Travato Battery Project

[wincrasher]

Right now I'm researching ways to add battery capacity to my new Travato. At this point, I'm only wanting more battery capacity. Inverters and solar may be other projects down the road. I want to do this piece-meal and not all at once, but I want the parts to fit together and not waste anything. Preference is to continue with batteries under the van - the wiring is all right there.

So for the battery project, I can either continue with AGM or go Lithium. The existing battery is a group 31 AGM. For Lithiums, I like the Smart Battery. I know there are other options - AM Solar offers a similar battery that can be configured in various custom sizes at an attractive price. Smart Battery claims it has built in battery protection circuitry and is truly "drop in". But they also note charging voltage must be 14.4 to 14.6 volts. Their 8D size battery is attractive - 300 AH and only 93 lbs - only about 23 lbs more than the existing battery, yet 3 times the usable capacity!

What I need to know is if the Progressive Dynamics 9000 series converter/charger in my van charges at that voltage, or can be adjusted to do it. I believe the alternator puts out that voltage, as I read 14.4 volts on the cab 12v outlets. Having to change out my charger would probably kill the idea of going lithium.

Whatever I go with will require some brackets. Probably custom fabricated. I think I have room for either 2 group 31 sized batteries, or a single 8D. Two 8D's could probably be made to fit, but I think that is just too much capacity for my usage.

[booster]

Never can have too much battery Good place to start in upgrades as it will somewhat determine the path on other upgrades.

My understanding of the Progressive Dynamics stuff is that they start with 13.6 volt output power supply, so that is what it would charge at. If you have a PD Charge Wizard on it, you will get a 3or4 step setup that will do 14.4 volts in boost mode, so you would just get into range there. They are straight timing units, as far as I have been able to determine, so you always get the 4 hours of 14.4 volts absorption whether you need that much or not, and you don't get more time if you do need it, unless you manually force it into boost again. The battery protection in the Smart battery would take care of the too much time issue, and shut off the charging itself, so no big deal. If you were short of time, you would not regain full capacity, but with lithium at least it would not hurt the batteries to not get full all the time, and you could just do another cycle if you wanted to get full.

As for the charging off the van alternator, you may find the alternator will vary the voltage quite a bit depending on load and temperature. The lithium batteries may pull a lot of amps if they are low, which would put the alternator at full output, heating it up and reducing output and voltage. Stock alternators normally aren't really happy at full output for long periods, so that might be an issue. You would also have to make sure you have big enough wiring for as much output as the alternator could send to the coach. Sterling does make battery to battery chargers that will limit the current to protect the wiring, and boost the voltage to help the batteries, and might be a good idea. I think they have the higher voltage settings on them, also.

Sounds like fun, it will be fun to see what you wind up with.

[wincrasher]

I do see that PD does offer a lithium specific charger/converter - the info is on their website. It may just be a drop in replacement. Not something I'm keen to do, but it is interesting reading.

I need to find out specifically what model I have and if it has the charge wizard built in or not. Getting the pendant is no big deal.

Most likely, this is the one I have: http://www.progressivedyn.com/rv_con...pd9245c_2.html

Alternator issues is not something I thought about. Presently, the house battery is charged via the alternator with the engine running. How that voltage is regulated, if it is, and any protection on the max amps, I have no idea. I do know the stock alternator is 180A max.

[booster]

I just took a look at the Smart Battery site to see the sizes and such. Interesting that the 150,200 300 AH are all in the same case size. Also interesting that they say the max charge and discharge rate are .3C, which is really, really low for lithium. That can't be right.

What is even more interesting is that the say the batteries have 100% of the rated capacity as usable. I think most of the lithium folks want 10% safety on each end (I think Davydd is using a bit more) of the charge cycle, so you lose 20% of what the batteries actually are. That would put the Smart Battery 100AH equal to a normal rated lithium at 120AH, so they don't look as much more expensive. The 300AH would be equal to a 375AH regular rated lithium, and have the usable power of a 400AH bank of AGMs taken to 25% SOC, which is deeper than most want to take them down. Very comparable to the 375AH of wet cells we have now, which serve us well.

