Shore power

[booster]

Definitions as I understand them, with explanation.


Converter--Changes a AC voltage to DC--In the case of RVs it is 110v AC to 12v nominal DC. They are unregulated transformer types in days of old. Now days they are commonly referred to as power supplies or regulated power supplies and are used in lots of applications in industry. The old converters needed a battery for stability, but not to generate power, the newer power supply types do not need a battery reference to hold voltage.


Battery chargers change AC power to DC power just like the definition of a converter. Early battery chargers were fixed voltage and construction just like a converter and did not need a battery to generate power, but did for stability.



The bottom line is that a converter is a battery charger if it is at the right voltage for the battery being charged. A battery charger is also a converter if it is supplying power to an RV.



The definitions get more involved when battery charger technology moves forward. Multi-stage, smart, intelligent, whatever, chargers use electronics to regulate the output voltage to better take care of the batteries they are charging. In an RV, they are also mulivoltage converters because they are supplying power to the RV at the same time, if you want to use that definition. Or you could just say you have a battery charger only, and the van power is coming from the battery, which is sometimes true and sometimes not in reality.


All this is well and good, and we can mostly agree that you do need a battery in the circuit if you have an old school converter that is also used to charge the batteries, but for stability not to make it function. If it is a very old system, there may be a chance that the converter would only power the coach DC circuits and not be connected to a coach battery or there may not be a coach battery. In this case the coach battery would only charge from the alternator. I have heard of such systems but never seen one.


What I still don't get is that you state a current day converter could be disconnected from a battery, which is technically true if such a converter were ever used in an RV. It would basically be the previously mentioned "power supply" and would be used only for single voltage. The currently used converter/inverter/chargers are all multistage chargers and they also supply power to the RV. Many also have an inverter to supply 110v off the batteries.



I would like to hear if there really is a converter/charger that does not need a battery reference to initiate, and still does multistep charging as many Roadtrek owners would be able to get rid of the AGM battery in their lithium systems with one, I think. As I mentioned about the brands I have owned, none of the multistage chargers/converters will start without a battery, and I have never heard of an RV coming with a converter (power supply) that does not need a battery to run. I will point out that the addition of a fixed voltage power supply was one of the very early suggestions that was discussed here on the forum in relation to the Roadtrek problem of not being able to restart their lithium batteries after a shutdown, before the did the AGM battery.

[cruising7388]

Originally Posted by booster

The bottom line is that a converter is a battery charger if it is at the right voltage for the battery being charged. A battery charger is also a converter if it is supplying power to an RV.

We regret to inform you that this dog just won't hunt

The converter has to deliver more than proper voltage to provide battery charging. That's only half the picture. It first has to deliver power to the loads demanded from the 12V distribution panel. If and only if there is additional converter output capacity remaining after this demand is satisfied will there be any net charging amperage directed to the battery.

I guess you could also call a battery charger a converter but that's a pretty tortured description considering that the charger isn't a discrete power source, but actually operates more like a low priority converter load.

[booster]

I still want to find out about a current converter, charger, or any other name unit that is used in RVs that does not need a battery connected to power the van. This would be a big deal for a lot of reasons, to a lot of people.



Tortured descriptions abound in this discussion, as the terminology has evolved in many directions over the years. Bottom line is what equipment is really available for the RV market. As I said before, the rest is semantics.



Once the OP lists what equipment he has, perhaps there can be some clarity as to what is happening with his system.

[cruising7388]

Originally Posted by booster

I would like to hear if there really is a converter/charger that does not need a battery reference to initiate, and still does multistep charging as many Roadtrek owners would be able to get rid of the AGM battery in their lithium systems with one, I think. As I mentioned about the brands I have owned, none of the multistage chargers/converters will start without a battery, and I have never heard of an RV coming with a converter (power supply) that does not need a battery to run. I will point out that the addition of a fixed voltage power supply was one of the very early suggestions that was discussed here on the forum in relation to the Roadtrek problem of not being able to restart their lithium batteries after a shutdown, before the did the AGM battery.

You're probably spot on that current generation converters won't deliver battery charging without sensing a battery. But that said, do you think it will also refuse to supply 12V to the distribution panel? What would be the purpose of that? I'll check again but I believe my Magnum will provide 12V power to the distribution panel even with all coach batteries disconnected. But perhaps the Magnum isn't typical since it permits charging to be switched on or off independently.

