[Archived]

Sounds interesting, Jerry. Will the article be available online somewhere? I might be a good candidate for just such an approach.

[Archived]

Looking forward to reading this article. Will you have the ability to publish / share on PC?

R

[Archived]

Hello,

I am wondering what is the advantage of lithium batteries.. I have a 1998 Featherlight XL and after changing out my 8 4D lead acid batteries to the original 8 4D AGMs they last so long that i don’t know why I would ever change them out.

I have dry camped for 3 days this weekend and keeping my eyes on the meter, I never got near the 23.8 volts needed to auto start my generator. Lights, aquahot, tvs, fridge on, cooktop ect. It was cool so I did not need AC.

I would love to hear thoughts on this.

Thanks

David Thomas

1998 Featherlight XL

[Archived]

Please provide us a link when able.

[gordon]

Hi David,

i am out in the field doing real world testing of this dual house battery set up while dry camping so did not see your post earlier.

Actually, we are in a nice Elks Club along the Oregon coast but not using their power pole. Everything is working flawlessly. Consumption and recharge times are tracking the projected patterns so I am ready to put the finishing touches on the article and tell the publisher it is a go. I will ask if it is ok to post a pre-publication version in the Articles section of this post.

I followed with interest your post about your ability to dry camp for up to three days on 8 4D AGM batteries. That is certainly more than most owners I know could do. Your refrigerator must be either propane or far more efficient than most residential refrigerators. Most refrigerators consume between 100 and 150 amps per day all by themselves so are by far the biggest energy hogs on the 120VAC side. With a 12VDC house system it would be difficult to run AC for very long so I exclude that from my analysis.

Besides running the refrigerator, cooking meals, watching TV, listening to a nice home stereo system, running hair dryers, Cpap Cpapmachines and other normal day to day necessities will consume most of the battery power available for the 120VAC loads every day. In our setup, the way we live in our coach, we use around 60% to 70% of the Li portion of the house battery bank which is devoted to 120VAC loads each day. Because it is not cold where we are we are using less than 50% of the lead acid (AGM) portion of the house battery bank that is devoted to the 12VDC loads.

‘The best living pattern that is emerging from both my theoretical calculations and this real world testing is to run the generator for an hour in the morning while cooking breakfast and heating water for showers and for an hour in the evening while cooking dinner. Our two Magnum 2800 inverter/chargers are set to CC/CV (constant current/constant voltage) with 14.4 VDC supplied to the 400 amp hours of Li batteries. That brings them to full charge quickly with just these two generator hours per day. The Progressive Dynamics 9270 converter/charger sees the AGM AGM batteries as being only partially discharged so leaves itself in absorb ot float mode unless I manually push the boost button which forces it into bulk charge mode. If in bulk charge mode, they come up enough during these two generator hours to keep them well above 50% day in and day out. If we were dry camping in cold weather the additional 12VDC draw of the Webasto heating system plus the reduced cold weather performance of the AGMs AGM batteries would perhaps require longer generator run times, perhaps three hours per day to keep the AGMs AGMs performing up to snuff.

I left solar off so I could get a good read just from the generator as the only source for recharging both halves of the new house battery bank. When we are south of the 37th parallel this winter I will add solar and upgrade the tests to see how much that changes anything in the real world.

In the article I make the point that no two people live the same way even if in the same coach so what is adequate power for one might fall short of expectations for another. Your experience of being able to dry camp for so long on AGM batteries alone certainly bears that out. And, to answer your question, given your experience with what you now have, I would recommend you not change a thing!

For others of us, to get the benefits of Li batteries with only half or so of the up front investment while also being able to enjoy the life remaining in our existing lead acid batteries is a real win-win.

Jerry

[Archived]

There will be no problem posting your article in our articles section if you like.

[Archived]

Hi Jerry,

Thanks for the infput..my fridge is a full size home type samsung..we don’t use hairdryers, and weather was so nice we did not use our Aqua Hot except for showers. We do go out during the day a lot and always use house master switch to turn off all lighting…In the evenings we tend to to to be early and have all lights off with just TV running… We only use cook top for breakfast and I use the grill the rest of the time.. Another point is my fridge and freezer is always crammed pack, maybe that is keeping the compressor for kicking on as much.

Maybe we are just using power less them most.

Thanks

1998 Featherlight XL

[Archived]

Jerry,

I’m sure you’re aware that charging your AGM’s for such a short duration in absorb will degrade the life of your batteries, as they will never be fully charged.

I applaud your project, but I can’t really see folks wanting to take on this conversion merely to reduce the cost of LI, most will go all AGM or LI and be done with it.

Ditto what Jon said, feel free to post in our articles section.

