Solar Energy Using Lithium Battery Storage

Connect the battery to a solar panel, + to + and - to -. Provided the panel voltage is greater than the battery voltage, the voltage being generated by sunlight, a current will flow, thereby charging the battery.

It may be worth inserting a rectifier into the circuit to prevent the battery discharging via a misbehaving panel; 1N4001 costs about £0.04.

NO. Bad slack user! This is not a good (or even sane) idea to say the least! .

I hope this was a joke as I cannot even begin to describe how wrong this is. Batteries and solar panels do not play well togeather in this way.

you should use a charging ciruit with microcontroller because lithium batteries need to be chargead in a specific way. i can't tell you exactly how, but you can surely find some sites about it. another important thing is: you must take care that you limit the output current of your battery. if it gets to hot, it will be damaged and can even explode (just remember those exploding laptop-batteries some time ago!!!)

Use the photovoltaic (available OTS) connected to a well designed (and not inexpensive) lithium cell charger (also available OTS). Lithium and NiCad cells should be charged rapidly at first and finished with float charge--be sure the charger will do this; be sure also that the charger will maintain float or turn off decoupled from cells once the cell reaches full charge. Do not use cheap charger (generally up to $20 is cheap) which will overheat the battery. With some effort you can probably find integrated solar chargers with all these features which you can adapt for your specific application.

English?

English- The spin imparted to a pool cue ball by striking it with cue stick tip at left or right of the arc of its medial plane. Variously : right English; left English.

Does this answer your question? or clarify the post to which the question was intended to apply? Whichever that was?

The most elementary solar system should be integrated by: 1) The solar module (more than one, will form a panel). 2) The controller (device that is in charge of allowing the right flow of energy, checking voltage and current correct levels, as well as amount of energy that the battery can storage). 3) The battery (more than one could be used, forming a battery bank). 4) The load, in case that direct current appliances or lighting are connected, with the right size (watts), can be feeded directly. However if you want some alternating current apparatus to be connected as a load, then, you need an inverter in between ( modifies dc into ac ) the system output and the load. In internet there are many examples with photos should be helpful.

As others have said LiIon batteries are not very tolerant to operating outside their design parameters and are prone to explode. As a result suppliers will generally not supply them to people as straight batteries unless you can demonstrate that you really know what you are doing. Normally what you do is stipulate the application and the battery suppliers supply the batteries pre packaged with special microcontroller chips that are used to monitor the batteries charging and discharging.

Judging by the initial question I would hazard to say that you are going to have trouble getting somebody to supply you with Lithium batteries. You may want to try using sealed lead acid batteries instead, they are cheaper, easier to use, far more tolerant to abuse and easier to obtain.

Based on Masu's comments I believe he/she is getting ahead of him/her self. I doubt that you would be trying to obtain large lithium batteries direct from the manufacturer, and small lithium batteries are easily purchased from numerous stores.

You did not indicate what type of lithium battery chemistry you were looking at (there are many) or the voltage, or how big it is. Are you also aware that only some types are rechargeable?

Recharging lithium chemistry batteries is a specialised field and great care must be taken to prevent damage to yourself and the battery. This application is not common, but it can be done, HOWEVER more information on your application is required.

Please work on the English too. This type of "English" (in its loosest sense) is not acceptable in industry or the business world.

"Based on Masu's comments I believe he/she is getting ahead of him/her self. I doubt that you would be trying to obtain large lithium batteries direct from the manufacturer, and small lithium batteries are easily purchased from numerous stores."

I depends on where you are. In Australia, for example, you can't buy any LiIon battery as an individual component, regardless of its size. They are not available at a retail level and can only be purchased from suppliers when you can show that you know what you are doing and are not going to injure yourself or some unsuspecting user.

PS MASU is really a contraction of two names, not a name it itself and I am actually a he.

Have you tried "Jaycar Electronics" (we have it here too). A small selection of camera battery Li-Ion cells is available from this retail outlet, and others like it. The more extensive range is available from larger distributors (accounts are not too difficult to get), and from overseas specialty battery suppliers (via the web). And no, I am not going to mention them as he would be better off using standard NiMH over Li-Ion for a solar application anyway (far less dangerous).

You just need to know where to look.

Actually I checked the Jaycar Australia web site prior to posting the last entry and they do not stock any LiIon batteries of consequence.

I am an electrical and control system engineer by trade and I am currently working on a project that requires rechargeable batteries with appropriate chargers. Since I am designing the whole thing from the ground up and the chargers will be internal to the system. When I was deciding what chemistry to use for the batteries I looked at using LiIon and ended up going for Pb Acid as none to the supplier were willing to supply the cells on their own. They all insisted on supplying them in packs and with chargers. I probably could have convinced them to supply me with the cells in the end but it much easier to go the Jaycar and by a SLA battery than stuff about with paperwork.

It appears that the litigious attitude we see so often in the USA has spread to Australia and everybody is frightened of being sued because of somebody else's stupidity.

A small range of Li-Ion batteries are available, but generally they are for cameras (hence they can be sold on the assumption that you already have the battery charger that came with the camera), and hence only useful to a backyard tinkerer. For project work, there is not much out there that can beat good old SLA as a rechargeable power source (or possibly NiMH) for system reliability and price.

Jack of all trades, you may find this interesting,

I recently got a new telescope that has a microprocessor based drive to track stars. By default it uses 8 AA batteries to power the scope and it eats them like nobody's business. At best you can expect to get 2 nights worth of viewing out of a set of Duracell alkaline batteries.