The evolution of chargers too smart by one half that won't even try to charge a significantly discharged battery IMO is an example of technology gone awry.

I don't think the Etrek AGM was implemented to provide battery sensing per se but rather to bring the lithium BMS out of its coma long enough for the alternator or converter to sense them. I think that's why RT suggests keeping the reset button pressed for 30 seconds to permit the charging source to bring battery voltage up above the BMS shutdown threshold.

[booster]

Since we have a Magnum also, I did do a couple of quick looks at how ours (MS2000 with ARC50 remote) behaves under various conditions as I have never used the "charger" on/off button on the remote and don't recall seeing anything in the instructions about it.


* Plug in normal and it starts charging after doing some checks


* Plug in with the batteries offline and it faults with "dead batteries, charge them" display. I tried turning the charger on with the remote at this point and it would not do it. What is interesting is that the remote panel was on, even though the van had no batteries connected and charger was not charging. I looked at the battery monitor shunt voltage and it read like 9v IIRC. They must have a low output to have enough power for the diagnostics and monitor to work while faulted.


* With the batteries online and plugged in to shore power with the charger in charge mode, shutting off the "charger" button shuts off the charging voltage and the van goes to battery voltage. It appears there is no output from the charger at that point, so all use would be off the batteries.


* THIS IS THE WEIRD ONE THAT I NEED TO RERUN TO CONFIRM. With the batteries online, shore power, charging, I shut off the charger so it was then running on batteries as previous test. I then disconnected the batteries. The remote continued to work and read the funny 9v again, and the 12v stuff in the van kind of worked at the 9v. I then turned the charger on and it went to 14.3v, which is the absorption setting for charging. This would also mean that the charger was then simply working as a power supply, or converter only, for the van. This was the only way I found to have it do this.


The last test would indicate that the Magnum has the electronics to set it's own voltage independently of a battery reference, but it doesn't determine if the power is any good. I let it run a very short time, as it really would be necessary to check for superimposed AC on the DC to see if it went bad (which is likely because the unit was probably not intended to run this way).


In the real world, it probably is not a useful method anyway as you need to have online batteries to get to the point of having the charger work with the batteries offline, so it wouldn't be useful for getting offline batteries back online.


Concerning the reason that Roadtrek added the AGM. We will never really know for sure why they added it, as they will never tell anyone.



The scenario of waking up the BMS to reconnect the batteries so the power sources is positively possible for batteries that have gone into discharged shutoff, and I think is similar to what ARV does on their lithiums.


The reason the AGM would also be used to directly activate the charging sources would be if the batteries were in low temperature shutoff because you would need the charging sources up and running, without the lithium batteries getting charge, to run the heaters on the lithiums so they come back online.

[Winston]

Originally Posted by booster

Since we have a Magnum also . . .

We have the Magnum 2812 with the ARC remote. We use it in connection with lithium house batteries.

We followed the earlier "definitions" discussion in this thread re: Chargers vs Converters vs Power Supplies and remain uncertain what, really, the Magnum is.

Our goal was to set-up each of our three charging sources (Magnum, MidNite Solar Classic, and Nations/Balmar 2nd alternator) to output as much current as possible (or a preset maximum current), then, when a predetermined voltage or charge level was achieved, to go into a Constant Voltage mode (i.e. Power Supply mode). This has been an exercise in theoretical wishful thinking for all of our charging sources.

We set the Magnum, using the ARC remote, to the CC/CV mode at a fairly low 13.4 volt level (this has to do with our studies that showed that 13.36 volts represents an 80-90% SoC - - a level that we wanted to maintain. As the Magnum cannot be programmed in hundredths of a volt increments, we chose 13.4 volts as the closest target.)

What we really hoped for, while parked for extended periods, is that the Magnum would function as a 13.4 volt power supply both maintaining our lithium pack at that level and supplying all the energy being demanded, elsewhere, throughout the vehicle.

The engineers out there may say "not possible" - - what do you expect to happen if the batteries are already at 13.4 or, even more problematic, above that level?

What we expected was a 'smart' Magnum . . . one that would not 'sink' current - - if it found itself connected to a battery already above 13.4 volts, it would just go into a high impedance output state and only begin to assume its "power supply" duties when the battery voltage dropped to 13.4 volts.