At $3500 for 300AH Smart Battery, vs about $1300 for 4 Lifeline GPL-4CT at 440 AH (330 usable at 25% SOC), the price is a lot closer than I expected to see, especially if it is a drop in with no extra charger, controllers, etc needed. The big difference is the 93# vs 264# for the lifelines, plus extra weight for heavier supports.

[avanti]

I appreciate the desire to build piecemeal, but as you suggest, it helps to plan ahead. One thing to consider is where you will locate an eventual inverter. High capacity inverters are pretty large, and it is best to keep them close to the batteries. You probably want to pick a place for the inverter, even if you don't acquire it yet.

Also, there are real advantages to combined inverter/chargers, rather than a separate converter (e.g., built in transfer switch; more seamless operation).

[wincrasher]

Originally Posted by avanti

I appreciate the desire to build piecemeal, but as you suggest, it helps to plan ahead. One thing to consider is where you will locate an eventual inverter. High capacity inverters are pretty large, and it is best to keep them close to the batteries. You probably want to pick a place for the inverter, even if you don't acquire it yet.

Also, there are real advantages to combined inverter/chargers, rather than a separate converter (e.g., built in transfer switch; more seamless operation).

Good points!

[Davydd]

Booster pretty much explained alternators. I think when you have a large battery bank at some point your engine alternator is not going to do the job. I suspect that is why Pleasure-way has been longtime resistant to adding second batteries in their Plateaus. Advanced RV says there is too much M-B computer functions controlling the alternator and satisfying the chassis first not to put in a second alternator. Lithium ion batteries can take as much current as you can throw at them which gives them the advantage of fast charging. Solar is going to supplement charging and maintain batteries but I doubt will be a satisfactory charge source.

At what point is lithium ion worth it? When it changes how you can use your B. In effect a large battery bank gives you the ability to use your entire B electrical system, 120V and 12v, 24/7 whether plugged into shore power or not. It actually feels like freedom in a way. My experience analysis says that point can be reached at 400ah of lithium ion which would be 600ah of AGMs as an equivalent. The problem with AGM is weight and size starts to limit your abilities to increase. The Roadtrek ETreks top out at 800ah with AGMs. My 800ah lithium ion B is equivalent to 1300ah of AGMs which is an impossibility weight an size wise in a B. Less than 400ah lithium ion and I think you are in a pick and choose mode and constantly monitoring and you definitely would need supplemental systems like propane and maybe generator. Also at some point you would need a large inverter/charger. With little battery power such an inverter/charger would be overkill if say running a microwave would suck your batteries dry. Then it is a why bother situation and go seek shore power.

The biggest advantage I see going part way is you could seek great comfort with a 12v compressor refrigerator. That is one of the big pluses I've enjoyed. Enough solar could supplement that extra battery need but solar is a bit unreliable. The other comfort is the ability to use your appliances but only in a need basis.

As you know, I've gone all in with the confidence I can travel anytime, anywhere and not have to plug into shore power, worry about my electrical usage and not sacrifice some usage part of the time or only have when plugged in or running a noisy generator (120v). I've pretty much determined I cannot do enough things electrically to exhaust my batteries unless I became a traveling contractor with power tools.

Air conditioning? Maybe 5 hours for me and I hope to never find out. Roadtrek with their two experimental lithium ion Bs might be trying to achieve 24/7 or as much as reasonable or needed. We haven't heard much from them on this. My philosophy is if it gets that dire seek shore power. It is too rare for me to worry about it but southerners battle that issue in the summer. Anyway you look at it, it is mega battery and solar systems to even hope to try and probably not a concern of this discussion.

