Lithium LifePo4 12v Batteries - Time For An Upgrade?

[Stay Frosty]

It would be good to have an idea in time of how long it's bad to store a lifepo4 battery when it's fully charged as in our case the solar keeps the battery full most of the warmer months.
Example was Busfest last year where the lowest we saw on the shunt display was 84% and average 98% full but I guess as soon as it's warm enough the battery could be emptied a bit much like conventionally draining down the water tank over winter.

 

[moomin-j]

It would be good to have an idea in time of how long it's bad to store a lifepo4 battery when it's fully charged as in our case the solar keeps the battery full most of the warmer months.
Example was Busfest last year where the lowest we saw on the shunt display was 84% and average 98% full but I guess as soon as it's warm enough the battery could be emptied a bit much like conventionally draining down the water tank over winter.

Even though you might not need it, perhaps it's a good idea to keep the fridge switched on 24/7 all year, when running a lithium leisure battery set up being topped up from solar?
I wonder if that would be enough draw to stop the lithium battery being at 100%?

 

[Stay Frosty]

Can't be drawing current when it's below freezing though as that's going to hurt the battery and realistically with the fridge I don't want to wear the compressor out.
If we were camping at the moment I think I'd have to rig up a heat pad for the leisure battery fed from the incoming starter battery feed via a frost stat.

 

[Bav]

Can't be drawing current when it's below freezing though as that's going to hurt the battery...

You can't charge a lithium battery when it's below freezing, but you can draw power from it (usually down to around -20C).

 

[Stay Frosty]

Fair enough but in our case we don't use our camper for camping during winter so the trade off, I guess, would be to drain off the remaining excess stored capacity on a warmer day.
Realistically a lot of this is just whittling about a non problem, come March/April normal service will be resumed although we always turn the fridge off between trips... old age thing

 

[Bav]

…we always turn the fridge off between trips... old age thing

Ditto

 

[Ayjay]

@Dellmassive @Higgidav. Cheers for your comments above in response to my earlier post #842. With the rising temperatures here in Glos, everything seems to be back to normal now BUT it didn't start to charge again until it hit 10° this afternoon (and we've been over 5° pretty much constantly since yesterday PM). In hindsight, I suspect that it might well have started to charge had I thought to switch the Victron Bluesmart off and on again some time earlier today.

 

[Drive Wayne]

Our Roamer was showing minus 2 this morning before I drove in to work (yes, on a sodding Sunday). Birmingum is a few degrees warmer than Walsallshire and it was taking a charge by the time I got there at 1 degree.
We always leave our fridge on, it's our overflow Prosecco fridge where 'if wifey can't see it' she can't be an alki can she!
I'm bad I know, but fridge is on 24/7, nothing bad has happened yet, I would hope for a few years on a new Sanjo (Dometic) fridge. It has the desired effect of pulling a bit out of the battery which is immediately put back in by driving the van and solar if the sun is out. The Roamer is usually on or close to 100% most of the time, it went down to 89% with 7 days of freezing temperatures thus no charging at all.
It does give me a great deal of satisfication running power tools/battery chargers etc in the garage from the van, I'll be so happy when we finally get solar panels on the house roof.

 

[Dellmassive]

Our Roamer was showing minus 2 this morning before I drove in to work (yes, on a sodding Sunday). Birmingum is a few degrees warmer than Walsallshire and it was taking a charge by the time I got there at 1 degree.
We always leave our fridge on, it's our overflow Prosecco fridge where 'if wifey can't see it' she can't be an alki can she!
I'm bad I know, but fridge is on 24/7, nothing bad has happened yet, I would hope for a few years on a new Sanjo (Dometic) fridge. It has the desired effect of pulling a bit out of the battery which is immediately put back in by driving the van and solar if the sun is out. The Roamer is usually on or close to 100% most of the time, it went down to 89% with 7 days of freezing temperatures thus no charging at all.
It does give me a great deal of satisfication running power tools/battery chargers etc in the garage from the van, I'll be so happy when we finally get solar panels on the house roof.

There is a sub thread for domestic and other solar stuff...

Solar Sheds & Other Non-t6 Solar Projects - How We Done It -

Solar Sheds & Other Non-T6 Solar Projects - How We Done It - @Pete C requested it, so here it is . . . . . Dell, What do the batteries in your shed power ? I too have a solar powered shed - perhaps we should have a separate thread for sheds :) Pete Lets Post here any NON - T6 related ECO...

www.t6forum.com

And also a T6F Whatsapp group for domestic solar..

 

[Ayjay]

Our Roamer was showing minus 2 this morning before I drove in to work (yes, on a sodding Sunday). Birmingum is a few degrees warmer than Walsallshire and it was taking a charge by the time I got there at 1 degree.
We always leave our fridge on, it's our overflow Prosecco fridge where 'if wifey can't see it' she can't be an alki can she!
I'm bad I know, but fridge is on 24/7, nothing bad has happened yet, I would hope for a few years on a new Sanjo (Dometic) fridge. It has the desired effect of pulling a bit out of the battery which is immediately put back in by driving the van and solar if the sun is out. The Roamer is usually on or close to 100% most of the time, it went down to 89% with 7 days of freezing temperatures thus no charging at all.
It does give me a great deal of satisfication running power tools/battery chargers etc in the garage from the van, I'll be so happy when we finally get solar panels on the house roof.

