Some thoughts about a next generation Classic.
The basic design is good so hardly any changes. Just please get some proper shunts inside it to accurately read incoming and outgoing amps. Same with volt meters. We need multiple Classics on same battery bank to agree on battery voltage.
Get boost conversion working, MN would be the only boost controller.. 8)
A couple more Aux, maybe 4 or 8 would be useful, nice to control vent fan, night light, force float, pwm water heater, pwm turbine dump, etc all at same time,
Terminal block that can take #4 but #2 would be nice.
Now the biggie.
Forget the MNLP and MNGP and in place a data processing module that fits in same place
Talks modbus to Classic via rs232 (as now) but is complete computer, arm CPU, decent amount of memory half to several gigs, SD card , Ethernet, couple of proper USB serials. Main function is to store logging and provide web interface into Classic. No propriety OS, use Linux, open source, encourage user base to develop / refine code. External inputs too, maybe battery/current monitor
Let the classic's CPU concentrate on mppt, buck boost and updating its modbus registers.
Forget logging on it, forget web server on it, let the new CPU do that.
Wireless Ethernet support too, connecting just like a laptop to a LAN, HDMI for screen
(It's starting to sound like an rPi :) )
Dgd
The Classic already has Cupron shunts and a good sense amps. The input needs calibration as well as the voltage but I believe you will find the output current (battery) is better than any other controller out there now.
boB
..sorry forgot about shunts, Ryan already told me that, memory fading, strike that from list.. 8)
Dgd
One thing that definitely needs to be betterized very soon is the battery
voltage accuracy. Not so much for charging goodness but for better
battery SOC measurement for when that software is ready using the
external shunt monitor.
boB
DGD
I think what you are asking for could be done now. The hardware in the Classic is robust enough so we get some enterprising individual to build said Black Box that interfaces via rs232 and walla. It could be a "Very Cool" open source project and could likely use something darn near off the shelf in the way of hardware. Linux is a must and open source is a must.
As for things Like Extra Aux and Battery Sense etc we are working towards a networked module that does all that so the black box you speak uf really just needs to be the brains of the operation. Talk and Receive Modbus from the MidNite RS232 network and turn it into whatever works in this black box. This sure seems to get back towards what Tom and I had been kicking down the road in another thread sort of and I will help in any way I can.
Ryan
Quote from: Halfcrazy on April 11, 2013, 05:55:57 AM
I think what you are asking for could be done now. The hardware in the Classic is robust enough so we get some enterprising individual to build said Black Box that interfaces via rs232 and walla.
As soon as I get this last 600m of fencing done I should be back to "my" projects, which includes exactly this one.
Throw thoughts and ideas, people. I'm interested.
By way of background - I live entirely off-grid (and have for about 6 years now) - including running two businesses and home-offices (one is an ISP). To save some power, I've done all my long-term logging, graphing etc on machines off-site.
This model won't suit everyone, but it's got a lot of upsides.
I don't know if this upcoming current shunt measuring thing would allow this, but I have been thinking about a nifty feature. My understanding is that battery life is often rated in charge/discharge cycles. It is also my understanding that it is good to get a battery down to 50% DOD once in a while so that the chemical reactions can happen deeper into the plates.
What if it was summer time and I was only into the batteries say 10% overnight? Could this current shunt allow me 3-5 days of nightly discharge while just keeping up with the loads while the sun is shining? I was just thinking that if I could stretch a charge/discharge cycle to three days instead of every single day, the lifespan of batteries might be improved.
Batt life is rated by number of discharge cycles, and the shallower the discharge, the more cycles. A fairly deep discharge is good occasionally, just like an EQ. My 50Kwh bank of L-16 are going strong after 8 years (3000 cycles) of 5-10% discharge nightly, with a few weeks in the fall having 50-80% discharge, before the hydro comes on.
Quote from: aroxburgh on April 12, 2013, 11:44:49 AM
In what universe is "walla"? ???
Do you mean "voilà"? ;D ;)
Al Roxburgh
I am not Ryan nor do I play him on TV!
I suspect he means "voila" as, in my experience that is how most Americans I know would pronounce it.
I pronounce it "Vi Olla" just to be contrary. ;D
Tom
My few cents,
Agree with VF. Am in the camp of fewer, somethat deeper cycles on Flooded batteries is better. For those like me with it is a struggle to cycle the battery bank to an SOC below 95% on an average day, I often need to shut off the CC for 4 or so days, and then manually switch the CC back on.
If this process could be programmed into the CC, a Battery Monitor or perhaps a Charge Manager, this would be very cool, and useful.
Others have mentioned that having the Boost Charge ability, where part of the Absorption stage occurrs at a programmed higher(or different) voltage than the main Abs stage might help some customers.
Another thought is because the Classic has so many useful Communication and Control functions, that perhaps a docking connector, or a docking cable that connects to a Manager box which has the Aux and Comm connectors on it. For the systems here, any such docking function would need a very shielded cable, or have the ability for the cable that connects twix the CC and this other box be run in metal conduit.