[wincrasher]

You bring up some good points. Sizing the bank for the intended usage is an important step.

Fast charging would not really be a driver for me, I would think, so if the alternator would be limited in what it could put into a battery bank, I'd be OK with it.

My first thoughts are I would like to just have more reserve time for my lighting and entertainments systems. Eventually, I'd like get an inverter and perhaps run the 900 watt microwave or possibly the 1200 watt water heater for short periods. That would almost eliminate my use of the generator except for days I'd need the air conditioner. I really don't carry any 110v devices that need power. My laptop is 12v native. Phone and cameras charge on USB. Coffee is on the stovetop. Can't think of anything else (don't say toaster).

I'm perfectly fine with using my LP gas for the cooktop and the refrigerator. Unlike some folks, I've had good experiences with the absorption fridge and have no problems continuing to use it on gas. I actually prefer to cook on a gas stove.

So considering the above I'd probably be OK with 200 ah or so of usable capacity. More is better, of course, as not only gives you more time in the field off-grid, but having to fast re-charge becomes less of an issue.

Considering I'm mostly a weekender, or do short trips, heading back to the shop and putting on a slow charge is really not an inconvenience I would think either. If my onboard charger or alternator couldn't fully charge, I could have a pigtail and use a proper bench charger to fully charge when I get home.

[Davydd]

I would think that the all times use of that 1200 watt water heater should be your main goal to resolve with your electrical upgrades. Anything else as a result would be a side benefit. I don't think I could live with hot water only when plugged into shore power. I really should say I don't think my wife could.

[markopolo]

To avoid having to undue upgrades later you pretty much need to decide what you want to end up with before starting.

If you just want more run time for lights and entertainment systems then adding a second AGM battery covers that.

If you want to run a 1200 watt appliance through an inverter then you'll probably need # 2 or better gauge wiring from the batteries to the inverter.

Booster mentioned wiring already. It might be 6 gauge in your unit. That would be good to carry around 50 amps. 1200 watts would be approx 100 amps.

I don't think 2 AGM's would be enough to use for the 1200 watt water heater on a regular basis if it works at all. It'll depend on the characteristics of those particular batteries.

[booster]

Not having a propane water heater does really complicate this for Windcrasher, since he has and likes the propane in the van. The 1200 watts for the water heater is going to be tough to cover with two batteries and a smallish alternator, as he probably looking at 120 amps or so once it goes through an inverter. Perhaps there is a way to do a propane water heater, but I seem to remember something about being too close to the fuel inlet. Beyond that, about all that is left may be to have a second or bigger alternator with all the associated wiring and count on running the van. Tough one to get around, I fear.

[wincrasher]

Thankfully I have an assortment of heavy gauge wire in the shop - got some lengths of 0, 2 and 4 guage wire. I think an inverter could live under that bench seat next to the water heater. That would put it within 2 to 3 feet of the existing battery.

The thing about this water heater is it only neesd to run for 15-20 minutes tops and the water will remain hot for several hours. So I'd think once in the early AM, and then once in the evening. So that shouldn't be a ton of amps consumed in any given day. Granted, the draw rate while it's on is how you size the wire.

I agree though, 2 AGMs is not going to cut it in that scenario. 4 would probably work, but that's alot of weight and space requirement.

[cargovanconversion]

I think, in general,it is time to buy lithium based on price. And that will only be improving over time.

And even though you'll see more and more lithium installed, I think that the technical issues of lithium with regard to RV usage, haven't been resolved at all and are still in constant flux. Issues around charging below freezing are being addressed now, but difference of opinion is still around as to the optimal maximum charging level. Keeping them charged at 100% is probably not the best practice. There are many more uncertainties about them and those are for me the main reason to hold off for a while until the technology matures.

I do think they have major advantages over both lead and AGM batteries and will be the way to go in the near future.

As a separate issue, I believe lithium batteries make a way better use of solar panels as well. Where tapering off lead batteries fails to make maximal use of solar capacity, lithium maximizes it.

