Advancing Alvar

[avanti]

Is your Espar coolant loop tied into the engine's coolant loop? If so, they could plumb the loop up into the battery compartment to use the residual heat to heat the batteries the same way they already do for heating the plumbing.

[avanti]

Originally Posted by Davydd

OK expert, how would you do it? It is a relatively easy non complex recovery and restoration so I don't know what your problem is with it.

There is absolutely no problem with it. I like it. My only point is that if you like this feature, you should like the "cold weather" recovery, too.

[gregmchugh]

What is the low temperature specification for discharging the batteries? Elite Power Systems specs -4 F for the battery as long as you are not charging it. Does ARV allow the batteries to be put online down to that temperature?

[Applegater]

Been watching this thread for some time. Thanks for the discussion David, it gave some good information as a headstart before I pick up Jake on 1/15/2016. The discussion reminds of one principle my Quality Engineers constantly reminded me, adding systems or subsystems to equipment increases the probability of failure and the increase is not linear but expodential.

[Davydd]

Originally Posted by avanti

Is your Espar coolant loop tied into the engine's coolant loop? If so, they could plumb the loop up into the battery compartment to use the residual heat to heat the batteries the same way they already do for heating the plumbing.

The Espar glycol system is totally separate from the engine cooling system. The waste heat is bundled with all the water lines and does groove down the side of the fresh water tank and I believe still returns to the heat exchanger in the loop at about 160 degrees right under the driver's door. So there would be plenty of heat. The fresh water tank is right under the sliding door. The batteries are behind the rear axle. Under the hood on the driver's side is a glycol reservoir with an attached electric heater as an option to diesel-fired when plugged into shore power.

It is an interesting idea but it seems it would somehow have to be manually controlled to be used only when you need to raise the temperature back above freezing. It seems it would be a nightmare to make it the primary heating system for the batteries. Could you just plumb the separate engine cooling system to do this? Mercedes Benz might not like that.

The diesel-fired heat exchange under the frame under the driver's seat above with the hot water heat exchange below.


The Comfort Hot glycol reservoir under the hood with the electric heater at the front. The white plastic container to the right is the overflow and fill.

[Davydd]

Originally Posted by gregmchugh

What is the low temperature specification for discharging the batteries? Elite Power Systems specs -4 F for the battery as long as you are not charging it. Does ARV allow the batteries to be put online down to that temperature?

The batteries are from Elite Power Solutions so -4 to +149 per spec are the operating temperatures where you can discharge the batteries. +32 is the point you can't (shouldn't) charge. So at +32 or thereabout the batteries disconnect so no charging can take place. That is designed and programmed by ARV and is just the failsafe measure. Could you wire so you can continue to discharge but not charge? Beyond my knowledge but ARV chose not to. You would just drain your battery with no ability to charge and compound your problems.

[avanti]

Originally Posted by Davydd

It is an interesting idea but it seems it would somehow have to be manually controlled to be used only when you need to raise the temperature back above freezing. It seems it would be a nightmare to make it the primary heating system for the batteries. Could you just plumb the separate engine cooling system to do this? Mercedes Benz might not like that.

Rixens has an optional engine-interconnect. It uses a separate heat exchanger under the hood, so you are not circulating your engine coolant through the Espar loop. My system is separate as well, but the Rixens setup looks pretty slick. It would be nice to have engine-heated DHW immediately after arrival. You can use it to pre-heat your engine with the Espar as well as the opposite. MB should't mind--some Sprinters come with Espar engine heaters as an option.

The reason I mentioned the engine interconnect is that, although there is plenty of heat available from the Espar, in the case that we are discussing, there would be no power to fire it, so you would really need the engine heat. It would work almost instantly, though.

[Davydd]

So basically in addition to the interconnect heat exchange there would also have to be a small pump powered from the chassis battery and another glycol loop to the battery box.

[avanti]

Originally Posted by Davydd

So basically in addition to the interconnect heat exchange there would also have to be a small pump powered from the chassis battery and another glycol loop to the battery box.

I was picturing just having the engine keep the existing Espar loop hot at all times, so you would use the existing pump. You are right that you would need some kind of bypass valve to turn off heat to the battery when you don't need it (possibly a mechanical thermostatic valve).

EDIT: Now that I think of it, having a small pump isn't a bad idea--easy to turn on and off.

[gregmchugh]

Originally Posted by Davydd

The batteries are from Elite Power Solutions so -4 to +149 per spec are the operating temperatures where you can discharge the batteries. +32 is the point you can't (shouldn't) charge. So at +32 or thereabout the batteries disconnect so no charging can take place. That is designed and programmed by ARV and is just the failsafe measure. Could you wire so you can continue to discharge but not charge? Beyond my knowledge but ARV chose not to. You would just drain your battery with no ability to charge and compound your problems.

The reason I brought this up is there could be the potential, as long as you were above -4 F, to still use the lithium batteries to power the Espar to use a glycol loop to the battery bank to heat the batteries up to the point where they can be charged. Just something to consider.

[gregmchugh]

Not that it really relates to this very much but some of the Alde propane heat/hot water systems in Roadtrek Sprinters have a heat exchanger and small engine coolant pump under the passenger seat. This allows you to heat the van while driving using engine coolant heat instead of propane or to use the Alde propane heat to preheat the engine on cold days. I would expect that there are some Espar systems to do the same thing. Same principle as heating the battery bank.

My feeling is that electric heating pads would be the way to go. Added wiring and heat pads seems simpler than plumbing a glycol loop to the batteries. Put in high enough wattage pads and a switch to power them from the chassis electrical and a thermostat to prevent overheat. Start up the van engine and engage the heaters. These heating pads could be independent of the current heating pads or maybe you could design it to have two wattages from the same pads to perform the heat from cold soak and the cyclic heat when up to temp.

