There's not much on the web about the performance of Li-ion batteries past their expected lifetime of 500 or so charge cycles.

Possibly interesting stuff here:-

https://en.wikipedia.org/wiki/Lithium-ion_battery#Battery_life

https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery

http://powerelectronics.com/site-files/powerelectronics.com/files/archive/powerelectronics.com/portable_power_management/battery_charger_ics/804PET22li-ion-battery-life.pdf

Thanks @crossy

A 2015 study by Andreas Gutsch of the Karlsruhe Institute of Technology found that lithium-ion battery storage lifetime could vary by a factor of five, with some Li-ion cells losing 30% of their capacity after 1,000 cycles, and others having better capacity after 5,000 cycles.

Rather odd, better capacity after 5000 cycles....whish that Karlsruhe Institute did publish the brand and type. ?

I don't think that solar pump, back a few pages, is 750 watts..wouldn't it have to be bigger?

I appreciate the links for LiOn batteries , that's our new life right? Sharing this good news about power integrity.I've always been offered to sell solar, as my cousin started a big business in Hawaii 30 years ago with photovoltaics let's buy batteries and make solar energy! Tanks, again!

I don't think that solar pump, back a few pages, is 750 watts..wouldn't it have to be bigger?

I appreciate the links for LiOn batteries , that's our new life right? Sharing this good news about power integrity.I've always been offered to sell solar, as my cousin started a big business in Hawaii 30 years ago with photovoltaics let's buy batteries and make solar energy! Tanks, again!

LiFePo/Li-Po batteries look to possibly hold more promise in the long term than Li-ion, but the problems with both of them is major variances in cell quality from manufacturer to manufacturer, questionable reliability / ability to achieve claimed cyclic life, and the fact that both need to be kept in in a narrow range of operating temps in order to work to spec.

I use Li-Po cells in some RC 'toys' I have, and even spending double or triple for "better quality" ones doesn't mean much, nor does spending mega dollars on incredibly smart chargers/balancers - they all still eventually bubble and blister (i.e. become throwaways) after 50-100 cycles. OTOH, my 2.5 year old Macbook Pro uses a Li-Po cell that still runs my computer for > 6 hours even after > 800 cycles - and it's not always nurtured in a nice temperature controlled environment either. Maybe we should be asking Apple where they buy their cells?

Lead acid is still cheaper by the Wh, a lot less fussy, and pretty much everyone knows how to make a good one - the only real downsides are space they take up, because at sensible DOD's you need so many of them ...

Specification:

Rated Current: 1.2A( shall not be less than 1.5A)

Maximum lift: more than 5 meters

Maximum flow: 840 l / h (horizontal flow) (Only can reach maximum flow with 18V,12V can get about half.)

Wires: three-core wire, bare head, length 1.5 m diameter 5.7MM (very rough)

Dimensions: 98 (H) * 38MM out Outlet OD: 12MM, inside diameter 9.7MM.

Just tested this pump again. Tied the hose up connected to a 7ah vrla battery, status voltage 12.8.

A 1.5 gallon bucket was filled in 20 seconds with nearly no head,hose length of 3.80m. At about 3m high 22 seconds. You can clearly see the difference in flow comparing to the pict posted yesterday. Its amazing better than the specs...????

Same test with this pump. According specs

I find that the biggest weakness in solar energy systems is storing the energy. I try to keep up with new battery technology. Lithium batteries still have some weaknesses.

Years ago Exxon developed a zinc bromine flow battery. The Aussies have now further improved that process and are manufacturing the units. Other than size and weight, they seem far better than other batteries, For interesting reading, Google Zinc bromine flow batteries.

ADDED link

http://www.nanalyze.com/2014/03/progress-of-redflows-zinc-bromide-flow-battery/

i find that the biggest weakness in solar energy systems is storing the energy.

Absolutely right. Basic need is water. you dont need battery to pump water from a well during the day. As per posted youtube examples you can have a rather powerful pump totally solar powered.

Second need is perhaps lamps. For this you dont need expensive very large capacity batteries also if you are satisfied living with some fans.

Laptops and other gadgets can also run cycle free during the day.

You want to run 19 aircons stay on grid hehehhee

For me the trick is to run as much as possible with as less as possible cycles. For this i have to adjust my lifestyle (a little bit i must say)

I don't think that solar pump, back a few pages, is 750 watts..wouldn't it have to be bigger?