[Archived]

Batteries have specific changing requirements based on the type of batteries. I am sure it is possible to have two specific types of battery systems for the conversion as long as each type of batteries has charging specific to the type battery. I expect the article will address that.

For those owners who may not be aware, as Tom points out proper charging is critical or a battery’s life can be adversely affected. In fact battery manufacturers are usually insistent that if a set of batteries has one go bad, all batteries in the set should be replaced with batteries with the same date codes because even trying to charge a set with batteries of different ages can be a problem.

Batteries are very important to our enjoyment of our coaches and as such need to be treated very well.

[Archived]

Yes, proper charging of both types of batteries is very important to longevity and properly recharging both lead acid and lithium batteries from the engine alternator, from shore/gen power, or from solar is covered in the article. Tom, as a battery supplier you may have a different experience than I have based on feedback from my previous articles and presentations. That feedback has mostly been how the viewer or reader likes the idea of going to lithium batteries but just can’t justify the up front cost and they say they are not willing to give up the life remaining in their existing lead acid batteries.

I designed this dual house battery bank system to address both those concerns directly. There does seem to be a consensus at this point that being able to gain the advantages of Li with half to two thirds the up front investment and still use out the remaining life in the lead acid batteries is seen by most as a win-win. Time will tell.

My testing on this short trip has shown real word performance to be right in line with design expectations. The unexpected part is how easy it is for average owners to do and how flexible the fine tuning options are in terms of getting the system to match how each individual lives day in, day out in their coach. In our case, based on this testing, I will be removing one more of the 8D AGM lead acid batteries and keeping the four LiFePO4 batteries I started with. That will leave us with 4 Li and 3 AGM batteries instead of the six 8Ds we started with. One generator hour during breakfast and one generator hour late in the day consistently leaves us with 30% to 35% capacity the next morning on the Li side (which only powers the 120VAC loads) and close to the same on the lead acid side (which only powers the 12VDC loads). For dry camping that is right where you want to be.

Once we get south this winter I will bring a small amount of portable solar into the picture (440 watts to begin with) to see how that impacts things. Our travel this year will be more sitting (including two months at The Palms RV resort in Yuma, AZ, and two months on the beach in Mexico) than has been our routine in previous years. That will mean more reliance on power poles and less dry camping, but I still like the dry camping option while traveling from place to place and while visiting friends and family.

I will be happy to answer specific questions as they come up and will let you know if/when the publisher and sponsor gives the ok to posting the article here. Thanks to Jon and Tom for letting me post it here once cleared.

Jerry

[Ron]

Jerry , on our coach all power is ran through the Inverters , so how would you deal with a situation as such ?

We also have 8 4D Lifelines . We also dry camp for extended time but unlike Dave I need to run the genny 2 hrs in morning and I like to also run 2 hrs in the evening . I never go under 70% or so . The way I understand it is you can only go 50% so many times so why do it . I also believe Vantare has the most quiet Genny box so to be honest what’s so wrong with running her a few hours a day .

Now one day I hope to have solar and LI just so like Jon i can say I do 🙂 and also help Tom for when heeds to repair that over the road truck lol

[David]

Each owner is going to have many choices when it comes to the purchase and management of batteries. There are few absolutes. One of the most critical absolutes however is if a set is maintained properly the life of the batteries can be greatly extended. Sometimes good battery maintenance interferes with ease of use so again, it comes down to choices for owners.

If batteries of all types get recharged by the time the state of charge reaches or is greater than 50% the number of charging cycles increases significantly compared to batteries that get charged via autostart when the selected voltage is significantly lower than 50%.

The cost of batteries is always going to be a factor and whether an owner views the coach as a long term purchase or something to be flipped every several years is a factor.

Now that we have two viable options with significantly different costs and performance making a choice is now difficult. To further confuse that decision is a coach with 6 8D batteries, never or rarely used for dry camping could be used by the owner easily with 2 8D batteries. The only problem is a future buyer may make heavy use of batteries in dry camping so what works for the owner today may not add, but may reduce the future value of the coach.

With LiFePo4 batteries that are “drop in” we have entered a whole new world. Further confusing owners is the fact the Li batteries may easily replace existing batteries, but with fewer batteries required. An owner has to determine if the switch to Li is justified with greater life, more power available per cubic inch, or less weight, or perhaps a blend of all three.

We are not yet at the point where some battery changes are justified. I recently switched 4 8D AGM for four 8D equivalent Li. It would take at least ten years of AGM purchases to break even, and for the projected remainder of the 35 year life of my Li, I am money ahead. I will not even try to make sense of my choice other than to say if things go as planned I will never change another house battery, nor will the next owner, nor the one after him.

