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Old 11-01-2017, 07:15 AM   #1
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DC power upgrade

We utilize mostly off grid campsites and in need of a better DC system. Most of our equipment is DC now, so avoided the extra burden of inverter load. When allowed we do use the generator for morning and evening high power times and during this time we do use a few AC appliances such as hair dryer and curler.

I've been digging into battery technology, solar, battery chargers and the rest to bone up. It's been two years of wading through much information including miss information or should I say poor information. An over abundance of poor information. To date I thought I would share my current thinking and analysis as this stuff is wholly fogged up by those that want to portray themselves as experts or just attempting to spend your money. Now, my thinking will evolve as new products hit the shelves or new info is obtained.

My personal take-

1. Lithium is not mature technology and to costly at this time. The batteries can achieve much and solve some problems but not worth it for me. Since the technology is in a state of flux, the hardware will become obsolete quicker. They have environmental problems below 30 degrees and high heat will destroy them. To many ways to screw them up, risk to high.

2. Lead acid is the workhorse and most forgiving, except the 50% rule is very important. You will see big drops in amp capacity if violating this rule even once. The loss is substantial if a half dozen or so actions. Yes, golf cart batteries the best of the best.

3. AGM is my choice given that violating the 50% rule doesn't affect these batteries near as much. They are 40% faster recharge which is all important. Because they can accept abuse more frequently as compared to wet cells, with less damage, users experience 2x lifespan.

4. A 75 Hr battery is good enough for my needs, except when it isn't. Meaning sometimes I can't time a generator charge or using the generator is prohibited.

5. A portable solar charger at a cost effective small scale should be a valuable asset when conditions are available to use it. However, i'm not going to change camping lots to facilitate the use. I'm not going to let solar control my camping experience.

6. My truck as most trucks have a robust alternator charging system. They do an excellent job of charging and maintaining your battery and quite efficient at doing so. These systems probably operate for minutes instead of hours. Thats a big minus. Also, modern vehicles have a load of electrical gadgets that can slow the battery recharge rate, especially in winter.

7. The alternator can charge your house battery while traveling and do so pretty well if traveling for some distance.

So, I've come up with this scheme for my needs. My truck fits a dual purpose agm nicely. This same battery a good fit for the travel trailer needs. I mount a dc to dc charger in the battery box of the camper. The device is a modern electronic 8 amp charger. It has safe guards for low source battery power and will not overcharge. It will power the camper and charge battery just like the AC converter. I will back truck up to trailer per usual and plug in the charger for overnight. This will provide excellent recharge for house battery. The generator will still be utilized, but I will also plug in an AC charger for the truck for 2x battery power storage feat. Also, the truck battery will be utilized only for night charging or moderated per my experience. This setup gives me max flexibility for recharge without generator if required. No dependence on iffy solar. Good slow recharge during night. My battery reserve jumps from 75 Hr to 150Ha. I have two good batteries for my trolling motor without any additional weight or cost. Check out Powerstream for dc:dc chargers. I'm thinking all boondockers should have these devices. Recharge you electric bike in the woods, no problem.
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Old 11-01-2017, 07:28 AM   #2
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Oh, most of you probably know the lead acid batteries need to be fully recharged to achieve good lifespan and provide max Ah. To accomplish full recharge daily is a good thing. So, the above strategy becomes most valuable.
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Old 11-01-2017, 09:29 AM   #3
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Interesting.
I have 4 golf cart batteries mounted in the bed of my truck with a 1500 watt inverter.
I run 200 Watts of solar into them when camped, truck battery is wired into the solar charge controller when running.
I used it for a week on just solar last June, it ran everything but the AC... Which I think it could handle if I used my 2500 watt inverter.
I plan on installing the batteries in my new fifth wheel instead of leaving them in the truck... I'm just not sure how to mount the solar panels, I'm not willing to put holes in my new roof
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Old 11-01-2017, 09:31 AM   #4
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i'm not sure lithium is an immature technology or that it will become obsolete soon. I can agree that it is currently expensive. it seems to offer advantages in capacity, weight, and ease of use. everything I read about it is positive and that you can expect at least a 10 year life span. if you were to buy a lithium setup that works for your needs and would last ten years, would you call that obsolete if a better version came out a couple of years later? using that logic we might never commit to anything (even our rv's) as something better is expected later. it's more a question of whether the additional cost provides corresponding additional benefits and that is an analysis that each owner needs to make based upon his needs.
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Old 11-01-2017, 11:05 AM   #5
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Lithium requires care to not suffer high heat. You have a long term term cost justification that otherwise could be compromised if not concerned and acting. Not good. Also, the lithium system I was looking at had a limitation of no battery charging below 30 degrees and no battery use below 0.

