Roadtrek Ecotrek and Voltstart

[Davydd]

Originally Posted by gerrym51

idiot lights do not work with lithium

So how does one know the status of their batteries in a Roadtrek?

[gerrym51]

Originally Posted by Davydd

Marko,

I'm no expert in regard to mixing batteries like AGM and Lithium Ion other than to suspect Rube Goldberg's lesser brother is adding more complexity onto something already in a state of confusion. The question I guess is does Roadtrek regulate two different charging profiles? I was only addressing the auto start features.

The lithium ion batteries living in a state of partial state of charge is a strange one. It makes no sense and everything I have read has been anecdotal speculation and a lot of meaningless nonsense in practicality. I've asked Advanced RV about this and it has been double-check with Elite Power Solutions the distributors the GBS lithium ion batteries I have. They have nothing to substantiate this. With the amount of cycles they have been tested to it would be a matter of non-concern anyway. To go 5,000 cycles would mean fully charging every single day for over 13 years. Over charging is a concern. Charging at below freezing is a concern and totally discharging is a concern. A good system would have all those safeguards built in. Advanced RV put the DOD at 80%. Roadtrek is a little more reckless at 90% DOD. Mine float at 99% SOC no matter what the charging source is applied. If I plugged into shore power, was under full sunlight on my solar panels and ran my engine alternator all at the same time it would bulk charge at over 300 amps input until it reached 99% SOC and then stay there and only accept additional charge to replace discharge which is about a rate of 6-10 amps per hour. I've set my DOD arbitrarily at 70% which is more conservative but have yet to reach that point where auto start would come on to charge. I think it would be very difficult to keep lithium ion batteries at a partial state of charge in a Class B when just a little bit of driving fully charges them each day on the road.

Davydd - marko is right- LFP batteries are better when left stored at about 60-70 percent. AGMs need to be constantly full charged

[markopolo]

Davydd's batteries are never stored. The system has been in use basically since day 1. I'd go with what Elite and ARV says for that.

[Davydd]

Originally Posted by gerrym51

Davydd - marko is right- LFP batteries are better when left stored at about 60-70 percent. AGMs need to be constantly full charged

I'll say it again since I must be writing to the ether.

"The lithium ion batteries living in a state of partial state of charge is a strange one. It makes no sense and everything I have read has been anecdotal speculation [such as here on Class B Forum] and a lot of meaningless nonsense in practicality."

Now I will add stupid to have lithium ion batteries bouncing around in a 40-50% range which would be less than an AGM range for little or no benefit even if there were some nugget of proof. Then I would venture to guess you could not easily regulate that range let alone the practicality of trying. Everyone on this board has been agonizing about how to keep from over charging. Then what part of 5,000 tested cycles (ARV's number) doesn't anyone understand? 13+ #%*& years! I guess you want to reach 7,000 cycles living with a crippled system?

[markopolo]

Davydd - what is the DC voltage in your system at say in the middle of the day now?

I think you're missing the point about it being an advantage to not have to worry about SOC with lifepo4 batteries.

And of course you want to fully charge them when in use so that you get the capacity you spec'd.

There is mixed info out there about float charging or not float charging. I can find support for both.

[avanti]

Originally Posted by Davydd

Now I will add stupid to have lithium ion batteries bouncing around in a 40-50% range which would be less than an AGM range for little or no benefit even if there were some nugget of proof.

There is nothing stupid about it. There is no question whatsoever that keeping a LI battery fully charged will shorten its life. You might decide that you don't care and that you don't expect to ever see your battery wear out, but it is a fact of physics. There is a message in the Tesla battery management system to the effect of "Repeated charging above daily usage may limit battery life". You get it if you needlessly top-off your battery when your daily driving habits would permit partial charges. The same logic applies to your ARV if maximizing battery life is a goal.

As Marko suggests, the capacity is there when you need it. But it is better not to use it when you don't.

