job for us then I'll fire up the ginny for 2 hours and use my 30 amp automotive smart charger. That is usually enough with the solar taking over from that point. While the ginny is running I switch the refrig from LP to AC, pull the lap tops off the inverter and use the ginny for them also.
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Old 11-23-2016, 11:56 PM   #33
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Hi Oneilkeys
My 2016 Vegas has a WFCO8955 Charger/converter. It does not charge my two house batteries higher than 12.55v which according to HandyBob is about 90% and is typical of a low quality unit. The most mentioned upgrade that fits right in is the Progressive Dynamics PD4655V which is a smart charger. I intend to do this in the spring when I get my unit out of storage.
Roger that. It is my Christmas present. I think it will be a worthwhile purchase and fit in with my RV lifestyle. If I can keep my batteries charged with a little solar and running my genny for an hour a day, I will be happy. The PD4655 gives you the ability to charge at 14.2 continuously providing max charge in a short period of time. Since I never run my generator for more than an hour, I will not worry about over charging the batteries. For those who boondock for long periods of time in the same location, solar makes a lot of sense. For those who plug in at a campground every night maybe one battery and a WFCO charger meets their needs. It just depends on how you use your coach and what your power requirements are.
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Old 02-06-2017, 06:15 PM   #34
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Update - I never did install the solar system. We don't dry camp that much atleast until my wife retires.
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Old 02-12-2017, 07:55 PM   #35
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Photo album is here...

https://goo.gl/photos/tq3f4tc22FXYQxaG6

[Reposted to fix a broken link]
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Old 02-12-2017, 08:01 PM   #36
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Thanks pghali, that's a great looking setup.
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Old 02-13-2017, 12:02 PM   #37
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Very nice install pghali really like the tray. How are the panels attached to the roof? Just screwed? Did you need to locate internal support to screw into?
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Old 02-14-2017, 12:03 AM   #38
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Very nice install pghali really like the tray. How are the panels attached to the roof? Just screwed? Did you need to locate internal support to screw into?
Thanks! I used 3M VHB tape (rp45) to secure the panels. The trick is to have lots of surface area in contact with the roof so that you don't go beyond the rated strength of the tape.
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Old 02-14-2017, 10:02 AM   #39
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That tape is good stuff, I've seen YouTube videos using only small pieces to hold panels. But not on TPO membrane. I've read that the tape sticks great but the membrane isn't adhered to the underlying material as can cause it to pull away at highway speed. Would love someone with more knowledge than me to weigh in on this concern.
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Old 02-14-2017, 12:11 PM   #40
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Converter

Quote:
Originally Posted by Terryo View Post
Hi Oneilkeys
My 2016 Vegas has a WFCO8955 Charger/converter. It does not charge my two house batteries higher than 12.55v which according to HandyBob is about 90% and is typical of a low quality unit. The most mentioned upgrade that fits right in is the Progressive Dynamics PD4655V which is a smart charger. I intend to do this in the spring when I get my unit out of storage.
Terry
I have a 2016 Vegas 25.2 and would like to upgrade my converter. Can you tell me where the converter is located on our coach.

Thanks
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