FitRV's lithium/alternator/inverter setup

[wincrasher]

Got a sneak peak at FitRV's new setup with the Nation's alternator, the Xantrax inverter/charger and the lithium battery. Balmar regulator.

I don't want to steal their thunder on the big reveal, but I was most impressed with much of what I saw.

What I can say is that it appears to all be working properly. Winnebago engineering was giving it a thorough examination during GNR and Xantrax was doing some tweaking. They are not using any detailed cell monitoring, but they do have display with battery drain and charging status, and give SOC. I witnessed 180+ amps of charging.

They are getting several hours of air conditioning on a 400 ah battery. The battery is housed completely inside the vehicle as to assure proper freeze prevention.

The only thing that needs work is protection for the second alternator. On the Promaster, it ends up hanging low and could be exposed to road spray/salt, or impacted by debris. Surprisingly, there is no cooling equipment as you'd see on ARV or Roadtrek. It would be better if there was a single, large alternator that could be used instead of a second. If there was such a beast, I'd probably be all over it.

[gregmchugh]

They initially had the same issue as Roadtrek had with damage to a coolant hose but that got fixed after a coolant leak...

[avanti]

Originally Posted by wincrasher

It would be better if there was a single, large alternator that could be used instead of a second. If there was such a beast, I'd probably be all over it.

I can't agree with you there. One of the biggest advantages of a second engine alternator is total isolation from the chassis electrical system. This is an increasingly important issue now that the OEMs are installing increasingly complex energy management systems for the sake of performance and fuel economy.

For example, modern Sprinter alternators are completely controlled by the ECM via the vehicle's CANbus. There is no conventional regulator or "B+" terminal on the alternator. AND, in our I4 there is a shunt right at the positive battery terminal. The ECM has its own opinions as to when and how much charging current to send to the battery. It is a VERY GOOD THING to have a second alternator that can be separately controlled to reflect the needs of your coach batteries.

[markopolo]

I looked at a few photos on their site earlier today: Where Has James Been and What Has He Been Doing??!!??

Forum member tex4judy was also working with Xantrex on a setup using Lithionics battery(ies) & Nations Alternator.

Some posts here: http://www.classbforum.com/forums/se...earchid=195062

It might be a nice alternative to the complete DIY route for this type of setup.

[booster]

Originally Posted by avanti

I can't agree with you there. One of the biggest advantages of a second engine alternator is total isolation from the chassis electrical system. This is an increasingly important issue now that the OEMs are installing increasingly complex energy management systems for the sake of performance and fuel economy.

For example, modern Sprinter alternators are completely controlled by the ECM via the vehicle's CANbus. There is no conventional regulator or "B+" terminal on the alternator. AND, in our I4 there is a shunt right at the positive battery terminal. The ECM has its own opinions as to when and how much charging current to send to the battery. It is a VERY GOOD THING to have a second alternator that can be separately controlled to reflect the needs of your coach batteries.

We have had this discussion several times, and I have to agree with both Avanti and Wincrasher, depending on the system you are dealing with.

With a vehicle like a Sprinter, where the onboard computers control all the charging functions, you don't have a lot of choice but have a standalone generator for the coach.

On other setups, that don't have such complete control by the vehicle electronics, there is some real advantage to having the extra capacity be available to both the van and coach.

I have been revisiting the second option a bit, mostly out of curiosity and some out of a redundancy viewpoint. A single big alternator won't really need a separate smart regulator, unless you want one for charging and don't want to monitor yourself, and if you do have a shutoff, you will have no voltage spike issues when you reconnect.

What the single big alternator doesn't give is a way to survive a failure of the very hard worked alternator, including trying to find one on the road. You have a similar issue with the separate alternator, but if the hard worked on dies, at least the van still runs. If the van one dies, it is a stock part to find which will likely be easier.

