On-grid domestic battery storage

Alnat1

In the very coldest days last December my battery discharged down to my set minimum of 10% by 8-9pm and I would revert to grid electricity. By 7-8am the battery had dropped to 8 or 9%, I am guessing because it was pretty cold in the garage.

It only happened on the very coldest nights when the temperature in there was under 9C. I don't know if the rate of charge/discharge was affected. I would normally have topped up overnight but was on Agile at the time and prices weren't dropping below my 33p cap, so no point.

Grandad2b

I wonder where the sweet spot for temperature is. If the battery is in an insulated box is it worth running some kind of trace heating (heat pump, perhaps)?
Maybe even something like a reptile heat pad at about 20W would be effective (20W x 24h = 480Wh).

orrery

Grandad2b said:

I wonder where the sweet spot for temperature is. If the battery is in an insulated box is it worth running some kind of trace heating (heat pump, perhaps)?
Maybe even something like a reptile heat pad at about 20W would be effective (20W x 24h = 480Wh).

How about the high temperatures in summer? I put mine in the garage because the temperature range in there is quite limited - it never goes below zero and it stay pretty cool in the summer.

1961Nick

My battery is located in the garage & during winter it's never in standby so the temperature sits around 15C - 25C. Last night with an ambient of 3C the battery didn't drop below 16C & it had 5 hours in standby during the Intelligent off peak window.

Grandad2b

orrery said:

Grandad2b said:

I wonder where the sweet spot for temperature is. If the battery is in an insulated box is it worth running some kind of trace heating (heat pump, perhaps)?
Maybe even something like a reptile heat pad at about 20W would be effective (20W x 24h = 480Wh).

How about the high temperatures in summer? I put mine in the garage because the temperature range in there is quite limited - it never goes below zero and it stay pretty cool in the summer.

The high temperature in summer wouldn't be a problem for me but I can see it might be for some. I read somewhere that capacity changes by about 10% for a 10˚ temperature change. Don't remember now if that was ˚C or ˚F. The bigger issue for me is the fact that many lithium batteries won't accept charge below 0˚C and some BMS limit charge and discharge below 5˚ so you'd want to keep your battery above that.

1961Nick said:

My battery is located in the garage & during winter it's never in standby so the temperature sits around 15C - 25C. Last night with an ambient of 3C the battery didn't drop below 16C & it had 5 hours in standby during the Intelligent off peak window.

That's reassuring.

zeupater

Grandad2b said:

orrery said:

Grandad2b said:

I wonder where the sweet spot for temperature is. If the battery is in an insulated box is it worth running some kind of trace heating (heat pump, perhaps)?
Maybe even something like a reptile heat pad at about 20W would be effective (20W x 24h = 480Wh).

How about the high temperatures in summer? I put mine in the garage because the temperature range in there is quite limited - it never goes below zero and it stay pretty cool in the summer.

The high temperature in summer wouldn't be a problem for me but I can see it might be for some. I read somewhere that capacity changes by about 10% for a 10˚ temperature change. Don't remember now if that was ˚C or ˚F. The bigger issue for me is the fact that many lithium batteries won't accept charge below 0˚C and some BMS limit charge and discharge below 5˚ so you'd want to keep your battery above that.

1961Nick said:

My battery is located in the garage & during winter it's never in standby so the temperature sits around 15C - 25C. Last night with an ambient of 3C the battery didn't drop below 16C & it had 5 hours in standby during the Intelligent off peak window.

That's reassuring.

Hi

That really depends on how you weigh performance against cycle life .... yes the charging rate has a sweet spot somewhere around 30C, but that is really related to rapid charge on EVs or very low storage capacity ESS setups with relatively high capacity charging equipment.
If you have a decent ESS setup then you've paid a considerable amount for it and will be looking to use it for a considerable time to get the best return on your investment .... Wouldn't temperature therefore be considered to be a problem in the summer if it's actually going to cost actual money & wreck any payback calculations?
HTH -Z

Grandad2b

Ok, I need a little more information How does high temperature (how high?) affect capacity? Is this effect permanent or just while subjected to the higher temperature? Are all chemistries similarly affected?

zeupater said: ...very low storage capacity ESS setups with relatively high capacity charging equipment.

Some numbers would be helpful. Are you talking about C/2 or lower?

As yet I don't have a battery (is that what you call ESS?) so this is all going to be considered before any purchase decision.

1961Nick

Grandad2b said:

Ok, I need a little more information How does high temperature (how high?) affect capacity? Is this effect permanent or just while subjected to the higher temperature? Are all chemistries similarly affected?

zeupater said: ...very low storage capacity ESS setups with relatively high capacity charging equipment.

Some numbers would be helpful. Are you talking about C/2 or lower?

As yet I don't have a battery (is that what you call ESS?) so this is all going to be considered before any purchase decision.

The operating range for pylontech batteries is;

0C~50C Charge
-10C~50C Discharge

Whereabouts are you going to put the batteries? 

mickyduck55

My batteries are in my garage which gets very cold in winter.. In the very low temps experienced last winter the rate at which the batteries charged was lower than when they are "warmer".  On rare occasions they would not fully charge during my TOU period.

1961Nick

I've downloaded the data for one of the coldest days last December with an overnight low of -6C to see exactly what happened to the battery temperature during the day. The temperature in the garage was around zero or below because the frost stat periodically fired up the boiler during the night.

00.00 - 05.30 Charge 11C -16C
05.30 - 23.30 Discharge 16C - 11C
23.30 - 00.00 Charge 11C - 12C

The overnight charge was 17.64kWh which was at the top end of a fairly narrow range.

I've also found the figures for 19/07/22 when ambient temperature reached 38C. Surprisingly the battery temperature only ranged between 29C & 34C & spent most of the day at 33C.