Van Williams.

[avanti]

+1, Van. I think you have summarized the state of the art WRT lithium exactly right. Prices are no longer prohibitive, but are still dropping fast. And the technology is no longer a lab experiment, but we are still on the learning curve. I am almost sure that when it is time to replace my current AGMs, it will be with Li. I bet by then it will be cheap and easy. In the mean time, we owe a debt of thanks to the brave pioneers who are blazing the trail.

[booster]

Like many of us, I have tried to make sense of lithium battery information, with only some success. Smart Battery would have you believe they can use 100% of the capacity to 8 volts, and be good for 2000 cycles, other places they tell you 80% discharge. They also say they can drop right in and be bomb proof. Lithionics rates their batteries in "lithium amp hours", which some how can be double what the normal amp hours are. As Cargovan stated, the industry is still shaking out, and nobody is really sure what will work best in an RV, and many of the claims are unsubstantiated.

It may have been put up on the forum before, but Technomadia did an update on their setup in Feb of this year. Very interesting, and refreshingly not sugar coated. They have seen more rapid deterioration than expected, which has mostly wiped out the cost balance of the lithium batteries. The information that they have dug up trying to define the early degradation is very interesting, and IMO, very well thought out. One of their big points was elevated temperatures (and not all that warm) and how it can cut life in half very easily. I would think that the typical hanging under the van setup in most B's would not be ideal from a temp standpoint, with hot pavement, engine, exhaust, transmission, differential, etc heat all there.

http://www.technomadia.com/2015/02/l...attery-update/

[Davydd]

With my lithium battery bank I believe the lower level and freezing has been addressed with many safeguards. At the upper end to full charging it floats at 99% but the charge rate stops to drop off drastically somewhere after 90% charged and approaches fully charged more slowly. I try to observe this to get a better handle on it with the Silverleaf monitor.

Roadtrek and others had lithium ion batteries but never gave any indication how they handled cold weather and I think at the time most didn't even know all the ramifications. In our Advanced RV each individual cell has a computer chip attached to it, controlling it, and monitoring cell temperature and voltage. Even though the lithium ion industry says you can go safely down to 10% or technically even 1% for that matter in voltage, Advanced RV arbitrarily set the lower end at 20%. What happens if you go that low the batteries shut down completely. To restart you have to start the engine or plug in to shore power and hold down a start button for nearly 6 minutes (or 1% charge) for the batteries to re-engage. To work around that potential restart delay and quite frankly nuisance, I arbitrarily set the low end at 25% which gives me 600ah usage out of 800ah. So, every 1% is 6ah. If it goes down to 25% the autogen will start the engine to charge the batteries without that 6 minute manual hold down delay. Autogen works with no key in the ignition. It auto starts at 25% or I can start it touching a screen button on Silverleaf. Also I can start it from a key fob or from an iPhone via wifi. Also, I have it programmed so the always on headlights with engine running will not come on with autogen. The lowest I have ever gotten down to was our first night in 5 degree overnight temperatures where we had the electric radiant floor on along with a nearly continuous cycling of the Espar diesel fired heater.That was 31%. I doubt I will have that many opportunities to get to that extreme and we didn't have to have the radiant floor on.

When the battery temperatures reach 40 degrees a sensor starts monitoring and an electric heating pad comes on inside the battery bank to keep the batteries above freezing so you can continue to charge. If you are fully charged you can continue to draw current from the batteries with no harm. You just cannot (should not) charge batteries below freezing. To prevent you from charging if the heating pad fails the battery system will shut down completely which means you will have to do something to bring the temperature back up like heat the battery bank, get to a heated space, head south, or wait for the temperatures to rebound. It doesn't affect the chassis battery.

The battery bank itself is enclosed in an insulated fiberglass box that is sealed. The box in turn is encased in a heavy steel angle cage and a 1/8" aluminum skid plate protects that assembly. All are mounted behind the back axle under the floor.

