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[cruising7388]

Originally Posted by booster

200ah capacity is useless if it is in low voltage or too cold cutoff. Then it has exactly zero amp hours and zero voltage.

We're talking about the aux AGM battery now planted in an Etrek, right? You're losing me here. I don't understand your point. The purpose of this battery is to provide a logic load for the generator or shorepower port and to provide sufficient suds to bring the BMS back to life. At least as promoted, other than this, it's on vacation. Why do you need a battery with sufficient capacity to start a V8 to accomplish this?

[booster]

Originally Posted by cruising7388

We're talking about the aux AGM battery now planted in an Etrek, right? You're losing me here. I don't understand your point. The purpose of this battery is to provide a logic load for the generator or shorepower port and to provide sufficient suds to bring the BMS back to life. At least as promoted, other than this, it's on vacation. Why do you need a battery with sufficient capacity to start a V8 to accomplish this?

So when you talked about 200ah you were referring to the AGM, not the module? Greg had been talking about 80ah. You need only enough to initiate and ballast the systems, which isn't much, but if it is wired in parallel, like it appears the Roadtrek is, it will see all the loads as soon as the lithium goes offline. At that point, who knows what you would need, as it would depend on what was on and how quick you caught it. If it was the inverter and some AC stuff, you could burn through 80ah in short order. The AGM is going to see overly high voltage much of the time if it is parallel to the lithium charging without a cutoff. Even Tesla seems to be finding this out with AGMs in their cars which have been failing quite quickly, so it really isn't along for the ride and is getting pretty badly abused, I think. Personally, I would rather just have a switch to kick in the van systems, where everything is available and has been isolated from discharge. That way you could start the engine and have good referenced charging system activation, with lots of amps available to recover. Roadtrek has other ideas, but they won't tell anyone what they are or how they are supposed to work, which IMO is a big negative. Also remember that if the batteries are in cold shutdown, it will take a lot of power to bring them back, so you absolutely would need the engine or shore power, but again you would need to reference them to the coach systems to get them to work.

[gregmchugh]

When the Ecotreks go offline the AGM becomes isolated from the van loads including powering the inverter. The AGM is on the charge terminal side of the Ecotreks along with the engine generator. On some vans the solar may on that side too. The battery disconnect switch is not powered from the AGM when the Ecotreks are offline and the DC loads and the inverter are also not powered from the AGM at that point.

The charge profiles used by any of the three chargers is not really known outside of Roadtrek. I have wondered if they really have them set to optimize lithium charging and live with AGM charging issues or if they have a charge profile set up that is more of a compromise with a reasonable charge getting to both types of batteries. What would be the downside of less than optimum lithium charging? Is there anything inside the Ecotrek module that tailors the charge or is the charge sent straight through to the battery cells? The cell balancing method is also unknown.

[cruising7388]

Originally Posted by booster

So when you talked about 200ah you were referring to the AGM, not the module? Greg had been talking about 80ah. You need only enough to initiate and ballast the systems, which isn't much, but if it is wired in parallel, like it appears the Roadtrek is, it will see all the loads as soon as the lithium goes offline. At that point, who knows what you would need, as it would depend on what was on and how quick you caught it. If it was the inverter and some AC stuff, you could burn through 80ah in short order. The AGM is going to see overly high voltage much of the time if it is parallel to the lithium charging without a cutoff. Even Tesla seems to be finding this out with AGMs in their cars which have been failing quite quickly, so it really isn't along for the ride and is getting pretty badly abused, I think. Personally, I would rather just have a switch to kick in the van systems, where everything is available and has been isolated from discharge. That way you could start the engine and have good referenced charging system activation, with lots of amps available to recover. Roadtrek has other ideas, but they won't tell anyone what they are or how they are supposed to work, which IMO is a big negative. Also remember that if the batteries are in cold shutdown, it will take a lot of power to bring them back, so you absolutely would need the engine or shore power, but again you would need to reference them to the coach systems to get them to work.

My guestimate of 200 ah derived from D's photo which looks like two 6 volt size 24s.

In any event your post makes me realize that I forgot a critical third requirement for the notorious backup AGM. Not only does it have to provide a logic load for any charging source plus a power source for BMS activation, it also first has to sample lion battery temperature and if below allowable limits it has to provide heater current to bring the battery into spec before permitting any charging source to execute. Under some circumstances that could require a battery of substantial ah capacity. Also, unless the battery is already within temp specs, that process is going to take longer than the proverbial New York second.

You suggest that the AGM is glued to the lions and consequently will be detrimentally subjected to the lion charging algorithms. I may well be missing something here but off hand, that is not the way I would build this. The UH generator is already potentially being pushed hard if the AC or other thirsty loads are on. So I would have the AGM aux charged by the OEM alternator which is loafing by comparison and producing charging parameters acceptable to an AGM battery. I'd employ a separator so that during engine alternator battery discharge, the AGM battery is isolated. In this configuration, this battery would serve both as a support for the lion BMS and as a switchable battery assist for the engine battery if needed.

I would have the AGM battery address the lion heaters only if the BMS shut the battery down. The same relay that turns on the battery would shut down the AGM connection. Otherwise, I'd just let the AGM battery float.

Sincerely yours,

Rufus Goldberg

[booster]

The AGM doesn't have to run the heaters, all it has to do is provide the initiation and ballast for whatever charging source you want to use. That source can then run the heaters until the lithiums come back online.

There have been extensive discussions on the forum about how it all could have been done better, based on the limited data we have. Many of the ideas look like they would work better than the RT systems.

I think it all comes down to the fact that the Roadtrek system was poorly done right from the start, as shown by the horrible rollout with near 100% failure rate and still questions and issues many months down the road. The fact that they are very reluctant to even admit there are issues leaves a lot customers in a tough spot.

As it stands right now, I would recommend the Pleasure-Way lithium system over the Roadtrek. The Pleasure-Way system appears to be just a Smart Battery type setup with a regular fixed voltage charger, which isn't great but at least it should work reliably for a while.

[cruising7388]

Originally Posted by booster

I think it all comes down to the fact that the Roadtrek system was poorly done right from the start, as shown by the horrible rollout with near 100% failure rate and still questions and issues many months down the road. The fact that they are very reluctant to even admit there are issues leaves a lot customers in a tough spot.

The rollout fiasco has been pretty well described but do you have any details on what issues remain at this point? Looking at R/T dealer offerings, lots of these coaches are coming with UH gen/lion/VS options. I would think that before widespread offering of these options they would have ironed out the operational issues if not the parasitic load issue, but maybe not. In any event, I'll have the opportunity to have a fully loaded 2017 800ECO + Solar 210Pop wrung out by a friend and learn where the rubber really meets the road on this stuff.

[TravelOn]

I'm having trouble with my PleasureWay house battery staying charged. I will follow and take any info that might help understand charging systems. This is my first RV.

[TravelOn]

I'm going to have my battery checked to see what it is charged to. Hopefully it just needs a charger put on it for a few hours. Keep reading the posts. There is so much info and wisdom shared.