Help Power suddenly depleted

Stretch60 · Senior Member

Help Power suddenly depleted

Ivan 01 · Guru

I am not an expert on solar but with the 10.5 volts in the battery before setting off it may have been too low of a voltage to activate your DC to DC charger while driving.
I guess if you were anywhere in nsw or Qld yesterday there was not a lot available over the day from Solar.
It may have been later in the day before the batteries got up to a point where the Dc to Dc kicked in.
I am sure others will have much better explanations as I am only learning this new technology on solar.

-- Edited by Ivan 01 on Wednesday 6th of July 2022 09:44:21 AM

dorian · Guru

I don't have much practical experience with these setups, either, but I would have expected that your Victron controller would have been configured to disconnect the battery before its state of charge dropped too low. In any case, a voltage of 10.5V would be near flat.

https://footprinthero.com/lifepo4-battery-voltage-charts

kgarnett · Senior Member

What type of fridge do you have ie is it a compressor fridge Was your inverter switched totally off when you went to bed?

At 12.5V you probably only had maybe less than 40Ah of capacity left and any load could easily further deplete the battery to the extent that the BMS may shut it down.

Ken

-- Edited by kgarnett on Wednesday 6th of July 2022 01:22:09 PM

Mike Harding · Guru

I know next to nothing about lithium batteries so this is little more than a guess but I suspect you totally drained the batteries and the battery management system (BMS) which is an integral part of lithium batteries has switched the battery completely out of circuit to prevent damage and the 2V you are reading is simply MOSFET leakage current seen by your DMM.

I suggest you either find a 240V supply and connect to it or ensure your solar is seeing plenty of sun and see what happens after a few hours.

It may be that once the BMS has gone into this mode it requires a specific procedure to exit it and charge the battery - the manual for the batteries and/or BMS should make all this clear.

Keep us posted please.

Are We Lost · Guru

As kgarnett asked, what fridge do you have? A compressor fridge only draws a few amps but the typical 3 way fridge draws a lot of power on 12v. I also agree with what Mike was saying about the BMS in lithium batteries. There are electronics inside the batteries designed to disconnect them when voltage gets too low.

Once the BMS has switched it off, the charger may not work. Maybe your Victron charger is designed for this, but many won't start charging. So if it won't charge check your manual. Also, is there an app to connect to your battery.. usually via bluetooth? Maybe there is accessible information that will help.

-- Edited by Are We Lost on Wednesday 6th of July 2022 02:01:37 PM

Whenarewethere · Guru

Have a look at the Victron community, I'm sure sticking in a range of key words you should be able to solve you Victron issue.

https://community.victronenergy.com/questions/5003/best-way-to-charge-multiple-lithium-batteries.html

Whenarewethere · Guru

A lot of handy data here:

https://www.victronenergy.com/support-and-downloads/technical-information

The energy unlimited book & The wiring unlimited book.

Ivan 01 · Guru

Whenarewethere wrote:
A lot of handy data here:

https://www.victronenergy.com/support-and-downloads/technical-information

The energy unlimited book & The wiring unlimited book.

Thank you for that link WAWT.

It looks like a great resource.

Stretch60 · Senior Member

Thanks guys, went fishing today hence late reply. Currently at eighty mile beach heaps of sun, although low in the sky but my panels got a good deal of sun and put in 900watt hours and batteries came up to 13.09 volts. And I agree with the fact about the BMS in the batteries. I think it may have been the inverter left on? Fridge is 12v compressor and yes only draws a few amps. I did check the anderson plug and found no power to van. Repaired that and the dcdc worked fine. We have 700ks tomorrow so will see what the sun and car can put in. 240v will not be available until Kununurra Friday night. Will keep you posted.
No did not catch a fish.

Stretch60 · Senior Member

The system also has a victron smart shunt which I thought would tell me the amperage use. I will go to the community and pick some brains. Thankyou all.

TimTim · Guru

At 10.5 volts your BMS has automatically shut down to protect the battery, or one cell may have hit low voltage, and yes leaving the inverter on may have caused this especially if you have a large inverter. So your BMS did exactly as it was supposed to do. Luckily your BMS has an automatic reset from low voltage as some require a manual jump start just like jumping a car battery. Others have a reset button.

Also were you running your fridge on gas or off the batteries?

At 12.5v you had approximately 14% of capacity left or 56Ah. You need to remember though that because the charge and discharge curve of LifePO4 is so flat and then climbs or drops off very sharply it is very difficult to determine the SOC of your battery using voltage, although you can get an approximate figure. At 12.5v for lithium which is about 14% SOC, it is nothing like the 12.5v for AGM which is approximately 80% SOC.

