Advancing Alvar

[Davydd]

Originally Posted by avanti

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?

Caught me. I had just edited my previous before I saw this. The heating pads are 12 volt pads with power coming off the batteries. That is so we can travel without plugging in which is almost necessary in the winter if boondocking and campgrounds with shore power mostly closed. There is more than enough battery power to do so considering I have two 5 amp heating pads and they don't stay on anymore than necessary. Also, when cold and boondocking I don't think I would sit very long without running the engine and/or driving.

I don't know how you can use shore power, engine generator or solar unless the batteries are connected. That's what I meant by impossible. They all charge and would attempt to do so with below freezing batteries. That's also why the batteries automatically disconnect when freezing is approached.

[gregmchugh]

What happens after the batteries disconnect as you approach freezing? Is there a procedure to get them back online? Is the engine battery power used to power the centralized control system and the battery management system at all times? Is the only way to get the batteries back online some method of externally heating up the battery pack?

I can see how you could design a system that would allow the heating pads to warm up the batteries using power from outside the lithium cells when they are disconnected and from the lithium cells when they are connected. The power could come from a shore connection or from the chassis electrical system or possibly from the solar or aux alternator.

[Davydd]

Originally Posted by gregmchugh

What happens after the batteries disconnect as you approach freezing? Is there a procedure to get them back online? Is the engine battery power used to power the centralized control system and the battery management system at all times? Is the only way to get the batteries back online some method of externally heating up the battery pack?

I can see how you could design a system that would allow the heating pads to warm up the batteries using power from outside the lithium cells when they are disconnected and from the lithium cells when they are connected. The power could come from a shore connection or from the chassis electrical system or possibly from the solar or aux alternator.

To power up the batteries and bring them back online it is a simple matter of holding down the battery shutoff toggle switch to the on position. If the battery temps are back up to above freezing they will connect again.

Since the system is designed to prevent charging batteries below freezing and all systems work with 12V heating pads to keep the batteries above freezing whether plugged in or not, I don't see another system is needed to heat the batteries. One system that works plugged into shore power or not seems adequate. The van also has an autostart feature to keep batteries charged and I have enough battery I doubt I would even need that under normal winter use.

The system is designed so you can tour and use your B off grid in below freezing conditions.

As I mentioned, you would have to deliberately turn off the heating pads or have a system failure to fail and there are two failsafe options already to prevent that.

This Silverleaf Li Ion Battery Status screen has a touch "Heat" button to turn the heating pads to on or standby. When on or standby, the tabs are green. When off the tabs are empty of color (or black.) When heat is actually on, a "flame" icon appears to the right as shown. I think the heat comes on when cell temps drop below 41.1 degrees F. (5 deg. Celsius) so there is a lot of safety factor built in.



Again, simply plug into shore power be it 15 amp or 30 amp. Advanced RV's recommended winter layover storage. Or simply disconnect your batteries at the battery disconnect/connect toggle switch which would be a remote unattended storage option. If batteries do go below freezing you can't connect them again until:

Move van to a conditioned space above freezing, i.e. heated garage.

Drive to a warmer climate.

Don't bother and wait for ambient temperature to rise back up above freezing.

Apply an external heat source as I mentioned. This worked at -5 in under 24 hours or so outdoors. This is a KISS method not a Roadtrek method.



I doubt the engine battery has enough reserve power to be used nor would a second battery system such as kludge solution AGMs have enough reserve either. If you are applying power from a shore system in the first place as suggested then the heating pads do their job and there is no need to disconnect the batteries.

[gregmchugh]

I guess it works for you but I will suggest that with the engine running there would be plenty of amps available from the chassis electrical system to power the heating pads and get the system operational which seems like a more desirable solution than the options you outlined. Just my opinion...

When the lithium batteries are offline is the Silverleaf control system still operational?

[avanti]

Originally Posted by Davydd

If batteries do go below freezing you can't connect them again until:

Move van to a conditioned space above freezing, i.e. heated garage.

