Travato Battery Project

[booster]

Originally Posted by avanti

I think that this high temperature issue is the biggest thing that is not yet being addressed by the RV world. Tesla certainly pays a great deal of attention to this. Their battery pack is liquid cooled as well as heated. Given that this battery is a large percentage of the total cost of the vehicle, battery lifetime is obviously a high-stakes question for them. I guess it is less of an issue for us, but still...

Hopefully less, but it will be interesting to see. Or live in Alaska!

What is amazing, if true, is how low the damaging temp can be. From the Technomadia article: information from Elite.

They have observed that a 10C (18F) temperature increase over a baseline room temperature of ~23C (74F) results in the number of lifetime cycles being cut in half.

This means at 33C (91F) usable battery life will be cut in half, and presumably to a quarter at 43C (109F). This is VERY substantial.

Between things like hot roads, hot from running, sunshine, and just plain hot weather, 91F is extraordinarily common. In the sun, the painted surface of our van will go over 100* when it is only 70* outside.

[cargovanconversion]

Originally Posted by avanti

I think that this high temperature issue is the biggest thing that is not yet being addressed by the RV world. Tesla certainly pays a great deal of attention to this. Their battery pack is liquid cooled as well as heated. Given that this battery is a large percentage of the total cost of the vehicle, battery lifetime is obviously a high-stakes question for them. I guess it is less of an issue for us, but still...

"this battery is a large percentage of the total cost" - Yup.

Different sources have mentioned temperatures as low as 60F above which the longevity of the lithium batteries could be negatively affected. Remember, that doesn't directly affect its current use, but is an important factor when making assumptions about the life of the battery. We all know the the 2000 or even 5000 cycles are probably exaggerated, but that's what sells batteries. I went the solar way about 30 years ago and don't want to make the same mistakes again. I think, these and other issues are being addressed now (especially by our enthusiastic RV guinea pigs), so let's wait just a little bit longer....

Van Williams.

[Davydd]

Cut my estimated life cycles in half (to 2,500) or a quarter (1,250) it is still way more than the optimistic AGM at 500. And probably more than the length of time I will own the B. It is much easier to run a lead-acid battery down killing life expectancies as there are no built in safeguards to prevent doing so on most all Class Bs.

BTW, Elite Power Systems is located in Tempe, AZ. I suspect they know a lot about hot temperatures. I visited their facility when I was out there. They hadn't yet seen an Advanced RV using their batteries. They told me with Advanced RV's setup I would never have to worry. It is extremely conservative.

Booster, we got to 90 degrees two times last summer in Minnesota. Don't you think I haven't factored that in in my decisions? We could high-tail it to Grand Marais and never have to worry in the summer. I covered the south already from San Diego to Savannah and as i mentioned never encountered anything over 85 degrees.

I suspect I've diffused the freezing issue. I have to admit I haven't given much thought to the heat issue. Mostly because I don't anticipate ever getting caught up in it out of my natural inclinations not to travel in hot weather as much as I avoid air conditioning religiously. So, I have never asked or know what Advanced RV has done in that regard other than I have all time access to monitor the battery temperatures and thus could act accordingly. Sure, I will get caught up in heat but never anything like living in Arizona in the summer. How much is too much?

[booster]

Originally Posted by Davydd

How much is too much?

That is exactly the question we all have been talking about, with most of the conclusions made focusing around the fact that it appears nobody really knows how much of an issue heat will be. To me, that means it shouldn't be assumed that there will be no problems, or that they will be trivial, and it also means that it shouldn't be assumed there will be catastrophic failures at every turn. Nothing wrong with a little skepticism--we all remember the all day AC running and recharging in 45 minutes claims

[cargovanconversion]

Originally Posted by booster

That is exactly the question we all have been talking about, with most of the conclusions made focusing around the fact that it appears nobody really knows how much of an issue heat will be. To me, that means it shouldn't be assumed that there will be no problems, or that they will be trivial, and it also means that it shouldn't be assumed there will be catastrophic failures at every turn. Nothing wrong with a little skepticism--we all remember the all day AC running and recharging in 45 minutes claims

Thumbs up! It's all about what we don't know yet. And that doesn't make a current system like Davydd's bad, we just shouldn't make too many assumptions.

Van Williams.

[booster]

Don't want to get this too far off of Wincrasher's original questions, but I have been reading a bunch and doodling a little.

Surprise for me #1---AGM battery manufacturers list nearly identical life reductions for their batteries as the numbers Technomedia posted for lithium. Some AGMs were in the 5 degree warmer for the halving of life, but nearly the same. Bottom line is that it is an issue, but on both types of batteries. The only real advantage AGMs have is that the damage from heat costs you less.

