Investigating Lithium battery generators

[Benjahmin]

A 40w panel is never going to be enough for somthing drawing greater energy then it can supply.

Well - yes. What I hadn't realised was that the cooler (which was a new purchase) does not turn on and off, like a fridge, so the panel never stood a chance.
This is the point of the whole exercise, to become more conversant with the realities of consumption and generation capabilities.

 

[WheezyRider]

For quite a few months I have been running a 180W panel, a 12V 40Ah LiFePO4 battery (so about 500Wh). With that I run a small 15litre compressor 50W 12V camping fridge, lighting and on sunny days, recharge the bike.

This has worked quite well, the biggest problem is the battery size. On sunny days, it gets full way too quickly, so I miss out on a lot of energy I could be using on cloudy days. Recently I have upgraded to a 400W panel, but the bottleneck remains the battery.

I am not sure about running freezers to store food. I think looking at alternatives for preservation like pickling might be better in some cases. I don't use a freezer myself. I feel it's like having a direct debit bleeding money out of your bank account all the time. Buy veg fresh and use it within a day or two. Cut down on meat. If you need stuff in reserve, buy tinned food.

I have found I can get by on about 1 to 2 kWh/day for the entire house. The biggest energy costs for electricity are boiling the kettle, cooking and running the washing machine. I cook once every 3 days and then use the microwave to warm stuff up. I put the washing machine on every 2 or 3 days. Harder to use solar for these as the wattages are so high you need a big inverter and battery. But I have plans...

 

[Benjahmin]

Thing is, when you grow veg, you get gluts, beyond ones ability to consume them, at various times. I make sauerkraut which is a great probiotic, but salting beans is a bit too - well salty to be healthy. So blanch and freeze is the way to go. SWMBO makes passata and the like when tomatoes a plentiful, this also gets frozen. Every November I take a lamb from a local small time farmer. He produces mainly for himself but has a few butchered for favoured folk. This also goes in the freezer (still have a couple of joints from last year).
I do keep around 3 months or so of food in store. This is a mixture of cans (no vitamins in them) and dry goods like rice, beans and pasta. I also keep a red cross approved small water filter capable of giving small amounts of potable water from surface water.
Am I a prepper? No, but it does no harm to have a self reliant mentality.
So the investigation into these generators is meant to help smooth over expected power outages (to keep food viable) rather than seeking an off grid capability. As desirable as that might be I don't have the land or resources for such an endeavour. So I'm seeking the best compromise I can.

 

[jonathan.agnew]

One needs the battery storage to run some off grid so a 6000kwh battery should cope with a few days bleak weather, all about doing the sums to see what may work and how many panels to keep said battery ticking over at above 60% imv.

A 40w panel is never going to be enough for somthing drawing greater energy then it can supply.

My house lays East /West aspect, from research I have done laying panels back to back on E- W orientation is more effiecient and produce more energy then a pure southerly aspect. Also the research says for this type of array the most effiecient angle is 10 degrees.
I have 6m x 3m garage roof I could easily lay a couple of 24v 400w panels to charge a battery set up just for garage use.

I hoping my house roof is going to be tyveked ,re- battened and new pointing done next year so I can't think of using any solar on the house roof until this work is done.

How much do you think a 6kwh battery will be? A powerwall is I think approximately 10kwh for around £10k

 

[Zlatan]

How much do you think a 6kwh battery will be? A powerwall is I think approximately 10kwh for around £10k

My supplier quoted £1500 per 3.2kwh...if bought with panels. (ie a system). If bought in isolation Vat would be added. (apparently one of Sunak's wiser decisions was stopping Vat on panels. Some installers are at moment interpteting that as panel systems, so it's worth looking around. (and probably buying a panel to lose the Vat??)
I, ve given up on panels in isolation tho, pricing heat pump and comparing with investing with Ripple (the e company not Cadburies). They are letting folk invest in Windfarms (minimum £6k).They offset the windfarms generation against your usage, but as yet don't know intricacies.. And like most things.. The devil is in the detail.
My grandad always insisted... If you don't know what to do do nowt. Which is great advice for some situations but can think of quite a few where had I done nowt I, d be long gone..
But £10k for 10kwh sounds very expensive.
I had big discussion with solar "expert" on this very issue. My camper an has almost exactly a 1kwh battery. (90ah @12v) and they cost £109 for a pair.Still think for static uses lead acid is fine.(my van is almost static) Solar companies are selling everyone lithium because sticking lead acids in loft might put stress on beams??
Personally can't see point in Lithium when you can buy lead acid @ around £80 per kwh. Especially at price you, ve been quoted.. That's £1k per kwh.. (about price of ebike batteries)???