Those are the safeguards. It is quite a bit. Still things can happen, but I suspect with those safeguards the chances of damaging batteries will be a lot less than the abuse that accidentally goes on with lead-acid batteries that is pretty common. I don't think Technomadia, which BTW was using the same batteries, had this many safeguards or cell monitoring. Also, I don't know if I agree about hanging under. They would stay about at the ambient temperature. Technomadia had them inside a storage room and as you know any RV not air conditioned will rise quite a bit above ambient temperature. I did give the loss of battery efficiency a lot of thought. I felt I probably could do what I am doing with a 400ah battery bank with careful management, 600ah with no doubt but 800ah will still have more reserve than I will ever need for as long as I anticipate having our B. Technomadia with 500ah in a big bus more than likely taxed their batteries more than I anticipate. They also primarily live in the southwest it seems. I hope to always stay and camp in more moderate climates. Also, Technomadia made a 4 year use report. Not many lead-acid house batteries last that long.

What I get is a totally transparent 24/7 120v/12v electrical system where my B operates totally identically electrically whether I am plugged into shore power or not. I now know for an absolute fact I can sit in the desert three days without moving in that way. I suspect longer extrapolating out to 5 days looking at the usage and probably longer with some battery management like shutting off the inverter when I don't need to use the 120v aspects. That would be about a 4 amps per hour savings. Anyway it closely couples with my tanks and intervals with refilling water and dumping which would require moving. Driving one hour easily restores a day's liberal use of electricity. I doubt I will ever invoke autogen or use the engine to charge batteries in a campground as one would do with an Onan generator. I deliberately setup and tested just about every way I could on our maiden trip. I have an antsy three day limit staying anywhere. If I stayed longer or changed my style I suspect a B would not be the optimum RV to do so. The batteries have totally changed my perspective on camping, "how we roll" (nods to Wendland ) where we camped, and where we venture simply in places like in the north between mid-October and mid-April which was a near impossibility or torture in our previous Bs.

[booster]

As a for instance, I was having cavitation problems with the underbody electric fuel pump on our old Challenger twin turbo because of high heat. When I took the temperature of the gas tank, which was in the far year (70's style steel tank) behind the rear axle, the tank temperature after a long highway drive in 85* weather was at about 105 degrees. The rear original rear axle in our Roadtrek, would run consistently at about 125+* or more and is right in front of where underbody batteries normally are. A quick online search says typical going down the road in a heavy vehicle differential temps are 140* to 180*, taken with an in axle temp gauge. When you sit a stopsign in warm weather, you can see the heat rising from under the vehicles around you. It would be very interesting to put a charting monitor on the underbody temp, and see what kind of variations there are, and how long the are at the various temperatures. It was interesting that Technomadia said that the battery manufacturers are now recommending the installs be done inside the RV.

I saw somewhere, don't remember where, that there was a way to charge in cold weather by having a very low current to the batteries that would be able to warm them enough to take regular charge. If automated in BMS, that sounds like it would be a very nice way to go. I would hate to have heaters kill the batteries to shutoff, and them have them not take a charge because they are too cold. Davydd, will your heaters run on shore power, or engine power, if the batteries are low and it is too cold to charge?

[wincrasher]

after a bit more reading, I've found some info on adding a12v element to my water heater. Also, I've found there is a marine type water heater similar to my 4 gallon Atwood that is 12v. My old cricket trailer had a 3 liter 12v water heater that worked well - I may call them and see if I could buy one from them. Anyways, changing up or modding the water heater may be a more reasonable project than an inverter and trying to run the Atwood off that.


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[avanti]

Originally Posted by booster

One of their big points was elevated temperatures (and not all that warm) and how it can cut life in half very easily.

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...

