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. -- View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Charger-auto-shutoff-external-switch-tp4665111p4665143.html Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com. _______________________________________________ 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)