I think if I were to do any upgrade to a system that could handle having the large charge rate combined with the van alternator, I would do a dual alternator setup, but make both of them the same alternator, probably a Nations/DC Power 180 amp XP, Denso style. That way they would have identical voltage regulators so they would share the load equally (within reason), run cooler, and last longer. If one failed, you would just keep going with reduced coach charging. You would also have as much charging as normal 3/0 or 4/0 cable could handle, as even hot you could get around 250 amps, I think. This just seems like the a good, redundant, very high performance way to go.

As always, different vans and desires would give totally different solutions.

[wincrasher]

One thing I forgot to mention, was that it appeared that the charging will stack - the charge rate was considerably higher with the engine running, and the shore power connected. I have no idea how this works, or if it's good, or if the other setups also work this way.

[cruising7388]

Originally Posted by booster

We have had this discussion several times, and I have to agree with both Avanti and Wincrasher, depending on the system you are dealing with.

With a vehicle like a Sprinter, where the onboard computers control all the charging functions, you don't have a lot of choice but have a standalone generator for the coach.

On other setups, that don't have such complete control by the vehicle electronics, there is some real advantage to having the extra capacity be available to both the van and coach.

I have been revisiting the second option a bit, mostly out of curiosity and some out of a redundancy viewpoint. A single big alternator won't really need a separate smart regulator, unless you want one for charging and don't want to monitor yourself, and if you do have a shutoff, you will have no voltage spike issues when you reconnect.

What the single big alternator doesn't give is a way to survive a failure of the very hard worked alternator, including trying to find one on the road. You have a similar issue with the separate alternator, but if the hard worked on dies, at least the van still runs. If the van one dies, it is a stock part to find which will likely be easier.

I think if I were to do any upgrade to a system that could handle having the large charge rate combined with the van alternator, I would do a dual alternator setup, but make both of them the same alternator, probably a Nations/DC Power 180 amp XP, Denso style. That way they would have identical voltage regulators so they would share the load equally (within reason), run cooler, and last longer. If one failed, you would just keep going with reduced coach charging. You would also have as much charging as normal 3/0 or 4/0 cable could handle, as even hot you could get around 250 amps, I think. This just seems like the a good, redundant, very high performance way to go.

As always, different vans and desires would give totally different solutions.

As you point out, if the coach alternator croaks you still have ignition and propulsion but what about the reverse? Out in the boonies, with totally independent systems like RT uses, what do you do if it's the engine alternator that quits? Without some way of getting some ignition support from the coach batteries won't you end up SOL in pretty short order?

If I was able to get it the way I wanted, I would do exactly what you suggest which is to employ independent identical beefy alternators and regulators. But what I would also do is have the wiring for both alternators run into some sort of terminal block where a dead engine alternator can be disconnected and the coach can be plugged in its place and keep you going down the road. In fact, with some conservative use of coach loads there would be no reason why as an interim fix you couldn't direct the still working alternator to address coach requirements in addition to the engine side.

The irony is that in earlier years the loss of the single alternator was not as consequential. As long as you cranked up the Onan reasonably soon after the alternator is kaput warning light came on, you could drive from coast to coast with the converter charger and smart separator set up. It's noisy. But it works. Trust me.

Which reminds me, one disadvantage of fully independent charging systems, is that, at least with RT, unlike their AGM setup which uses a bi-directional separator, there is no way to charge a depleted engine battery from shore power. Unless you hook up an independent charger, the only way it can be charged is from the alternator but if the battery is so inadvertently depleted that it can't start the engine, that doesn't help. On the RT 210/190 coaches with the UH alternator, there is no battery boost to get some temporary suds from the coach batteries and if memory serves, Mercedes curiously prohibits the coach builders using their platform from installing a battery booster assist feature.

[booster]

In my scenario of two parallel, identical, 180 amp alternators connected for both the coach and van, if one quits you should be able to just go on as is (unless the failed one shorted). All you would lose would be the very high amp coach battery charging. That is why it is nice to have the parallel and on both the van and coach, no need to disconnect and reconnect anything, and you get more coach charging than having them with only one to the coach when both are working. Even if they both died, you could run the van off the coach batteries to get somewhere.

We don't use an automatic separator, just a manual relay controlled from the cab. I have an ammeter on the coach batteries I can see while driving so I can shut off the engine charging when the batteries get full.