Divorcing the comm/control functions would allow easier wiring, and perhaps accommodate up to #2 AWG cables, at least on the CC's Battery connections. This accommodation of larger cable has been touched on before.
Also agree that having control functions be open-sourced and very open for the geeks among us to extend functionality of battery charging.
Having said the above, do realize that any hardware/firmware/software that is the steward of charging often, VERY EXPENSIVE batteries, making certain that great care must be taken to not damage batteries. Also realize that when charging functions have many more variables, that testing all of these variables, finding and fixing bugs, and getting a product actually shipped could be very expensive for almost any Solar manufacturer, IMHO.
Always wanting SO much more, Vic
Quote from: Volvo Farmer on April 12, 2013, 07:31:16 AM
I was just thinking that if I could stretch a charge/discharge cycle to three days instead of every single day, the lifespan of batteries might be improved.
Good thinking VF! I think that not only would you extend your battery's life, but you would also increase (over the life of the battery) the ratio of kwh stored to dollars spent.
The only problem I see is that when you get to your target SOC (after 3 sunny days) it might be cloudy and require generator charging.
--vtMaps
I don't know about black boxes and linux computers much. But it would be kind of nice if the Classic could do Boost Charging like the XW controllers. For folks that have batteries that are difficult to get the SG up in normal absorb times the Boost Charging feature helps shorten the required absorb time.
--
Chris
OK, we'll see about putting in a boost charge function at some time.
I have not seen any studies that show how much of an improvement
in battery life this extra stage provides but it does kind of make sense,
doesn't it ?
boB
Quote from: boB on April 14, 2013, 12:45:29 AM
I have not seen any studies that show how much of an improvement
in battery life this extra stage provides but it does kind of make sense,
doesn't it ?
I've never seen Schneider/Xantrex make any claims about battery life being improved. Just more efficient battery charging. After we bought our XW system I tried it and it does work. The XW Power System has a setting for Bulk, Absorb and Float. If you set the Bulk voltage higher than Absorb it starts the absorb timer when absorb voltage is reached but it charges the battery at the higher bulk setting for one hour, then drops to the absorb voltage.
It shaves roughly one hour off the absorb time with our bank, and still gets the SG to 1.255-1.260. And the other side benefit for me has been that it doesn't get the batteries as hot by the end of absorb as the "traditional" method.
I've simulated it several times with the Classics by operating the boost charging cycle manually, and it works every time - shortens my 4 hour absorb to 3 hours.
I got to thinking there's probably lots of folks who are not familiar with this. So this is an excerpt from Schneider's manual on it:
Boost charging allows for better utilization of flooded lead acid batteries under moderate cycling in off grid or grid support applications. Boost charging encourages a short duration charging voltage—above the gassing voltage—at the beginning of the absorption charge state. Testing has shown that boost charging improves battery performance by providing a regular mixing of the liquid electrolyte. Boost charging specifically discourages capacity-robbing acid stratification and plate sulfation.
Boost mode charging can be enabled by selecting the Custom battery type and by setting the bulk voltage higher than the absorption voltage. The multi-stage charge algorithm then attempts to use the higher for the first hour of the absorption stage, unless it is interrupted by the max absorption timer or exit current threshold.
• Boost charging encourages gassing of flooded Lead acid batteries.
• Boost charging is NOT recommended for AGM, GEL or any other electrolyte-limited and/or valve-regulated sealed battery application.
• Boost charging may result in higher than normal water consumption. However, the benefits of boost charging are likely to be greater than the extra watering effort. Check battery water levels at least once per month.
• Boost charging has maximum benefit when used on batteries that experience moderate cycling. An unoccupied cottage, for example, where batteries are full the majority of the time may not benefit from boost charging, especially if battery watering is difficult.--
Chris
Larger screen for us people with glasses & dont hook in remotely every day?
Not sure if its possible right now as still getting around menus/functions but time of day that absorb/boost/float was acheived is nice. Just helps knowing soc over those cloudy days.
I guess time in float kindof does that but then i gotta do maths?
My system is on a remote mountain peak which provides power for radio equipment. It is difficult and time consuming to get to.
I personally don't need boost. What I need is remote voltage sensing of the battery voltage. The external shunt will also be very useful.
I want a CC that is reliable at logging data, either onboard or on a web site (needs to have high availability, not off line very often). BTW, I only use ethernet connections, no modbus, no RS232, etc.
I want a system with a sophisticated UI that I can program to either text or email me when certain conditions occur... such as not achieving float for say 2 days, email me if the AUX output energizes the generator, email me if battery voltage goes below a threshold, if it gets too hot, etc.
I would like to be able to remotely update the firmware, without having to be physically in front of the unit.
I am sure there is more.
Tracy
Communications engineer in New Mexico, USA
The ability to speak Xanbus, would be great ;)
I think Boost mode is opposite of what Surrette and SMA advocate. They do not want the batteries to get fully charged every day!
More on this later.