[Davydd]

I'm thinking if I lived in the south I would be saying, "Meh" and wouldn't be too concerned about any of this.

[Applegater]

Actually I live in the west, travel all over the west, as well as British Columbia, Alaska, the Yukon, Alberta and say "meh" as well. If I wanted an expedition vehicle I would have bought an Earthroamer!

[pattonsr]

I believe Davydd stated that ARV disconnects the batteries at +32 or thereabout so no charging can take place.

If one starts up the Sprinter then the second alternator is running. It is directly connected to the Lithium bank through a Balmar regulator. What does the Balmar regulator do when it finds the batteries disconnected?

[avanti]

Originally Posted by pattonsr

If one starts up the Sprinter then the second alternator is running. It is directly connected to the Lithium bank through a Balmar regulator. What does the Balmar regulator do when it finds the batteries disconnected?

The Balmar has both an "ignition input" and a "positive voltage sense" wire that goes from the battery to the Balmar. Both of these must see power before the Balmar will produce any current. Presumably at least one of them is disconnected along with the battery.

[Davydd]

Originally Posted by Applegater

The discussion reminds of one principle my Quality Engineers constantly reminded me, adding systems or subsystems to equipment increases the probability of failure and the increase is not linear but expodential.

I hope everyone keeps this issue in perspective. When the outside temperature hits 32 degrees or even 20 degrees, maybe 5 to 15 degrees this is a non-issue. The batteries stay way warmer. It is when the actual battery hits 32 degrees does the system arbitrarily disconnect for the protection and longevity of your batteries not because it won't provide power. So you are really looking at it as a winterizing or de-winterizing type of task and not something you might encounter on the road or while driving or in a routine manner like exercising an Onan generator. No one seems to agonize about the winterizing and de-winterizing tasks. It is just something that has to be done and there is really no easy shortcut to accomplish it. The same with cold batteries from cold storage. You can figure it all out in advance and act accordingly so it never happens if you choose. In the case of de-winterizing if you do choose cold storage, no one does it while it is still cold do they? So when you de-winterize this might not even be a task at hand as the batteries will warm back up naturally.

Taking Applegater's comment I think so far just about every suggestion to dummy proof heat restoration might be just adding a lot of unintended consequences. The whole system is complex enough as it is.

Staying plugged into shore power is my preferred solution. I've always done that with my Bs for a decade. It was 8 degrees this morning. My battery bank cell average was 46 degrees. I saw the heat flame icon on for just the third time in my periodic checking since it turned cold.

My first week on the road last winter when I picked up Alvar was 24/7 below freezing from about 5 to 27 degrees. I would venture not too many Class Bers encounter or desire to put up with those kind of conditions. I had no choice. I picked up Alvar in Cleveland and drove it home to Minnesota and then hit the road and didn't encounter above freezing temperatures until New Mexico. I hope you understand why I don't feel this is much of a priority.

[booster]

Originally Posted by Davydd

I hope you understand why I don't feel this is much of a priority.

I hope you understand that just because your opinion is that it is a not a priority, others are not required to feel the same way. You don't get to determine other folks opinions. There is no need for you to defend your choice, as it is yours to make, but there is also no requirement for others to agree with it.

[pattonsr]

I am guessing that the heating pads that ARV puts in have a thermostat. I would assume that if the thermostat goes crazy or fails on a trip one would have to at sometime go back to ARV so they could drop the batteries and do the repair. I would not feel comfortable with someone else doing the repair

In that spirit of not having to call off a trip in progress, why not have some redundancy built in. I am thinking of a concept like the way seat heaters work. Have a switch somewhere to manually turn on extra 12v pads without using a thermostat to insure they come on. Have the 12v from the Sprinter battery tied to the ignition just like seat heaters.

So while on a long winter trip, one could be assured that if the primary lithium heat pads fail to work properly, one has a way to manually provide the heat. Note that this also works as a slow solution (6.7 hours of driving somewhere) to the battery shutoff problem that all of you have been discussing.

Cars have seat warmers to warm up our behinds. Why not the same concept to warm up the Lithium batteries using power from the starter battery with the engine on just like the way seat warmers work.

[gregmchugh]

It is my impression that there may be no thermostat but control logic in the system software to monitor the individual battery cell temperatures and cycle the heating pads to keep the batteries above 40 deg. Failures of the hardware, temp sensors and the heating pad controls, are possible of course but not as likely as the failure of a traditional thermostat. I would not think that redundancy would be warranted in this case but others can, of course, feel otherwise...

[pattonsr]

gregmchugh,

Since the batteries are the lifeblood of an ARV sprinter, I would like a plan to keep the batteries above freezing if the primary heating doesn't work. It really doesn't matter what fails in the heating logic. What I do know is that everything fails given enough time..

I live in Austin, TX and if it freezes here it is usually just during the nighttime. One year it was like 24 degrees for two days. The local utility hit its all time electric consumption. And then the unthinkable. Several Texas electric generation plants failed since they froze due to inadequate insulation. So Austin instituted rolling blackouts which are supposed to be 5 minutes off and 55 minutes on.

My neighborhood instead got 55 minutes off and 5 minutes on. The weak link in a pool is the pump for keeping the water moving during a freeze. I never considered having basically no electricity during the night during freezing weather. I would have given my right arm for a whole house backup generator that night.

In twenty five years, it has happened only one time but I had no backup plan to prevent a pipe in the pool gunite from freezIng and cracking.