Advancing Alvar

[avanti]

Originally Posted by Davydd

There has been a lot of discussion about state of charge (SOC) and what is best for lithium ion batteries. There is a common belief that SOC is best hovering around 60%. I am not sure how valid that is as most of what I have research has been anecdotal.

I fully support your wish to keep your van powered up. I often do the same thing.

BUT, the claim that storing LI batteries with a middling SOC is optimal for battery health is not "a common belief", it is established science.

Battery manufacturers such as Panasonic say so:
Battery Storage FAQ, battery manufacturer's recommendations for storing batteries, storing lead acid, sealed lead acid, NiCad, NiMH and lithium ion batteries

Cadex says so:
Chapter 15: Caring for Your Batteries from Birth to Retirement

Woodbank (UK) says so:
Battery shelf life and battery storage recommendations

Battery University says so:
BU-702: How to Store Batteries – Battery University

As I have previously reported, both Apple and Tesla say so.


There is absolutely nothing wrong with choosing to keep your batteries fully-charged if you find it convenient--they are meant to be used. But, unless you can cite a reliable source to the contrary, I see no reason to doubt the generally-accepted guidelines for optimal long-term storage.

[Davydd]

Avanti,

All those sources you cite are for long-term storage of disconnected batteries. As I mentioned I am keeping my batteries active and plugged into shore power through the winter for a reason.

1. As I mentioned, even though I don't use the van as a daily driver, I am in and out of it frequently. This will be our first winter at home and I am already treating it like a man cave because it is so much more comfortable than our previous Bs.

2. I did just use it on a 5 day trip this past week after winterization.

3. I could disconnect the batteries and let them go cold over the winter but do anticipate one or two winter camping trips and definitely Mike Wendland's Freezeout Adventure. In order to do so I have to maintain battery temperatures above freezing, thus plugged into shore power, though I have a method to bring the temperature back with external heat outdoors even if below 0 F. if needed.

When I mentioned the 60% SOC, under the circumstances that is an anal recommendation if anyone thinks they are going to drive around and use their van within that narrow range. Yes, I have read that numerous times as a recommendation and think it stupid. As I have previously mentioned, I drive almost every day on the road. That means a typical overnight use of battery energy is going to recharge back to 100% in generally under an hour.

I have mentioned I also like to keep the inverter on 100% of the time while boondocking so as to have a fully functional van all the time electrically same as being plugged into shore power. That includes heating, no propane electrical cooking, coffee brewing, lights, fan, incidentals but not air conditioning. Another reason is our articulating beds run off 120vac. I am constantly adjusting them. I now know I can sit 3 days that way with ease which is about my mental antsy state of mind limit anyway since I like to move. I figure if I carefully monitored my electrical use, turned off the inverter, and behaved identically as I did with my previous Class Bs, I could go a week which coincides nicely with tank dumping and water replenishment.

I think the most unique thing about lithium ion batteries is the need for their temperatures to be above freezing in order to accept a charge without damage. That drives a lot of decisions. BTW, my battery bank is sealed and the whole protected iron assembly weighs over 400 lbs. There is not an option of removing them and putting them in a cool basement over the winter.

[Davydd]

Originally Posted by booster

The whole idea of how to define the state of charge is pretty interesting, and arbitrary, I think. You have to define the zero and 100 percent points, and that is up to interpretation depending on how you define it. Then you put a safety factor on each end over the zero point and under the full point by what ever percent you chose. So pretty clear to that point.

Then you get to define how you make the meter read. Is 0% start of charge really zero charge or with safety factor? If 100% really full or with a safety factor on it? How that is done would determine how your meter reads SOC. It could be zero to 100% or it could be (picking random factors) 20% to 90%. I wouldn't count on Roadtrek's 10% to line up with anybody else or Smart Battery's run to zero percent really being zero for anyone else. None of it really matters, if you know how they did it, like davydd does.

It is very interesting that ARV is starting to cycle the batteries on charge. We have to assume it is to address the "don't leave them full and on charge" problem that has been discussed a whole bunch here. It is also the profile the Magnum has been recommending for lithium, basically their CC/CV program with a shut off and rebulk when the voltage drops. What it isn't is the Progressive Dynamics constant full voltage on full batteries setup on their charger, which is probably worth noting.

