House Battery Charging Issue on UHG

[jpzlaw]

I had what I thought was an intermittent charging issue with the (secondary, Thor installed UHG) alternator in my 2023 Tellaro 20 L. At first, I noticed the batteries would occasionally not charge while driving or running the engine. I brought it to the dealer and they replaced the lithium batteries, checked the harnesses and fuses, etc. Worked fine on the trip home, but after a few days, I started noticing the same problem again. The batteries would charge just fine on shore power or solar, but at times would not charge at all with the engine running, unless I revved it up to about 3000 RPMs, at which point I would get maybe 5 to 15 A of charge. I could also get the house batteries to charge on the chassis alternator by pressing the emergency start button on the dashboard. I was a little queasy about doing this for anything more than a few seconds, however.

At this point, I figured the issue was either the second alternator itself, the wiring, or the voltage regulator. After a few days, however, I finally noticed a pattern. I’m only having the problem below about 33°. When the weather warms up, it charges fine. At first, I thought it was the battery monitoring system, but why then, would shore power and solar work, as well as the chassis alternator for charging the house batteries in cold weather?

I finally came across posts in this forum and elsewhere about how the Balmar 618 regulator will cut back to minimal charging below 32 degrees. I spoke to Belmar tech and they confirmed that what I’m seeing is exactly in line with how they program these regulators they sell to Thor. I asked if I could change the temp cutoff setting on the 618 but he advised against it. I would also need an additional communication cable and the Bluetooth dongle in order to do this.

Based on that conversation I may be reluctant to change anything. I’m also going to cancel my return appointment with the dealer because everything is apparently working the way it’s supposed to!

But that does raise the question of how do you charge below freezing if you don’t have shore hook up? A long enough drive or period of time in cold weather will deplete the house battery bank. I could carry a small generator, use the emergency start button, or I guess I could let the dealer undertake more work that they’re probably not familiar with in order for me to be able to program the 618 regulator. BTW, the Balmar tech wouldn’t give me his opinion about using the emergency start button, but I think he probably thought it was a bad idea. Even with a fully charged chassis battery and all chassis electrical loads off it’s still likely to put quite a load on the chassis alternator.

Any thoughts? Do you guys agree with these conclusions? Was this a lot less complicated before lithium batteries?

Joe

[robertj1961]

You are 100% correct about charging being much less complicated before the lithium batteries.

There have also been problems charging with generator or shore power during freezing weather. I had the Relion BMS system completely shut down when trying to charge the batteries with the Onan generator during cold weather. When this happens, the van is left with no DC power at all until the system resets. The Relion battery computer system (BMS) is designed to heat up the batteries first, and then allow charging during cold weather. I am not sure how the UHG system is set up to do this as I have the Onan generator and do not have the UHG (Under hood Generator) but have not had much success charging in freezing temperatures. Fortunately, I am in North Carolina and not as severe of an environment as many are dealing with.

Thor really did not think this system through and there have been several reported issues, many that seem to be related to the lithium batteries during cold weather.

I would encourage you to read the Relion Data sheet at their website regarding temperature limitations etc. but it is well documented that Lithium batteries do not like to be charged during freezing temperatures.

To make matters worse, on the 200a/h setup, Thor installed the batteries outside underneath the van in front of the rear axels. Their access is somewhat challenging and they are exposed to the elements. The 400a/h and 800a/h setup at least have the batteries inside the vehicle.

[RonRM]

You are experiencing normal behavior for the 2023 20L in sub 32deg weather.

The 15amps is the heaters coming on. If you only see 15amps, then it goes to zero, could/should be that your batteries are at 100%, or regulator temp cutoff. The cycle for the battery BMS in cold weather is - cut off 12v, heat to 41deg internal, enable 12v, charge.

IF - big IF...this only happens when the regulator battery temp gets above 32deg...IF it doesn't, then the regulator will not engage the UHG at all (after a time out)

I believe I read that the Balmar regulator has a fixed number of minutes where it allows the UHG to deliver charge, whether anything needs it or not...I suspect, it does this regardless of temp, and the batteries see the current and go into heater mode. The UHG times out, sees it's battery temp sensor below 32, and turns off the regulator...I'm pretty sure that's what's happening...could have misinterpreted it, but I read is somewhere and then saw a YT video of a guy who swapped out the Balmar stuff for another UHG...and complained about the fixed charge time.

