Lithium 80% DOD rule

[gregmchugh]

Greg,

I've read that. They could have been computer glitches or some other problems I have not encountered. I've had my share but always recovered. I had one shut down from cold temperature when I first got my ARV and that was due to misreading a switch and I had the battery heaters shut off and didn't realize it. When I figured it out I could have prevented it but I let it happen because my experimental mode kicked in and I wanted to see if the shutdown and recovery worked. It did. From that experience ARV has since made that mistake more failsafe with additional positive feedback redundancy on the Silverleaf screen as I described earlier. That is also now how I can monitor when the battery heating pads come on and how long they might stay on at given temperatures.

My only other time was deliberate to drive down the SOC without Autogen activated and everything worked as described in ARV's manual including that need to hold down a toggle switch until a readable 1% SOC back to 21% brought power back on. I'll take that might never happen little inconvenience over carrying an AGM battery with its own issues.

I also had a moisture problem in heavy sudden rains that shorted out the battery electronic sensor connections. In that case the batteries came back online automatically with no need to hold the toggle switch when the connections dried out. As it turned out a sudden pressure differential was sucking water into the supposedly sealed battery case. That was solved by a dime-sized Gortex valve on the case. I have an insulated fiberglass case. ARV, I noticed, is now building insulated stainless steel boxes as of last spring but I have no knowledge of what they are now doing beyond that. The stainless steel boxes eliminated all the heavy iron mounting cage that was protecting my battery case. The skid plate protector is still there. I had the very first build using Elite Power Solutions GBS batteries. I was a big boy and knew what I was getting in to.

This second year everything has been bullet proof so far though I have had Balmar regulator temperature sensor issues, Nation alternator issues (and why I enthusiastically upgraded to that Delco), macerator failure and a VB Air Suspension bag leak. Advanced RV has taken care of all that immediately either at their shop, a field visit, or in my case Mercedes Benz dealers in Scottsdale, AZ and Shreveport, LA. I took care of my own Sprinter problem of the power steering line freakingly coming off at the Mercedes Benz dealer in Littleton, CO. All in all, those three visits to MB dealers cost me about 6 hours of total wait time at the dealers. I have a good impression of MB service.

If the SOC is over 20% on a shut down the restart toggle hold is almost instantaneous so you can deliberately shut down your battery bank for storage and not have that hold down agony. I understand as you surmised ARV can plug in a computer and read a log of what had happened to their electronics. They had done that when I was in their shop.

Very good, thanks for the info...

 

[mojoman]

Going on the third year of the inferior Promaster and homemade lithium system, problems so far, I have a loose arm rest.

 

[avanti]

I don't recall if Roadtrek ever stated that they install a custom version of the Balmar but they could possibly be doing that...

I doubt that very much. It is fully-programmable. Moreover, it is completely sealed and potted.

 

[gregmchugh]

I doubt that very much. It is fully-programmable. Moreover, it is completely sealed and potted.

But, it is possible that they buy units that have a software version customized for their use, isn't it?

 

[avanti]

But, it is possible that they buy units that have a software version customized for their use, isn't it?

Guess so. Not sure what they would want that it can't already do, though.

 

[gregmchugh]

Guess so. Not sure what they would want that it can't already do, though.

Very likely you are correct but with Roadtrek buying probably nearly 1000 per year these days they could likely get a custom software build if they wanted something added...

 

[gregmchugh]

Going on the third year of the inferior Promaster and homemade lithium system, problems so far, I have a loose arm rest.

Did someone say your unit was inferior? Shame on them...

 

[avanti]

Very likely you are correct but with Roadtrek buying probably nearly 1000 per year these days they could likely get a custom software build if they wanted something added...

BTW: I am pretty sure that the diagnostic display shows a firmware version #, so if it were different, we probably could tell.

 

[gregmchugh]

BTW: I am pretty sure that the diagnostic display shows a firmware version #, so if it were different, we probably could tell.

Very true, maybe an owner of a recent Roadtrek with Ecotreks will check that out...