My mate installs back up power systems for hospitals, banks, call centres and the likes who must have instant back up perfectly stable.. The switch over time is nano seconds.. He installs banks of hundreds of lead acids.. (think biggest he did was 280 lead acid, deep cycle, apparently they limk them to give 400v between - and + and 240 between central point and either terminal. (couldn't understand how?) but point is in this static application they would never use Lithium but every solar panel system supplier in country insists Lithium is way to go.. Think its called profit. What do they want to sell us. £1k of lead acid or £10k of lithium?? I wonder.

 

[guerney]

Thing is, when you grow veg, you get gluts, beyond ones ability to consume them, at various times. I make sauerkraut which is a great probiotic, but salting beans is a bit too - well salty to be healthy. So blanch and freeze is the way to go. SWMBO makes passata and the like when tomatoes a plentiful, this also gets frozen.

I've taken to reducing the volume of my frozen produce by using a electric centrifugal juicer (I'd use the masticating type, but can't afford the dental plan), and reducing in a pan. After freezing in little bags, simply defrost, add water, herbs and whatever to make delicious soups or sauces. I still have concentrated frozen pumpkin juice from last year. Reducing volume could reduce the number of freezers used and power requirements, but juicers do discard much probiotic friendly fiber.



These tomatoes were reduced over 8 hours and stick-blended, and further reduced. Then they taste a lot like those expensive jars of sun-dried tomato paste.

 

[guerney]

Am I a prepper? No, but it does no harm to have a self reliant mentality.

I may have become a prepper - I still have masses of beans from the start of the pandemic. Lately I've been sprouting then more often, to increase their nutritional content, reduce anti-nutrients, use as veg replacements, and in order to use it all up. Pictured are minced brown sprouted chickpeas, using a hand canked mincer (meat grinder). Cooked, it tastes delicious... like some sort of nut actually. I cook sprouted beans, because of ecoli fears. They're much easier to chew like this, I have not a lot of teeth left!

 

[Zlatan]

I may have become a prepper - I still have masses of beans from the start of the pandemic. Lately I've been sprouting then more often, to increase their nutritional content, reduce anti-nutrients, use as veg replacements, and in order to use it all up. Pictured are minced brown sprouted chickpeas, using a hand canked mincer (meat grinder). Cooked, it tastes delicious... like some sort of nut actually. I cook sprouted beans, because of ecoli fears. They're much easier to chew like this, I have not a lot of teeth left!

View attachment 48810

There must be a use to put all that methane to.. I, m sure some ICE could power a alternator running on it..??? (It's a joke Guerney but my emojis don't show up on here)
Seems CNG is methane.. On a winner Guerney. Eat the sprouts /sprouted beans, collect the methane (twice) and stick with the Minor 1000. (I loved mine)

 

[guerney]

There must be a use to put all that methane to.. I, m sure some ICE could power a alternator running on it..??? (It's a joke Guerney but my emojis don't show up on here)
Seems CNG is methane.. On a winner Guerney. Eat the sprouts /sprouted beans, collect the methane (twice) and stick with the Minor 1000. (I loved mine)

The back-ignition via the hose sticking out of my ar*se sounds risky. Disappointingly, beans are less farty when sprouted and cooked.

 

[WheezyRider]

My supplier quoted £1500 per 3.2kwh...if bought with panels. (ie a system). If bought in isolation Vat would be added. (apparently one of Sunak's wiser decisions was stopping Vat on panels. Some installers are at moment interpteting that as panel systems, so it's worth looking around. (and probably buying a panel to lose the Vat??)
I, ve given up on panels in isolation tho, pricing heat pump and comparing with investing with Ripple (the e company not Cadburies). They are letting folk invest in Windfarms (minimum £6k).They offset the windfarms generation against your usage, but as yet don't know intricacies.. And like most things.. The devil is in the detail.
My grandad always insisted... If you don't know what to do do nowt. Which is great advice for some situations but can think of quite a few where had I done nowt I, d be long gone..
But £10k for 10kwh sounds very expensive.
I had big discussion with solar "expert" on this very issue. My camper an has almost exactly a 1kwh battery. (90ah @12v) and they cost £109 for a pair.Still think for static uses lead acid is fine.(my van is almost static) Solar companies are selling everyone lithium because sticking lead acids in loft might put stress on beams??
Personally can't see point in Lithium when you can buy lead acid @ around £80 per kwh. Especially at price you, ve been quoted.. That's £1k per kwh.. (about price of ebike batteries)???