[wincrasher]

I was warned by someone in WGO engineering that they've seen some drop-in lithium batteries damaged by using the "boost" switch to start the engine off the house batteries. Why do you suppose that could be?

[gregmchugh]

You could just carry jumper cables to start the engine from the coach batteries if you have a dead chassis battery.

[Davydd]

Originally Posted by wincrasher

One thing I forgot to mention, was that it appeared that the charging will stack - the charge rate was considerably higher with the engine running, and the shore power connected. I have no idea how this works, or if it's good, or if the other setups also work this way.

Advanced RV "stacks" as you put it. You can simultaneously charge engine idling, shore power and solar. When I tested with my old Nations 270 alternator with shore power and was charging well over 300 amps. I have the 4/0 wiring from alternator to battery and battery to inverter to manage those high amps. I may test soon with my new Delco 320 alternator. It charges at a rate of over 230 amps at high idle auto start. So I suspect I could get over 350 amps charging in an optimal setup on a sunny day. The 4/0 wire will still handle that. The charts say 380 amps for 4/0 chassis wiring. This would be for testing purposes only. There would be no practical reason to need to do so.

[booster]

Originally Posted by wincrasher

I was warned by someone in WGO engineering that they've seen some drop-in lithium batteries damaged by using the "boost" switch to start the engine off the house batteries. Why do you suppose that could be?

The only reason I can think of is that the electronics in the battery (BMS, relays, etc) are sized for the anticipated maximum load that the coach would use, not a much higher (maybe) starting load of the engine.

[cruising7388]

Originally Posted by wincrasher

I was warned by someone in WGO engineering that they've seen some drop-in lithium batteries damaged by using the "boost" switch to start the engine off the house batteries. Why do you suppose that could be?

On first impression it seems somewhat dubious that a lithium battery, per se, would be damaged by this considering that lithiums are becoming ubiquitous in the current generation of jump starters. The typical bridging and charging sequence is typically only a few seconds. You might not want to charge lithiums very from the engine alternator employed, but I'm hard pressed to see how temporary paralleling them to a discharged flooded cell or AGM battery could cause the battery any concern. But on second thought, what WGO might be referring to is not damage to a stand alone lithium battery, but in a coach environment, damage to its associated BMS. Just Guessing.

[cruising7388]

Originally Posted by booster

The only reason I can think of is that the electronics in the battery (BMS, relays, etc) are sized for the anticipated maximum load that the coach would use, not a much higher (maybe) starting load of the engine.

Sure, the BMS might conclude that its associated battery has shorted but I would think that all it would do is shut it down until the load is released and would damage neither the battery nor the BMS.

[booster]

Originally Posted by cruising7388

Sure, the BMS might conclude that its associated battery has shorted but I would think that all it would do is shut it down until the load is released and would damage neither the battery nor the BMS.

The BMS probably wouldn't be measuring current and wouldn't trip until the voltage dropped. By then the relay contacts could be fried or something else melted.

[Jostalli]

Originally Posted by wincrasher

I witnessed 180+ amps of charging.

Only 180+ amps of charging? That does not seem worth it to me. I'm happy with 100 amps charging my LiFePO4 batts with the stock Promaster alternator.

[wincrasher]

As you know, the output is not constant. The readings bounce around a bit. It would peak much, much higher. It was also much higher with the shore power on. Don't recollect if the air conditioning was running while we were looking at the display.

[Davydd]

Originally Posted by wincrasher

As you know, the output is not constant. The readings bounce around a bit. It would peak much, much higher. It was also much higher with the shore power on. Don't recollect if the air conditioning was running while we were looking at the display.

If you think the air conditioning was running in northern Minnesota last week which was about perfect weather wise you had to be a real wimp.

[BBQ]

.

Look at the way that 2nd alternater hangs down on the bottom.

[cruising7388]

Originally Posted by BBQ

.

Look at the way that 2nd alternater hangs down.

Undoubtedly by design. The output probably increases on rainy days when it's water cooled.