I do read blogs and posts that have compers investing thousands to achieve home like power. I read they still run into trouble for instance, if stranded with transmission or engine problems and parked on sunny lot in Texas sun with no power or no battery cooler. Keeping batteries in zero state of charge to long due to extended absence and finding an unexpected battery drain. Camping in shady areas or with no sun for weeks. No one is perfect and sooner or later one is apt to do the battery a disservice.

For my needs having 4x6 is overkill. Most of these folks are 5thers or class A people that want full time or extended stays. They set out with the requirement of grid quality power. I went the cheaper alternative that is common in the travel trailer campers. Utilize propane as it is the cheapest and most powerful source of energy off the grid. I remember my Dad's camper had a gas mattle light that was very comfortable. It acted as a heat source, bright light, and bug killer. Perfect for camping in cool nights. Back then they had no efficient LED lights. Our tv and attached dvd player is 12v dc that is pretty common nowadays. One can look at the AC transformer on the plug and find it is converting power to 12v DC. Cut the cord and plug it into DC works find. Lots of good fans run 12v and same for a small ceiling fans. This stuff and lights take minimal power.

Same for genny. I took the Yamaha 900w as I've found my battery charging needs are low wattage, but for long time periods. So, since our power needs are minimal this generator is obvious choice. The unit runs extremely low fuel consumption. Most of it for us on the low speed runs 1 cup per hour. We have a separate breaker for all duplex receptacles. I keep that off and power these outlets per 12v DC with a small jumper from cigarette plug to common house plug. It's 8 amp fused and will blow first to protect all components if forgetting something. We have 12v LED and 120v LEDs light bulbs for side table lamps. The music and radio system is 12v.

I bought a low wattage hair dryer 600w and my wife likes the 300w setting. The curler is only 60w. The converter doesn't take that much power if off of bulk change and it should be if your treating your batteries right. This is our AC needs for a couple hours per day powered by generator.

I bought a 5,000 watt common window AC. These units keep increasing efficiency and lowering amperage draw. The 900w generator easily runs it, about 650 watts. It should keep the bedroom or kitchen area cool. I figured out a simple two piece mount of wood that is easy to install unit when AC needed. Also, needed a painted insulation board block. This is just a temporary solution as we only camp in off season to avoid crowds. Only needed for some freak weather condition.
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Old 11-01-2017, 03:44 PM   #6
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Trees

I have the common wfco converter and am a bit concerned on their timid charge rate. The best or most recent engineering reports have proved charging rates can increase with no detrimental battery life. The common or old thinking was based on theoretical limits. This may be what wfo is utilizing. Good if you are most often hooked up to utilities. Bad if you boondock. I read once that the 8900 series converter drops the 14.4v bulk charge at 50% DOC. By today's standards way to early. Sure no problem if sitting on grid power, but a problem when the generator is running. These converters work well with AGMs as well.

Not to many campers have good info on this, but their is enough out their to raise the red flag. I have the question waiting for reply from Progressive Dynamics that is front runner replacement.
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Old 11-06-2017, 08:29 PM   #7
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Originally Posted by trees View Post
I have the common wfco converter and am a bit concerned on their timid charge rate. The best or most recent engineering reports have proved charging rates can increase with no detrimental battery life. The common or old thinking was based on theoretical limits. This may be what wfo is utilizing. Good if you are most often hooked up to utilities. Bad if you boondock. I read once that the 8900 series converter drops the 14.4v bulk charge at 50% DOC. By today's standards way to early. Sure no problem if sitting on grid power, but a problem when the generator is running. These converters work well with AGMs as well.
Agreed on the WFCO converters not being suitable for generator recharging (or rapid recharging from shore power). I could never find a WFCO spec for when the WFCO switched from 14.4V to 13.7V. I never caught my WFCO at 14.4V. I also never caught it dropping to trickle charge, either - even after several weeks on shore power.

