Roadtrek/Hymer Lithium/2nd alternator/Voltstart issues?

[gerrym51]

Booster and Avanti-

roadtrek is using this to boost amp output.

supposedly will combine amps from the van alternator also-not just the extra

I don't know if it's only 800eco and up


https://www.bluesea.com/products/762..._-_12V_DC_500A

[cruising7388]

Originally Posted by gerrym51

Booster and Avanti-

roadtrek is using this to boost amp output.

supposedly will combine amps from the van alternator also-not just the extra

I don't know if it's only 800eco and up


https://www.bluesea.com/products/762..._-_12V_DC_500A

Considering that the factory alternator is pretty much loafing, paralleling the two alternators under high load demands would help, but wouldn't it require that both alternators, regulators and pulley ratios be identical?

[avanti]

One of the great advantages of a second-engine alternator is precisely that it AVOIDS any electrical connection between the chassis and the house. My house system has no electrical connection to the chassis whatsoever, with the trivial exceptions of a Trik-L-Start and a "boost" relay for emergency starting.

Modern vehicles have increasingly complex electrical systems and connecting to them is fraught. Modern alternators are controlled via CANbus messages from an ECU. Increasingly, this ability is used to implement "intelligent" charging systems that reduce battery charging during acceleration and deliberately under-charge the starter battery at first--saving room for the harvesting of energy during coasting. This amounts to a simple "regenerative braking" system of the kind seen in hybrid vehicles. The sensors and algorithms used to implement these strategies are complex, poorly-documented, and rapidly evolving. My 2014 Sprinter I4 has a complicated-looking sensor (no doubt a shunt and probably more) mounted right on one of the battery terminals.

Given all of this, the days in which one can casually draw a bunch of "extra" current from the chassis alternator are coming to an end.

[booster]

Originally Posted by gerrym51

Booster and Avanti-

roadtrek is using this to boost amp output.

supposedly will combine amps from the van alternator also-not just the extra

I don't know if it's only 800eco and up


https://www.bluesea.com/products/762..._-_12V_DC_500A

That is just a plain old separator, albeit an expensive one. It ties the engine generator to the batteries and the solar is already there. Of course they may or may not add together, based on what voltage they are running at.

[booster]

Originally Posted by cruising7388

Considering that the factory alternator is pretty much loafing, paralleling the two alternators under high load demands would help, but wouldn't it require that both alternators, regulators and pulley ratios be identical?

As Avanti says, you can't really tie them together because of the electronic controls on the newer units. That said, our 07 Chevy does not have the fancy controls, and we do have two alternators tied together, full time.

We have a 250XP and a 280XP DC Power Engineering units, so a total of 530amps of output. We run an Ample Power remote regulator that allows two stages of reduced output. We are set to run at about 285 amps or 180 amps to the batteries, plus whatever the engine takes. This output is low enough to not overheat the alternators, so we have constant output at setpoint, hot.

Personally, I think the two parallel are more practical than the single stand alone, as they share the load better. It seems silly to have one alternator constantly heat cycling, and the other barely doing anything, but others would disagree.

You do want very similar alternators, but they don't have to be identical, as ours aren't and work fine, but you control them both off the same regulator.

[cruising7388]

Are you using lithium or lead acid for your house batteries.

[avanti]

What you COULD safely do is to use a DC-DC charger, such as one of the Sterling units and connect IT in parallel with the second alternator. Such a device limits current such that you can observe the OEM guidelines for current take-off. I think the Sprinter allows 40 or 50 amps. Not quite as awesome as Booster's setup, but could represent a properly-engineered system that would help even out the load on the second alternator.

[booster]

Originally Posted by cruising7388

Are you using lithium or lead acid for your house batteries.

440ah of Lifeline GC2 AGM batteries.

[cruising7388]

Originally Posted by booster

440ah of Lifeline GC2 AGM batteries.

Since your AGMs and the engine battery have similar if not duplicate charging profiles, this certainly works but if the coach batteries are lithium and the engine battery is lead acid, how could you provide the different charging profiles with paralleled alternator sources using a common regulator?

[booster]

Originally Posted by cruising7388

Since your AGMs and the engine battery have similar if not duplicate charging profiles, this certainly works but if the coach batteries are lithium and the engine battery is lead acid, how could you provide the different charging profiles with paralleled alternator sources using a common regulator?

If what I am guessing about lithium charging is true, I don't think it would be an issue because you could use the same voltage of somewhere in the low 14s volts. They make a big deal about lithium chargers needing to run at 14.7 volts, but that takes a lithium to full/full which they say isn't good for them. Best guess is that you use a disconnect relay set at something like 13.8v, which puts you at the knee of the charge profile and will leave you at about 90-95% charged, and the van battery stays happy at the voltage.

Of course, I don't want the other issues with lithium, so it is mute for us, and why we chose AGM instead.