My mate installs back up power systems for hospitals, banks, call centres and the likes who must have instant back up perfectly stable.. The switch over time is nano seconds.. He installs banks of hundreds of lead acids.. (think biggest he did was 280 lead acid, deep cycle, apparently they limk them to give 400v between - and + and 240 between central point and either terminal. (couldn't understand how?) but point is in this static application they would never use Lithium but every solar panel system supplier in country insists Lithium is way to go.. Think its called profit. What do they want to sell us. £1k of lead acid or £10k of lithium?? I wonder.

The problem with lead acid is cycle life. Even for deep cycle batteries, this is not great. Most of the deep cycle batteries/leisure batteries you can buy for solar stand alone systems are only able to give about 300 cycles and that is at only 50% depth of discharge (DoD). In a back up situation (eg in a hospital) where you expect very few cycles (how often do long power cuts occur? Not that often), lead acid will be fine and last years.

However, if you have a solar stand alone system, LiFePO4 batteries will give typically 3000 cycles at 80% DoD. Only use to 50% and cycle life can be double that.

A 100 Ah lead acid leisure battery is likely to be about £100 or so (but you can only really use 50% of that capacity if you want 300 cycles). A 100 Ah LiFePO4 battery will cost about £350. So, more expensive, but not that much more considering the longer cycle life and that can be 80% DoD rather than 50%.

 

[Zlatan]

The problem with lead acid is cycle life. Even for deep cycle batteries, this is not great. Most of the deep cycle batteries/leisure batteries you can buy for solar stand alone systems are only able to give about 300 cycles and that is at only 50% depth of discharge (DoD). In a back up situation (eg in a hospital) where you expect very few cycles (how often do long power cuts occur? Not that often), lead acid will be fine and last years.

However, if you have a solar stand alone system, LiFePO4 batteries will give typically 3000 cycles at 80% DoD. Only use to 50% and cycle life can be double that.

A 100 Ah lead acid leisure battery is likely to be about £100 or so (but you can only really use 50% of that capacity if you want 300 cycles). A 100 Ah LiFePO4 battery will cost about £350. So, more expensive, but not that much more considering the longer cycle life and that can be 80% DoD rather than 50%.

I agree about cycle life but suspect the discharge argument is thrown in by Lithium battery retailers.
All batteries are rated under similar legistlation/rationale. The most popular obviously being ah(converted to wh to comparer differing voltages) . Batteries are checked over 10 hour cycle to full discharge / terminal voltage. A 200 ah (lead acid or Lithium) battery must be able to supply 20a per hour for the 10 hours,if not it does not receive the 200ah rating.
A 100 ah battery is a 100 ah battery. It wouldn't get that rating if it went flat after only supplying 50% of the rationg. If so, it makes a mockery of ratings.
And Lithium are prone to destroying themselves rather more frequently if not charged/looked after carefully. (Had 2 bosch pedelecs batteries that cried off, refused charge at under 2 years old)

The cycle argument is much less valid if deep cycle (thicker plated) lead acid are utilised and provision is made to ensure correct charging post full discharge. (done via intelligent charging, battery conditioning)
The 90ah deep cycle lead acid on my camper van cost £59.99 13 years ago. Van has intelligent charging system (including a conditioner, which over charges to clean plates occasionally) and battery still runs fridge for 2 and half days when off hook up.
My thoughts are a similar system for house but charged via panels and using 5 or so of the same batteries. (I can buy 5 for £275)
Now even if those 5 only give 3kwh (I think they, d give 5 but??) that represents a £1200 saving over the cheapest Lithium I have had quoted. (suspect buying 5kwh in Lithium would be neater £3k)????
At £109 for a pair of Lead acid even if they only last 5 years its still financially valid.

