Your Lifepo4 just hit 80% depth of Discharge, how were you informed?

[wholybee]

Originally Posted by Simi 60

And they aren't accurate anyway.
At least our victron isn't.
It always reads quite a bit different to the JBD BMS Bluetooth app

Mine is quite accurate, and if setup properly is more accurate than the JBD BMS. (I have an Overkill, which is made by JBD)

The way I judge that is is accurate, is that after several weeks of not hitting 100%, when I do charge to 100% the Victron reads very close to 100% (98%-99%) when full charge is reached and it resets.

The BMS is usually off by a bit more when this happens. But, they corelate very closely for the first couple days.

The difference, I think, is that the BMS is only a counter, excluding charge efficiency and perkurt. Those factors are _almost_ negligible for LFP. But after a number of cycles over a few weeks, they add up.

Of course the Victron needs to be setup for LFP. By default it is set for Lead, and will be very wrong for LFP.

[s/v Jedi]

The Victron BMV is very accurate. When it’s displayed SOC is different from reality then it isn’t configured correctly and/or you haven’t fully charged the battery for a very long time.

[Ballsnall]

Originally Posted by Fuss

You're sailing along not a care in the world and behind the scenes your Lifepo4 just hit 80% depth of Discharge.

Is there a problem?
Most decent LFP batteries are cycle rated to 100% DOD. Just keep cruising.

[sailorboy1]

I find it "amusing" some boaters aren"t very concerned about the power going out on their boats. I am not very interested in that my batteries CAN fully discharge and recover. I am more interested in maintaining power on the boat

[wholybee]

Originally Posted by sailorboy1

I find it "amusing" some boaters aren"t very concerned about the power going out on their boats. I am not very interested in that my batteries CAN fully discharge and recover. I am more interested in maintaining power on the boat

This. A prudent sailor will recharge whenever there is an opportunity so the lights stay on. The LFP battery of course doesn't care, but I want my stuff to work.

[Simi 60]

Originally Posted by wholybee

.

Of course the Victron needs to be setup for LFP. By default it is set for Lead, and will be very wrong for LFP.

I see nothing in the instructions about setting the battery monitor for LFP, perhaps I missed it?

What I have done is....

Charge to cuttoff of LFP, near enough 100%
Set AH of victron to match BMS at that point and synchronised the victron.

Seems ok for several days but they drift apart after that.
Victron can show 80% and BMS can show 40%
I suspect it's because the LFP are still at 26.? V and the victron sees that voltage as full

Add: google is my friend.....maybe

https://battlebornbatteries.com/conf...etooth-dongle/

And

https://www.victronenergy.com/media/...id%20batteries.

[CarlF]

It took me about a year to “reprogram” myself from 40 years of worrying about battery SOC.

I just don’t think about the battery SOC very often with lithium. The 1600 watts of solar panels mean I can go for many days at anchor with it just hanging between 30% when the sun comes up and and 80%+ at dusk. At anchor I take a look at the SOC after the sun had gone down and the solar panels aren’t charging - if it’s under 40’% I’ll run the genset to bring it up to about 70%.

The Victron BMV alarms at 10% but it’s never gone off.

[wholybee]

Originally Posted by Simi 60

I see nothing in the instructions about setting the battery monitor for LFP, perhaps I missed it?

What I have done is....

Charge to cuttoff of LFP, near enough 100%
Set AH of victron to match BMS at that point and synchronised the victron.

Seems ok for several days but they drift apart after that.
Victron can show 80% and BMS can show 40%
I suspect it's because the LFP are still at 26.? V and the victron sees that voltage as full

Add: google is my friend.....maybe

https://battlebornbatteries.com/conf...etooth-dongle/

And

https://www.victronenergy.com/media/...id%20batteries.

You found it. The Peukert and Charging Efficiency are the critical values to change for LFP.

[s/v Jedi]

I recommend reading the manual of the BMV and program it according to the instructions in it. Take note of “charged voltage “ setting and their recommendations.

Also, enter correct values for charge efficiency, Peukert’s number etc.