[cruising7388]

Originally Posted by booster

As Avanti says, you can't really tie them together because of the electronic controls on the newer units. That said, our 07 Chevy does not have the fancy controls, and we do have two alternators tied together, full time.

Are you sure about that you can't do what you have done in a current year Chevy? Sure, the CAN overlay provides more complex instructions to the alternator than simpler battery voltage sensing but these instructions are not for correct alternator regulation, per se, but to diminish or drop the alternator load during a Wide Open Throttle condition and perhaps gain a little mpg in other engine states. There's nothing new about that. WOT commands were implemented as far back as OBD I although then it was typically limited to de-clutching the dash AC compressor when going pedal to the metal, while simultaneously altering distributor advance, fuel/air ratio, etc.

In any event, I don't think CAN instructions address the alternator directly. They simply override the default computer field winding program and instruct the computer to increase or decrease field winding current to comply with the CAN instruction. Consequently, I don't think there is any issue with disconnecting the computer field windings and utilizing a smart regulator to control the alternator in its stead. It might throw a code in a code reader, but I don't think it would affect engine or alternator operation. In your installation didn't you do just that - disable your computer controlled field windings?

[booster]

Originally Posted by cruising7388

Are you sure about that you can't do what you have done in a current year Chevy? Sure, the CAN overlay provides more complex instructions to the alternator than simpler battery voltage sensing but these instructions are not for correct alternator regulation, per se, but to diminish or drop the alternator load during a Wide Open Throttle condition and perhaps gain a little mpg in other engine states. There's nothing new about that. WOT commands were implemented as far back as OBD I although then it was typically limited to de-clutching the dash AC compressor when going pedal to the metal, while simultaneously altering distributor advance, fuel/air ratio, etc.

In any event, I don't think CAN instructions address the alternator directly. They simply override the default computer field winding program and instruct the computer to increase or decrease field winding current to comply with the CAN instruction. Consequently, I don't think there is any issue with disconnecting the computer field windings and utilizing a smart regulator to control the alternator in its stead. It might throw a code in a code reader, but I don't think it would affect engine or alternator operation. In your installation didn't you do just that - disable your computer controlled field windings?

They changed them right after our year, which has a plain old internally regulated alternator from the factory. All the computer sees from ours is a field % signal that they use to compensate idle, it appears, and a voltage trigger for the fault light. The later years have the full blown energy/mileage saving thing going on, where they even have an ammeter on the starting battery so they can reduce or stop charging at various times to save fuel. There is quite a bit of information on the GM truck forums concerning just eliminating the feedback stuff and going with an internal or externally regulated alternator, with a lot of different opinions. Some say all the happens is the alternator light comes on, and others say it messes up idle, mileage, shift points, you name it. Some models do have cheater adapters available that are supposed to take care of the issues, but I don't know if the vans do, or if they even work. Nations does not sell anything for, or want anyone to, run parallel systems, and that included me. Adam repeatedly tried to talk me out of doing it, but I am glad I didn't listen, at least to this point.

[avanti]

Originally Posted by cruising7388

In any event, I don't think CAN instructions address the alternator directly. They simply override the default computer field winding program and instruct the computer to increase or decrease field winding current to comply with the CAN instruction.

Modern alternators have no field input at all. They are 100% controlled by the CANbus. An ECM tells it what voltage to produce (including possibly "0") and it does so.

[booster]

With as picky on control as they seem to be these days, I am a bit surprised that they don't throw a fault code just from the load of a 280 amp alternator, which uses something like 8 hp. That is a lot of load for the engine being at idle.

[cruising7388]

Originally Posted by avanti

Modern alternators have no field input at all. They are 100% controlled by the CANbus. An ECM tells it what voltage to produce (including possibly "0") and it does so.

I certainly nay be missing something here, so correct the error of my ways.

I don't see how any externally regulated alternator can operate without field current input. Earlier designs that used computer control of the alternator had only battery voltage sensing that adjusted alternator field current. I think the purpose of employment of CAN enhancement in controlling alternator parameters was to accomodate a myriad of inputs in addition to the battery voltage reference. My understanding is that multiple input process is accomplished with an interface in the computer, not the alternator.

So whether the computer core generates alternator field current demands directly as in OBDI/2 or whether it is generated by an integrated CAN network, doesn't it still have to deliver field current to the alternator input terminals?

[booster]

Avanti knows much more about this kind of stuff, but it certainly makes sense what he says about a Canbus signal only to the alternator. The alternator would then have a "regulator" that generated a field current based on the Canbus signal, which would be varied by the main computer. That way they save running the big wires required for remote field regulation, with all the power stuff internal to the regulator. Just a guess, though.