These are the regulator params...see - Min Battery = 0C (32f). Below that the regulator cuts out. I dont know where the temp sensor is, suspect near the batteries. That parameter can be adjusted, either with the BT dongle or a procedure directly on the regulator.

Program, UFP-CFP
Charging Station, Fixed Bulk
Regulator Temp, 30 � C
Calculated Tar. Voltage, 14.3
Regulator Soft Rev, 5.00
MAX Field %, 100
Regulator Hours, 5.1
Field Output %, 34
Small Engine Mode, 0
Battery Temp #1, 24 � C
Alternator Temp #1, 28 � C
Battery Temp #2, Open
SLP, 0.0
Battery Type, UFP-CFP
SmartLink Device ID, 129
Sensor Enforcement,
Long/Short Display, 0
Alternator Failure Advisory, 1
Start Delay, 1
High Voltage Limit, 14.5
Compensation Limit, 14.4
Bulk Voltage, 14.3
Bulk Time, 0.1
Absorb Voltage, 14.2
Absorb Time, 0.2
Float Voltage, 13.5
Float Time, 18
Low Voltage Limit, 12.7
Field Threshold Bulk to Abs, 65
Field Threshold Float to Abs, 65
Alternator Temp Threshold, 110
Max Battery Temp, 44
Min Battery Temp, 0
Battery #1 temp. sensor open or not found, E11
Battery #2 temp. sensor open or not found, E13
Alternator #1 temp. sensor open or not found, E15
FUP, undefined
socsec, F7F-30-06E3


Good news, you don't need to rev the engine, the UHG can put out max amps even at low/idle RPM.

Plugging in, battery does the same heater dance, but there is no temp sensor on the MasterVolt...so once they heat up, they charge.

Like Robert said...had they put the batteries inside that would limit the situation.

If you unscrew the beds and get a look underneath, you will see that there is plenty of room (after the rat nest of wire/plumbing is cleaned up) to move the batteries inside. They could have easily done this and not sacrificed a square inch of existing storage.

Perfectly normal for the system as designed...it's just a crappy design, unless you are blessed with year round weather above 32f...then it's not bad at all.

Ron

[RonRM]

Oh yeah...forgot to add...

Using the e-start button, while it will charge the batteries from the chassis alternator for a period of time, but it's not regulated to charge lithium. You could damage the chassis alternator or the batteries...probably ruin the alternator first, the batteries will protect themselves via the BMS, if you do it too long. No idea how long is long.

In a pinch, there are lots of service stations that will let you bumb a few minutes of 120V power. I've seen outlets on light poles in grocery store parking lots.

There is a trick where the e-start comes in handy. If you drain the lithium to zero, and they don't have enough power to run the internal BMS. You can use the e-start to 'reset' them and bring them back to life. There is a YT (I think it was from Thor) explaining how to do this.

Ron

[jpzlaw]

Thanks, guys! I appreciate the info and expertise (far in excess of my own!). Frankly, I’m more relieved that things are at least working the way they were (somewhat inartfully) designed than I am frustrated with the issues that the design presents. I can now just imagine the frustration - rather than experience it - had I returned, AGAIN, to the dealer.

While I like the idea of moving the batts inside, it seems the failure to charge that I’M experiencing is not a battery thing. That’s because the only no charge condition I have is with the UHG in low temps. So maybe I could just find a way to warm up the regulator heat sensor, rather than change its parameters?!? RELiON says those batts should work down to almost zero. Maybe if I find the regulator heat sensor - and Balmar did not know where it was - I could find a way to warm just it up, if needed, and sort of trick it into charging.

Does that seem reasonable?

[Judge]

Originally Posted by jpzlaw

RELiON says those batts should work down to almost zero. Maybe if I find the regulator heat sensor - and Balmar did not know where it was - I could find a way to warm just it up, if needed, and sort of trick it into charging.

Does that seem reasonable?

LiFePO4's can work down below freezing but they won't necessarily charge when temps are below freezing if your batteries have a built-in BMS.