The telescope however can be driven from an external 12 V source and after experimentation I ended up using a 7.5 AH 12 V Sealed Lead Acid battery which has now operated the telescope for some 6 nights without showing any sign of voltage drop.

Anyway to cut a long story short even if I only used the SLA battery once it would cost less than half what it would have using the Duracell alkaline AA batteries.

It kind of makes one wonder doesn't it?

It shouldn't do. Alkaline AA batteries have around 2.7-3.1AH each at 1.5V. 8 in series will give you around 12V at say 3Ah. A 12V SLA battery has a fairly slow linear discharge curve thru its discharge cycle (100% full to empty) and is fully discharged at around 10V. Alkaline batteries have a steep discharge curve down to about 1.25V each, and then follow a less steep linear discharge curve (down to about 1V). So, the 8 AA batteries will reach 10V after being discharged by about 25% (under a moderate load of around 160mA). If the current is quite high it will deop even quicker. So, the AA batteries have less than 1/2 the capacity of the SLA battery and the voltage drops much quicker. Once it drops below the level required to power your telescope (which may be as high as 10V) the electronics stop working and the batteries need to be replaced.

Obviously the AA batteries don't last as long as a SLA powering the external 12V source (which seems to indicate that the small AA batteries are just for portable short-term application convenience), in which case perhaps the telescope would be better wired to a fixed power supply in the long term.

"It shouldn't do. Alkaline AA batteries have around 2.7-3.1AH each at 1.5V. 8 in series will give you around 12V at say 3Ah."

I did a bit of research on alkaline batteries and yes they do have that sort of capacity but it is dependant on the discharge rate. The higher the discharge rate the lower the recoverable energy becomes. In other words the harder you bush them the less you get out of them. AA Alkaline batteries can have a capacity less than 1 AHr in high drain applications and that is what appears to be happening in this situation.

The problem with the telescope mount is that it has two electric motors that when moving the telescope as speed can pull close to 2 A. This isn't a problem for the SLA battery but degrades the alkaline batteries considerably.

I also tried running the telescope from a 12 V 2 A power supply based around a 7812 regulator chip. It had some strange effects and would cause the telescope to start moving at full speed in a random direction. I am not exactly sure about what was happening to cause this to occur but part of the diagnosis was the test the telescope using the SLA battery to make sure the problem wasn't in the telescope. As you have probably gathered it works fine on the battery so the problem must be in the power supply. I am away from my workshop at the moment so I havn't got access to all my tools to diagnose the problem further at the moment but ultimately the plan is to build a 12 V uninterruptible power supply using the SLA battery.

The upshot of it is SLA batteries are hard to beat economy wise and if you can cope with the mass are worth serious consideration.

LOL! 2A out of 8 series linked AA batteries, no wonder they didn't last long. Have a look at the 7812 datasheet, it cannot handle currents that high. Use a multimeter (or scope) to monitor the output voltage (the voltage regulation and internal current limiting circuitry is probably going crazy).

Have you tried AA NiMH batteries, although they are only 1.2V they hold their voltage very well under high current applications and have a very shallow discharge curve. They will still not last as long as a SLA battery, but they will offer a more portable solution (and far better than Alkalines). As an added bonus they are also easily rechargeable.

Why do you need a battery backed-up 12V power supply for the telescope? Are you performing steller tracking or something.

"Have a look at the 7812 datasheet, it cannot handle currents that high."

The telescope only pulls 2A while it is being moved at full speed, when it's tracking it draws far less. I do have to admit though that the concept of running it on AA batteries isn't the best idea I have heard and I don't think the designers really meant it to be used that way. The regulators that I am using can supposedly pump out a maximum of 2,000 mA provided they don't overheat but I havn't actually measured the current. I fused the output of the transformer with a 2A fast blow fuse and it hasn't blown so the current isn't exceeding 2A by much if in fact is it actual is at any time.

I havn't tried the NiMH batteries but the SLA works well and the size isn't a problem. By the time you have the tripod, scope, mount, eyepieces, dew shields etc. the battery is only a minor part of the equation. One of the things I need to do is install a couple of fans to stop condensation from forming on things like the sighting system so the drain on the battery is going to increase.

"Why do you need a battery backed-up 12V power supply for the telescope? Are you performing steller tracking or something."

In a word yes, I have a camera adaptor and intend to take deep space images that require long exposure times. I am particularly interested in things like comets and asteroids as well and the southern hemisphere is fairly under monitored on this front. I am not up to that level yet but that's what I would ultimately like to do. By the way the scope is a 125 x 1900 mm Cassegrain scope with a computerized tracking and finder. It works pretty well but unless you mount the scope in what's called and equatorial mount the objects it track will rotate as then move across the sky. The mounting can do this but for the time being while I am playing and learning I am using it mounted horizontally because it's easier.

The current project is a study of the moons of Saturn and Jupiter, whenever the sky is clear I have a close look and do a sketch of the position of each of the moons that's visible. Saturn is currently at it's closest to earth so the rings are quiet a majestic sight. We are currently closing on Jupiter so it is getting bigger day by day, you can currently discern the striations of clouds around the equator and am looking forward to when Jupiter is at its closest in about 3 months.

This is my first astronomical telescope and I must admit I am enjoying it an wonder why I waited so long before I got one.

Are we using Lithium batteries or Lithium Ion? The Lithium batteries I've used in the past were not rechargeable. Once we know we are using rechargeable batteries, try Google or maybe Home Power magazine (http://www.homepower.com) for some articles on basic solar/PV articles. Good luck!

thank you all for the comments that u have posted.......i got some idea