At 13.09v, from the charge curve that would approximate to about 39% of capacity so 156Ah. Charts and discussions about SOC are here https://diysolarforum.com/threads/lifepo4-voltage-chart.3156/

The accuracy of a shunt can creep over time especially if you do not fully recharge your batteries. However, when you do fully recharge the shunt will or can be set automatically reset the SOC to 100%.

I do have a Victron shunt but at the moment it is sitting on a shelf crying out to be connected but that wont happen for a few months yet.

These videos may help you.

www.youtube.com/watch

www.youtube.com/watch

Hope this all helps.

By the way 400Ah of LifePO4 is a nice size battery smile

-- Edited by TimTim on Thursday 7th of July 2022 12:23:41 AM

-- Edited by TimTim on Thursday 7th of July 2022 10:08:19 AM

TimTim · Guru

Oh I forgot to mention, Mike is correct that the less than 2v is from the BMS.

The way that the BMS is connected, when it switches off you do not get a voltage reading of the actual battery through the battery terminals, so dont be concerned with that exceptionally low voltage reading. When things go wrong with a lithium battery in 99% of cases it will be the BMS and not the cells. In your case nothing has gone wrong and the BMS has just done as it was intended. At least you know that it works.

Now how do you catch fish? smile

-- Edited by TimTim on Thursday 7th of July 2022 10:00:12 AM

Ivan 01 · Guru

It appears that Stretch is on the right track which is good.

This is a great topic for solar info. It is giving me loads of info to study.

Thanks

TimTim · Guru

Yep he doesn't have any real issues except running his batteries down biggrin .

Oh....and not catching fish confuse

Stretch60 · Senior Member

Haha, turned the corner and heading to kununurra and then onto Darwin to hookup on some barra!!

Did I forget to mention it wS 400ah of batteries? Linked in series/ parallel so thought it would be good for a few days? Yes I know one is parallel and other is series can't ever remember one from other. 4 x 100ah wired together for 12v x 400ah. Smart shunt may not be wired correctly as it doesn't show ah used or time remaining.

Stretch60 · Senior Member

Oh and fridge runs 12v only.

Mike Harding · Guru

Glad to hear all is back on track for you :)

But keep in mind even 400Ah of battery is not infinite - energy in *must* be greater than energy out.

TimTim · Guru

Looks like your shunt is wired backwards as your output should have a negative value.

https://community.victronenergy.com/questions/13235/bmv-712-not-showing-consumed-ah.html

Sorry it wouldn't let me insert the link.

Ok looking at your SOC it is saying 100% but your battery voltage is indicating 12.97v which is approximately just under 40% from my calculation. You will need to ignore the SOC until your battery has been fully charged and work on the voltage to get an approximate of the remaining capacity.

Ok I see you have a DC/DC charger, if you have been traveling some distance your battery would of been at full voltage. Seems to me something is not right.

-- Edited by TimTim on Thursday 7th of July 2022 09:08:25 PM

Are We Lost · Guru

TimTim wrote:
<snip>
https://community.victronenergy.com/questions/13235/bmv-712-not-showing-consumed-ah.html
Sorry it wouldn't let me insert the link.
<snip>

To insert a link, make sure you are in the Advanced Editor.

Type a description that describes the link (my example below). Then highlight that text and click the chain (link) icon in the menu.

In the popup panel, paste the URL for your link, then in the Target cell choose "Open link in a new window". Insert.

Victron Help - Not showing consumed AH

TimTim · Guru

Are We Lost wrote:
TimTim wrote:
<snip>
https://community.victronenergy.com/questions/13235/bmv-712-not-showing-consumed-ah.html
Sorry it wouldn't let me insert the link.
<snip>

To insert a link, make sure you are in the Advanced Editor.
Type a description that describes the link (my example below). Then highlight that text and click the chain (link) icon in the menu.
In the popup panel, paste the URL for your link, then in the Target cell choose "Open link in a new window". Insert.
Victron Help - Not showing consumed AH

Hi Are We Lost, thank you. Im smiling here because Im in Advanced editor and many of the icons are greyed out. It seems to come and go. Maybe if I log out and log back in that will work.

Stretch60 · Senior Member

Thankyou all, yep makes sense will check it out when we get to Darwin. Good run today and good charge. Now on 240v and going well. In Kununurra and nice and warm.

