2021 RT Chase: Trying to understand (and fix) my coach electric

[booster]

Originally Posted by Richard Cranium

Did I read this right?

You have LiFePo and AGM batteries connected? all the time?
They have pretty drastically different full charge and charging profiles. If the AGM has less voltage than the lithiums they could be trying to charge the AGM all the time.
I only have 200AH LiFePOs in my rig but they are completely isolated from the starting lead acid and I get 2 + days running the fridge, WiFi, and lights before they shut off. I never run the A/C by choice, so I can't say how long that would run. Since it's an 06 I'm betting it isn't efficient and would kill 200 AH pretty quickly.

This was the normal system for Roadtrek and most owners learned to treat the AGM battery as disposable. It was only there to provide a battery connection to the charging equipment if the BMS shut down the lithium batteries so they could reactivate.


Quite a few systems have been done that way.

[PreciousRoy]

Updates!

Updates! New inverter is in. Solar charger has been relocated down into the ventilated inverter cabinet and a panel array disconnect placed in the upper cabinet.

The new inverter/charger has been installed and programmed. The new unit is a Renogy REGO 3000W Inverter/Charger. Aside from being a little bit wider and having slightly different cable entrance, the swap was a snap. While I had everything apart I tidied up the other 12VDC wiring in there.

Now all 3 charging sources are installed and working, and all 3 have been configured for lower charge voltages to keep the KS2 batteries happy.

Battery Testing!

So far, I've run for several hours with both Lithium modules turned on and 1 to 3 charge sources connected. In that time, I have not had one single battery cutout. I plan to leave the fridge on overnight to draw down some of the capacity since everything I did yesterday barely drew them down a tenth of a volt.

I've also learned that the voltage display on the Firefly panel is not all that accurate. It is lower by 0.2-0.3V than the voltage reported by the inverter. This could be actual voltage drop between the inverter terminal connection point and wherever the voltage sensor for the Firefly is, or more likely it is just a calibration error. Either way, not a big deal. I've disabled the low voltage buzzer on the Firefly since the inverter has better logic.

So far, other than the expense of having to replace the inverter (my fault), I'm happy with my system. I've mapped all the battery-side wiring and now that I understand it better, I can work within its limitations.

For grins, I measured the power draw of my A/C and Microwave while I was at it. The A/C draws ~450W with fan on low, ~550W with fan on high, and ~950W with compressor and fan. The microwave draws 690W when heating. If I were careful with usage, I could even drop in an induction burner if I wanted.

I also found an orphan DC circuit bundled up and shoved under the bed. Might have been wired for a power sofa I guess. It's at least 10AWG wire so it might be useful for a future project.

[booster]

Originally Posted by PreciousRoy

Updates!

Updates! New inverter is in. Solar charger has been relocated down into the ventilated inverter cabinet and a panel array disconnect placed in the upper cabinet.

The new inverter/charger has been installed and programmed. The new unit is a Renogy REGO 3000W Inverter/Charger. Aside from being a little bit wider and having slightly different cable entrance, the swap was a snap. While I had everything apart I tidied up the other 12VDC wiring in there.

Now all 3 charging sources are installed and working, and all 3 have been configured for lower charge voltages to keep the KS2 batteries happy.

Battery Testing!

So far, I've run for several hours with both Lithium modules turned on and 1 to 3 charge sources connected. In that time, I have not had one single battery cutout. I plan to leave the fridge on overnight to draw down some of the capacity since everything I did yesterday barely drew them down a tenth of a volt.

I've also learned that the voltage display on the Firefly panel is not all that accurate. It is lower by 0.2-0.3V than the voltage reported by the inverter. This could be actual voltage drop between the inverter terminal connection point and wherever the voltage sensor for the Firefly is, or more likely it is just a calibration error. Either way, not a big deal. I've disabled the low voltage buzzer on the Firefly since the inverter has better logic.

So far, other than the expense of having to replace the inverter (my fault), I'm happy with my system. I've mapped all the battery-side wiring and now that I understand it better, I can work within its limitations.

For grins, I measured the power draw of my A/C and Microwave while I was at it. The A/C draws ~450W with fan on low, ~550W with fan on high, and ~950W with compressor and fan. The microwave draws 690W when heating. If I were careful with usage, I could even drop in an induction burner if I wanted.

I also found an orphan DC circuit bundled up and shoved under the bed. Might have been wired for a power sofa I guess. It's at least 10AWG wire so it might be useful for a future project.

Sounds like progress.


One thing that I am finding more and more as I test our installation again with the voltage references moved all to together and very close to the batteries, is that with lithium any extra cable length between the batteries and the voltage references messes stuff up and lot more than I would have suspected.


It makes sense, though as even .1v loss due to reference location can leave the batteries very short charged, especially when charging at low voltages like you and I are doing.

[Dadi]

Originally Posted by PreciousRoy

Balmar Charger Config and More Testing

With the inverter/charger dead but still connected (this was important because the connection points for the Firefly coach disconnect switch and solar chargers were at the inverter terminals), I set to re-configuring and testing the Balmar UHG controller.