Good information.

I originally thought when I was reading my Silverleaf screen I was thinking the SOC went from 0 to 100% over the whole 800ah battery bank. I have since learned the 20% was locked out meaning if the batteries ever got that low they would disconnect. That means on the screen 0% means there is still 20% battery life. Now I have to go back and see how my calculations were affected because 1% would be 8ah used up over 800ah and 1% of 640ah would be 6.4ah. So, when I wake up in the morning and see 82% SOC (typical of a Walmart stop) that would mean about 115ah used instead of 144ah.

My Autogen setting is programmable. I can turn it off or I can adjust it to start the engine at any percentage but that percentage as I mentioned is going to be higher over the whole 800ah than 20% as I mentioned. I don't know how Roadtrek calculates it but it appears it is fixed based on voltage that equates to a 10% SOC and that's when Voltstart comes on. My experimenting with my Autogen is if you have a lot of power use on there is a delay in start up and you could slam right through your programmed SOC. My question is if running an air conditioner would the Voltstart come on a delay after triggered by the 10% SOC setting and be somewhere in a lower SOC before coming on? If I remember those battery curves there is a sharp drop off in lithium batteries that actually start higher than 10%.

I think the high end does mean 100%. At least mine reads 99% most of the time and I doubt there is a programmed 20% reserve on top of that.

That is the other unique aspect of lithium ion. There seems to be no forgiveness for overcharging or complete depletion of the batteries.

[gregmchugh]

Probably better discussed on one of the Ecotrek or Voltstart threads but there are now multiple reports that Roadtrek is, at least in some cases, installing an add-on AGM battery in vans that were supposed to be pure lithium. My personal speculation is that it is to resolve issues with triggering Voltstart but it could also be for another issue they have found.

I will add a comment in one of those threads also on this...

[Davydd]

I just successfully tested my battery system while plugged into shore power. As I mentioned before I had it reprogrammed last week, shore power would quickly bulk charge batteries up to 100% and then hold a 99-100% charge by constantly replacing amps as they deplete. It was kind of like watching a ping pong match on the Silverleaf monitor screen with amp numbers jumping up and down. The newly reprogrammed system is suppose to charge up to 100% and then turn off until the batteries deplete down to 90%.

First, I found that with all 12V system draws turned off, except my wifi router and cell phone booster, there is an almost steady 5 amp draw from those two things plus the Silverleaf controller, alarms, parasitic and whatever. That would mean it would take 13 hours for the batteries to draw down to 90% SOC with no charging. I went two days trying to catch the 90% moment to see it change over. I was either away or it happened in the middle of the night. So this morning I turned on every light, the back radio, the 12V refrigerator and got the draw up to anywhere from 12 amps to 18 amps if the refrigerator was actually running. The electric heat from the Rixen Espar system drew directly from shore power as did the electric floor heat. While on shore power the inverter was off. But in this test I could draw no more than 18 amps which got me about a 4 hour wait.

I caught the moment and it performed as it was suppose to. As soon as it hit 90% SOC shore power started bulk charging at a default low power rate of about a net 40 amps which means it should recharge from 90% up to 100% in about 40 minutes and then start the 13 hour no charge cycle again. A high power rate which my 30a electrical service can provide will recharge in less than 20 minutes but is not necessary. This is supposedly better than just leaving the batteries constantly at full charge while plugged in for winter storage.

Other things I learned while plugged into shore power is the Outback inverter/charger is off except for the battery charging for the short period of time. Shore power goes directly to the 120V systems for the Rixen Espar electrical heat and hot water, and the underfloor heating pad. The Rixen diesel-fired heat brings the van temperature up to its temperature setting fairly quickly. The electric heat probably won't be adequate on its own with below freezing temperatures so I could still probably carry one of those ceramic 1500w cube heaters when plugged into shore power if I don't want to expend diesel fuel.

[avanti]

Originally Posted by Davydd

The electric heat probably won't be adequate on its own with below freezing temperatures so I could still probably carry one of those ceramic 1500w cube heaters when plugged into shore power if I don't want to expend diesel fuel.