It is important that the BMV resets to fully charged every time the (solar) charger finishes charging which for LFP means when the absorption voltage is reached. This is why “charged voltage “ is set a little below that.

In between these fully charged resets the BMV counts Joules going in/out of the battery. When the shunt is installed correctly (many mistakes are made with wiring to battery terminal instead of to the load side of the shunt), this Joule counter is very accurate. When the related settings in the BMV are correct then the BMV indicated SOC% is correct.

[Simi 60]

Originally Posted by s/v Jedi

I recommend reading the manual of the BMV and program it according to the instructions in it. Take note of “charged voltage “ setting and their recommendations.

Also, enter correct values for charge efficiency, Peukert’s number etc.

It is important that the BMV resets to fully charged every time the (solar) charger finishes charging which for LFP means when the absorption voltage is reached. This is why “charged voltage “ is set a little below that.

In between these fully charged resets the BMV counts Joules going in/out of the battery. When the shunt is installed correctly (many mistakes are made with wiring to battery terminal instead of to the load side of the shunt), this Joule counter is very accurate. When the related settings in the BMV are correct then the BMV indicated SOC% is correct.

Yeah, while I appreciate the effort I can't say I get that excited about it
The batts perform 100 times better than the AGM we had so I'm winning as far as I'm concerned.
I checked the settings and I had done them a year ago as per the first link above yet it's clearly not playing nice so I'm not wasting any more time.

I'll just use the BMS app, easy ( I can check the batts from the comfort of my bed in the morning) consistent and looks so pretty in comparison.

[s/v Jedi]

Originally Posted by Simi 60

Yeah, while I appreciate the effort I can't say I get that excited about it
The batts perform 100 times better than the AGM we had so I'm winning as far as I'm concerned.
I checked the settings and I had done them a year ago as per the first link above yet it's clearly not playing nice so I'm not wasting any more time.

I'll just use the BMS app, easy ( I can check the batts from the comfort of my bed in the morning) consistent and looks so pretty in comparison.

Then there is a problem with the shunt installation. All current to/from the battery must go through the shunt.

Also, you can download the VictronConnect app and enjoy all readings and settings from the comfort of your bed in the morning as well

Just for others reading this: accuracy of the Victron BMV is much higher than for most BMS systems, plus it gives a total overview of the whole bank of batteries. It is accurate to 0.01V, 0.01A, 0.1Ah and 0.1% SOC.

[sailorboy1]

I don't even feel the battery monitor settings are as important using LFP over lead acid. The charge efficiency is almost 100% and PE is so close to 1 that just counting amps is pretty close to correct. If the BM says 100% and the batteries are "only" 98% it matters little to the batteries. Unlike lead acid that did need to truly get to 100% and stay there a while.

Of course it has only been 6 weeks LFP for me and I don't have some fancy BMS that I can check. Still learning to just believe the new battery story as science over magic.

[Simi 60]

Originally Posted by s/v Jedi

.

Also, you can download the VictronConnect app and enjoy all readings and settings from the comfort of your bed in the morning as well

.

No, I can't
Victron 702 does not have bluetooth

And even if it did, if it's anything like other victron Bluetooth it'd be to weak to get a signal.
I need to be almost standing next to one of the victron chargers we have to get Bluetooth signal.

Others have similar issues
https://www.google.com/search?q=vict...obile&ie=UTF-8

[s/v Jedi]

Originally Posted by Simi 60

No, I can't
Victron 702 does not have bluetooth

And even if it did, if it's anything like other victron Bluetooth it'd be to weak to get a signal.
I need to be almost standing next to one of the victron chargers we have to get Bluetooth signal.

Others have similar issues
https://www.google.com/search?q=vict...obile&ie=UTF-8

The BT transceiver is in the display and the range is 10 meters. There used to be a weaker BT module but never for the BMV I think.

[Fuss]

Just so I have some warnings separate from the Victron main systems, I have installed some really cheap battery alarms alongside each battery. They cost 10 euros each and were really hard to program with the 2 buttons. However, once done there is a 2nd line of defence. They now give a low voltage warning beeping at 21.7v and show the voltage, capacity and also the temperature.