Redarc BMS 30, not for use in Cold temps

[Chadx]

Much to my surprise, I just received the cold weather charging error on my REDARC. I've had this new slide-in pickup camper since spring and this is first cold weather charging. I'm in MT and it dropped to about zero degrees F. last night. Truck and camper are out in the shop where it's about 20 degrees. Camper is winterized. We haven't take it out the last couple weeks so I went out to check on it and state of charge of the AGM battery was down even though it is plugged into shore power. Noticed the charging error and looked it up in the REDARC manual:
Message: Output battery under temperature fault
Cause: Output battery is below 32°F
Action: Charger will halt charging until battery is above 41°F

I've never had a camper that would not charge in the cold. This doesn't make sense. Unless an AGM or lead acid is dead (which can easily be derived by the voltage), there is no reason not to charge when battery temp is below freezing. I have an AGM and so have the REDARC set to AGM. But even an RV lithium would have a BMS so no reason for the REDARC to not sent current when below 32 degrees. The REDARC says the current battery temp is 26 degrees Plugging into shorepower won't charge it. I assume it also would not if I started the pickup and associated DC voltage came in or if I backed it out and solar input came into the REDARC.

If I was out camping when I discovered the REDARC won't charge in the cold, I'd be in serious trouble. Glad I found this shortcoming when at home. Like on this REDARC, my previous charger you could choose the battery type (lithium, AGM, lead acid, etc.). You could also custom program the charging parameters (voltage, amps, etc.) and it would automatically compensate for cold temps which is typical. Was excited that this unit came with a REDARC, but this shortcoming is very surprising. When winter remote camping or in a ski hill parking lot, it wouldn't make sense to heat camper all day when you are away just so solar can charge the battery.

This seems like an oversight. I just emailed REDARC and then searched and found this thread. Hopefully they will remedy with the mentioned sensor. Really surprised this didn't come up with other customers of this slide-in pickup camper as they are made in Canada. Hope this can be resolved as it makes little sense to not allow charging in cold temps for AGM and lead acid. And even for lithium, the BMS should be what controls the battery taking current rather than the charger making the decision for the battery. I'll share when REDARC replies.

 

[john61ct]

Because lithium.

Yes those still using lead should be able to disable , but really you need to

get a different charger, or

fool it into thinking the battery is over 41°

 

[vomhorizon]

What a bummer. A $1200+ system which I assume will shut absolutely all forms of charging below a temperature threshold (which is quite high from what I can make out)? I was once considering this for my build but was a bit reluctant about placing most of my charging bets on one piece of hardware which could break down and kill any trip.

 

[Chadx]

Because lithium.
Yes those still using lead should be able to disable , but really you need to
get a different charger, or
fool it into thinking the battery is over 41°

Fankly, "Because Lithium" makes zero sense because I'm not charging lithium and do not have it on lithium setting. I've not run across any other solar charger or battery management system that will not charge an AGM or Lead Acid battery once the temp hits 32 degrees F. because there is no technical reason for a system not to. Their system not having the ability to charge in cold weather truly makes no sense and it outside the norm, hence why it caught me off guard because it's not something one would even think about checking (plus, this is the system that came with my camper and it wasn't a custom component-by-component build). Would be as random as a car not going into reverse if your windshield wipers were on. Why would one even check that? Ha.

The response of "get a different charger or fool the battery" isn't reasonable as this is a top shelf charger installed by the manufacturer and built and used in Canada. Seems REDARC has learned of this shortcoming is making changes to remedy, but that it was ever even programmed this way is hard to believe. And their owners manual differs from real world perfomance.

Owner's manual notes:
Thermal Specifications Operating Temperature -40°F to 176°F
SLA, AGM, or Calcium Charging Temperature -13°F - 140°F (32°F - 140°F when Vop <10.5V)
GEL or LiFePO4 Charging Temperature 32°F - 140°F
Over Temperature Shutdown Yes

Temperature Compensation
Standard Lead Acid, AGM, Gel or Calcium Battery +16.7mV / °F < 77°F < -16.7mV / °F
Lithium Setting 104°F < 0.28%/°F < 140°F

 

[Chadx]

What a bummer. A $1200+ system which I assume will shut absolutely all forms of charging below a temperature threshold (which is quite high from what I can make out)? I was once considering this for my build but was a bit reluctant about placing most of my charging bets on one piece of hardware which could break down and kill any trip.

I actually like the idea of one unit being the solar controller, DC charger, AC charger, etc. Electronics such as these are typically quite reliable. I really love this system minus this one shortcoming, which doesn't even match their owners manual.

Will mention that the charging cut off threshold is 32 degrees F but once it trips, it won't start charging again until the battery temp (based on the battery temp sensor) is warmed up to 41 degrees F. A typical RV charger uses the battery sensor to adjust the voltage input when charging AGM/lead acid battery in cold weather (more voltage) or less voltage (hot weather). REDARC has this.

From the owners manual:
11. The Manager30 has a separate battery sensor to monitor battery conditions and state of charge even while The Manager30 is in standby mode. The battery sensor monitors current, voltage and temperature of the house batteries.
12. Automatic temperature and voltage drop compensation.

