I've noticed the batteries aren't charging fully in the 4 hour window of Octopus - the draw from the Grid is the same, gen1 inverters, inverter power at 2.576kW.
One battery is 88%, the other 93% both from 4%.
Temperature of batteries at start 10-12 degrees C.
They've previously charged fully from 4% before - is this as a result of the cooler weather or something more sinister?
Thoughts would be appreciated.
94jdh 4 hours at 2.5kw (That'll be AC) so knock losses off that of 5% approx.
Still gives DC capability of 9.5kwh in 4 hours per inverter.
Cold does affect the SoC readings
TheDragon (GivEnergy)
I thought the cold may have an influence as it's been charging fully previously - when I have the Gen1 inverters swapped out for the gen2 versions hopefully that will counter the cold and losses.
I've set my 8.2 battery to charge at 2kW and been going from 5% to 90% no problem within the window (30 mins spare yesterday). Where I think I've seen a difference is in the discharge efficiency - it seems lower than in warmer weather. I guess this is expected. I haven't really done any proper calculations but it seems the difference between the house draw and the discharge rate is a bit bigger than before, maybe a few %. My battery is in the garage, not outdoors.
IanMac
Yes my batteries are in a separate garage at the end of the garden and have a relatively long armoured cable run so there are some expected losses but it has been coping with full charges from 4%.
What is strange is the maximum charge is dropping slightly compared to each previous day. The outside temperature may also have dropped slightly each day but I've not checked that.
@IanMac What is the reason for the reduced charging speed? What benefits are you expecting?
rio911 There's just no need for it to be higher if I can get it to charge over the 4hrs. Whether there is a benefit in terms of battery life, I don't know. Because we charge a car almost every night, defer the dishwasher and the eddi heats the hot water for 45mins off-peak (there's just not enough excess solar at the moment), I decided to trim the charge rate down. The charger we have reduces amperage if the house load is too high (we have a 100amp fuse so probably not an issue), so it might avoid that from happening.
So this morning, again from 4%, one battery is 87%(56.49 Volts), the other 90%(56.5 Volts) charged.
Batteries in separate garage and starting temperature of batteries between 11-12 degreesC.
If the temperature is going to have a significant affect on charging from empty to full in the Winter months then a Gen1 isn't going to cope with fully charging a 9.5kWh battery in a 4 hour window - on this basis, those with them mounted outside, on theory, will have an even bigger problem?
I'd be trying to get on Intelligent Octopus if I had a larger battery capacity. 6hrs of off peak solves many issues and great if you are a high milage EV driver. Problem is you can only get the tariff if you own specific cars or an Ohme Charger. Also the off peak rate is 10.5p now, and peak 42p. Pretty much 33% more expensive off peak than Go.
IanMac Go is 12p off peak
rio911 What is the reason for the reduced charging speed?
There are two benefits to minimising charge rate during a timed charge period that I can think of. One is that the cable losses will be lower since the loss is the square of the current multiplied by the resistance. Halving the charge current will reduce cable losses to a quarter of what they would have been. Not a significant loss since the cables should be sized appropriately. The other benefit is if you can set the charge rate to a value that charges the battery to your charge to % right at the end of the period, there is no mini charge/discharge cycle as the inverter holds the battery at the set level. Again, not a significant benefit.
andydsmith That's crazy it's gone up already. I only joined Go back in September and it's 7.5p for me!
IanMac It changed in October. Go Faster is still not available either which could be an issue for me later this year. Though I expect prices to go up again in April before falling July ish (maybe)