Drive to a warmer climate.

Don't bother and wait for ambient temperature to rise back up above freezing.

Apply an external heat source as I mentioned. This worked at -5 in under 24 hours or so outdoors.

That is a very elegant system. My only quibble is with the above list of "last gasp" alternatives. There could easily be a small power brick dedicated to warming the battery when on shore power. This would permit one to totally shut down the system for storage and have a non-kludgy alternative for starting up in cold weather. With the Silverleaf system, this could be made totally automatic. I understand you say you don't want to do this, but given how easy it would be, it really should be there as an option.

EDIT: I also agree with gregmchurgh -- a system such as I describe could also be powered by the chassis.

[Davydd]

Are you guys thinking this through? It took a 1500 watt electric oil heater overnight to bring batteries back to above freezing. Exactly how is running an engine maybe that long to power some "power brick" which most likely would never be needed going to be a better solution? Like I said, if you have a power source then there is no need to disconnect the batteries. Logic says if you are going to periodically use your B in the winter then stay plugged in. That's what I am doing. If in cold storage the odds are you most likely will not bother until ambient temperatures are back above freezing. If you are seriously planning to reactivate in the winter from cold storage, you will most likely be doing so to seek warm weather and batteries will reconnect naturally.

Most winter climates are not as cold as Minnesota. I think I am dealing with the extreme. Most everywhere else would have ample days above freezing to reactivate cold storage without any kludges. My "power brick" is that oil-filled electric radiator. I doubt I would ever use it again beyond that test. Something like a 1500 watt ceramic cube heater might work too but I am not going to bother to test it. I would never need it away from home because once in use the system is designed to stay above freezing. Then the "power brick" is the battery bank itself.

In answer to the Silverleaf screen question. Battery disconnect means no power. The Silverleaf screen is completely off as it runs off the coach and not the chassis. That's why there is a physical battery connect/disconnect toggle switch. Hold down toggle and batteries reconnect in a matter of seconds and the screen comes to life. The other failsafe is if batteries run down to 20% SOC (or 0% on the usable SOC Silverleaf screen readout) you have to start the engine or plug into shore power and hold down the toggle switch for up to 6 minutes to charge and raise the SOC 1% to reactivate the batteries and Silverleaf screen. The only way this will happen is if you turn Autogen off at the Silverleaf screen and let the batteries drain down. This I tested as well. I wanted to see how all this worked.

[booster]

I think we need a little clarification about davydd's heaters. In the past, he has said that they are 110v heaters run off the inverter, which brought up the repeated question as to why they couldn't just be switched to 110v when on shore power with cold disconnected batteries. Now we hear that they are 12v heaters run off the batteries themselves, and that brings up the question as to why they couldn't be switched to chassis power to warm them up.

It just makes no sense to have such a sophisticated system that can only be recovered to function by parking it inside to warm up. This question has come up repeatedly for a long time, and we never have heard what ARV says about why they did it this way.

[gregmchugh]

Putting a1500 watt oil heater under the van to heat the complete battery compartment would use a lot more power than needed by the internal heating pads, not a very reasonable comparison in my view...

[avanti]

Originally Posted by gregmchugh

Putting a1500 watt oil heater under the van to heat the complete battery compartment would use a lot more power than needed by the internal heating pads, not a very reasonable comparison in my view...

Correct. The two ways of heating are not remotely comparable. Kind of like comparing heating your room with using an electric blanket.

[avanti]

Originally Posted by booster

It just makes no sense to have such a sophisticated system that can only be recovered to function by parking it inside to warm up. This question has come up repeatedly for a long time, and we never have heard what ARV says about why they did it this way.

Totally agree. I suspect that this is simply a minor oversight on ARV's part (or something the just haven't gotten to). Totally forgivable and easily remedied. I think we need to differentiate between "a great van" and "a perfect van".

[gregmchugh]

Davydd, you mentioned above that you have two 5 amp heating pads that heat the battery bank. Is that correct? Drawing 10 amps from the chassis electrical to heat up the batteries is easy...