[gregmchugh]

Back to my question on discharging a bank of mixed AGM batteries and Lithium battery modules, all 12 volt and all connected in parallel. I don't think I saw a response that indicated that there were any issues except for deciding the voltage the Lithium Battery Modules should use to take the battery module offline during discharge and what voltage should be set to start the generator for recharging. Any other technical issues during discharge?

[Davydd]

Originally Posted by markopolo

Davydd - what is the DC voltage in your system at say in the middle of the day now?

I think you're missing the point about it being an advantage to not have to worry about SOC with lifepo4 batteries.

And of course you want to fully charge them when in use so that you get the capacity you spec'd.

There is mixed info out there about float charging or not float charging. I can find support for both.

The best advice for storing over winter or any long term is to stay plugged in if you can. If you can't, then totally disconnect the battery. A lithium ion battery will stay viable up to a year in disconnected storage mode. In the case of plugged in the SOC will rise to 99% in a short time and then stay there. As voltage the average cell is generally about 3.35v and four in series for a nominal 12v battery is about 13.4v. While parked, I mentioned several things stay on including the inverter, the Silverleaf screen, two wifi routers, audio visual, cell booster, parasitic, alarm, etc. That ranges up to about a 6 amp continuous draw. If I keep the refrigerator on when traveling it would be about 10 amps. The charging then floats and replenishes that draw to stay at a steady 99% SOC while plugged in or when driving. There is no overcharging. You can watch the interaction on the Silverleaf screen.

Originally Posted by avanti

There is nothing stupid about it. There is no question whatsoever that keeping a LI battery fully charged will shorten its life. You might decide that you don't care and that you don't expect to ever see your battery wear out, but it is a fact of physics. There is a message in the Tesla battery management system to the effect of "Repeated charging above daily usage may limit battery life". You get it if you needlessly top-off your battery when your daily driving habits would permit partial charges. The same logic applies to your ARV if maximizing battery life is a goal.

As Marko suggests, the capacity is there when you need it. But it is better not to use it when you don't.

Read what you quoted from Tesla again. If I start out at a 99% SOC, use a daily amount and then charge back to 99% SOC then you are not overcharging.

You might also want to quote everything I said earlier. Both ARV and Elite Power Solutions claim keeping the batteries topped off will not diminish performance and they claim test results to 5,000 cycles. You well know a day's liberal use of energy will be recharged in a very short drive. At the end of the day in a campground batteries will start out fully charged. If you plug into shore power they will stay fully charged. I've stated examples of such numerous times. If I park for two or three days boondocked I will not charge my batteries every day because there is no need to. My auto generator feature hasn't been used yet other than testing and experimentation.

I look at the common sense of this. You are theorizing on some idea of using a tiny fraction of your battery in a 20-70% SOC range or half your battery capacity to accomplish little, IMO, if using the batteries they way I am still have a theoretical life of 13+ years and that is assuming you use and recharge every single day which I don't. You now know how ARV does it. It is hard to tell what Roadtrek does but I doubt they are keeping you in a state of partial charge. All those 200ah lithium ion battery systems that are popping up certainly are not designed for a partial SOC.

[avanti]

Originally Posted by Davydd

Both ARV and Elite Power Solutions claim keeping the batteries topped off will not diminish performance

This claim is simply wrong. All lithium- and nickel-based batteries store optimally at less than 50% SOC. I can cite any number of authoritative sources, but I know from previous experience that this will do no good, so I won't bother.

However, I will continue to attempt to help you understand that there is a difference between usage and storage. Nobody is suggesting that you shouldn't use the full capacity of your battery when you need it. But, if ARV has their system configured such that the recommended long-term storage mode keeps the batteries at 100% SOC, then they have shipped a non-optimal design, hard though that may be for you to accept. The Tesla system does not do this by default--you need to tell it if you are going to need full charge at the start of a trip. THAT is what the message I quoted is about.

[booster]

Just my opinion, but I think arguing over the details of lithium battery care is an exercise in futility. They haven't been out very long, you can find something to support whatever theory you believe, and none of it has been proven because of the short time they have been out. There is no real difference in believing they will last 5000 cycles, or believing they will die earlier do to "whatever" cause. The only real life test we have is Technomadia, at least that I know of, and theirs failed do to speculated heat issues, but it was not a controlled test, and is a sample size of one, so it is really statistically insignificant, and the actual cause is not really known for sure.