Don't forget that there is often a heat-strip in the air conditioner as well.

[Davydd]

I don't think there is a heat strip in my air conditioner. I suppose I should check. The controls are through the Silverleaf screen. With the air conditioning right over the beds I never cared for it anyway. The heat strip on my Great West Van never got used in favor of the ceramic cube over it and the Suburban. If the electric heater turns out not adequate I could just use the diesel-fired heater. I know that works well and it really does not use that much diesel to worry about it.

I'm testing and experimenting for Mike Wendland's Tahquamenon Falls Freezeout get together this January. It should be fun. It meets all my needs -- snowshoeing and a brew pub.

[Applegater]

We have had both a heatstrip in the airconditioner as well as a heatpump/AC. The heatstrip did very little, we used a small ceramic heater. The heatpump worked well but was a lot noisier than a ceramic heater. Like David we will use a small heater.

[Davydd]

Dang it took me nearly 11 months to verify the last piece of information about keeping lithium ion batteries above freezing. Who would have thunk I would have had to wait until December 18th in Minnesota?

The air temperature finally went down to 17 degrees this morning and sustained itself below freezing for over a 24 hour period. For one thing the battery temperatures are consistently 10 degrees above ambient and as high as about 20 degrees above when under a load. That has been my observation. This is a photo of the lithium ion battery status for each cell reporting voltage and temperature this morning. The "Heat" button you see is set to turn on as indicated by the green tabs. If I touch it I can turn it off but there is no need. If heat is not needed it will automatically stay off. But once the battery temperatures reach, I think, 41.1 degrees F. (5 degrees C.) the electric heating pads will turn on and bring the temperature up. I took this photo at about 6:20 AM. The little flame indicator next to the heat button indicates the heating pads are actually on. I went back out at about noon today and that flame indicator was off but the lowest battery temperature dropped to 41 with outside air at 23 while I was watching. So, I checked again an hour later and that flame indicator was back and the battery temperatures were back up. So it appears to be doing its job. It will turn on and off as needed.

I just had a software upgrade on the Silverleaf that put the heat button on the screen. Before I had a small round button toggle switch but had no way to know if the heat was actually on other than looking at the battery status screen temperatures. Now I know when the heat actually goes on and off.



Watching this stuff is like watching paint dry. Watching it in snatches is hit or miss. I had no way to speed up the process the way I did with running down the batteries to see how the battery pack floated between 90% and 100% SOC when plugged in.

[mikes47]

David, have you heard anything about MAXIMUM battery temps? Last spring as we were touring the southwest, the battery temps displayed over 100 degrees at some points. Given the time of year and the ambient temps, the batteries are closed up inside a box, so maybe that's fine. Given that LI batteries don't like to be charged when too cold, I wondered about whether there is a corollary on the high end. Can't say that I notice any bad outcomes.

[Davydd]

Our battery specs say they have an operating temperature range from -4 to 149 degrees F. Frank said 145 to me. I asked this question of Frank in light of the report by Technomadia that used the same batteries. He wasn't concerned. Technomadia had degradation and speculated some of it was temperature related. Of course they lived in the southwest through the summer months with their batteries in for the first three years I believe in an unvented space including a 7 week stint sitting on hot asphalt in the summer. They said the temperature that might contribute to lifetime degradation was 109F. They got that from Elite Power Solutions the distributor of our batteries. When you talk about batteries it seems every measure is on some kind of charted curve.

The warmest day on the road for me all this past year was 87F. At home this summer we went over 90F just a couple of times. My battery temperatures exceeded 100F a few times. They shot up real high one time when the batteries were equalizing and I called Frank about it. They never came close to the maximum. I would guess you and I in the upper Midwest encountering occasional heat probably don't have much concern.

Technomadia covered several more points that could have contributed, so who really knows how much heat contributed to it? The other contribution points Technomadia brought up were:

Over floatation: We get a lot of panic around here about that, but then looking at all the sources it came down primarily in regard to battery storage being happy at a lower SOC. Technomadia's take was bouncing around from 85-95% SOC instead of 100% was the happy point. As I pointed out you are going to fully charge in a matter of minutes. ARV is now programming a bounce between 90 and 100% as I described. In effect when you are parked your batteries are resting (mine typically a half day.) That is probably the best compromise to the question and something Technomadia was not doing.