[Davydd]

Originally Posted by gregmchugh

Davydd, you mentioned above that you have two 5 amp heating pads that heat the battery bank. Is that correct? Drawing 10 amps from the chassis electrical to heat up the batteries is easy...

Yes, but that is 10 amps per hour and would require you to run your engine to get those amps off your chassis battery in a very short time. That makes no sense in cold storage.

Originally Posted by gregmchugh

Putting a1500 watt oil heater under the van to heat the complete battery compartment would use a lot more power than needed by the internal heating pads, not a very reasonable comparison in my view...

Reasonable? If you have a power source I said you need not disconnect your batteries. You are missing my point. This is something I anticipate never doing again now that I know how everything functions and understand the parameters. If I were to plan on putting my B in cold storage with batteries disconnected for the winter then maybe this might be an issue but not if taking it back out in March or April in above freezing temperatures. So really it comes down to do you need something complex and built in or just know an external solution in case it ever happens? It should never be an issue for me. At home I prefer to be plugged in and have use of my B. And as I said, on the road and in use there should never be a need to plug in just to heat the batteries when using my B in the winter.

As I said, know and understand your parameters. What you are suggesting is akin to carrying a generator and battery charger in your car instead of jumper cables or calling AAA. Sure, *hit happens. I don't carry a spare tire either. What you think is a problem is very low on the priority list of needs.

[gregmchugh]

Well David, I do understand how the current design works just fine for you with your usage scenario. I simply have the audacity to suggest that other owners may have different needs based on how they use their van that would lead them to desire something different. The added option of heating the batteries from chassis power may not seem like an unnecessary feature to other buyers even if it seems so to you. I realized long ago that your van is perfect to you but there just may be other buyers with somewhat different needs than you. Or is that really such a stretch of the imagination that it is not conceivable to you?

[Davydd]

I've laid out a detailed explanation as to why I would most likely never need or use the feature. In turn you fail to accept that. I'm sure if someone wanted it Advanced RV could provide it.

So far all I have read is running your engine and no one has an idea how long that would take to raise 228 lbs of battery from -5 degrees to above freezing. I think impractical. I've read "power brick" and have not a clue as to what that would be and if anyone is suggesting AGM batteries then they are kludgingly thinking like a Roadtrek engineer.

Then again, I may be wrong and Booster right. I was testing with the heater turned off to let the batteries go cold. If those heating pads are 110v instead of 12v then maybe I could heat them up just plugging in while the battery is disconnected. That's something I need to explore. My curiosity is piqued now because when I checked this afternoon (plugged into shore power) the batteries were in discharge mode giving up about 3 amps, the inverter was disabled (no charge) and using the 120v systems were active and not drawing amps from the battery. I take that to mean 120v when plugged in bypasses the inverter and the 120v systems only use the inverter when off shore power.

If the heating pads are 110v the only problem is the Silverleaf screen readouts and touch controls turn off when the battery disconnects. The question then begs does that turn off the heater or once turned on stays on? There are still controls when the battery is disconnected that don't allow the battery to reconnect until above freezing. Lots to check.

[avanti]

Originally Posted by Davydd

I've laid out a detailed explanation as to why I would most likely never need or use the feature. In turn you fail to accept that. I'm sure if someone wanted it Advanced RV could provide it.

We all accept that. It is just that it is blatantly obvious (to us) that a "typical" user WOULD want such a feature. Plus, it is technically trivial to provide. It is just unreasonable for you to defend its absence. If anyone other than ARV had committed such a blunder, you would be all over it.

So far all I have read is running your engine and no one has an idea how long that would take to raise 228 lbs of battery from -5 degrees to above freezing. I think impractical. I've read "power brick" and have not a clue as to what that would be and if anyone is suggesting AGM batteries then they are kludgingly thinking like a Roadtrek engineer.