[Davydd]

Originally Posted by booster

As a for instance, I was having cavitation problems with the underbody electric fuel pump on our old Challenger twin turbo because of high heat. When I took the temperature of the gas tank, which was in the far year (70's style steel tank) behind the rear axle, the tank temperature after a long highway drive in 85* weather was at about 105 degrees. The rear original rear axle in our Roadtrek, would run consistently at about 125* and is right in front of where underbody batteries normally are. When you sit a stopsign in warm weather, you can see the heat rising from under the vehicles around you. It would be very interesting to put a charting monitor on the underbody temp, and see what kind of variations there are, and how long the are at the various temperatures. It was interesting that Technomadia said that the battery manufacturers are now recommending the installs be done inside the RV.

I saw somewhere, don't remember where, that there was a way to charge in cold weather by having a very low current to the batteries that would be able to warm them enough to take regular charge. If automated in BMS, that sounds like it would be a very nice way to go. I would hate to have heaters kill the batteries to shutoff, and them have them not take a charge because they are too cold. Davydd, will your heaters run on shore power, or engine power, if the batteries are low and it is too cold to charge?

I can constantly monitor each battery cell temperature. I can't recall the highest I've seen but I don't recall anything over 80 degrees but the hottest temperature we encountered on our trip was 85 degrees. The temperatures seemed mostly close to the ambient temperature. I just did my morning check of our parked B plugged into shore power. The average battery temperature was 52 degrees and the outside temperature was 42. I don't know if there are safeguards when the temperatures rise too high like there are for low temperatures. That would be something to check. I think the top range is 125 degrees but don't quote me on that.

There is always current draw going on with the batteries. It ranges anywhere from 6 to 10 amps just sitting with nothing on and the inverter on standby. I would guess the Silverleaf monitor being turned on is a draw like a miniature TV. I can dim it down but usually don't bother or I could extend it's programmable night use that currently turns the screen off between 10 pm to 7 am to 24 hours when parked. Touching it turns it back on to read for a set period. That draw probably does keep the batteries warmer but if the temperature is dropping down to something like 0 degrees F I doubt any draw could keep the batteries from dropping below freezing of 32. When plugged in the shore power takes over through the inverter/charger to run all electrical systems including the heating pad to keep the batteries warm. Driving or running the engine will do the same in that it will charge the batteries and in turn run the heating pad which I assume is 120v through the inverter. Driving will replenish faster than taking out. The heating pad will come on when the batteries reach 40 degrees thus you can keep charging and heating with either way. If parked for the winter you can disconnect the batteries. There is a breaker for that and then there would be no charging no matter what the temperature. The battery bank will survive a winter disconnected and uncharged. Of course there would be no house electrical systems on either. Or you could leave it plugged into shore power fully charged and the heating pad will keep the batteries above freezing.

If these systems fail then the batteries shut down when below freezing making it impossible to even try to charge them. They can be fully charged but will still shut down. That is just the safeguard. Like I mentioned before, you can then externally heat the batteries even outdoors, you can wait until the ambient temperature gets warm enough to bring battery temps back up, you can still drive which means you can go south (extreme solution) or go to a heated garage. The bottom line is enough safeguards are built in that you are not going to be able to put a charge to a frozen battery and your worst outcome is making do with a house battery disconnect situation until you remedy the problem. I guess in theory you could continue to use your battery power when the batteries are below freezing without charging until depleted but Advanced RV chose not to allow that. That would seem like a race to battery disaster for something that has to be taken care of anyway. The weak link is the heating pad has to work. If so, everything will be OK. If not, the safeguards protect the batteries. Of course if you never use your B in cold weather it would never be a problem. Overnight drops down to the teens with temps above freezing during the day didn't seem to drop the battery temperatures below 40 degrees. That is generally the worst condition most B campers endure. I picked my B up on January 26, endured 5 degrees the first night and no temperatures about freezing day or night for the first five days camping. That was an unusual situation but it gave me great insight.