 

[john61ct]

Fankly, "Because Lithium" makes zero sense because I'm not charging lithium and do not have it on lithium setting. I've not run across any other solar charger or battery management system that will not charge an AGM or Lead Acid battery once the temp hits 32 degrees F. because there is no technical reason for a system not to.

Yes I agree 100%, not making excuses for this stupid design flaw

just explaining the reason they made that mistake.

Personally I prefer to buy separate best of breed devices, each function sized for the needs of that specific use case

each separately replaceable when it breaks.

DCDC in particular, I require custom user-adjustable output voltage setpoints

I find Redarc generally overpriced, but patriotic Aussies do love buying local. . .

 

[Chadx]

I follow you now.

Some aspects of the REDARC that I did like:
MPPT solar controller (vs the cheaper PWM that I used in my previous camper)
The DC to DC (because my Tundra pushes notoriously low voltage but the REDARC boosts it to appropriate voltage and programmable amperage before sending it to battery where my previous camper was wired through the voltage detercor switch but otherwise truck voltage to the battery and that was rather low/slow).
Everything being in one unit is incredibly space savings compared to separate solar controller, DC/DC converter, AC/DC charger, etc.

And I am in Montana so no preference for Australian made goods. Ha. For use in the US, they are actually quite overpriced, but again, was included with this camper and am quite happy with the unit except for this cold weather charging issue.

 

[vomhorizon]

Some aspects of the REDARC that I did like:
MPPT solar controller (vs the cheaper PWM that I used in my previous camper)
The DC to DC (because my Tundra pushes notoriously low voltage but the REDARC boosts it to appropriate voltage and programmable amperage before sending it to battery where my previous camper was wired

Yeah it checks most of the marks if you are looking for a combined system. But these days you can build a best of breed system for far less and one that is more optimized for one's needs. But as you said if you don't have space to put 2-3 individual components then that becomes an issue and may be something why you may wish to pay a premium for though it would be interesting to see what a side by side mounted profile looks like for some of the more compact DC-DC chargers and MPPT's.

 

[Pinnacle Campers]

Maybe going off topic but related,
It amazes me that there isn't any user friendly lithium BMS's that have heater pad output and monitoring.

 

[john61ct]

It amazes me that there isn't any user friendly lithium BMS's that have heater pad output and monitoring.

The usual meaning of the term BMS has nothing to do with the type of unit under discussion in this thread.

The EV market uses the term TMS for thermal management system, and that usually involves hydronics, circulating temperature regulating fluid through the battery packs.

With mobile House banks being a pretty insignificant market compared to EV, and

both freezing-weather usage **and** DIY lithium both very separate and tiny proportions of that tiny market

there is litte reason to be "amazed" that heating cells remains in the DIY arena.

Relion has the heating function built into their OTS drop-ins, there will likely be others in ears t come.

 

[john61ct]

This is as it was designed

Actually, I just found what you're looking for in the manual. Check out page 6.

https://www.redarc.com.au/Content/Images/uploaded/Manuals/BMS1230S2%20Instruction%20Manual.pdf

Operating Temperature* -40°C - 80°C

* The Manager30 will only charge the battery when the battery temperature is between 0°C and 60°C in order to protect the battery from damage.

 

[vomhorizon]

Relion has the heating function built into their OTS drop-ins, there will likely be others in ears t come.

I believe Battle Born also has the internal heating lithium battery option, but those are only on offer (for now) for their OEM offerings and tieups with some RV and trailer OEMs.

 

[Chadx]

Heard back from REDARC last night and as a previous poster noted, they made an update to their battery sensor/shunt to correct the issue and they suspect mine pre-dates this update (even though my camper was just built this spring). I owe them an image of the bottom of the sensor so they can run the numbers on the part number and serial number. I suspect it will turn out to be the old unit and the most recent part number will be needed to make the REDARC behave as the owners manual says and charge AGM and Lead acid down to -13 F. More to come...

 

[Chadx]

I sent image of my shunt/sensor and REDARC said it was the old part. They are sending me the newer part number and having me return the old. This is only the shunt and battery sensor; not the entire unit. I should then be good down to the -13 F charging for agm/lead acid speced in the owners manual. They were surprised my new camper had the old spec sensor as they said they didn't ship any of the old to north America in 2019 and my numbers indicated it was a 2019 REDARC unit (camper is a 2020 built this spring).

In the meantime while I wait for the part to arrive, it warmed up from 0 F to 40 F yesterday so my battery was up to 35 F. and the REDARC charged normally. I'm back up to 100% SOC.

Looks quite easy to change the shunt/sensor when it arrives and I'll do it myself. Great customer service!

 

[Chorky]

Well that absolutely sucks for most of North America.

This sensor will allow charging of lead acid batteries down to -25degrees C. PDF attached.

Interesting. -25C is only -13F. In my bit of the world, thats about the average winter temp.... I wonder if sticking to AGM, fabing up some heated blankets, and using a more old school method is going to be the way to go for those of us in colder climates. Obviously there is a solution seeing as how many rigs are on the north slope....