Hi guys
I just took a look at this site and what he's offering is the same principle as the Xantrex and Morningstar diversion controllers except that its switching will be relatively slow.
It dumps the load into a water heater or some other resistance load when the voltage reaches 13.9v (for 12v system) and then switches off again on the way down at 12.9v. This cycle might take a few seconds and then the voltage will start to rise again as the charging sources again feed into the battery, bringing its charge back up to the dump voltage, at which time it switches the diversion load on again.
And so it goes on switching the diversion load on again off again and keeping the battery voltage between 13.9 and 12.9. This is exactly what is done by a switch mode controller, or pulse width modulation controller, except that these do the switching at thousands of times per second. And with the solid state PWM controllers the voltage of the battery is kept pretty much exactly at the target voltage, rather than fluctuating between the limits.
The names of these devices describe well what is happening. Switch mode is switching on and off quickly, and pulse width modulation is a fancy way of saying the same thing. The width of the pulse is really the length of time the pulse of load dumping is taking. And this width, or time connected to the load, is modulated by the voltage sensor. And whether with width of the pulse is 2 or 3 seconds, or just 2 or 3 thousandths of a second, its still pulse width modulation, just a difference in timing.
You can achieve the same result by using a dual battery switch that is offered at 4WD or offroad accessories car shops. You know the kind of switch that watches the voltage of the main battery and when it rises to say 13.5v it closes a relay which connects the second battery. The idea of this switch is that when the main battery has a good charge level it connects the second battery into the circuit so it can be charged as well. If instead of connecting a second battery, you connected a load, it would act as a diversion mode regulator. It will switch the load off again at around 12.7v and allow the battery to begin charging again.
And so back to this charge controller in the link... its really a pretty simple device and nothing modern or groundbreaking in what he's proposing. He just added a generous mix of hypebole to make it sound more than it is.
I'm thinking that the only way to get MPPT as well as diversion load is to have two devices, a MPPT device in series, but without voltage regulation, and the diversion load controller in parallel so that we can harvest the power that is excess to battery charging needs.
Cheers
Chris
On 27/06/2012, at 1:57 AM, Carter Quillen wrote:
Aaron,Went to the link you supplied out of curiosity.This guy definitely has a unique take on charge controlling and I think a lot of people like Outback, Xantrex, and Morningstar might respectfully disagree with his conclusion and methods. Everyone seem to be in agreement that an MPPT charge controller will help you get significantly more, (20-35%) from your wind or solar generator yet he's saying never connect a solid state device between them and your batteries. I would not agree with that myself.But if all you want to do is keep from frying your batteries, this device might be the simlest and cheapest way to accomplish that. For me, I just shelled out $650 for an OutBack FlexMax 80, MPPT charge controller and plan to install it next week with no regrets. I believe this particular vendor is just wrong in many of his assertions but that's just my opinion.CarterFrom: Aaron <akenai@yahoo.com>
To: "electricboats@yahoogroups.com" <electricboats@yahoogroups.com>
Sent: Tuesday, June 26, 2012 11:43 AM
Subject: Re: [Electric Boats] Diversion load controllers (was Measured solar panel output)
__._,_.___
.
__,_._,___
No comments:
Post a Comment