I replaced it with a "drop-in" PD converter/distribution panel (PD 4135) replacement for the WFCO 8735P. The PD holds 14.4V to about 90% SOC, and reliably goes into trickle after 44 hours at 13.7V. That's about as hard as I want to push the batteries during recharge. It's relatively fast, but won't cook the battery, even in 95 degree Texas heat.

Today's AGMs are designed to handle conventional wet battery charge programming, even though these are sub-optimum for AGM battery capabilities.

just my thoughts and experiences
Fred W
2014 Rockwood A122 A-frame with 2 235AH Interstate GC-2 6V batts ($150 Costco) for 4 nights dry camping without recharge
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camping Colorado and adjacent states one weekend at a time
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Old 11-07-2017, 11:55 AM   #8
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Fed, thanks for the info. You have some good stuff there and in line with what I read. Even the AGM battery recharging. The price on these batteries is dropping as they become more popular. Battery manufacturer is claiming the AGM battery is well suited for the high amp load that modern cars now draw with all the luxury items and hybrid technology. They run this stuff often with engine off. The AGM, to me, looks to be a good fit for travel trailer as well.

I will check out your model. I think PD has a specific one to replace my old converter. Funny, when I over discharged my marine battery and hooked up the generator. Our amperage draw other than battery recharging is very modest. Sure enough the generator would go to high load high rpm per the bulk charging. But, would only run maybe a couple minutes at this high charge rate.
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Old 11-20-2017, 11:20 PM   #9
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Trees, hybrid cars don't use the lead acid or AGM batteries for anything other than starting, and they only start up the computers, not the engine. Upon start, or boot, the car's computers check everything and then connect the main "traction battery", which nowadays is almost exclusively lithium ion based. A few years ago, hybrids like the Prius used nickle metal hydride.

AGM would probably be used more for longevity than any serious load in a hybrid.


On topic, I recently got a 2015 194HW a-frame... and I'm going to do some stuff! I'm looking at a 100Ah AGM battery to use. I have a 100W solar panel and a cheap PWM controller which I'll use short term. I'll just lean the panel up against the camper wherever the sun is best. Eventually I'll put 2x100W flexible panels on the roof, and get a good MPPT charge controller.

Later on, I will put the battery in a rolling box, and put the charge controller, breakers and other bits so it will basically be a "solar generator" like you see people build on YouTube. That way, I can remove the battery from the camper pretty quickly.

My camper does still have the WFCO converter... which I've heard a few times, and in this very thread, sucks kinda bad. I'll replace that with a Progressive Dynamics converter. I'll also be installing one of the wired-in Progressive Industries power management things. That way I never have to worry about the dongle thing going missing.
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Old 11-21-2017, 08:41 AM   #10
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Thanks for the info. You're on top of power needs.

I'm utilizing the truck AGM as stand by power needs of camper and DC to DC charger. A few days ago, I needed a fresh battery to run furnace all night. I disconnected camper batter and utilized truck battery directly. I will get a small DC to DC charger to top off camper battery at night. A long slow charge when not using much battery. Mount the charger in battery box. I can power the charger from extension to trailer plug in truck. This should be a major improvement in battery charging.

I like solar, but still need generator, so I'll may wait awhile with solar setup.

AGM is basically a dual purpose battery, but I did purchase a dual purpose marine AGM. Alternator does an excellent job of charging battery.

I haven't decided on AGM for camper? May just go with inexpensive golf cart battery. Changing out the converter is the key for boondocking. With that change, dc to dc charger, and generator I should be all set. AGM is better, just I may be o.k. with cheaper batteries.

The AGM manufacturers stated the growing popularity of AGM batteries in cars due to the high level of electronic devices. Mild hybrid technology is expected to become very popular. All cars will have some level of this technology. The original plan was 24v AGM system. All pieces of mild hybrid technology had to be very cost effective. Payback one year. A no brainer for inclusion within sticker price.
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