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Search took 0.00 seconds. Search: Posts Made By: noelex 77
Forum: Electrical: Batteries, Generators & Solar 09-05-2014, 08:32
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

Thanks for doing the testing. I know this sort of data must be a lot of work and its great that you share this with the forum :thumb:
Forum: Electrical: Batteries, Generators & Solar 13-03-2014, 00:09
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

The Vmp of my panels is 17.9v, but this is at STC with a cell temperature of 25c. I think the NOCT with an air temperature of 20c is about 16.2v, but I don't have the NOCT specs in front of me.

My...
Forum: Electrical: Batteries, Generators & Solar 12-03-2014, 23:44
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

It is a shame to throw away power because of the limit of the controller, but if you have excess its not really important.

The controller has to protect itself to limit the current and it may be...
Forum: Electrical: Batteries, Generators & Solar 12-03-2014, 23:14
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

Yes :)
Forum: Electrical: Batteries, Generators & Solar 12-03-2014, 22:52
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

For those that have not seen this sort of display before this is a result from my MPPT controller in typical conditions near the middle of the day

The 330w of panels I have are actually ...
Forum: Electrical: Batteries, Generators & Solar 12-03-2014, 19:23
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

A lot of MPPT show input and output figures enabling the MPPT to be readily seen, but unfortunately they are a little deceptive (at least all the ones I have measured). They exaggerate the output...
Forum: Electrical: Batteries, Generators & Solar 12-03-2014, 18:49
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

I have sometimes thought using the underside of the solar panels to heat up fresh water for showering could be made to work. It is hard to gain much improvement in solar output even a 25c reduction...
Forum: Electrical: Batteries, Generators & Solar 12-03-2014, 18:15
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

There are a couple of MPPT controllers that will boost voltage (Ganasun make one). They are designed for using 6v panels with a 12v system, or 12v panels with a 24v system.

For 12v (nominal)...
Forum: Electrical: Batteries, Generators & Solar 12-03-2014, 15:58
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

The short answer is no.

There is some debate between the efficiency of series and parallel connection, particuarly with the isolated shading that is common on yachts the result is difficult to...
Forum: Electrical: Batteries, Generators & Solar 09-03-2014, 19:26
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

No. The relative improvement in output gained from the MPPT voltage conversion falls as the the cell temperature rises and the Vmp falls.

The self consumption of MPPT controllers and the losses in...
Forum: Electrical: Batteries, Generators & Solar 09-03-2014, 17:55
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

:thumb:. That would be great.
Forum: Electrical: Batteries, Generators & Solar 09-03-2014, 17:50
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

It is easy to measure the cell temp with an IR thermometer (every boat should have one anyway)

Ambient temperature is a factor, but the cells heat up reasonably well in bright conditions with...
Forum: Electrical: Batteries, Generators & Solar 08-03-2014, 16:50
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

Yes the I/V curve is quite steep so the effect is not large. A quick calculation shows if the bench supply had modelled the typical solar panel I/v curve the current gain improvement from the the...
Forum: Electrical: Batteries, Generators & Solar 08-03-2014, 16:32
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

You are quoting STC figures. This is a common area of misunderstanding. STC figures are a consistent standard that is fortunately used by all solar panel manufacturers, but these numbers are designed...
Forum: Electrical: Batteries, Generators & Solar 08-03-2014, 06:00
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

It might have been a good demenstration if they had actually used a solar panel :)

The assumed Vmp of 17.4v is unrealistic, or at least untypical. It also assumes the the solar panel current is...
Forum: Electrical: Batteries, Generators & Solar 08-03-2014, 04:43
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

I make the Vmp about 11.9v, but if your Vmp reaches this level you are in serious trouble. The charge current will be very low with any controller and a parallel connection.

The "series" boys...
Forum: Electrical: Batteries, Generators & Solar 08-03-2014, 03:34
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

Using the display that is on some MPPT controllers listing the current in and out is a very poor way of estimating the advantage of the MPPT conversion. The displays exaggerate the difference. Which...
Forum: Electrical: Batteries, Generators & Solar 08-03-2014, 02:44
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

The improvement would be between 13 and 16% :). A cell temperature of 70c is a high and a Vmp of between 15 and 16v is a little low, but factor in the self consumption of the controller and some...
Forum: Electrical: Batteries, Generators & Solar 07-03-2014, 17:35
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

If the regulator is in low duty cycle PWM it is heavily regulating. Effeciency is not needed at this stage, in fact operating the panel outside its optimum parameters is a bonus.
Forum: Electrical: Batteries, Generators & Solar 07-03-2014, 00:10
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

If the solar panels are producing more power than the combined demands of the loads and battery acceptance then the controller will be regulating and MPPT technology makes no difference.

The...
Forum: Electrical: Batteries, Generators & Solar 06-03-2014, 21:32
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

There is no fundemental difference between how MPPT controllers and PWM manage these issues.

Some controllers have better adjustability and suitability than others, but this is not a feature that...
Forum: Electrical: Batteries, Generators & Solar 04-03-2014, 02:50
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

As Dave says there is no fundamental difference in battery management between MPPT controllers and controllers that are not MPPT.

The best controllers of both types (MPPT and none MPPT) are quite...
Forum: Electrical: Batteries, Generators & Solar 03-03-2014, 19:08
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

A brief reading of the specifications is a bit deceptive. The Vmp is measured with a flash of light, keeping the cell temperature low. In practice the cell temperature will be much higher and the...
Forum: Electrical: Batteries, Generators & Solar 19-02-2014, 14:50
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

Manufacturers are very reluctant to reveal data about the self consumption of their controllers. In fact the only way seems to be to go out and measure it yourself.
It is particuarly a concern for...
Forum: Electrical: Batteries, Generators & Solar 18-02-2014, 13:46
Replies: 185
Views: 47,366
Posted By noelex 77
Re: MPPT Charge Controller for LifePO4 Batteries

The best controllers like the Outback use a fair bit of power to operate their complex tracking circuitry. Using one per each 200w panel is not likely to be the best option.

There are circuit...
Showing results 1 to 25 of 35
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