The above would tell me that at least passive cooling, maybe active (fans), might be needed and cost effective for both types of installations.

Surprise #2---The no charging of lithium when batteries are too cold thing is kind of interesting. I really don't like the idea of electrically heating with power from the batteries, unless you are on shore power or driving. Not everyone who goes lithium is going to have power to waste. You don't need to be heated when discharging, so don't heat then. If the BMS is like Davydd's and gives the cell temperatures, and disconnects the batteries if the are too cold to charge, you need/want it to do that only when you are charging. You have large amounts of 12 volt power available when the engine is running or on shore power so if your battery heater is 12 volts, it looks to be pretty simple to make it so you can run the heater off shore power or engine with a few charge relays, even if the batteries are off. The BMS is going to protect the lithium anyway, so the risks are very low. I think this is fairly important to the retrofit people who want to leave the inverter off 99% of the time and have native 12 volt for their van systems. A system like this would make it so you could not get stuck with batteries low and cold with no easy way to recover. Start the engine and run the heater until the batteries warm up, and start charging. Using it this way would indicate you use big heaters to recover quickly, as they will only be on when really needed, with ample power available.

I think Surprise #2 could be what could make a person from the cold lands much less afraid of a lithium system, especially as a retrofit, as long as the BMS can do what is required to interface and give information as needed to do the 12 volt heater setup. This is a system that could probably also be easily built into the lithium kits that folks like AMsolar are currently putting together.

[gerrym51]

If your going lithium I would go with the Smartbattery. i researched them and watched the videos a while ago. the thing for me is that everything seems to built into an individual battery box when you get from them.i would use one or 2 of their batteries.


You might also look at Northstar tppl agms. although roadtrek uses a different size on the Zion Northstar does make tppl agms that fit different battery sizes

[Davydd]

Smart Batteries are terribly expensive. It might be a choice for a DIYer but I think the converters (Roadtrek and Advanced RV) have moved on from there in developing less expensive and more sophisticated systems. Companies like AM Solar are also offering more sophisticated packages that go beyond dropping in a substitute lithium ion battery for a lead-acid battery.

I don't know if I would ever consider lithium ion at this point unless it could change how one could use their Class B as I hope I have achieved. What I have I just doubt could be achieved otherwise with any other kind of battery (equivalent to 12-13 typical distinct 12v AGM batteries) because of space and weight issues. Roadtrek hit the wall with ETreks at an effective use with an 800ah AGM battery bank that is really equivalent to about a 500ah lithium ion battery bank.

[booster]

Originally Posted by gerrym51

If your going lithium I would go with the Smartbattery. i researched them and watched the videos a while ago. the thing for me is that everything seems to built into an individual battery box when you get from them.i would use one or 2 of their batteries.

You might also look at Northstar tppl agms. although roadtrek uses a different size on the Zion Northstar does make tppl agms that fit different battery sizes

The Smart batteries do have some advantages, but are spendy. What isn't clear anywhere in their information is if their BMS addresses the below freezing changing cutoff. I think that is an essential part of having lithium. I am going to get a hold of them and see what they say about it. If their BMS system addresses the issue and gives and output to say so, then the system I described above could be built to heat the batteries only if needed. It would be a relatively easy system to build at that point.

[booster]

Originally Posted by Davydd

I don't know if I would ever consider lithium ion at this point unless it could change how one could use their Class B as I hope I have achieved. What I have I just doubt could be achieved otherwise with any other kind of battery (equivalent to 12-13 typical distinct 12v AGM batteries) because of space and weight issues. Roadtrek hit the wall with ETreks at an effective use with an 800ah AGM battery bank that is really equivalent to about a 500ah lithium ion battery bank.

I think you are correct when you look at the folks that occasionally boondock, tend to drive a lot, and/or get plugged in at least once a week. At that point, you don't need huge capacity, so weight is less of an issue, and if you get yourself a good battery charger and engine generator control system, you won't have early failure issues with AGM or even wet cells.

I also think that there will be an alternative market built around the singular quality of lithium that allows them to never be fully charged and never need the long absorption charge time. I would see that market as the much lower use folks running mostly on solar for extended periods of time, maybe in the high desert or on the beach. These would also probably be the folks that use much less water, tank capacity, etc so they don't even move much for that. Their lithium setups would also be much smaller, so cost would be less of an issue. We would nearly fit this profile, but not quite all the way.

[Davydd]

Originally Posted by booster

Don't want to get this too far off of Wincrasher's original questions, but I have been reading a bunch and doodling a little.