Stretch60 · Senior Member

Update for those who assisted, had 240v up until now so batteries went into float nicely charged. At Willare Bridge heading back to 80 mile beach. Unpowered site so using batteries. Couple of lights, water pump for shower, hour or so of telly and fridge running. Voltage has remained stable. Unable to measure amps used as I have not addressed the shunt wiring yet. So 4.5 hour drive to 80 mile some solar and batteries should be good. Obviously system is working as it should, just the hiccup with the accidental discharge.

TimTim · Guru

Great to hear. Dont forget your shunt wiring smile .

https://community.victronenergy.com/questions/13235/bmv-712-not-showing-consumed-ah.html

-- Edited by TimTim on Monday 18th of July 2022 04:48:56 PM

Dick0 · Guru

Stretch60 wrote:
Update for those who assisted, had 240v up until now so batteries went into float nicely charged. At Willare Bridge heading back to 80 mile beach. Unpowered site so using batteries. Couple of lights, water pump for shower, hour or so of telly and fridge running. Voltage has remained stable. Unable to measure amps used as I have not addressed the shunt wiring yet. So 4.5 hour drive to 80 mile some solar and batteries should be good. Obviously system is working as it should, just the hiccup with the accidental discharge.

Also, with Lithium batteries, you need to charge each battery individually if they have been depleted until each battery is within .5V of each other. THEN connect all batteries back in parallel. It is to do with the BMS management between the batteries.

Jaahn · Guru

Dick0 wrote:
Stretch60 wrote:
Update for those who assisted, had 240v up until now so batteries went into float nicely charged. At Willare Bridge heading back to 80 mile beach. Unpowered site so using batteries. Couple of lights, water pump for shower, hour or so of telly and fridge running. Voltage has remained stable. Unable to measure amps used as I have not addressed the shunt wiring yet. So 4.5 hour drive to 80 mile some solar and batteries should be good. Obviously system is working as it should, just the hiccup with the accidental discharge.
Also, with Lithium batteries, you need to charge each battery individually if they have been depleted until each battery is within .5V of each other. THEN connect all batteries back in parallel. It is to do with the BMS management between the batteries.

Hi smile

I am uncertain if that statement refers to a couple of parallel battery sets or the individual cells in a battery ??

I understood that a quality BMS would control the cell equalisations as it charged and finished it off when it reached full voltage. Which is why you should charge to a sufficient voltage high enough for that to happen. Is that correct. aww

Or do the cheap drop-in batteries have BMS that are sub standard, too small or incapable of doing the cell balancing in difficult situations. It has been said some of them actually have lots of small cells instead of 4 big cells. We are all trying to learn the new technology and the good and bad technology for sale. hmm

Jaahn

Dick0 · Guru

Jaahn wrote:
Dick0 wrote:
Stretch60 wrote:
Update for those who assisted, had 240v up until now so batteries went into float nicely charged. At Willare Bridge heading back to 80 mile beach. Unpowered site so using batteries. Couple of lights, water pump for shower, hour or so of telly and fridge running. Voltage has remained stable. Unable to measure amps used as I have not addressed the shunt wiring yet. So 4.5 hour drive to 80 mile some solar and batteries should be good. Obviously system is working as it should, just the hiccup with the accidental discharge.
Also, with Lithium batteries, you need to charge each battery individually if they have been depleted until each battery is within .5V of each other. THEN connect all batteries back in parallel. It is to do with the BMS management between the batteries.
Hi
I am uncertain if that statement refers to a couple of parallel battery sets or the individual cells in a battery ??
I understood that a quality BMS would control the cell equalisations as it charged and finished it off when it reached full voltage. Which is why you should charge to a sufficient voltage high enough for that to happen. Is that correct.
Or do the cheap drop-in batteries have BMS that are sub standard, too small or incapable of doing the cell balancing in difficult situations. It has been said some of them actually have lots of small cells instead of 4 big cells. We are all trying to learn the new technology and the good and bad technology for sale.
Jaahn

Hi Jaahn,

Not the type of cells which matters and not the cost of batteries that matters. The battery manufacturer will provide advice whether their batteries require a voltage equalisation of within .05V prior to several battery connection to allow and assist each BMS to sense across all batteries and maintain an even charge. I see this type of recommendation of many brands of batteries. This was brought to my attention when I researched lithium batteries prior to installation. Yes, there are differences in quality of BMS types that are suitable/unsuitable in connecting multiple batteries. The spec data sheets will reference the correct connection and charging procedures.

Stretch60 · Senior Member

Battery manufacture supplied literature states up to 4 batteries and all will work with internal BMS. Same batteries as Dicko.