[avanti]

Originally Posted by cruising7388

I don't see how any externally regulated alternator can operate without field current input. Earlier designs that used computer control of the alternator had only battery voltage sensing that adjusted alternator field current. I think the purpose of employment of CAN enhancement in controlling alternator parameters was to accomodate a myriad of inputs in addition to the battery voltage reference. My understanding is that multiple input process is accomplished with an interface in the computer, not the alternator.

So whether the computer core generates alternator field current demands directly as in OBDI/2 or whether it is generated by an integrated CAN network, doesn't it still have to deliver field current to the alternator input terminals?

Certainly these alternators still need field currents. It is just that they aren't really "externally regulated", at least not all of them are. Instead of a field current input terminal, there is only the LIN interface. Built into the alternator is a chip like this one:

LIN-Controlled Alternator Voltage Regulator | News content from Power Electronics

(there are several others). The ECU tells the chip what it wants, and the chip itself generates the field current appropriate for that goal. So, there IS a field current. It is just not exposed outside the alternator.

Here is an interesting article that discusses the broader issue of charging second batteries in the presence of intelligent power management:

Aux Battery Charging With Smart Alternators | 12 Volt Planet

[cruising7388]

Originally Posted by booster

Avanti knows much more about this kind of stuff, but it certainly makes sense what he says about a Canbus signal only to the alternator. The alternator would then have a "regulator" that generated a field current based on the Canbus signal, which would be varied by the main computer. That way they save running the big wires required for remote field regulation, with all the power stuff internal to the regulator. Just a guess, though.

Sure, if the regulator generating field current is located in the alternator, then any instructions from the CAN bus to the alternator will be at a signal level which is a really cool way to do it although I wonder how that internally buried alternator module survives egg frying temps

So I think what Avanti is describing is a hybrid arrangement where the regulator is physically located in the alternator but is controlled by computer CAN bus commands. This has got to complicate disabling this system in favor of a third party external regulator like the Balmar.

In doing some internet surfing I haven't run across anything that describes this except this comment that's a little fuzzy to me:

"Depending upon the application, the voltage regulator can also be externally integrated into the powertrain control module (PCM). In more modern applications, the PCM controls an internal voltage regulator through bus communications system or a reference voltage wire to modify the charging mode according to driving conditions. "

[avanti]

Originally Posted by cruising7388

This has got to complicate disabling this system in favor of a third party external regulator like the Balmar.

In doing some internet surfing I haven't run across anything that describes this

The following is from the Sprinter Body & Equipment Guildlines 2015:

NOTE: A new generation of regulators is used in the Sprinter. The alternator regulator is equipped with a LIN (Local Interface Network) interface. The characteristics of the LIN alternators are fixed in the engine control unit. For this reason aftermarket alternators cannot be retrofitted. As of model year 2010 w. engine type OM642 (6 cylinder) a 220 Amp alternator (STD) is available.
As of model year 2014 w. engine OM651 (4 cylinder) a 200 Amp alternator (STD) is available. An optional 250 Amp alternator (code M60) is available.
No D+ (engine running positive signal) output is available at alternator with LIN Bus technology, only at the Upfitter connector EK1 (see Chapter 6.3.1.) under driver seat.

So, basically, the retrofit you describe is just not possible. As I said earlier, these developments are making second-engine alternators and/or DC-DC chargers a practical necessity.

[booster]

Interesting article and is what I suspected was going on. In particular, the battery to battery charger information was interesting as I had read a whole bunch on that when I was trying to determine how to build our parallel system. They do have some fallacy in the information, but of course they are trying to sell them (like 5X faster charging).

When I was looking, they listed up to 180 amps output on the UK site, only 120 here in the US. Still looks like 120 here, but also in the UK, as the 180 has disappeared there (I don't think it was ever really available), but now they list a 240 amp in the UK, but of course that is not actually available, either.

https://cdn.shopify.com/s/files/1/06...713d83.pdf?751

Two things kept me from doing the battery to battery instead of the Ample Power regulator. One was that I could only get to 120 amps. Second was that I was stuck with their charge profile, and could not force the stages to make sure I got fully charged, and not overcharged, as they don't run off a shunt. An advantage the battery to battery charger would have had was that the alternators could have kept their very nice Denso regulators, that have their own overtemp protection built in, although they kick in a quite a high temp, it appears, compared to a Balmar, for instance. With the Ample Power external regulator, I could set 2 output limits and also force the stages manually to whatever I want, so I went that way.

I think a 180amp battery to battery charger would be the best setup if it ran off a shunt so you could set tail amps for stage transition. It would set and forget, with no operator input needed.

Avanti, IIRC in the past you mentioned something about Mercedes saying that the most you could take off their stock alternator was something like 45? amps, I think. On a setup like that, the battery to battery charger might not work if MB is actually comparing alternator output against what the van is supposedly using for stuff and battery charging. Have you heard anything about that situation?