Skip to main content ↑ ↓
Topic: Victron BMV 712 settings for Ampere Time (now Li Time) Batteries (Read 3430 times) previous topic - next topic

Victron BMV 712 settings for Ampere Time (now Li Time) Batteries

First of all, Ampere Time has been rebranded as Li Time.

I've been getting bogus charge information on my Victron BMV 712 lately (it showed an unrealistic full state of charge after just a small amount of solar in the morning.) This got me to digging into the app settings for the BMV 712 Smart Monitor.

Did a full charge of the batteries with solar and inverter/charger to float and then synchronized the battery monitor. This cured the false indication of 100 percent charge after only 30 minutes of solar. But then I started digging in further to the gear settings for the "battery" on the app. I had not updated it completely for my two 300 Ah Ampere Time batteries. I created a support ticket and here is the information they sent me:

Battery capacity: 600Ah (that would vary according to your setup)
Charged voltage: 14.6V
Discharge floor: 10%
Tail current: 2%
Charged detection time: 3m
Peukert exponent: 1.05
Charge efficiency factor: 99%
Current threshold: 0.10A
Time-to-go averaging period: 3m

"And I would like to remind you that to charge our 12.8V 300Ah LiFePO4 battery, we recommend the charger supporting Lithium Iron Phosphate Battery charging mode(LiFePO4 mode).
And the DC charging voltage should between 14.2V to 14.6V.
Pls confirm with the above requirements with the manufacturer as they are more familiar with their products." (Ampere Time support)

As to the info sent by Li Time, the charged voltage seemed high to me. The Battle Born setting for that is 14.1, which of course is higher than the default setting for conventional batteries. Also the efficiency, discharge floor, and Peukert settings are different for lithium vs conventional. Li Time settings mirrored the Battle Born settings, which I found on the AMSolar website, with exception of the charged voltage.

I notice that Li Time now offers several more battery options including self heating batteries. There were also some good sale prices on the litime.com website today. If you are looking, suggest you hop right over and check it out.

Re: Victron BMV 712 settings for Ampere Time (now Li Time) Batteries

Reply #1 –
With the 712, also remember to turn off "battery starts synchronized". If for whatever reason you drain your batteries or lose power to the 712, you will restart at 100% once power is established and give you a false indication of power storage.

This seems to have happened to several rv friends this winter as they think they're charging up to 100%, running the microwave and killing their power because they're actually only at 20%.

Re: Victron BMV 712 settings for Ampere Time (now Li Time) Batteries

Reply #2 –
I built a couple of LifePO4 batteries in 2021 and they have held up well.  Each 272AH battery has a BMS (2 Total) and I have a victron BM712 and they never track together after the first cycle of discharge unless they are charged back to "100%SOC".  Not sure why but just assuming they don't measure the AH the same way when charging.  My charge comes from Victron solar controllers (2) 95% of the time.  I don't use the Xantrex charger much since it doesn't have a Lifpo4 setting.  Sometimes the battery voltages are off between the victron and the BMS. But using a voltage meter the BMS seemed to be the more accurate voltage for me?

This is the reply I got from the BMS supplier.

On Fri, Oct 8, 2021 at 7:59 PM Support Team <support@overkillsolar.com> wrote:
Hi Tommy,
I took a look at my Victron setup and see the same issue/feature, I haven't tried to address it but will now.  I did notice in the Victron app there is a manual "Synchronize SOC to 100% " so next time my batteries are at 100% (based on the XiaoxiangBMS App)  I am going to hit the Synchronize button.  On the BMS the SOC (XiaoxiangBMS App) 100% is reset when the cells get over 3.5oov on average (so 14.0V for a 4S battery)    I think I will have to repeat this process every so often as the readings slowly drift apart.

If you are successful in synchronizing these apps let me know how how you did it.

My thinking is they will never show a true SOC but just an WAG (wild ass guess)  depending on the parameters you have inputed during setup.  I will ping overkill back and see if they have figured out anything.

I do believe that a Battery monitor is useful but would not want to depend on it for something serious.  Just another tool in the drawer.
Put this up a few months ago and got no replies?  Any ideas? Victron products Showing wrong voltage?

Re: Victron BMV 712 settings for Ampere Time (now Li Time) Batteries

Reply #3 –
I havnt checked mine yet but I put my charge to 13.8-14.4 max.. I leave a light on when it sits and thats when its set to 13.8v

Tommy check and make sure all ground are correct to the shunt... It will not keep it correct if you have a ground on the wrong side.

Re: Victron BMV 712 settings for Ampere Time (now Li Time) Batteries

Reply #4 –
Tommy, my Xantrex SW3012 has a customize setting option. I was able to put the exact parameters  that Ampere Time instructions ask for

Re: Victron BMV 712 settings for Ampere Time (now Li Time) Batteries

Reply #5 –
Quote from: craneman –
Tommy, my Xantrex SW3012 has a customize setting option. I was able to put the exact parameters  that Ampere Time instructions ask for

Yeah I actually remembered that back whenever, called Xantrex and they said mine was not customizable.

Re: Victron BMV 712 settings for Ampere Time (now Li Time) Batteries

Reply #6 –
Quote from: NevadaBornRvR –
Tommy check and make sure all ground are correct to the shunt... It will not keep it correct if you have a ground on the wrong side.

I have checked that and didn't see anything out of wack.  May let them give it an eyeball at quartzsite for approval.  Most of those guys have forgotten more than I'll ever know!

Re: Victron BMV 712 settings for Ampere Time (now Li Time) Batteries

Reply #7 –
Latest reply from inquiry yesterday.

We have not found a way synchronize the two.  I would not worry too much about it as the SOC  is not used by the BMS to control the operation it is just available as a quick estimate of the charge level.  You could adjust the Capacity configuration numbers to better match the Victron settings.

Regards,

Troy Ball
Independent Customer Support Engineer
troy@overkillsolar.com
 

Re: Victron BMV 712 settings for Ampere Time (now Li Time) Batteries

Reply #8 –
My Xantrex is not customizable but one of the gel settings was really close to the lithium battery settings.