Here are the settings I landed on (sort of a hybrid between the SUIET Hacks and KS2-recommended settings). These are very gentle to the batteries and will result in not getting the absolute max capacity but that's no longer the primary goal.

Program: UFP
High voltage limit: 13.6v
Temp Co limit: 13.6v
Bulk voltage: 13.5v
Bulk time: 6h
Abs voltage: 13.5v
Abs time: 6h
Float voltage: 13.5v
Float time: 6h
Low volt limit: 12.7v
Bulk/Abs field limit: 27%
Float/Abs field limit: 65%
Alt temp limit: 100C
Batt temp limit: 52C

I also configured the startup delay to 10s so I'd have a chance to start the engine and go back to watch the voltmeter.

I started the test by turning on the coach batteries at the Firefly. AGM voltage was 12.2 at startup.

Turning on Lithium Batt 1 raised system voltage to 13.1 and held stable.
Turning on Lithium Batt 2 raised system voltage to 13.3 and held stable.

I started the engine at this point and went to watch the voltmeter. After 10s, the voltage raised to 13.5 as expected and held steady. After roughly 2 minutes, Batt 1 clunked off.

Resetting Batt 1 resulted in it clunking off again after 7 sec.
Resetting again, clunk off in 5 sec.
Resetting over and over resulted in near immediate cutout. Batt 2 stayed online the whole time.

I ran the engine for roughly 30 minutes, charging Batt 2. When I turned the engine off, system voltage held stable at 13.5v.

With all charging off, I reset Batt 1 again. Instant clunk-out. I said screw it, left the batteries on, and went inside for lunch and did some other work.

After a few hours I went back to the van. System voltage had dropped to 13.4v. On a whim, I reset Batt 1 and it stayed latched. I ran the overhead fan and lights for hours while cleaning up and doing other stuff and both batteries stayed online the entire time. Final voltage when I shut it down was 13.3v.

My theory on Batt 1 is that its internal BMS is reading the system voltage or charge current inaccurately and shutting down too early. For what it's worth, Batt 1 seems OK to charge slowly off of Batt 2 while both are connected, as long as the voltage stays at 13.4v or below.

I verified that by engaging Batt 1 only and observing the system voltage drop to 13.1v. (This is with no chargers active) Batt 2 only raised the system voltage to 13.4v. With both batteries engaged, system voltage hunted between 13.3v and 13.4v and both batteries stayed on.

The "nominal" voltage range on the nameplate for the KS2 batteries is 12.0v-13.2v anyway, so I'm going to call this OK for now. I may be leaving capacity on the table, but I'd rather underuse the battery and get some use from it than nothing at all.

I cannot believe these things left the factory with the Solar MTTP set to 14.4v, UHG set to 14.8v, and inverter/charger seemingly pumping out ~15v regardless of setting. Original owners probably traded it in after 6K miles because they were sick of the damn thing having no battery power and didn't want to mess with it.

I plan to reconfigure the UHG for 13.4v today and retest.

I’m an RV newbie, and reading all the research and discussions here amazes me—there’s so much to learn! We just purchased a new Roadtrek Chase 50 with only 1,000 miles on it. It was barely used, but as the second owner, I don’t have a warranty with Roadtrek, even though the RV is less than a year old.

I feel like something might be wrong with the system because we’ve received several low-voltage warnings after driving for about 5 hours. I’m hesitant to make any changes yet and am focusing on finding a way to monitor the status of the batteries, charging sources, and overall system health.

Unfortunately, Roadtrek directed me to KS2 for support, and while their customer service is quick to respond, their answers aren’t very actionable.

My question is: what’s the best way to get detailed information from the batteries about their status? The batteries report their voltage to the Firefly system, so there must be some communication method in place.

By the way, for the solar charge controller, I bought an RG-45 dongle - https://www.amazon.com/dp/B0C53B8T4Y...fed_asin_title that connects via Bluetooth and an app, which gives me the solar charging status.

[mumkin]

Originally Posted by Dadi

I’m an RV newbie, and reading all the research and discussions here amazes me—there’s so much to learn! We just purchased a new Roadtrek Chase 50 with only 1,000 miles on it. It was barely used, but as the second owner, I don’t have a warranty with Roadtrek, even though the RV is less than a year old.

It sounds like there is a reason why this was traded in so quickly. It says that you are in New Jersey? I suggest that you take a trip over to Northeast RV in Beavertown PA since you are without of warranty. Nick and the crew know the Roadtrek and Promaster systems better than most everyone. They don't have a website, but do have a facebook page. Nick is very good about helping people troubleshoot over the phone when he can. I would also suggest that you join the Zion and Simplicity owners group on Facebook.

The phone number for Nick is (717) 513-5457

[Dadi]

THANK YOU for the info about Nick. I will give him a call. i also joined the RT Zion group in Facebook. again thank you very much