 

[Benjahmin]

I used to be a plant maintenance engineer for BT.
Telephone exchanges back then were 50v D.C. derived via a self regulating rectifiers. These would have their output across an open cell lead acid battery, rooms full of them, to smooth spikes and act as backup.
Thing is the backup ability was only there to span the time it took the auto start generator to kick in, somewhere in the region of 10-12 seconds at worst. So they were never deep cycled. They fumed when on charge. Specific gravity readings had to taken regularly and I constantly had loads of small holes in my clothes.
They were run through discharge tests, if memory serves I think it was annually, and voltage readings taken throughout. A battery capable of delivering 2000A would be doubled i.e. there were two of them, to keep voltage sag to a minimum.
This says to me that to use lead acid effectively I need double the capacity, a generator and a control system. That's why I'm looking at these power cubes.

 

[WheezyRider]

I agree about cycle life but suspect the discharge argument is thrown in by Lithium battery retailers.
All batteries are rated under similar legistlation/rationale. The most popular obviously being ah. Batteries are checked over 10 hour cycle to full discharge / terminal voltage. A 200 ah battery must be able to supply 20a per hour for the 10 hours,if not it does not receive the 200ah rating.
A 100 ah battery is a 100 ah battery. It wouldn't get that rating if it went flat after only supplying 50% of that.
And Lithium are prone to destroying themselves rather more frequently if not charged/looked after carefully. (Had 2 bosch pedelecs batteries that cried off, refused charge at under 2 years old)

Not quite. Ah ratings are usually at 1/20 of the capacity. So a 200 Ah rating would be 10 A for 20 hours. Try and take 20 A out and it would not last 10 hours. Yes, a lead acid battery can supply down to 10%, no problem...except that this does damage to the electrode structure, which cannot be recovered and so cycle life is then reduced.

Some lithium cells are better than others...also there are different chemistries. So LiFePO4 have a much better cycle life than the typical lithium batteries found in Pedelecs, where range and weight is more important than cycle life (capacity of LiFePO4 is a little less than comparable pedelec battery for given weight). Also, a lot comes down to how good the BMS is. My pack I bought from Yose power has just decided not to charge up. The pack is fine, it's just a crappy BMS. I'll replace it and the battery will be useable again. Bosch do all sorts of tricks I'm sure to build in obsolescence, to make you buy another pack 2 years down the line.

 

[jonathan.agnew]

Not quite. Ah ratings are usually at 1/20 of the capacity. So a 200 Ah rating would be 10 A for 20 hours. Try and take 20 A out and it would not last 10 hours. Yes, a lead acid battery can supply down to 10%, no problem...except that this does damage to the electrode structure, which cannot be recovered and so cycle life is then reduced.

Some lithium cells are better than others...also there are different chemistries. So LiFePO4 have a much better cycle life than the typical lithium batteries found in Pedelecs, where range and weight is more important than cycle life (capacity of LiFePO4 is a little less than comparable pedelec battery for given weight). Also, a lot comes down to how good the BMS is. My pack I bought from Yose power has just decided not to charge up. The pack is fine, it's just a crappy BMS. I'll replace it and the battery will be useable again. Bosch do all sorts of tricks I'm sure to build in obsolescence, to make you buy another pack 2 years down the line.

Tesla switched to lifepo4 on standard range model 3 for cost reasons a year ago. Curiously it advised customers to charge more often to 100% than on lithium before. Although I suspect it may last longer.

Tesla Recommends Charging Model 3 RWD's LFP Battery To 100%

Tesla has issued revised charging guidance for the entry-level Model 3 RWD equipped with equipped with lithium iron phosphate (LFP) battery cells.

insideevs.com

 

[Benjahmin]

Just found this which nseems to be a half way house between a stand alone portable power source and a Tesla power wall. Claims to achieve a near instaneous change over at a power outage, though haven't found the price for the 'smart' unit yet.
Their price for a 400w solar panel seems o.t.t. and not much use charging a 3.6Kwh battery in winter.
Also it does seem to blur the lines between what is storage and what is a generator even more.
I shall look some more at this one.

Buy EcoFlow DELTA Pro Portable Power Station — EcoFlow UK - EcoFlow UK

Official EcoFlow DELTA Pro: ✓ Capacity：3600Wh ✓ Battery Cell Type: ‎Lithium Ion Click to learn more!

uk.ecoflow.com

 

[Benjahmin]

I've had a power meter on the small freezer for 48 hours now. It seems to run a little under 50% of the time.
I want to be able to cover an assumed 4 hour power break (if we get cycled power interuptions I'm assuming they won't be longer than this because of the problems that would ensue - anyone remember how long they were in the 70's?).
So, over 4hours this little freezer uses 148Wh.
I can't get the big fridge freezer out to get the monitor on it. It's much bigger, opened more often but is much newer so, hopefully, more efficient. I'm going to assume a 3 times greater consumption on this - so 444Wh in 4 hours.
Meaning a freezer usage of 592Wh over 4 hours. If I run with needing 1KWh for freezers I'll be well in.
This is looking doable, the unit I linked to above is 3600Wh, leaving plenty of room for a couple of led lights and maybe a radio.