To a very limited extent, that is what it does. It goes into the required high impedance (open output) state when confronted with >13.4 volts. But what it doesn't do, is remember to assume its duties as a 'power supply' when the voltage drops to 13.4 volts. Instead, the batteries keep supplying the loads, the voltage drops, and drops . . . and sometime, later, at a not completely predictable lower voltage, the Magnum says: "Oh, I think I'll turn-on". How much drop before the Magnum wakes up? Not a whole lot, maybe in the order of 0.1 volts (e.g. 13.3 volts). But this is huge for lithium.

We telephoned Magnum to inquire "what gives" and to determine whether our unit was faulty. Their answer was something along the lines "It will turn-on when it thinks it should." Great. When "it thinks" . . . I bought the ARC in the understanding that "I could think" and program the Magnum (as a Constant Voltage 13.4 volt source). Wrong. As noted, the CC/CV Magnum mode is just another of my theoretical, hypothetical . . . . chargers . . .

What's the bottom line? We look to discover what each of our chargers 'really does', then accommodate those realities.

[booster]

Sounds like your Magnum is doing some similar things to what we see in use with our "normal" AGM battery system.


The problem, at least for us I think, is the hysteresis and then some delays and smoothing they throw on top of things. We see it in the Magnum, but even more in the Blue Sky solar controller.



There don't appear to be firm voltage or amperage "set points" that would be like an on/off trigger, but more like points that have to be over/under X volts average for at least 13.75 seconds. The hysteresis can lock the units in a stage forever if conditions dictate it. The solar does this regularly as it will rebulk charge whenever it sees below float voltage at the output for a short time, which can happen when a cloud goes over or an appliance is run. Once in bulk, it has to go all the way to full parameters of 14.4v and .5%C amps to go back to float. It will rarely meet those criteria in the later afternoon or clouds, so it will sit in Bulk limbo at 14ish volts until dark, which isn't good for the batteries.


I think a lot of these issues show the benefit we could all get if the charging was completely controlled off of monitored state of charge based on amps in/out, so the voltage bumps up and down from conditions changing or loads on and off wouldn't mess it all up.

[markopolo]

Progressive Dynamics Inteli-power series power converters will supply regulated, filtered DC without the need for a battery in the system.

I can disconnect the house batteries in my van and run directly off the power converter when plugged into shore power if desired.

[avanti]

Originally Posted by markopolo

Progressive Dynamics Inteli-power series power converters will supply regulated, filtered DC without the need for a battery in the system.

I can disconnect the house batteries in my van and run directly off the power converter when plugged into shore power if desired.

Yeah. I use the one I pulled from our old van (replaced with a real inverter/charger) as a 12VDC shop power supply. Works fine.

[booster]

Originally Posted by markopolo

Progressive Dynamics Inteli-power series power converters will supply regulated, filtered DC without the need for a battery in the system.

I can disconnect the house batteries in my van and run directly off the power converter when plugged into shore power if desired.

Does the PD go back to it's base 13.6 (?) voltage if there are no batteries in the system? Will the pendant still change the voltage? Does it work the same when plugging in without batteries as when you disconnect the batteries after running, which is what seems to confuse the Magnum?


I seem to remember some PD testing on units with Charge Wizard that indicated that if you plugged into shore power with mostly full batteries, the unit would go directly to float and not run a charge cycle. If that is the case is would be looking for batteries with the Charge Wizard. IIRC, the base PD is simply a power supply if it does not have the Charge Wizard on it, so having it run without batteries makes sense if it is a standalone. Not so sure what the Charge Wizard does if active.

[booster]

Originally Posted by avanti

Yeah. I use the one I pulled from our old van (replaced with a real inverter/charger) as a 12VDC shop power supply. Works fine.

I assume this is without a Charge Wizard? Or with?

[markopolo]

Originally Posted by booster

Does the PD go back to it's base 13.6 (?) voltage if there are no batteries in the system? Will the pendant still change the voltage? Does it work the same when plugging in without batteries as when you disconnect the batteries after running, which is what seems to confuse the Magnum?

I seem to remember some PD testing on units with Charge Wizard that indicated that if you plugged into shore power with mostly full batteries, the unit would go directly to float and not run a charge cycle. If that is the case is would be looking for batteries with the Charge Wizard. IIRC, the base PD is simply a power supply if it does not have the Charge Wizard on it, so having it run without batteries makes sense if it is a standalone. Not so sure what the Charge Wizard does if active.

Mine defaults to 13.6V if no batteries are in the system. I think it will end up at 13.6V if either no battery present or battery removed while in operation.

