Adding batteries to existing solar system

Coastalwatch

Our installation was only completed on Wednesday. A discharge and charge cycle was required and eventually completed overnight.

Unsure if a full charge was achieved as on waking next morning the battery was showing just 69% and subsequently discharged by teatime. The next day the charge lasted through to 21.30,  included below is a graph showing the days consumption.

Not totally convinced it's reached full charge, for the first three hours it appeared to be drawing barely 2 kW as the graph shows when the inverter is capable of delivering three! Otherwise it seems to show the battery performing as it should do.

The Givenergy App plainly shows which direction energy is flowing between the house and grid, battery and PV array so easy to follow, but it's early days as yet and lots still to understand.

Hope the above is helpful if not in anyway conclusive!

mickyduck55

My plylontech batteries do not charge at the full capacity of the inverter.. I found last year when we had a much colder winter that the freezing temperatures in my garage where the batteries are housed reduced the charge rate significantly.  I also have the charge rate set to 80% .. supposedly the slower charge rate is "better for them",  TBH I dont know but they still get a full charge overnight.

QrizB

mickyduck55 said:

... the freezing temperatures in my garage where the batteries are housed reduced the charge rate significantly.

It's generally advised that you should never charge lithium iron phosphate (LiFePO4) batteries of they are below freezing,as it's saod to damage them permanently.

LiFePO4 batteries intended for cold weather use are often equipped with electric heaters to reduce the risk of this happening.

JKenH

QrizB said:

mickyduck55 said:

... the freezing temperatures in my garage where the batteries are housed reduced the charge rate significantly.

It's generally advised that you should never charge lithium iron phosphate (LiFePO4) batteries of they are below freezing,as it's saod to damage them permanently.

LiFePO4 batteries intended for cold weather use are often equipped with electric heaters to reduce the risk of this happening.

Presumably if you shouldn’t charge them below freezing then you shouldn’t discharge them below freezing either. (Although off topic does this mean that if you jump into a car on a freezing cold day you have to precondition the battery before using it? Incidentally how would this work with charging an EV on a timer, say, to take advantage of Octopus Go when it is freezing?)

JKenH

JKenH said:

QrizB said:

mickyduck55 said:

... the freezing temperatures in my garage where the batteries are housed reduced the charge rate significantly.

It's generally advised that you should never charge lithium iron phosphate (LiFePO4) batteries of they are below freezing,as it's saod to damage them permanently.

LiFePO4 batteries intended for cold weather use are often equipped with electric heaters to reduce the risk of this happening.

Presumably if you shouldn’t charge them below freezing then you shouldn’t discharge them below freezing either. (Although off topic does this mean that if you jump into a car on a freezing cold day you have to precondition the battery before using it? Incidentally how would this work with charging an EV on a timer, say, to take advantage of Octopus Go when it is freezing?)

I’ve copied this question to the BEV thread to keep this one on track.

Coastalwatch

mickyduck55 said:

My plylontech batteries do not charge at the full capacity of the inverter.. I found last year when we had a much colder winter that the freezing temperatures in my garage where the batteries are housed reduced the charge rate significantly.  I also have the charge rate set to 80% .. supposedly the slower charge rate is "better for them",  TBH I dont know but they still get a full charge overnight.

Thanks MD, that's useful to learn, so something else for me to wrestle with. Guess we are all on a bit of a learning curve. Our batts are in the garage also but it is attached with only the door and roof exposed to the elements. There is no heat within but may not get quite as cold as a stand alone one might. Maybe I need to think about insulating the door and also the roof in order to maintain a consistent temperature!

 In fact I've just realised a schoolboy error on my part! On the graph I posted, the units along the bottom were half hour while vertical column was kWh, so not kW as I was reading it as. Thus the 2kWh's mentioned in previous thread were in fact a 4kW delivery!

QrizB

JKenH said:

QrizB said:

mickyduck55 said:

... the freezing temperatures in my garage where the batteries are housed reduced the charge rate significantly.

It's generally advised that you should never charge lithium iron phosphate (LiFePO4) batteries of they are below freezing,as it's saod to damage them permanently.

LiFePO4 batteries intended for cold weather use are often equipped with electric heaters to reduce the risk of this happening.

Presumably if you shouldn’t charge them below freezing then you shouldn’t discharge them below freezing either. (Although off topic does this mean that if you jump into a car on a freezing cold day you have to precondition the battery before using it? Incidentally how would this work with charging an EV on a timer, say, to take advantage of Octopus Go when it is freezing?)

Discharging below zero C is meant to be OK. My only LFP batteries are inside my house and if it's below freezing there I have other problems so it's not something I've studied.

I wonder what the Pylontech user instructions say about temperature.

I haven't given much thought to what this means for people who don't charge at home and who might arrive home with an almost-flat battery on a cold night, then intend to drive to a charger in the morning. I *guess* the car might be smart enough to spend the first few minutes on the charrger warming the battery, before trying to charge it?

This will be more of an issue in Canada, Norway etc. than the UK.

QrizB

QrizB said:

I wonder what the Pylontech user instructions say about temperature.

Quoting myself, sorry about that.

From page 5 of https://enertik.cl/manuales/pylontech/manual_pylontech_us3000c.pdf

Working temperature: 0-50 deg. C charge, -10-50 deg. C discharge.

mickyduck55

QrizB said:

mickyduck55 said:

... the freezing temperatures in my garage where the batteries are housed reduced the charge rate significantly.

It's generally advised that you should never charge lithium iron phosphate (LiFePO4) batteries of they are below freezing,as it's saod to damage them permanently.

LiFePO4 batteries intended for cold weather use are often equipped with electric heaters to reduce the risk of this happening.

Hi my garage is not usually below freezing it is attached to my house but is significantly colder than inside.  My sons batteries that are inside charge at a much higher rate than mine.. typically if it is cold they start of with a low charge rate and it ramps up over the charging period.  I guess this is the BMS doing its job of protecting them from harm...

mickyduck55

Coastalwatch said:

mickyduck55 said:

My plylontech batteries do not charge at the full capacity of the inverter.. I found last year when we had a much colder winter that the freezing temperatures in my garage where the batteries are housed reduced the charge rate significantly.  I also have the charge rate set to 80% .. supposedly the slower charge rate is "better for them",  TBH I dont know but they still get a full charge overnight.

Thanks MD, that's useful to learn, so something else for me to wrestle with. Guess we are all on a bit of a learning curve. Our batts are in the garage also but it is attached with only the door and roof exposed to the elements. There is no heat within but may not get quite as cold as a stand alone one might. Maybe I need to think about insulating the door and also the roof in order to maintain a consistent temperature!

 In fact I've just realised a schoolboy error on my part! On the graph I posted, the units along the bottom were half hour while vertical column was kWh, so not kW as I was reading it as. Thus the 2kWh's mentioned in previous thread were in fact a 4kW delivery!

There was quite a bit of chat about this last winter.. the recommended solution was to put some insulation round the batteries..