Surprise for me #1---AGM battery manufacturers list nearly identical life reductions for their batteries as the numbers Technomedia posted for lithium. Some AGMs were in the 5 degree warmer for the halving of life, but nearly the same. Bottom line is that it is an issue, but on both types of batteries. The only real advantage AGMs have is that the damage from heat costs you less.

The above would tell me that at least passive cooling, maybe active (fans), might be needed and cost effective for both types of installations.

Surprise #2---The no charging of lithium when batteries are too cold thing is kind of interesting. I really don't like the idea of electrically heating with power from the batteries, unless you are on shore power or driving. Not everyone who goes lithium is going to have power to waste. You don't need to be heated when discharging, so don't heat then. If the BMS is like Davydd's and gives the cell temperatures, and disconnects the batteries if the are too cold to charge, you need/want it to do that only when you are charging. You have large amounts of 12 volt power available when the engine is running or on shore power so if your battery heater is 12 volts, it looks to be pretty simple to make it so you can run the heater off shore power or engine with a few charge relays, even if the batteries are off. The BMS is going to protect the lithium anyway, so the risks are very low. I think this is fairly important to the retrofit people who want to leave the inverter off 99% of the time and have native 12 volt for their van systems. A system like this would make it so you could not get stuck with batteries low and cold with no easy way to recover. Start the engine and run the heater until the batteries warm up, and start charging. Using it this way would indicate you use big heaters to recover quickly, as they will only be on when really needed, with ample power available.

I think Surprise #2 could be what could make a person from the cold lands much less afraid of a lithium system, especially as a retrofit, as long as the BMS can do what is required to interface and give information as needed to do the 12 heater setup. This is a system that could probably also be easily built into the lithium kits that folks like AMsolar are currently putting together.

Technomadia had several reasons for unanticipated drop in performance. Still after 3.5 years they were at 76% capacity. For one the heat issue might be legitimate but for the first part of the test they kept their batteries in an unconditioned space mostly in the southwest where 110 degree temperatures were common. We all now know how hot an RV can get if unconditioned. Secondly, on the float issue I don't know if they are right or not but it will be a good question to ask at Advanced Fest. It is hard to tell with Technomadia because they admitted they were mostly on shore power, had an unusual 7 week condition sitting on hot asphalt and probably taxed their battery bank to the limit frequently with air conditioning. Those are pretty unique unusual conditions I doubt I would encounter. So, 76% might be as bad as they present. I doubt they could have done what they did with AGM batteries and I think they believe that too. They also mentioned their batteries are not as good as what Elite Power Systems is selling today and that they had no sophisticated monitoring tools for individual battery cell voltage and temperature. That all adds up. Taking the worst circumstances, I don't know how long I will have my Class B but my previous were 5 and 4 years. If in 4 years I am at 76% I would still have effective use of 456ah of battery which is still more than I need for 24/7 off grid use with my decade touring history. I feel comfortable in that.

With the cold issue I have already outlined all the scenarios. Basically living in Minnesota I will encounter cold that Technomadia never once encountered. I also right out of the stall encountered several straight days under constant all day freezing temperatures and survived it. That was an extreme condition I doubt any of us are willing to put up with but had to be done to pick up a new Class B and bring it home. I was off-grid and survived. Yes the batteries in use keep their temperature up and you can continue to draw even when cell temperature is below freezing. But Advanced RV has designed their system so there are many safeguards. The heating pad just prevents freezing so you can continue to charge. Typically if your batteries are fully charged in winter conditions you could just disconnect the batteries and they will last a Minnesota winter that way. If plugged into shore power the 120v heating pad should keep them above freezing. I do wonder how Mike Wendland's experimental lithium ion battery ETrek performed in Michigan Upper Peninsula Roadtrek winter rally last January. They don't say a lot about their Roadtrek in how it performs.

BTW, I took a lot of photos of my Silverleaf screen documenting overnight battery usage on our southwest trip mostly in Arizona in February. I went back through them last night and the highest temperature reading was 87 degrees in the Excalibur parking lot on the Las Vegas Strip. I think it was one of the 85 degree days but I can't say for sure. The batteries are sealed in about a 1/2" fiberglass shielded and insulated box under the van.

[Davydd]

Originally Posted by booster

I think you are correct when you look at the folks that occasionally boondock, tend to drive a lot, and/or get plugged in at least once a week. At that point, you don't need huge capacity, so weight is less of an issue, and if you get yourself a good battery charger and engine generator control system, you won't have early failure issues with AGM or even wet cells.

I also think that there will be an alternative market built around the singular quality of lithium that allows them to never be fully charged and never need the long absorption charge time. I would see that market as the much lower use folks running mostly on solar for extended periods of time, maybe in the high desert or on the beach. These would also probably be the folks that use much less water, tank capacity, etc so they don't even move much for that. Their lithium setups would also be much smaller, so cost would be less of an issue. We would nearly fit this profile, but not quite all the way.