Personally, I don't know if they will last 5000 cycles, but I am skeptical because no other style lasts as long as they claim. I also don't believe all the vendors that say their style of charging is right for lithium. My guess is that being totally full in storage MAY slightly reduce life. Another guess is that leaving any type of "float" or other current source, long term will not be great for them. But--no proof.

As a comparison, take a look at AGM recommendations and life predictions. AGMs have been around for many years, and there is still a huge variation in what the "experts" claim is the best for them in use. I just can't believe that the lithium folks have it all together in 1/100th of the time compared to AGM.

My question to me, and everyone, would be: What if davydd's batteries have an issue in 3 years? Would it be significant, aberration, or pervayer of doom? IMO, until there is a lot more information, is that we would not know.

If I had lithium, I would not have constant float on them in non-use, and would use a full cutoff charger for normal charging. I would make sure I had redundent cold weather charging protection and good monitoring of heat in the battery compartment. To me, this would make sense, as these are some of the top POSSIBLE problems for lithium, and without knowing for sure, CYA is a good thing when you spend that much. Of course, I would also not have a setup that kept everything running when you are stored

[gerrym51]

Originally Posted by avanti

This claim is simply wrong. All lithium- and nickel-based batteries store optimally at less than 50% SOC. I can cite any number of authoritative sources, but I know from previous experience that this will do no good, so I won't bother.

However, I will continue to attempt to help you understand that there is a difference between usage and storage. Nobody is suggesting that you shouldn't use the full capacity of your battery when you need it. But, if ARV has their system configured such that the recommended long-term storage mode keeps the batteries at 100% SOC, then they have shipped a non-optimal design, hard though that may be for you to accept. The Tesla system does not do this by default--you need to tell it if you are going to need full charge at the start of a trip. THAT is what the message I quoted is about.

I have also read several concuring comments on lithium like avanti said-however LFP banks in rv's is still rare. lots more info on this stuff in cruiser forums. boats have much more experience with tppl agm and LFP battery systems

the main problems seem to be that users treat LFP like agm's and treat tppl agm's like lithium.

although all 3 agm,tppl agm,and lfp are batteries they all have different charging capabilities and requirements

[Davydd]

I covered longterm storage of either keep it plugged in or disconnect the battery. Since I have my van at home and I am in it almost daily for many things be it tinkering or whatever, I keep it plugged in and it stays at 99% SOC. If I were a full timer I would have no choice in the matter. It is not a Tesla. Tesla's don't replenish your batteries when underway so you can adjust how much you need to charge when parked and estimate your usage. In all practical matters, if you drive a B routinely or desire to stay plugged into shore power when stopped at a campground there is no practical way to stay in a state of partial charge and would be a waste of your battery capacity for no perceivable return on investment if you arbitrarily programmed out 40-70% of your amp hour capacity.

Technomadia claimed they lost 24% of their batteries after 3-1/2 years in admitted full time brutal use in the summer Southwest. That means they still had 380ah out of 500ah and still functional batteries. They kept their batteries in an enclosed unconditioned space - almost an oven it appears. They had first generation batteries from Elite Power Solutions and they had no sophisticated cell monitoring for voltage, temperature and equalizing. In comparison, under similar conditions Technomadia said they destroyed AGM batteries in about one season. People seem to forget that fact. Their heat supposition was just that since they had no real data. Elite Power Solutions says performance is good up to 145F. It is quite possible Technomadia could have exceeded that when they admitted they were stationary parked on hot asphalt for 6 months in Arizona. Also, I am not sure how far they drew their batteries down or what kind of controls they had. 10% was conventional belief then. Roadtrek still goes with that. The drop off curve starts sooner. ARV elected to more conservatively cut off at 20%. I've programmed my Autogen to come on at 30% so will never go below that, and I have not reached that yet either.