A "power brick" is common parlance for the small inverters that you plug into a 120VAC outlet when you need a small amount of DC current. The thing that recharges your cell phone is a power brick. There is the equivalent of a power brick inside your NovaKool fridge so that it can be run from 120VAC (although ARV may or may not use it). This was suggested in the context of an assumed "two 5A 12VDC heat pads". A power brick could certainly power such an item. Now you have a clue.

Then again, I may be wrong and Booster right. I was testing with the heater turned off to let the batteries go cold. If those heating pads are 110v instead of 12v then maybe I could heat them up just plugging in while the battery is disconnected. That's something I need to explore. My curiosity is piqued now because when I checked this afternoon (plugged into shore power) the batteries were in discharge mode giving up about 3 amps, the inverter was disabled (no charge) and using the 120v systems were active and not drawing amps from the battery. I take that to mean 120v when plugged in bypasses the inverter and the 120v systems only use the inverter when off shore power.

Your Outback has a built-in AC transfer switch. When you plug in to shore power, the inverter section of the Outback is disabled (after first checking for AC power quality) and the transfer switch switches all AC loads to the shore power input. So, your inverter is NEVER involved when proper shore power is available.

[gregmchugh]

David, I don't really understand how I could have made it more clear that I accepted that you had no interest in this feature for your van...

[avanti]

Originally Posted by Davydd

no one has an idea how long that would take to raise 228 lbs of battery from -5 degrees to above freezing. I think impractical.

Just for the record, a back-of-the-envelope calculation:

The specific heat of a LiFePO battery is roughly1350 J/kg.K
ref: http://iopscience.iop.org/article/10...3/1/012014/pdf

so, to raise 228 lb worth of such batteries by 37 degrees F, we need 2870108 joules of heat.

Our assumed 10 amps (120 watts) worth of heating pads produce 7200 joules/minute.

2870108 / 7200 = 399 minutes or roughly 6.7 hours.

Of course, if it were a toasty 14 degrees F, or if we splurged with 20 amps of heat, that would be cut in half.

[pattonsr]

avanti,

Some random thoughts.

You said "your Outback inverter is NEVER involved when proper shore power is available".

True for the Outback but not true for the Magnum MSH3012M hybrid which augments shore power.

In any case, what if the heaters (12v or 120v) fail to work when you need them? What is the solution then? Redundancy?

What if you are stranded in deep snow for days and the diesel fuel runs out. I think cold dead Lithium batteries are the least of ones problems.

I agree finding a backup solution to warming batteries is a good idea. It seems like the first thing to determine is whether 12v or 120v warming pads are being used. I bet Davydd finds out ARV did use 12v warming pads.

[booster]

Originally Posted by pattonsr

avanti,I agree finding a backup solution to warming batteries is a good idea. It seems like the first thing to determine is whether 12v or 120v warming pads are being used. I bet Davydd finds out ARV did use 12v warming pads.

The 12v heating would be the obvious choice, I agree. I only brought it up at this point because when the van was being built, davydd repeated many times that the heaters were 110v through the inverter. It was questioned many times then, as it made little sense. It was that setup of needing the 12v from the batteries to get the 110v from inverter for the heaters that was given as the reason you had to go inside and warm up. The engine generator would not initiate without having a battery in the circuit for reference, so the only other place would be off the engine alternator.

[Davydd]

Running an engine 6.7 hours is a non-starter for me. I think that idea can be dismissed. I could not leave that unattended. I won't even get into all the worryworting over idling that goes on about Sprinters. That makes my idea of the external heat source a better idea. Plug it in, walk away, come back later.

I haven't read any of the voluminous information on the Outback. But if those heating pads are 110vac then just maybe the solution is already at hand and I am mistaken. If not and a power brick is all it takes then that is a simple solution. Would that make Alvar perfect again? Even I don't believe that though I haven't tinkered and modified yet like I did with my two previous Bs. I want that secret basement compartment that Robert De Niro had in his RV in the Meet the Fockers movie.

The Advanced RV is set up to run 12v only for the NovaKool refrigerator.