 

[cruising7388]

url]http://elitepowersolutions.com/docs/EMS%20Operation%20Manual.pdf[/url

I can't seem to access their website and when calling I get an answering machine.

 

[gregmchugh]

I can't seem to access their website and when calling I get an answering machine.

I just got there on my iPad...

 

[gregmchugh]

I can't seem to access their website and when calling I get an answering machine.

There is also info at this website that retails the Élite Power lithium system.

RV Lithium Battery

 

[Davydd]

It is easy to read out the settings of the Balmar using a magnet and the little display. Well, not easy, but only because it all goes past so fast. It keeps repeating, though. Best to video tape a cycle.

Magnet?

My Balmar readout is under my dash on the driver side. Only it is mounted upside down and you are right about the readout going fast. It was impossible to mentally keep up with it upside down so I took the iPhone and videoed it and then flipped the video.

 

[avanti]

Magnet?

Yeah. The display is controlled via a magnetic reed switch (they do that so the unit can be completely sealed -- the boaters like that). There is a spot where you hold a magnet to make changes. You need to put the unit in "verbose" mode if you want to see the gory details. Then it spews out even more obtuse numbers.

With mine, I got an official BALMAR screwdriver with a magnet on the handle. If you didn't get yours, then ARV must be hoarding them.

 

[markopolo-ClassB]

In theory, all the charging sources should be in float for a full battery, but many don't do that. Add to that the fact that at the 12.8 volts that a full AGM is at, the lithiums would need a full charge. In the case of the Balmar, it will initiate a charge cycle every time it is turned on. If the AGM were just sitting there by itself, full, with the voltage above what the Balmar considers full, it would likely go to float directly (with the possible issue of locking in absorption if there is not a 4 amp load seen). With the Roadtrek setup, the lithiums are going to be very close to that threshold, so they must be doing something in the settings to get the Balmar to go to charge voltage, or maybe just the high current to lithiums will do it. Either way, at 12.8v, which the chart says is 10% SOC of the lithiums, the AGM is still full, so when the Balmar goes to charge voltage, the AGM will see it while full, for the full charge cycle.

I would think all the other charge sources would also have similar confusions as the lithiums will need to charge badly at 12.8, but the AGM is full. The common charges and solar controllers run on algorithms to guess what is needed, so if they are using them I doubt they are could accurately interpret high current at a voltage that should indicate at full battery.

Some charging sources do run a charge cycle every time they are activated. Progresssive Dynamics is one of them, and will run 4 hours at absorption every time they are turned on and go into absorption (I am not sure if any of them go directly to float if they see high enough voltage).

Since we don't really know how Roadtrek is doing it, it is very hard to guess, but I don't see how the standard charging profiles would work if the check voltage before going to full charge, unless they can change the threshold up to over 14+ volts, as they would never get to full charge voltage.

They may be using charging sources that allow fixed voltage charging, all the time, or that do a full charge every cycle, regardless of voltage at starting, and turning off the lithiums with the BMS. This is the way most lithium setups like to work, it appears, but it would be hard on the AGM battery. Of course, Roadtreks could be in float voltage most of the time, even when they shouldn't be, if they are using normal AGM profiles as was mentioned. Not ideal for sure, but if they had a high float voltage they might get by.

Without actually having the meters on a Roadtrek under some varying conditions, we are only guessing, and based on all the surprises we have seen, it could be anything.

Re: paragraph 3 - Just a note about the Progressive Dynamics converter/charger in my van. I'd describe what I think happens at start up as a pressure test. If required amps exceed X amount to reach Y voltage then full charge cycle begins. If not then it goes into Normal mode 13.6V. I could test to see if it alternately goes straight into float if different parameters are met. I think I've seen that also.

I would assume lithium and lead acid would have, for lack of a better term, different pressure profiles. My guess is that you'd see more amps at lower voltage with lithium compared to lead acid when charging. The size of some of the lithium battery banks we're seeing guarantees high amp flow.

 

[gregmchugh]

Ever since Roadtrek added the auxiliary AGM battery in parallel with the Ecotrek modules there have been various ideas floated about the reasons for the add and the effects of the add.