Now it's a question of looking at battery capacity, output configuration (a lot of them seem to go overboard on usb's), charge methodology (mains, 12v, solar), physical size and all sorts of other stuff set against price/affordability.

I would really like an installed battery/power wall. But my solar array is only 1.75Kw max (assumed 50% export - yeah right!) and my house is very small. I've been advised that most standard battery systems would be over sized in that there would not be enough solar left over( after domestic use) to charge the battery so it would cost to charge from the mains, kind of not the point of shelling out the huge cost.

 

[flecc]

anyone remember how long they were in the 70's?).

Two hour long off periods, a maximum of three of those in each 24 hour period, one per eight hours evenly spaced. The times were on a rota so everyone got fair shares of peak usage down times. Of course some of the two hour off times were in middle of the night periods when freezer doors would not be opened, so having little ill effect then.

The times were pre-programmed so we always knew when a cut was coming, helpful since one could have a jug of milk out of the fridge in advance, thus avoiding the fridge door being repeatedly opened for a cuppa during a down time.

Similarly these days one could plan what was needed from the freezer for a meal and remove it before the down time for slower defrosting in the fridge.
.

 

[WheezyRider]

I've had a power meter on the small freezer for 48 hours now. It seems to run a little under 50% of the time.
I want to be able to cover an assumed 4 hour power break (if we get cycled power interuptions I'm assuming they won't be longer than this because of the problems that would ensue - anyone remember how long they were in the 70's?).
So, over 4hours this little freezer uses 148Wh.
I can't get the big fridge freezer out to get the monitor on it. It's much bigger, opened more often but is much newer so, hopefully, more efficient. I'm going to assume a 3 times greater consumption on this - so 444Wh in 4 hours.
Meaning a freezer usage of 592Wh over 4 hours. If I run with needing 1KWh for freezers I'll be well in.
This is looking doable, the unit I linked to above is 3600Wh, leaving plenty of room for a couple of led lights and maybe a radio.

Now it's a question of looking at battery capacity, output configuration (a lot of them seem to go overboard on usb's), charge methodology (mains, 12v, solar), physical size and all sorts of other stuff set against price/affordability.

I would really like an installed battery/power wall. But my solar array is only 1.75Kw max (assumed 50% export - yeah right!) and my house is very small. I've been advised that most standard battery systems would be over sized in that there would not be enough solar left over( after domestic use) to charge the battery so it would cost to charge from the mains, kind of not the point of shelling out the huge cost.

Only 4 hours? If it is a decent freezer, if you keep the door shut, it should not defrost in that time frame. The freezer I bought 12 years ago had a certification not to defrost in 24 hours if power was cut and the door was kept closed. If you have a reasonably well insulated freezer, it's properly maintained and the door seals are good, I would not worry about only 4 hour blackouts.

 

[Danidl]

I used to be a plant maintenance engineer for BT.
Telephone exchanges back then were 50v D.C. derived via a self regulating rectifiers. These would have their output across an open cell lead acid battery, rooms full of them, to smooth spikes and act as backup.
Thing is the backup ability was only there to span the time it took the auto start generator to kick in, somewhere in the region of 10-12 seconds at worst. So they were never deep cycled. They fumed when on charge. Specific gravity readings had to taken regularly and I constantly had loads of small holes in my clothes.
They were run through discharge tests, if memory serves I think it was annually, and voltage readings taken throughout. A battery capable of delivering 2000A would be doubled i.e. there were two of them, to keep voltage sag to a minimum.
This says to me that to use lead acid effectively I need double the capacity, a generator and a control system. That's why I'm looking at these power cubes.

The other point would be that the BT spec'ed Battery will be solid lead plates and capable of a 30 year lifetime. No domestic unit ,even so called deep cycle can compete

 

[Woosh]

The other point would be that the BT spec'ed Battery will be solid lead plates and capable of a 30 year lifetime. No domestic unit ,even so called deep cycle can compete

LiFePO4 batteries for powerwalls are specified for 20 years / 6000 cycles, about right for powerwall applications.