There's no pendant on my unit - there is no plug for that option on the Mighty Mini all-in-one AC / DC panel unit.

The circuitry does look at system voltage and possibly resistance at startup and then determines what mode is required.

[cruising7388]

Originally Posted by booster

The last test would indicate that the Magnum has the electronics to set it's own voltage independently of a battery reference, but it doesn't determine if the power is any good. I let it run a very short time, as it really would be necessary to check for superimposed AC on the DC to see if it went bad (which is likely because the unit was probably not intended to run this way).

The Magnetek 63xx converters that once were very popular were notable for needing to see a battery for a stable output. Their filtering section was so inadequate that the battery also served as sort of a smoothing capacitor which mitigated AC ripple. I think that current converter design no longer necessitates this.

I can also confirm that my Progressive PD9270 provided power to the 12V distribution panel even with disconnected batteries. I had both the PD and the Magnum installed and could toggle between them. The charging protocols were quite different and IMO, the PD did a better job keeping the batteries fully charged. The Magnum would often let battery voltage drop to 13.1 - 13.2 before waking up and I couldn't find any setting in the ARC50 display that addressed this.

BTW, thanks for taking the time to look into this and making this a very interesting thread.

[booster]

Been doing some reading on PD and it led to Iota also. It appears that perhaps some of the units that use an everyday fixed voltage converter/power supply based component and then add a separate piggyback controller to make it a multistage "smart" controller look for a battery and if they don't see one revert back to a fixed voltage output, perhaps just shutting off the piggyback control. It appears, so far, that PD and some IOTA units are that way.



Our Magnum must be doing something similar, under some conditions, but reverts to 9v so not useful to run most things, and you can't do it without batteries to start with. None of the other modern chargers I have seen do similar, that I know of, although they possibly could though some special, odd, procedure like the Magnum did.


It is odd that folks like ARV, who had no cold recovery process other than "take it inside" wouldn't have just put one of the fixed voltage units in place, to run the battery heaters if they were in cold shutdown. You would still need a plug in to do it, but that is much easier.



One thing that I would wonder about with all of this would have to do with other charging sources like the engine generator or solar. If either the engine generator or solar were to be activated because you had a fixed power supply running, but not a battery in the system, would the power generated by the engine generator or solar be adequately controlled? I know from experience that you can run the engine generator with the shore charger also running, as I have done it accidentally and all was fine with a battery online. If the power sources would have control problems without the ballast of the batteries, that would certainly be a good reason why most battery chargers will not activate without batteries online and be usable as coach power only as then they would allow other sources to also activate without the batteries connected.

[Winston]

Originally Posted by booster

The problem . . . is the hysteresis and then some delays and smoothing they throw on top of things. We see it in the Magnum, but even more in the Blue Sky solar controller.

There don't appear to be firm voltage or amperage "set points" . . .

Our MidNite Solar Classic seems more flexible (or less encumbered) than your Blue Sky . . . at least in the context of lithium charging.

This solar controller - - one of our three charging sources - - comes the closest to our idea of a perfect controller. Our definition of a perfect controller (again, for lithium) is a two stage controller where:

Stage 1: Give it All You've Got (current), until a predetermined voltage is reached (or, better yet as you suggest, a given SoC is reached); then,
Stage 2: Become a Constant Voltage source (power supply) at that voltage.

The MidNite Solar Classic, through its detachable external control panel allows for the programming of this one set voltage (but not, to our knowledge, to a given SoC).

MPPT controllers are ideally suited for this configuration as their comparatively high voltage input (from the solar panels) allows them to 'regulate-down' to the ~13 volt battery level at full available current, regardless of increasing battery voltage during the charge cycle (the change in battery voltage is comparatively small (percentage wise) compared to the large 'delta' differential between the PV panels and the battery).

But, alas, the MidNite solar controller is still based on that old Bulk, Absorption, Float system of lead-acid batteries. The Bulk mode, fortunately, is the previously mentioned Stage 1: "Give It All That You've Got" . So, as long as we can maintain the Controller in Bulk mode until the predetermined, programmed voltage (13.4 for us) is reached (at which point the MidNite switches to Stage 2 (the constant voltage stage) and supplies whatever current is demanded by the battery (a diminishing amount) and the loads (so long as the loads do not exceed the capability of the solar array under then extant sun conditions), we're ok. The Midnite Solar Controller calls this second Stage 2, guess what, the Absorption stage - - but it's really our desired constant voltage stage.