I appreciate the links for LiOn batteries , that's our new life right? Sharing this good news about power integrity.I've always been offered to sell solar, as my cousin started a big business in Hawaii 30 years ago with photovoltaics let's buy batteries and make solar energy! Tanks, again!

LiFePo/Li-Po batteries look to possibly hold more promise in the long term than Li-ion, but the problems with both of them is major variances in cell quality from manufacturer to manufacturer, questionable reliability / ability to achieve claimed cyclic life, and the fact that both need to be kept in in a narrow range of operating temps in order to work to spec.

I use Li-Po cells in some RC 'toys' I have, and even spending double or triple for "better quality" ones doesn't mean much, nor does spending mega dollars on incredibly smart chargers/balancers - they all still eventually bubble and blister (i.e. become throwaways) after 50-100 cycles. OTOH, my 2.5 year old Macbook Pro uses a Li-Po cell that still runs my computer for > 6 hours even after > 800 cycles - and it's not always nurtured in a nice temperature controlled environment either. Maybe we should be asking Apple where they buy their cells?

Lead acid is still cheaper by the Wh, a lot less fussy, and pretty much everyone knows how to make a good one - the only real downsides are space they take up, because at sensible DOD's you need so many of them ...

IMHO Don't get too wrapped up about temperature ranges of batteries, LiFePOP4's work better than lead acids above 30 deg C. Lead acids would be better in a cooler environment. That is to say below 30 deg C.

There are some excellent comments about the variable quality of the LiFePO4 cells. I have also heard about the wide ranges of cycle life expectancy across the range of manufacturers. I think there should be an ISO number for them.

I don't think that solar pump, back a few pages, is 750 watts..wouldn't it have to be bigger?

I appreciate the links for LiOn batteries , that's our new life right? Sharing this good news about power integrity.I've always been offered to sell solar, as my cousin started a big business in Hawaii 30 years ago with photovoltaics let's buy batteries and make solar energy! Tanks, again!

LiFePo/Li-Po batteries look to possibly hold more promise in the long term than Li-ion, but the problems with both of them is major variances in cell quality from manufacturer to manufacturer, questionable reliability / ability to achieve claimed cyclic life, and the fact that both need to be kept in in a narrow range of operating temps in order to work to spec.

I use Li-Po cells in some RC 'toys' I have, and even spending double or triple for "better quality" ones doesn't mean much, nor does spending mega dollars on incredibly smart chargers/balancers - they all still eventually bubble and blister (i.e. become throwaways) after 50-100 cycles. OTOH, my 2.5 year old Macbook Pro uses a Li-Po cell that still runs my computer for > 6 hours even after > 800 cycles - and it's not always nurtured in a nice temperature controlled environment either. Maybe we should be asking Apple where they buy their cells?

Lead acid is still cheaper by the Wh, a lot less fussy, and pretty much everyone knows how to make a good one - the only real downsides are space they take up, because at sensible DOD's you need so many of them ...

IMHO Don't get too wrapped up about temperature ranges of batteries, LiFePOP4's work better than lead acids above 30 deg C. Lead acids would be better in a cooler environment. That is to say below 30 deg C.

There are some excellent comments about the variable quality of the LiFePO4 cells. I have also heard about the wide ranges of cycle life expectancy across the range of manufacturers. I think there should be an ISO number for them.

As we both say, the problem with LiFePo and Li-Po is, where are the respected manufacturers and their trustworthy R&D, testing and specs? I'm yet to see anything commercially available from the most respected Li-ion brands like Panasonic and Samsung, for example.

As for temperature, the problem there is not about ambient temps per se - it's about the temps these relatively tiny cells get to under load. in 30c ambient, I've seen Li-Po's get to > 70c with just a 5C load (even cells rated to 30C loads) - not much more than that, and they start boiling/blistering and it's game over. From what I have seen, sure they have awesome power density and peak current ability, but they just don't have the surface area/thermal mass to actually keep themselves cool.

Can anyone explain me how this guy can cook with an electric rice cooker and draws only +/-100watts from out his solar systems.

https://m.youtube.com/watch?v=qf82pbPdsuk

Can anyone explain me how this guy can cook with an electric rice cooker and draws only +/-100watts from out his solar systems.

https://m.youtube.com/watch?v=qf82pbPdsuk

Could be using one of these, 12V 100W rice cooker.

http://www.dx.com/p/oushiba-c2-mini-100w-car-electronic-rice-cooker-dc-12v-268740#.VyRKPb7EOuQ

Wow @crossy....did not know that you can cook rice with a 100watt rice cooker. Wondering how long it takes to cook a little bit of rice.......