As I recall, one comment was that the AGM would have the benefit of reducing a large initial charge current when multiple Ecotrek modules were online.

Is this what will happen?

 

[markopolo-ClassB]

The charger will try to raise the system voltage to whatever the charger settings dictate. It will take X amps to do that.

Avanti & Booster will likely know if a regulator can do what you describe.

 

[booster]

Ever since Roadtrek added the auxiliary AGM battery in parallel with the Ecotrek modules there have been various ideas floated about the reasons for the add and the effects of the add.

As I recall, one comment was that the AGM would have the benefit of reducing a large initial charge current when multiple Ecotrek modules were online.

Is this what will happen?

I would doubt that the AGM would reduce any current to the lithiums for a couple of reasons. First is that unless the lithiums are discharged too far, the voltage is going to be at least 12.8v per our previous comments and the chart posted. At that point the AGM is going to be full, or nearly so, so it won't accept much current at all. Second would be that lithiums accept charge much better than AGMs at any given state of charge. Basically, they show lower resistance to current flow than the AGM, so they will get nearly all the current.

The charger will not be able to hold the voltage anywhere near setpoint on discharged lithiums, so the voltage will be set by the SOC of the lithiums, for the most part. Once the voltage on the lithiums starts to rise as they are charged, the AGM will start to take some amps, even though it is already full for the most part. The thing to remember is that an AGM that is totally full will only accept about .5% of it's 20 hour rating when being charged at 14.4 volts. That is only 1 amp for a 200ah battery bank, and Roadtrek's is much smaller than that.

 

[gregmchugh]

I would doubt that the AGM would reduce any current to the lithiums for a couple of reasons. First is that unless the lithiums are discharged too far, the voltage is going to be at least 12.8v per our previous comments and the chart posted. At that point the AGM is going to be full, or nearly so, so it won't accept much current at all. Second would be that lithiums accept charge much better than AGMs at any given state of charge. Basically, they show lower resistance to current flow than the AGM, so they will get nearly all the current.

The charger will not be able to hold the voltage anywhere near setpoint on discharged lithiums, so the voltage will be set by the SOC of the lithiums, for the most part. Once the voltage on the lithiums starts to rise as they are charged, the AGM will start to take some amps, even though it is already full for the most part. The thing to remember is that an AGM that is totally full will only accept about .5% of it's 20 hour rating when being charged at 14.4 volts. That is only 1 amp for a 200ah battery bank, and Roadtrek's is much smaller than that.

Thanks, that makes sense, I am just trying to separate the truth from the speculation with regard to the mixed battery bank...

So far, the two facts that seem clear are that the AGM activates the chargers and that it allows powering the battery heaters from the engine generator...

 

[booster]

The charger will try to raise the system voltage to whatever the charger settings dictate. It will take X amps to do that.

Avanti & Booster will likely know if a regulator can do what you describe.

Using a regulator is probably the best way to reduce the charge current from an engine generator, if that is what you are looking to do.

The Balmars appear to be able to set to reduce output in 5% (?) increments, so you can turn them down. Of course, they also turn themselves down 50% when they get hot, and then cycle up and down. Avanti's test data seemed to show that he averaged something in the 60-70% of rated capacity of the alternator when hot, in hot weather.

The Ample Power regulator has two settable output levels that are continuously variable (settable) and triggered by 12v inputs from switches or thermostats. This allows for having two lowered outputs available besides the full output of the alternator.

I think there is some very good merit to using the turned down outputs, even with AGM batteries. If you turn down the output to whatever level it takes to just make it so the alternator isn't thermal cycled from hot to cool to hot repeatedly, you will still get the same average amps, but it will be much easier on the parts not to be thermal cycled. The only thing you would lose would be the few initial minutes of higher output as the alternator heats up the first time.

I think we are going find out that the big lithium banks are going to be hard on alternators used as engine generators, as they are going to be constantly in the heat cycling output condition for long periods of time. This may be the reasoning behind ARV moving to the massive 100% duty cycle alternator.