Use some common sense. Even if lithium ion batteries were only good for 2,000 cycles some conservatively claim, that is 5-1/2 years of using and charging your batteries back to 100% EVERY SINGLE DAY. That ain't going to happen in the real world even for full timers.

As for AGMs they can vary greatly. Is there a Class B that has low voltage protection other than Roadtrek's Voltstart or can you abuse them and run them down to completely dead? So easy to do with an absorption refrigerator left on 12v when parked. I know from experience Pleasure-way had no overcharging protection until 2006 and I think there were Class Bs available that still didn't have that in the past year or so. Lithium ion is not 1/100th experience of AGM. AGMs were not common in Class Bs just a decade ago. Technomadia installed their lithium ion batteries about 5 years ago now and boaters have been at it longer in more extreme conditions. Billions are walking around with lithium ion cell phones most charge 100% every night. There seems to be no clarion to keep them in a partial state of charge.

Partial state of charge may be theoretically more optimum but it makes absolutely no common sense and there is little reason to get anal over it.

[avanti]

The actual science of Li does not depend on anecdotal evidence from random RV users (or upfitters). It comes primarily from the electric vehicle world, where these things matter very, very much. That's why I keep mentioning Tesla. Trust me, they have done the research and they understand issues that affect battery life. Things that are of casual interest to the RV world represent an existential threat for Tesla. They have done the science. It is really not a matter of opinion.

[Davydd]

Apple is even more heavily invested in battery life and their research says 100% SOC does not harm their lithium ion batteries. I'm heavily invested in both Apple and Tesla and have researched them extensively, however, I will stand on my last sentence of my previous message.

Partial state of charge may be theoretically more optimum but it makes absolutely no common sense and there is little reason to get anal over it [for RV batteries].

[avanti]

Originally Posted by Davydd

Apple is even more heavily invested in battery life and their research says 100% SOC does not harm their lithium ion batteries.

Apple's advice on long-term storage:

Batteries - Maximizing Performance - Apple

Store it half-charged when you store it long term.
If you want to store your device long term, two key factors will affect the overall health of your battery: the environmental temperature and the percentage of charge on the battery when it’s powered down for storage. Therefore, we recommend the following:

Do not fully charge or fully discharge your device’s battery — charge it to around 50%. If you store a device when its battery is fully discharged, the battery could fall into a deep discharge state, which renders it incapable of holding a charge. Conversely, if you store it fully charged for an extended period of time, the battery may lose some capacity, leading to shorter battery life.
Power down the device to avoid additional battery use.
Place your device in a cool, moisture-free environment that’s less than 90° F (32° C).
If you plan to store your device for longer than six months, charge it to 50% every six months.

I don't quibble with your right to choose not to worry about battery life, and I am not even saying that your position is irrational. But to claim that storage at 100% SOC is not detrimental (or that we don't know whether it is detrimental) is factually incorrect. It does matter, this is well-known, and others may have values that differ from yours.

[booster]

Davydd is still quoting single sources which is exactly what I was referring to. Fact is nobody knows, so we all have to look at the available data and decide for ourselves which we think is the most likely to be true.

I may believe on thing, Avanti another, Gerry another, Marko another, davydd still another. At this point none are proven and telling folks they are stupid for having their own analysis is just not what we need in the long run to learn all we can as time goes on.

It is interesting the davydd says "I know from experience Pleasure-way had no overcharging protection until 2006 and I think there were Class Bs available that still didn't have that in the past year or so." He is absolutely correct, and we have had many, many, many discussions about that fact on the forum. They also don't have any method of assuring full charge, either. With that being the case, it is almost a certainty that the AGMs in current and past Bs will fail early. So what does that tell us? It says the manufacturers and charger vendors are giving us stuff that doesn't work very well, while telling us how great it is. I would bet you could count the amount of AGM factory installs that made the 1000 cycles that are claimed on the fingers of one ear. This sounds very much like the hype we are also hearing from the lithium vendors both batteries and chargers. Why is there any expectation that the vendors, or at least business variety, would do any better, or be any more accurate on lithium. In my mind, not much expectation of it. I repeat, as some have gotten chastised for in the political area, "we don't know what we don't know yet" about lithium systems.