Although I said in my post that I thought the charge might have been kickstarted by switching the Victron on and off, I reckon that starting the engine (ie. switching the Ctek D250SE on and Victron off) might have had the same effect). That said, I'm kind of surprised that yours started charging on the drive into Brum when it was still only 1° as the manual as posted by @Dellmassive above indicates over 5° as the tipping point. Maybe the ambient temperature in the van was up enough but what do I know!

 

[Drive Wayne]

Although I said in my post that I thought the charge might have been kickstarted by switching the Victron on and off, I reckon that starting the engine (ie. switching the Ctek D250SE on and Victron off) might have had the same effect). That said, I'm kind of surprised that yours started charging on the drive into Brum when it was still only 1° as the manual as posted by @Dellmassive above indicates over 5° as the tipping point. Maybe the ambient temperature in the van was up enough but what do I know!

It won't play at zero, but fires up at 1 degree. I'll screen shot my settings innabit...

 

[Drive Wayne]

OK! Picture of the Roamer app this morning accepting a solar trickle at 4 degrees. It was taking a trickle yesterday at just 1 degrees.
The victron 12-12-30 and the Victron mppt 100/20 are both set to 5 degrees cut off.
Today plenty of low sun, a couple of amps going in at under 5.
Thoughts please gentlefolk?!!

 

[Drive Wayne]

OK! Picture of the Roamer app this morning accepting a solar trickle at 4 degrees. It was taking a trickle yesterday at just 1 degrees.
The victron 12-12-30 and the Victron mppt 100/20 are both set to 5 degrees cut off.
Today plenty of low sun, a couple of amps going in at under 5.
Thoughts please gentlefolk?!!

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Only solar though, nothing from the B2B, usually around 30 amps when that's online...
Normal?

 

[Ayjay]

@Drive Wayne - The key word that you used and which I hadn't picked up on in your earlier post was 'Roamer'! Mine's a Renogy and the built in management system does all the charge switching on and off on its own. I'm not qualified to comment on the 'Normal?'.

 

[Drive Wayne]

So, is Roamer clever in a brutish way or a bit dim?! There doesn't seem to be a way of setting the Roamer so it cuts out at low temps, it just does it at zero. Is that good enough?

 

[Dellmassive]

The Roamer does the same as the Renogy.

the Renogy Blocks charge below 0c and release above 5c.

Roamer show the same on the sheet: (Blocks charge below 0c and release above 5c.)

https://roamer.com/cdn/shop/files/12-230SEATBASE3_Datasheet.pdf?v=11185111990065001993

.

the settings can be seen in the Roamer BMS . . (I've not been able to get into the Renogy BMS)

 

[Dellmassive]

OK! Picture of the Roamer app this morning accepting a solar trickle at 4 degrees. It was taking a trickle yesterday at just 1 degrees.
The victron 12-12-30 and the Victron mppt 100/20 are both set to 5 degrees cut off.
Today plenty of low sun, a couple of amps going in at under 5.
Thoughts please gentlefolk?!!

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the Orion doesnt have a temp sensor - ? how did you check the 5c setting?

unless you are using a BMV712 or battery sense and broadcasting a local VE-Smart?



same with the vic MPPT, but it has a basic internal temp sensor, that it uses for SLA voltage compensation.


so neither of them have the lithium low temp blocking - unless you have the external temp sensor.







+++

3. Features

www.victronenergy.com

....

3.10.2. External temperature and voltage sensor​

The (optional) Smart Battery Sense is a wireless battery voltage and temperature sensor and can be used with the solar charger. It measures the battery temperature and the battery voltage and sends this via Bluetooth to the solar charger.

The solar charger uses the Smart Battery Sense measurements for:

• Temperature compensated charging using the actual battery temperature, rather than the solar charger's internal temperature. An accurate battery temperature measurement will improve charging efficiency and prolong the life of lead-acid batteries.
• Voltage compensation. The charge voltage is increased to compensate in case there is a voltage drop over the battery cables during high current charging.

The solar charger communicates with the Smart Battery Sense via Bluetooth using a VE.Smart Network. For more detail on the VE.Smart network see the VE.Smart Networking manual.

Alternatively, a VE.Smart Network that measures battery temperature and battery voltage, can also be set up between a solar charger and a BMV-712 Smart or SmartShunt battery monitor that has been equipped with a Temperature sensor for BMV, without the need for a Smart Battery Sense.


....

 

[Drive Wayne]

On the victron App. On both bits of kit

 

[roadtripper]

The important thing to note is the hysteresis.

Charging is blocked if temperatures drop below zero. That block is released when the temperature climbs over 5.

So it's still entirely possible to be charging at 4 or 1 degrees - just means the temperature hasn't crossed zero and been blocked.

Why is this done? It's very common in control systems as you don't want things flipping state backwards and forwards as the accuracy of a reading moves around maybe several times a minute so you tend to define it as "once a system is in state A it needs to definitely have moved far enough to be in state B"

 

[Drive Wayne]

On the victron App. On both bits of kit

View attachment 226559

I'm still clueless, why was the Roamer sucking up some sun below 5 degrees? It shouldn't should it? I do hope there are similarly dim-witted folk out there like me who are enjoying an edumacation on the essentials! Thanks @Dellmassive