A Li switch can be competitive with AGM if the buyer only buys the equivalent useable amp hours, or if the number of batteries is reduced greatly because of less need for battery power. My point to all this rambling is to make battery purchase decisions based on all the different factors, including battery life, amount of useable power needed, how the batteries are maintained, and where the coach will be used.

Li is definitely going to be a greater factor in the future, but it should be used for the right reasons.

[Jim/Chris]

Al,

As a general rule for Lifelines, 30% DOD would require about 2 hours of charge time and 30 – 50% would need 3 hours, so your doing good. The difference in life cycles would be about 2000 for 30% DOD and 1000 for 50% DOD. There are a bunch of variables like temperature, charge voltage, battery size, but in the real world, 2 – 3 hours is where most will be on charge time.

[Dan]

Erika and Al,

In my normal travels I never dry camp this long without being on a pole o running my generator..this trip was an outlier. It is rare that I don’t need heat or AC..this was just the perfect weather trip.

You are correct on my generator, I can’t hear if from inside the coach and outside standing right by the generator bay door, it can barely be heard.

I agree on babying the AGM’s and do so as i have been listening to Jon and the group for all there thoughts on keeping the batteries in the best shape possible.

Thanks

David Thomas

1998 Featherlight XL

[Chad]

A few thoughts for you to consider on battery use.

1) your residential refrigerator is the biggest power hog in your coach. It will require between 100 and 150 amps each and every day you are dry camping. Look at that number in comparison with the capacity of your battery bank to see how big a load that really is. Now add in all the other 120VAC loads you use day in and day out.

2) When new, lead acid batteries of the 4D size will be rated for between 200 and 220 amp hours of capacity. That is what you pay for, but you can only access between 100 and 110 amp hours without damaging the lead acid battery. An 8D is a bit larger and will be rated when new at between 200 and 250 amp hours of capacity of which you can access only 100 to 125 amp hours. Once you start hammering those lead acid batteries with high amp draw applications like running your 120VAC appliances through an inverter, those capacity numbers will drop – sometimes significantly. The easiest way to think about capacity is to consider one 100 amp hour rated Lithium battery from a well known supplier to be equal in real world capacity to one 4D or 8D lead acid battery. it makes little difference if the lead acid battery is called SLA, AGM, flooded, or GEL.

3) Always check the amp draw of anything you plug into your wall outlets. You might be surprised to learn that some Chinese 120VAC induction cook tops will draw 10 to 12 amps every hour while they are plugged in and turned off! That means that every day they are plugged in, even when turned off, they will eat up as much as 240 amps of your battery capacity doing nothing. Some home stereo systems or older flat screen plasma TVs will also have high parasitic power draw even when turned off. The easiest way to check is to unplug everything in your coach where you can get to the wall plugs. Note on your inverter display the number of amps currently being supplied through the inverters. That will be the power draw in DC amps. That is the draw for all the things where you cannot get to the wall plugs. Now plug in one appliance at a time, wait a few minutes and read how many more amps are required to power that one appliance. Write it down. Go on through everything you plug into a wall outlet and you will find the real power hogs.

4) The way to know if you have enough battery capacity to effectively dry camp the way you live in your coach is to look at the battery capacity when you first get up in the morning. If that reading is between 20% and 30% of battery capacity remaining you are good to go. Keep doing whatever you did to get there. If it is lower, then you will either need to run your generator longer each day or add/change the battery capacity or type.

5) Solar supplies much less real world power than you might hope. A typical 100 to 120 watt solar panel will produce between 4 and 6 amps per sun hour. Sun hour is a calculation made by USDOE of the equivalent hours per day the sun is at the right angle to your panels to deliver full amps. Your panels may be exposed to the sun for longer, but much of that time will be at the wrong angle to do you much good. Depending on where you are parked, how you angle your panels, how clean they are, no shade, etc., you will average 4 to 6 sun hours per day. That means you will be able to put back into your batteries between 16 and 36 amps per panel per sunny day. Way less than that if it is raining or cloudy. Remember that residential refrigerator that eats up 100 to 150 amps each and every day? How many 100 to 120 watt panels will you need just to service that thing? And, keep in mind that most everything in the solar business is rated at max capacity, not at what you are likely to get in the real world.

6) voltage is a lousy way to try to estimate capacity left in a lead acid battery of any type. Voltage is only indicative of state of charge and only if the battery has been at rest for hours neither being charged or discharged. 12 to 12.2 VDC at rest for hours is 50% discharged. The only way really to measure capacity or state of charge is with a shunt based battery monitor. They are not very expensive but buy one from a known marine supplier, not an eBay cheapy that may or may not be anywhere near accurate.

More later.

Jerry

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1984 96" with 8V92TA

(remodeled Liberty Coach)

Greenwood, MO