There are others on the evdl that are much more knowledgeable than current hardware and software than I, and I hope that they post their thoughts.
In my career, I did both, and used skills to always keep the customer happy. So, I'd like to take a step back from what you are saying and try to see more, so that a bigger picture is seen by all those that are wanting to help you. I am thinking a bit more detail from you would be helpful. Is this the EV you are discussing? http://www.evalbum.com/3440 You stated that you are comfortable with programming. Of what type? Apps, GUI, OS, ... which, what, where? You also said you could do hardware, but it is not your comfort zone, so the simpler the better. Is that right? But basic soldering, &stuff is not a problem, you just want to use someone else's design, right? >From what I have gathered, you would like to: -use your existing Russco charger, but include a way to have it turn off in two-hours after the charge cycle is complete, so as to ensure the pack is not over charged. There are others (like the circuit David posted) that can aid you in this quick and cheap quest. But I am feeling that your concern is from a past experience with a prematurely aged pack from what you have concluded is from overcharging. ... I am also thinking that what would help you the most is to really-know what is going on with your pack (whether it is being under or over charged). Under charging a PbSO4 pack is bad, same as cooking or over-charging a pack. Perhaps in the future, after this current project is done, you may want to consider something more detailed, that would not only turn off the charger, also gather data on your pack. This could also be helpful on the other EVs you own and or when you change to a different pack chemistry. Awhile ago, evdl member Chuck Hursch http://www.ebeaa.org/graphics/chrabbit.jpg was working on a project to gather data on his EV pack http://electric-vehicle-discussion-list.413529.n4.nabble.com/USB-Serial-in-EV-tp455094p455097.html Rather than building a specific analog to digital (dac) circuit to communicate via a port on a computer, he chose an off the shelf idea: a digital multimeter (MM) that had a serial port. After figuring out how to interface the MM serial port to a laptop (I helped, by installing a couple OS' on it for him, winxp & linux), the laptop would record the charging data. The data was accessible via blue tooth to his upstairs PC for him to crunch. I am thinking you could do something similar that would fit 'your' needs, but using today's inexpensive goodies ... Change is exponential/rapid, and much has improved since then. Now, there are MM that have a USB port http://www.ebay.com/itm/Digital-Multimeter-Voltmeter-Thermometer-Ohm-USB-CD-C-Continuity-Frequency-Diode-/280965494690 Instead of keeping a huge laptop in the EV, there are inexpensive tablets with USB ports running Android OS http://www.ebay.com/itm/321166025705 (ignore the pictures and look at the specs at the bottom of the page) Android OS is Linux based http://en.wikipedia.org/wiki/Android_(operating_system)#Linux And there are development tools for those programmer types that are comfortable with 'having a go' http://developer.android.com/about/versions/jelly-bean.html So if later you were so inclined, the prices would be even lower (tablets are so cheap now, who knows, by then they may giving them away in cereal boxes), and you could easily tuck a small tablet under the dash or in the glove box. It would monitor the pack voltage to not only ensure the charger was turned off at the time you want (2 hrs), but record your pack data, so you too could know the health of your pack. PbSO4 packs age, thus so does their finishing voltage. There is also the benefit of being able to use the tablet's other feature to amuse yourself while you are waiting for the charge (like adding a low-cost infotainment system to your EV). And the tablet could also offer cloud apps, so your data could be stored elsewhere for later retrieval. The sky is the limit, you could run wild with ideas, and then ... see what fits your needs :-) {brucedp.150m.com} - On Thu, Sep 12, 2013, at 04:05 AM, Steve Powers wrote: > I was having an off-line discussion with Lee, but I am going to post my > question because it may spark new ideas and be valuable to people besides > me. Here it is: > > When I asked Russ, he clearly said my charger has no shutoff at all. It > wasn't until the 3 stage models that the shutoff became standard on the > charger. Probably the main board is the same, but not populated. He can > upgrade it, but it isn't inexpensive and will only be an analog shutoff, > not > the latest digital shutoff design. I wonder if the red LED flashes when > is > changes from CC to CV. If so, I could tap into that trigger and run a > timer > of it. But, I think on mine the LED is always on when it is plugged in, > never flashing. > > > To start from the beginning, here is what I am really looking for. Now > that > I have this new (new used) charger, I want to be sure I don't cook the > batteries by leaving it on too long. The whole reason I went with the > Russco was to get better control over the charging of my batteries to > extend > their life. I am getting rid of a QuickCharger and a Zivan K2, both of > which tend to cook the batteries and offer no method to slow charge if a > lower current outlet is used. I'm kicking myself for buying one without > the > shutoff, but that's a whole different story. With the current pack, I > don't > care, but I am going to replace it soon. So, something possibly external > to > the charger to measure either voltage at a certain high threshold or > current > (voltage across a shunt) at a low threshold that triggers a timer of > fixed > value (2 hours I think). So, the trigger is a voltage level, followed by > a > time delay, followed by opening a high power relay (disconnects ac input > from the charger). > > I've seen all the other options of a fixed timer, but then I have to know > exactly how long the overall charge cycle needs to be which I will never > get > right and will vary depending on depth of discharge. And, they are > usually > fixed at 8 hours which isn't helpful at all. > > Things I have at my disposal > - RadioShack DMM with serial communication > - plenty of high power relays and contactors > - several electromechanical and electronic timers (the kind you buy at > WalMart or Home Depot) > - I don't have any computer controlled relay switches, but I could buy > one > relatively cheap > > I could do this with a PC hooked to the meter and a USB controlled relay. > I'm very good at programming, much better than I am with hardware or > analog > circuit design. But, I think that is overkill for what I am trying to > do. > Instead, I really want a black box solution, self contained, powered off > either 12V DC or 120V AC that hooks across the battery pack and > mindlessly > opens a relay 2 hours after the voltage (adjustable) threshold hits. In > the > simplest sense, it could be powered by the pack itself. I envision, a > manual switch where I connect this "contraption" across the battery pack > when I want to charge. If V< ~170V (need to look up exact value for 144V > flooded pack) it allows the AC current to flow to the charger. Once it > reaches the threshold, it starts a timer and opens the relay 2 hours > later. > The charger is essentially unplugged and my batteries are saved from > being > overcharged. That's what the built in analog shutoff essentially did on > the > previous Russco charger I had. > > I think a lot of people who are going to Lithium want a similar extra > safety > feature in case their BMS fails. Do you have any ideas to make a cheap > black box solution for people who aren't Electrical Engineers but have > basic > abilities to build circuits from a simple schematic? I would think this > is > easy, but may require a small micro. > - -- http://www.fastmail.fm - Send your email first class _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