Have a 12v 195watt one cup watercooker and its "acceptable slow"

zero watt solar cooking

Problem with solar (oven) cooking is the unstable weather. Better trying to cook dc later.

Here is a company who makes/sells 12v cooking appl. Whish i can buy that microwave here. Coffeemachine is here available. Other products on the vid i dont need.

https://m.youtube.com/watch?v=3ONLeNcUALo

Wow @crossy....did not know that you can cook rice with a 100watt rice cooker. Wondering how long it takes to cook a little bit of rice.......

Have a 12v 195watt one cup watercooker and its "acceptable slow"

According to one of the reviews "about 30 minutes", but (of course) it doesn't say just how much rice.

Our normal-use 220V rice cooker is 400W.

Herr naam asked me before how i will arrange warm water. I have ordered this 120watt warm water maker. Will install it in the smallest waterfilter housing. Hope i can about 80-100ltr warm water per day for shower and washing "nidnoy" dishes. At least i can try to test this idea. Will keep you updated.

Or if possible i bend the heater part and wrap this in.

Herr naam asked me before how i will arrange warm water. I have ordered this 120watt warm water maker. Will install it in the smallest waterfilter housing. Hope i can about 80-100ltr warm water per day for shower and washing "nidnoy" dishes. At least i can try to test this idea. Will keep you updated.

You need to re-visit your high-school physics lessons.

120W = 120 Joules per second.

Specific heat capacity of water is 4,200 J / kg / ^oC

So your 120 W heater will raise 1kg (1 Litre) of water by 1 ^oC in 33 seconds.

It's intended to heat a cup (say 0.1L) to a temperature suitable for coffee (say 90 ^oC) which it will do (starting at 25 ^oC) in about 3.5 minutes.

Direct solar water heating is the way to go, even a coil of cheap black pipe in the sun will provide a zillion times more hot water than wasting your valuable solar electricity.

But when the heater part already reach a high temperature can i not heat the waterblock? Some do with peltier. Will the water flows through the block (2-3ltr pm) get a bit warmer??

There are different sizes of such blocks.

I agree that direct sun is much more efficient, even with plastic bottles.

But when the heater part already reach a high temperature can i not heat the waterblock? Some do with peltier. Will the water flows through the block (2-3ltr pm) get a bit warmer??

There are different sizes of such blocks.

I agree that direct sun is much more efficient, even with plastic bottles.

If you want to make hot water, just paint some copper pipe black and run the water through it. Peltiers are a total waste of energy for this purpose.

Oh dear. To quote a certain fictional Scottish engineer, "ye cannae change the laws of physics Jim".

Ok. It was just an idea for having wamer water in the evening. Not possible,then the idea of direct sun heating and store it in an insulated tank.

Thanks for your lessons @crossy and @imho

Ok. It was just an idea for having wamer water in the evening. Not possible,then the idea of direct sun heating and store it in an insulated tank.

Thanks for your lessons @crossy and @imho

Maybe try to find a vendor who can supply this without the crazy shipping price?

http://www.aliexpress.com/item/Non-pressurized-compact-solar-water-heater-220V-50-Liter-vacuum-tube-47-700mm-NEW/32618572633.html

I have 2 solar hot water systems using a similar vacuum tube system (but mine are pressurized ones) and they make crazy hot water, and still keep it hot over rainy days.

Such systems are here in shops available. I only need warmer water for evening's and early morning shower. Also more hygienic for washing dishes.

It would be a challenge to make a DIY one as simple as possible.

But when the heater part already reach a high temperature can i not heat the waterblock? Some do with peltier. Will the water flows through the block (2-3ltr pm) get a bit warmer??

There are different sizes of such blocks.

I agree that direct sun is much more efficient, even with plastic bottles.

If you want to make hot water, just paint some copper pipe black and run the water through it. Peltiers are a total waste of energy for this purpose.

copper = expensive, black rubber hose = cheap,

Peltier = +

Such water blocks are being used for the cooling with peltier and not warm up. Pc cooling for example

Like this one @naam. If its effective, why not??

Like this one @naam. If its effective, why not??

Nice one George. But in my garden all the plants run for cover at watering time because they know how hot the water is in my 40 Metre green/blue hose at the end of the day

40m??? Wow....

How about this? Will this give warm or hot water?