Lack of Balance/Laggard Cell: We have built in automatic cell balancing. Technomadia didn't have that. The didn't have the individual cell computer chip sense boards we have to tell us voltage and temperature of each cell. Back to that temperature question. Technomadia could only speculate about it because they didn't have a way to measure cell temperatures.

The Edge Was Bleeding (and Still is): We have better batteries than Technomadia got in 2011. It is an open question about improvements. For those waiting for lithium ion technology to mature in another 5 years I find bemusing because I am at an age that waiting is just lost time. I may not even have an RV in 5 years.

That's a lot of stuff to mull over. Their performance degradation was 25% over 3.5 years, but keep in mind their lifestyle was destroying AGM batteries in as little as a year. They just may have been testing to the extreme. We may yet have some unknown problems but I am not fretting over it. I had a moisture problem interfering with the communications and causing a shut down that I think has been solved. I think Advanced RV has pretty much addressed the known as much as possible.

Here is Technomadia's article:

Living the Lithium Lifestyle - 3.5 Year Lithium RV Battery Update

[Boxster1971]

Originally Posted by mikes47

David, have you heard anything about MAXIMUM battery temps? Last spring as we were touring the southwest, the battery temps displayed over 100 degrees at some points. Given the time of year and the ambient temps, the batteries are closed up inside a box, so maybe that's fine. Given that LI batteries don't like to be charged when too cold, I wondered about whether there is a corollary on the high end. Can't say that I notice any bad outcomes.

The folks at Technomadia mentioned the ill effects of high temps on the life of their lithium batteries, the same brand used by ARV.
Living the Lithium Lifestyle – 3.5 Year Lithium RV Battery Update | Technomadia

On edit I see that David already mentioned Technomadia's article.

Also all production Electric Vehicles with lithium batteries have both battery heating and cooling systems.

[Davydd]

Originally Posted by Boxster1971

The folks at Technomadia mentioned the ill effects of high temps on the life of their lithium batteries, the same brand used by ARV.
Living the Lithium Lifestyle – 3.5 Year Lithium RV Battery Update | Technomadia

On edit I see that David already mentioned Technomadia's article.

Also all production Electric Vehicles with lithium batteries have both battery heating and cooling systems.

I just covered that in great detail in the message just above yours. Did you not read it?

On edit Technomadia dismisses some comparisons to electric vehicles and use of batteries. Their batteries are not the same either. At least Tesla's aren't. Technomadia used 100ah cells. ARV uses the 200ah cells. They are both from a company called GBS and Chinese I assume like almost all lithium ion cells you can purchase. In real observation I don't see how heat is going to be an issue with mine.

[Boxster1971]

Originally Posted by Davydd

I just covered that in great detail in the message just above yours. Did you not read it?

On edit Technomadia dismisses some comparisons to electric vehicles and use of batteries. Their batteries are not the same either. At least Tesla's aren't. Technomadia used 100ah cells. ARV uses the 200ah cells. They are both from a company called GBS and Chinese I assume like almost all lithium ion cells you can purchase. In real observation I don't see how heat is going to be an issue with mine.

I responded to Mike47 before I read you post. They showed up on different pages on my iPad. If you stay away from really hot places, like you do, then the LiFePO4 batteries will do OK. Time will tell if these batteries can live up to their manufactures cycle claims without total climate control.

[Davydd]

Originally Posted by Boxster1971

I responded to Mike47 before I read you post. They showed up on different pages on my iPad. If you stay away from really hot places, like you do, then the LiFePO4 batteries will do OK. Time will tell if these batteries can live up to their manufactures cycle claims without total climate control.

I think I mentioned I never encountered temperatures of over 87 degrees on the road for 152 days this past year and over a decade rarely traveled where I even needed air conditioning. My record day was 100 in Kansas. Since the batteries have an operating range up to 149 degrees I would question just how acute heat was actually the culprit Technomadia claimed. It seems it was but just one contributing factor among many and they never had a way to verify it. So, I would say I don't have much to worry about in the too hot category. Any attempt at cooling would be wasted on me and I imagine the majority of people.