My BigBattery LiFePO4's will discharge down to -20F but the built-in BMS will prevent them from charging below 32F.

This is not an issue for me because when I upgraded my coach to LiFePO4's, I installed them inside the coach under my dinette seats. I have a Xantrex Inverter / Charger that is installed in an outside storage bay but it will work and charge in temps down to -4F.

So if your batteries are exposed to temps below freezing, warming up the regulator temp sensor may not be the answer.

[jpzlaw]

Originally Posted by Judge

So if your batteries are exposed to temps below freezing, warming up the regulator temp sensor may not be the answer.

Right… my recollection is that they DID accept a charge from shore power at a time when it was fairly cold - like 20’s. With any luck it’ll get that cold again and I can confirm that fact (did I really say that? Cold again?)

But I’m starting to think I will reconsider bringing the batteries inside. But I’d still have to warm the regulator sensor, as well…

Anybody know where that sensor is, or could be?

[Judge]

Originally Posted by jpzlaw

So if your batteries are exposed to temps below freezing, warming up the regulator temp sensor may not be the answer.


Right… my recollection is that they DID accept a charge from shore power at a time when it was fairly cold - like 20’s. With any luck it’ll get that cold again and I can confirm that fact (did I really say that? Cold again?)

But I’m starting to think I will reconsider bringing the batteries inside. But I’d still have to warm the regulator sensor, as well…

Anybody know where that sensor is, or could be?

in

It could possibly tied into the ambient temperature sensor for the outside temp displayed on the dash?

[robertj1961]

Originally Posted by Judge

LiFePO4's can work down below freezing but they won't necessarily charge when temps are below freezing if your batteries have a built-in BMS.

My BigBattery LiFePO4's will discharge down to -20F but the built-in BMS will prevent them from charging below 32F.

This is not an issue for me because when I upgraded my coach to LiFePO4's, I installed them inside the coach under my dinette seats. I have a Xantrex Inverter / Charger that is installed in an outside storage bay but it will work and charge in temps down to -4F.

So if your batteries are exposed to temps below freezing, warming up the regulator temp sensor may not be the answer.

I agree with Judge that warming the regulator is not the answer.

Reason being you could damage the expensive batteries if you were able to "trick" them in to charging below 32F. It is ok to discharge them but not charge Lithiums when it is that cold out. The reason it is ok to charge the Relions to -4 F on shore power is because Relion found a way to heat them up FIRST. That is assuming all works as it should when you plug in. There is up to an hour delay while they are heating before they actually start charging.

I found out the hard way when trying to charge them on my generator below freezing conditions it did not work. It actually tripped the generator breaker on the Onan and shut down all DC power until temperatures warmed up and the BMS reset. For some reason, when plugging in to shore power, did not have the problem and the Relion BMS did not shut everything down.

For now, it sounds like Ron is correct that best solution is to find a power plug when temperatures are that cold.

[jpzlaw]

Yes, I agree. It’s too bad the UHG doesn’t heat first, then charge. Seems like a simple thing to accomplish.

Worst case I can lug along my 3,000 watt Generac inverter generator. It’s fairly light and quiet and was able to run the 13.5k btu a/c on our last travel trailer.

Thanks again to everyone! Joe

[MCP]

All good info in the posts above. Here in balmy Valley of the Sun North Phoenix, i've had similar condition when it has dropped to frost temps. Rare, but happens. Also happened in northern MN in October. Not so rare there!

FWIW, on 2023 Tellaro 20k with d2x100ah Relion there is a temp sensor at the positive of one of the batteries. Interestingly, Balmar literature says the sensor should be connected at a negative post near the center of the bank. Not sure if that would make a difference. The sensor is a two wire cable that goes to terminals 7 and 8 on the regulator. If you haven't done so already, you can go to the Balmar web site and look at the wiring diagrams for both the alternator and regulator, MC-618. Some of the same info may be available on the Thor Owner's Resource also.

There is also a temp sensor on the alternator. It also connects to the regulator. I originally thought there may be a low temp cut off for the alternator, but it is only a high temp cutoff. On one of those cool mornings, I ran the engine/alternator for a while and it finally kicked in, but I think it was just the battery and ambient temp rising a degree or two naturally, thereby reaching above the magic cutoff point.

