Renogy BMS sleep mode ?

[st1650]

I set up a shed with solar panels to power a 12v POE wifi setup on my acreage.

I used to run cheap 2x 100a lifepo4 batteries and never had an issue but I saw Renogy had their self heating batteries on sale so I decided to give it a try rather than passively insulate my cheap batteries.

Core- 12V 300Ah Deep Cycle Lithium Iron Phosphate Battery with self-heating function

Meet Renogy 12V 300Ah Core Series Battery, your trusted, one-stop solution for upgrading from Lead to Lithium. Compatible with Renogy's solar panels, solar charge controllers, and inverters, this battery delivers a seamless upgrade experience without any compatibility issues.

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My main issue is that my setup doesn't draw more than 1a so every night the BMS goes into "shelf" mode and the battery reads 12.3v and I guess gets re-awaken by my Victron mppt controller at some point when theres enough sun.

It feels like a terrible idea and not at all explained in the manual.

So does that means that I run the risk of the mppt controller being unable to wake the battery up ? Can this set up last long term ? Can I bypass this by setting up a smart switch to run a 2a load for 15min every 12 hours ?

Also if the bms is in sleep mode and it gets below 0C at night ... will the self heating still works ? Is there a way to disable this "feature" ?

 

[sunshine_eggo]

It feels like a terrible idea and not at all explained in the manual.

Sleep modes are becoming more common and are often confusing.

So does that means that I run the risk of the mppt controller being unable to wake the battery up ? Can this set up last long term ? Can I bypass this by setting up a smart switch to run a 2a load for 15min every 12 hours ?

No. The Victron will output absorption voltage even if a battery is not present, so the BMS should always wake up when it senses current.

Also if the bms is in sleep mode and it gets below 0C at night ... will the self heating still works ? Is there a way to disable this "feature" ?

Question for Renogy; however, self-heating should NOT occur until a charge is applied as the battery will not (should not) drain itself to stay warm. By this logic, the BMS should be awakened by the MPPT and should then use the incoming current to energize the heaters.

 

[st1650]

Sleep modes are becoming more common and are often confusing.



No. The Victron will output absorption voltage even if a battery is not present, so the BMS should always wake up when it senses current.



Question for Renogy; however, self-heating should NOT occur until a charge is applied as the battery will not (should not) drain itself to stay warm. By this logic, the BMS should be awakened by the MPPT and should then use the incoming current to energize the heaters.

So I did a test last night to verify the behaviour when drawing a stable 1.75a current overnigt. I fully charged it with a AC charger beforehand ...

It still looks super weird how it's constantly jumping in and out of "sleep mode" even during the day in absorption mode on the mppt controller. I just can't see how it's good for the cells to constantly jump from below 12.3v to 14v

I got an answer from Renogy and it seems like the battery needs at least 10a of charge to self heat which is kind of not great because what if the battery is at full capacity and then it won't charge itself at night then you get overcast sky and cold weather now potentially it'll just freeze itself...

 

[Brother_Bluto]

I am finding the "sleep mode" function to be a very, very bad idea when using the batteries in an RV application. I don't full-time in my RV, so it can spend some time in storage (several months over winter) and is under cover so no solar. If I need to get in and use something 12v... I must have the truck with me to get a charge and wake them up. It is now winter... so they are below their ability temperature wise to accept a charge. Renogy has been zero help and deny the batteries automatically go to sleep. Looking hard at swapping to batteries with an on/off button.

 

[st1650]

I am finding the "sleep mode" function to be a very, very bad idea when using the batteries in an RV application. I don't full-time in my RV, so it can spend some time in storage (several months over winter) and is under cover so no solar. If I need to get in and use something 12v... I must have the truck with me to get a charge and wake them up. It is now winter... so they are below their ability temperature wise to accept a charge. Renogy has been zero help and deny the batteries automatically go to sleep. Looking hard at swapping to batteries with an on/off button.

Exactly, I wouldn't mind the feature if there was a way to disable or customized it through a bluetooth controller ...
Also because I bought them on sale, they have a terrible exchange/return policy. I certainly won't spend anymore on Renogy

 

[jeff.lankford]

I am finding the "sleep mode" function to be a very, very bad idea when using the batteries in an RV application. I don't full-time in my RV, so it can spend some time in storage (several months over winter) and is under cover so no solar. If I need to get in and use something 12v... I must have the truck with me to get a charge and wake them up. It is now winter... so they are below their ability temperature wise to accept a charge. Renogy has been zero help and deny the batteries automatically go to sleep. Looking hard at swapping to batteries with an on/off button.

Does the battery not wake up simply by placing a load on it? Why do you need to apply a charging voltage first?

 

[jeff.lankford]

I just can't see how it's good for the cells to constantly jump from below 12.3v to 14v

I'm certain that the individual cells are not rapidly changing state as you imply. All that is switching is the battery's connection to the outside world. Internally, the battery voltage is remaining somewhat constant.

 

[sunshine_eggo]

So I did a test last night to verify the behaviour when drawing a stable 1.75a current overnigt. I fully charged it with a AC charger beforehand ...

It still looks super weird how it's constantly jumping in and out of "sleep mode" even during the day in absorption mode on the mppt controller. I just can't see how it's good for the cells to constantly jump from below 12.3v to 14v

This is absolutely, positively NOT what's happening. The cell voltages aren't changing at all. The BMS is reporting a different voltage. The BMS is the battery's interface with the world. It tells you what it wants to tell you.

I got an answer from Renogy and it seems like the battery needs at least 10a of charge to self heat which is kind of not great because what if the battery is at full capacity and then it won't charge itself at night then you get overcast sky and cold weather now potentially it'll just freeze itself...

The battery absolutely, positively won't "freeze itself." The battery can DISCHARGE down to -20°C (most do anyway). Below -20°C, it will cut-off DIScharging. I have never seen a published temperature at which the electrolyte in LFP batteries will freeze. A quick google suggests -60°C.

 

[Brother_Bluto]

Does the battery not wake up simply by placing a load on it? Why do you need to apply a charging voltage first?

No, they are not waking up with applying a load. The only way I have found to wake them up is to apply a charge. The Renogy CS team finally turned it over to their technical team - sent them data two weeks ago form the BT app & a BT log downloader (BT still works on all 4 batteries, but no current across the terminals). Haven't heard anything back. Very annoying and pretty much done with Renogy.

 

[Swami]

See my recent solution on this problem. It may help. It was designed for a remote LCD display but could work just as well to stop the BMS itself going into sleep mode

JBD Remote LCD Sleep hack

I've had much annoyance at the wonderful JBD remote LCD-02 unit going to sleep after 3 mins of standby. I like to glance at it on my boat at anytime. But it requires a button push to wake up. So here's my hack: 1. I figured out it is not any function of the BMS, so it is inaccessible even by PC...

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