I have been monitoring the other end this month now that we have cold weather. The battery heating system has two prevents for charging below freezing. The first is the batteries would simply disconnect and not be chargeable if the cells got that cold. The second are the small heating pads embedded with the batteries. They come on and go off as needed. So far, the batteries stay consistently in a range between 41 and 50 degrees with an average around 44 for all cells with temperatures down to about 7 degrees so far this month. More times than not, when I check the status, the heating pads are off. It doesn't take much energy to keep the batteries well above freezing.

Technomadia only lost 25% functionality in their batteries over 3.5 years despite what I considered extreme abuse by them among the several factors. Even if that happened I have enough battery power to continue to use my B and travel as I have for longer than I anticipate keeping it.

So, when everyone else says they will wait 5 years for technology to catch up I figure if still traveling and enjoying 24/7 a fully functional electrical use B off grid that I will say, "Welcome to the joy of true independent travel." I seriously don't know if I will be traveling as much in five years and I doubt many on this forum will either. In the past decade I've seen quite a turnover with the people I have met on the road. Time in this crowd is precious.

[avanti]

Originally Posted by Davydd

So far, the batteries stay consistently in a range between 41 and 50 degrees with an average around 44 for all cells with temperatures down to about 7 degrees so far this month. More times than not, when I check the status, the heating pads are off. It doesn't take much energy to keep the batteries well above freezing.

One reason this is true is that a discharging Li battery is exothermic, so there is a self-heating effect. Your heating pads would be much more important if your vehicle were completely shut down.

[Davydd]

Originally Posted by avanti

One reason this is true is that a discharging Li battery is exothermic, so there is a self-heating effect. Your heating pads would be much more important if your vehicle were completely shut down.

The self heating effect is anywhere from 6 to 20 degrees in my observations so far. 10 degrees is a pretty good assumed average when sitting with little load. If that held then getting down close to 10-25 degrees the heat would be needed. If I was completely shut down then there would be no charge to the batteries and they can get as cold as they want as there would be no charge or discharge, and of course no functional use of the B coach. Heating them would not be practical nor I think possible via being plugged into shore power. The heating pads are 12V and get their power off the batteries. Shore power of course charges the batteries.

The problem of course is if one wanted use the B one could not use it until such time they brought the batteries back up above freezing by being in a conditioned space like a heated garage, drove south to warm weather with no use of the coach electrically until the batteries came back up above freezing, or by applying an external heat source. The last I have figured out using one of those oil-filled electric portable radiators set flat on a mechanic's creeper and slid under the battery box. That was tested and worked. You can bring batteries back up when it is 0 degrees outside to 50 degrees in under 24 hours. How do I know that? I let the batteries automatically shut down and disconnect when they approached 32 degrees with the heating pads turned off. However, I prefer to just stay plugged in as I am in and out of the B all winter. That is the simplest.

[Jostalli]

I don't know what to think about Technomadia's articles related to their LiFePO4 batteries. I don't see any real technical reporting so I can't take it too seriously. They aren't experts in the field. Just early adopters. None of the guys on cruisersforum.com reported 25% loss after 3.5 years. I don't recall reading anyone report a loss at all. Some of these boats have had the same packs for over 5 years.

[avanti]

Originally Posted by Davydd

Heating them would not be practical nor I think possible via being plugged into shore power.

Why is that? Couldn't the heating pads be powered from shore power until the battery got warm enough for the charger to turn on?

[Davydd]

Originally Posted by Jostalli

I don't know what to think about Technomadia's articles related to their LiFePO4 batteries. I don't see any real technical reporting so I can't take it too seriously. They aren't experts in the field. Just early adopters. None of the guys on cruisersforum.com reported 25% loss after 3.5 years. I don't recall reading anyone report a loss at all. Some of these boats have had the same packs for over 5 years.

I agree with you. I had voiced some of my opinion in message #851 about it. It seems a lot of people have taken their observation as gospel and steered away from LiFeP04. Keep in mind these are the same people who have admitted destroying AGMs in a single season. They max out use.