Mike

[RonRM]

Actually, you are good if you change the param or find the temp sensor and keep it warmer.

In either case, the batteries will protect themselves. The heaters will take them to 41F internal no way to damage them in cold weather. That's my reasoning for changing the low temp param, lowering a bit more.

Take a look at page 3 - Pin 7/8 are where the temp sensor is connected. You can follow the wires and find the sensor. It will probably be near or on the batteries. The regulator in the 20L is under the passenger side head-rest, basically behind the fuse box.

https://balmar.net/wp-content/upload...S-MC-614-H.pdf

There is a temp sensor on the UHG. That sensor is very important, as it provides feedback to limit the amount of current as the UHG heats up. As the UHG heats up the regulator limits the field, which in turn reduces the temp of the UHG - keeping it from burning up.

Check out the pic on post #19

https://www.thorforums.com/forums/f4...etc-33115.html

The regulator is the blue box on the top right. Your rat nest will not look exactly like that, I added a secondary shunt/monitor and a battery cut-off. All small part of my 'Re-Engineer the Mess' project.

You can watch the led display, it will cycle through params and values while the engine is running. Dunno, if it displays the temp. With the BlueTooth dongle, you can see quite a bit more. I think the display has a limited set of values it displays, when the engine, if you select Alternator in the menu.

Not exactly a cold weather issue, but more so an issue in general with the design. If for a variety of reasons, the load is switched off (ie. the battery BMS disconnects), and the UGH is putting out current - engine running...a condition called field dump can occur. This could put excessive voltages on the 12v system throughout the coach. There is a device that Balmar sells that should have been put in this system. This thing https://balmar.net/product/apm-12/. It's the equivalent of a surge protector to protect against field dump, basically a zener diode that is strapped across the output of the alternator.

Ron

[RonRM]

Just want to clear up the battery temp statement...

"In either case, the batteries will protect themselves. The heaters will take them to 41F internal no way to damage them in cold weather. That's my reasoning for changing the low temp param, lowering a bit more."

The LT-100's have an "internal" temp sensor, that's the device that switches the BMS into disconnect/heater mode, NOT the regulator temp sensor.

The temp sensor on the regulator is a separate device...it is near redundant. I think they put it in the system hoping it would 'follow' the internal battery temp. Two things, hope is not a strategy, and no way it would follow the 'internal' temp of the battery...the batteries have heaters and the BMS by itself gets hot. The regulator temp sensor will almost always be below the internal temp of the battery...it's just stupid.

I'm not saying do what I do, but I put the APM-12 on the alternator and lowered the temp setting to -15C/-4F (to stay just 5C above min charge temp - in case the heaters fail). If I have issues, I'll lower it even more. I don't feel like there is anyway to ruin the batteries, since they heat up before they charge.

BTW, I have tested this, but not extensively. I also tested, leaving the rig plugged in for months. My rig sat outside, covered, plugged in, for the entire Wisconsin winter - it got down to -20ish - zero issues. When it gets really cold, my monitors show that the battery disconnects 12v, heats up and then charges; just like its supposed to.

Next year, I'll flip that big switch in the post pic linked above. That will completely disconnect and isolate the batteries for storage vs. having them float charged (not damaging - float charging, but not ideal)

Ron

[holtcg]

Originally Posted by jpzlaw

Right… my recollection is that they DID accept a charge from shore power at a time when it was fairly cold - like 20’s. With any luck it’ll get that cold again and I can confirm that fact (did I really say that? Cold again?)

But I’m starting to think I will reconsider bringing the batteries inside. But I’d still have to warm the regulator sensor, as well…

Anybody know where that sensor is, or could be?

If it's not very close to the batteries, it's in the wrong place.

[16ACE27]

Originally Posted by jpzlaw

Right… my recollection is that they DID accept a charge from shore power at a time when it was fairly cold - like 20’s. With any luck it’ll get that cold again and I can confirm that fact (did I really say that? Cold again?)

But I’m starting to think I will reconsider bringing the batteries inside. But I’d still have to warm the regulator sensor, as well…

Anybody know where that sensor is, or could be?