So, why then isn't the MidNite solar a perfect controller?

We believe it's the wiring and those inevitable voltage drops. The MidNite solar senses voltage at the solar controller on the passenger wall of the CamperVan while the batteries are on the driver's side. The MidNite Solar 'thinks' the batteries are at the prescribed 13.4 volt level but due to the several tenths voltage drop to the batteries, the batteries have not, in fact, reached this point.

Were we to configure an external battery voltage sense wire for the Controller, this problem should 'go away'. But that's too much work. Instead, we "accommodate" our reality by either letting the batteries complete their final charging at a lower current, or, temporarily, reprogramming the Controller to a higher constant voltage point. This latter alternative is very easy to do using the remote Controller control panel and we'll manually reset it back to 13.4 volts when we see battery voltages that we like or, more likely, when our SoC meter advises we've reached our target.

But, your right, the best approach would be to control all of our chargers based on State of Charge data. Maybe we'll reconfigure in the future.

[avanti]

Originally Posted by booster

I assume this is without a Charge Wizard? Or with?

Without.
Sorry.

[booster]

Originally Posted by avanti

Without.
Sorry.

Nothing to be sorry about on that


It is what I expected, for the most part. I think the units that were single stage converter/charger/battery wreckers probably just default the control off even if it was there, and what you have would be an old school converter/charger that would be single stage, but perhaps with a bit better wave form with no battery. Have you happened to put a meter on it to see how much AC is on top of the DC voltage?


The more I think about it, the more I think it is likely most of the chargers will not run without a battery is because they don't want to initiate another charge source that couldn't handle the no battery thing.

[arvee]

I had this too on my Pleasureway Excel. Make sure the 110 plug is plugged into the receptacle behind the converter breaker.

[cruising7388]

Originally Posted by booster

One thing that I would wonder about with all of this would have to do with other charging sources like the engine generator or solar. If either the engine generator or solar were to be activated because you had a fixed power supply running, but not a battery in the system, would the power generated by the engine generator or solar be adequately controlled? I know from experience that you can run the engine generator with the shore charger also running, as I have done it accidentally and all was fine with a battery online.

Indeed there is plenty to wonder about because there seems to be very little reported regarding the consequences of multiple charging sources addressing battery(s). Roadtrek indicates that with respect to battery charging, their alternator, converter and solar controller all work in concert with each other although they don't explain how this is accomplished.

I agree that charging batteries simultaneously from an alternator and and a shoreside or an Onan driven generator won't damage anything, but it's not necessarily accomplishing anything either. At least in my trial and error experiments, if the two charging sources are in the absorption (voltage control) stage, in terms of charging delivered, the battery only recognizes the higher voltage charging source. If the charging voltages are identical, the battery recognizes and accepts charging from both sources.

I was unable to replicate a dual source bulk charging condition, but the conventional wisdom is that if multiple charging sources are in the bulk (current control) mode, even if their delivery voltages are different, the battery will still recognize and accept them. I wonder how wide the voltage disparity can get before this no longer works.

Class B upfitters isolate the coach alternator system from the OEM alternator with one interesting exception which is the setup provided in the Galleria Li3 that provides parallel operation of both alternators. My understanding is that when the batteries are sufficiently discharged to promote bulk charging, the Nations alternator is paralleled with the Sprinter alternator to deliver combined charging amperage to the battery. But when recharging progresses to some set point, the Balmar regulator shifts to the absorption mode, and the two alternators separate. What perplexes me is how this works because while the Nations alternator may be bulk charging, I think the OEM alternator is by design, a voltage controlled device with a Canbus network that provides unique instructions to it. But if it actually works, since the 200 amp OEM alternator pretty much loafs, dual charging pushes this setup pretty close to what the 330amp Delco can deliver.

[booster]

When charging sources are in bulk, they are basically constant current devices running flat out, so they both/all should be putting out as much as they can as they are below voltage setpoint. Once you get to absorption, then minor differences in setting or control of voltage would make a major mismatch in which source does the most work, but it shouldn't slow down the charging as the batteries are to the point of accepting less than the sources can supply.


It would be very interesting to see how the Galleria setup works, as they two regulators are certainly not going to match. In bulk, they would probably work as stated above, so they may just shut the Nations back off as soon as the system gets to absorption. That would likely be the easiest to implement and the safest for all the part, but that is also unknown. The Balmar will also run two alternators, so they may have the factory unit off the Canbus and on the Balmar.