Right now I think I have achieved the right balance in that I can sit as long as my tanks can without moving or charging. That could be a week even though I never intend to do so. The longest time I have ever come close to that has been at socials and rallies and they have always had electrical hookups to satisfy everyone's needs. I can also live off grid all the time as I proved to myself from February 23 to April 1. I'll call that the Mad Max approach in case Armageddon comes. I would just have to pirate diesel fuel and water.

[stanw909]

To Windcrasher I would suggest going out as soon as possible and get the exact battery you have currently on your rig so they are relatively even in year and strength. I think you shouldn't have too much trouble finding or fabricating brackets and git r done. You already know from your last rig that the battery set-up works well. You just need more of it. I know it's quite sexy to get into lithiums but AGMs have done pretty well for a number of years. Sportsmobile has been using AGMs for a long time with great success. Maybe, go on the Sportsmobile forums and snoop around.

[markopolo]

Like Stan says - doubling the existing 100ah AGM capacity would be a nice upgrade. I think you could get away with not upgrading the wiring and isolator etc.

This Smart Battery datasheet - http://www.lithiumion-batteries.com/upl ... 20Data.pdf - shows how much the cycle life of the battery is affected by depth of discharge. Yes, you can discharge them 100% but the datasheet indicates that would greatly affect cycle life.

Davydd's lithium setup: having greater capacity than necessary and limiting the depth of discharge would be a good model to follow if going DIY.

[wincrasher]

Well, after poking around under the van yesterday, I've basically come to the conclusion that I just do not have room to add more than one additional Group 31, without some serious modifications. I agree with Stan, that I just need to fab some brackets to make that happen. So for just extra capacity for lighting and entertainment systems, I'm really hard pressed to spend the $2400 for 2 drop in lithium batteries to replace the AGM's - and still not have enough juice to run a serious inverter and run the microwave or water heater. I think an additional AGM and the brackets would total $400 or less.

The tough thing with projects is not getting carried away. Spending thousands of $ to avoid 15 minutes of generator run time each day is kinda nutty if you think it through. Other than the hot water issue, I'm pretty happy with the "go anywhere" aspects of this van - my coach can go 4 to 5 days between servicing the tanks or the LP gas supply for the most part - which was my goal with selecting this van anyways.

What may be a better project, so that I have hot water on demand, may be some kind of remote switch so I can start the generator from the driver's seat. That way, as I get within 1/2 hour of a destination, I could kick on the generator and have hot water on arrival. Not sure how I would do such a thing. Maybe there is a ready made gadget for this.

[booster]

I totally agree that sounds like the best way to go, as you really do need more battery, especially with the electric water heater. Even 200 AH isn't all that much in the big scheme of things, if you have any high use things like compressor frig. Will you have any way to tell how many amps are going into the batteries off of the engine when it is running? That would be very interesting information, I think. You might want to slap in a Trimetric meter while you are adding the battery, as it would be very easy to do then.

[booster]

Originally Posted by markopolo

Like Stan says - doubling the existing 100ah AGM capacity would be a nice upgrade. I think you could get away with not upgrading the wiring and isolator etc.

This Smart Battery datasheet - http://www.lithiumion-batteries.com/upl ... 20Data.pdf - shows how much the cycle life of the battery is affected by depth of discharge. Yes, you can discharge them 100% but the datasheet indicates that would greatly affect cycle life.

Davydd's lithium setup: having greater capacity than necessary and limiting the depth of discharge would be a good model to follow if going DIY.

Did you link the right graph? The one in the link shows what the capacity of the battery will be (compared to 100% when new) after "X" amount of cycles. I don't think they show depth of discharge on this one.

[gerrym51]

Wincrasher-since a dual alternator system is now available for the promaster-maybe you could install that and the 2000 watt inverter that's in the zion. that way when running the engine at least you could use the high watt devices and then the other devices on battery.

i studied the battery i'm getting and its reserve capacity is slightly more than 210 amps of standard agm. if you got a second group31 and the dual alternator that could work

[booster]

Cycle life vs depth of discharge is kind of hard to find for lithium.

Here is one from Lithionitics

https://www.ervsolar.com/Lithionics-Battery

It appears that you have to get pretty low DOD before you get huge gains. I was a bit surprised at how low the difference between 50% and 80% DOD in cycle life, but that is one of the selling points that lithium uses-more capacity in the same AH battery.

[markopolo]

I read the data wrong

I get it now - after 500 cycles the battery would have 96% of its original capacity. After 2000 cycles it would have 80% of its original capacity. Thanks for catching that.