Originally Posted by holtcg

If it's not very close to the batteries, it's in the wrong place.

Why would the regulator sensor be close to the batteries?

[RonRM]

Seems to be confusion...there isn't a regulator temp sensor or any sensor that measures the temp of the regulator. Warming/Cooling the regulator is not necessary nor an issue.

Yes, the temp sensor is connected to the regulator, it is there to measure ambient temp NEAR THE BATTERIES to tell the regulator to charge or not.

The reason it's stupid, the batteries do a fine job of measuring their internal temperature and deciding on whether they will accept a charge or heat to then accept a charge.

There a second temp sensor connected to the regulator, it is very important, as it measures the temp of the UHG - without it, the UHG would literally melt it's internals.

Ron

[holtcg]

Originally Posted by RonRM

Seems to be confusion...there isn't a regulator temp sensor or any sensor that measures the temp of the regulator. Warming/Cooling the regulator is not necessary nor an issue.

Yes, the temp sensor is connected to the regulator, it is there to measure ambient temp NEAR THE BATTERIES to tell the regulator to charge or not.

The reason it's stupid, the batteries do a fine job of measuring their internal temperature and deciding on whether they will accept a charge or heat to then accept a charge.

There a second temp sensor connected to the regulator, it is very important, as it measures the temp of the UHG - without it, the UHG would literally melt it's internals.

Ron

I don't think it's stupid, as many inexpensive LiFePo4 batteries do not have an internal sensor and could be permanently damaged by charging in below freezing temperatures. Watch some Will Prowse reviews on YouTube and see what I mean. Even some batteries that claim low temperature protection had none in evidence when torn down.

[RonRM]

Totally agree, some lesser capable devices need the sensor. Charging at low temps is detrimental to LiFePo4's.

There are tons of samples of batteries species that do not have low temp sensors, and tons and tons that do not have internal heaters.

But...That is not the case in our rigs (Tellaro, Sequence with the Relion badge...many of the other Thor product use these and some models use other brands not as capable), these are Relion Lt-100's completely capable of mitigating cold weather charging, by engaging internal heaters.

Totally agree again...I can site chapter and verse of Will saying the same thing...batteries that have internal cold temp cutoff and/or heaters do not benefit one bit from an external temp sensor..."it's dumb" literally a quote from him, I prefer to be a bit more abrupt....it's stupid!

The issue is the battery internal sensor is aways going to be warmer than the external sensor (BMS alone will contribute to the internal temp being higher). That would even be the case without heaters

With batteries with heaters, as these are, no issue whatsoever if there were no external temp sensor. These batteries will divert charge to the heaters, when they reach 41f internal, they will take a charge...no matter the outside temp (well at least in WI where it got down below -25F this winter) - Charging no issue for me - albeit plugged in an MasterVolt charging the batteries, the MV inverter/charger does not have an external temp sensor...it just see low voltage and starts doing it's thing. Batteries go into heater mode, then charge mode, MV sees top end voltage and shuts down charging, batteries drain down to a voltage threshold , rinse and repeat...

The bottom line here, is that Thor took a prior to 2019-2020 AGM battery design and simply replaced the batteries with the LT-100's and didn't consider the capability of the batteries. They left most of the stuff pretty much the same - Balmar alternator, shunt, regulator, external battery temp sensor, external alternator temp sensor (really import - glad this is there!), MasterVolt inverter charger.

Some of the 2020-2022 stuff used MasterVolt batteries...far better design, not without issues, but totally integrated on a can-bus. The inverter/charger actually talks back and forth to the batteries...that would be nice.

The current design, with the LT-100s, is all voltage/time threshold triggered. As you probably know, lithium batteries have very flat discharge curves...making voltage near obscure to determine SOC. One needs to either take them to the top and calibrate for 100% or take them to the bottom and calibrate for 0% SOC.

Not that's a big deal, just not as optimal as devices that can actually count coulombs and tell the other how much or little current is flowing and in which direction. The Balmar display/shunt kinda does this, but the thing is so flakey that it reboots is firmware if you look at it wrong...then you have to wait for a number of cycles before it gets accurate again. I overcame that issue with a a secondary shunt that has data logging an remembers where stuff is at any given time.


Ron