I don't what the big deal is about shutting off the power to the coach when stored. On ours, I throw the master switch and pull the solar fuse, which is right next to the switch. 15 seconds tops. Why not?

[wincrasher]

Not all Lithium is the same either. All your Apple products are lithium-polymer. I thought Tesla cars were the same (confirm?). LiFePO4, from my readings, isn't effected by leaving at any specific SOC. Leave them full, leave them partially charged, there is not really any data indicating conclusively either is damaging. LiPO's on the other hand, there is plenty of evidence they are damaged storing at high SOC. I've ruined a fair number on my R/C toys to attest to that.

We have no idea if, when your iphone says 50% charge, what that means. 50% of the total capacity? 50% of the allowed capacity with the reserve SOC discounted. I suspect that is the case, as I usually draw my phone down to a couple % points everyday and I get the same amount of use out of it after several years. If you notice, when you un-box a new item from Apple, the SOC is usually 30-40% and you need to charge them up. They must know a thing or two about it.

My thoughts on this are pretty simple. I could care less if the cycles are 2000 or 5000. If I were to get 3-4 years out of a battery pack, I'd claim I got fair value. The key is sizing your pack large enough to give you comfortable use. So if you are comfortable going with a small pack, then draw down to 10% SOC and save some money on the size of the pack. If you are more fearful, then double your pack and draw down to 20%. And so on.

In the real world, I think the only people with real worries would be folks wanting to run air conditioning and hammer their battery packs day in and day out. I think that is an expensive and fool-hardy exercise. But that's me I guess.

[Davydd]

Originally Posted by avanti

I don't quibble with your right to choose not to worry about battery life, and I am not even saying that your position is irrational. But to claim that storage at 100% SOC is not detrimental (or that we don't know whether it is detrimental) is factually incorrect. It does matter, this is well-known, and others may have values that differ from yours.

Didn't I agree partial state of charge may be theoretically more optimum? I said it twice. I'm not arguing it is not true. I'm just saying agonizing over it is showing a lack of common sense given the expected performance numbers and how best to use your battery capacity. And I pointed out even at greatly reduced performance numbers from what is expected it is still not something to be concerned about.

There are also other factors that seemingly some with no lithium ion battery experience have any concept of. If I wanted to store, and did so off site in a storage facility, I could do so in one second. It is a complete battery disconnect switch. But I explained, I am in and out of my van daily it seems. I use it even in the winter. The other reason is with lithium ion batteries you can't just turn them off and on in freezing temperatures. If the battery temperatures go below freezing then you can't charge them. So, if you turn power back on, if you are not charging, you will run the batteries down in a few days. The only way you can charge is you have to keep heat on the batteries. That means either a conditioned space, built in heating pads, or applying heat locally to the batteries from an external source. Since I do plan to use my B this winter in Minnesota I am keeping it plugged in and heated and that means it would be next to impossible not to have 99% SOC.

[gerrym51]

Booster-don't standard agm's start to lose charge the longer they sit without being trickle charged?

[BobB]

Originally Posted by wincrasher

Not all Lithium is the same either. All your Apple products are lithium-polymer. I thought Tesla cars were the same (confirm?).

A Fortune article in May reported that:

"The batteries that Tesla has been using, sourced from Panasonic, for its Model S electric car are mostly likely a lithium-ion battery with a cathode that is a combination of a lithium, nickel, cobalt, aluminum oxide. The battery industry calls this an “NCA battery” and they’ve been around—and made by Panasonic—for many years. Typically, lithium-ion NCA batteries use a combination of 80% nickel, 15% cobalt and 5% aluminum. It’s unclear what mix Tesla and Panasonic’s battery combination is. ................In contrast, Musk said that Tesla will use a lithium-ion battery with a nickel, manganese, cobalt oxide cathode for its grid battery. Called an NMC battery, it’s meant to be used for daily cycling for a home, business, or certain types of clean power. "

Any battery chemists out there to explain that?