Thank you , Lee. Some concerns about cost may drop away because I am not aiming at automotive EVs - for now , maybe never.
Because I need to go for some grant funding, I have to be aimed at manufacturers - job creation is what everything is about these days (I don't disagree). The automotive manufacturers will likely build their own labs. But, the LEV (and smaller) market is in need of some help. I think electronic loads are a good idea, but I will have to roll my own stuff for a while; that will be a good learning experience I am sure. Just guessing, I suspect I can do a lot with 50A of current and load. 6000W is pushing 10 HP. Electronic loads that size would be costly. I need to sort this out better though. I am trying to put together a survey to collect information about testing people need but can't do, testing they would far out if the cost was right, and so on. I need a range of packs sizes in this space. I know there is still some lead acid being used, so I probably need to consider that, but the arc of the future is probably Lithium batteries. I am already set up to use National Instruments DAQ and Keithley DMM instruments. I already program extensively in LabVIEW, so we will stick with that (also the university has a site license for it). We get an academic discount on hardware and NI has an extensive array of choices. I am still interested in seeing DIY setups - that is always very instructive. On Fri, Nov 7, 2014 at 12:30 PM, Lee Hart via EV <email@example.com> wrote: > Roger has some excellent advice here. It reflects a lot of what I do > myself. :-) > > Roger Stockton via EV wrote: > >> Thought I'd mention that while a programmable load is an *excellent* >> way to discharge when testing batteries, it can be pricey... >> > > Indeed. Programmable loads get very expensive if you are dealing with high > power (high voltages and/or high currents). They are also effective room > heaters. Good in Minnesota winters; but bad in Arizona in the summer when > you're already paying to air condition. > > If you already have a data logger or other means of >> measuring/controlling a load and charger, then perhaps consider using >> a passive load in parallel with a smaller electronic load, so that >> you can save money on the electronic load purchase. >> >> A simple QBasic program on an old laptop controlled the relay for >> the load and another for the charger via the parallel port. >> > > This is the approach I use. I have a couple of $50 DAQ118 analog/digital > I/O modules that plug into my PC. They have several 12-bit analog inputs > (to read voltages, currents, and temperatures), outputs (to throttle the > charger, and digital output channels (operate relays to select various > loads). > > They are run by a PC with software written in QuickBASIC. I have an old PC > that is too slow for anything modern; but has a parallel port and is > rock-solid-reliable and can run tests for days. > > These modules were bought in 2002. I'm not sure if they are available > today, but there are lots of equivalents. > > I also have a Keithley 576 Measurement and Control system. This is a > stand-alone data acquisition controller. Rather tedious to set up, but lots > of channels, high precision, and very versatile. > > I use these with a commercial battery charger for charging, and a custom > made load box that basically consists of a bunch of big power resistors, in > a box, with a fan, and relays to select the load resistance in a stepwise > 1-2-4-8 sequence. > > I started out with a battery cycler setup consisting of a bank of 12VDC >> Edison-base (household screw-type) light bulbs >> > > Light bulbs are a good *and* cheap load resistor. :-) As Roger says, they > have the useful feature of drawing a roughly constant current despite > changes in voltage. This is a simple way to get an approximately constant > load current despite the sagging voltage as the battery discharges. > > I've used car headlights (about 4 amps each) and taillights (about 1 amp > each) as load resistors for 12v battery testing. > > A simple QBasic program on an old laptop controlled the relay for >> the load and another for the charger via the parallel port. >> An E-meter with the RS232 comms option provided voltage, current, >> etc. measurements to the QBasic program. >> > > This describes the most common load tester I use. I have a few E-Meters / > Link 10 / ProLink meters (all the same meter, but sold respectively by > Cruising Equipment / Heart Interface / and now Xantrex). These measure > volts/amps/watts/amphours/watthours/time/temperature and send the data to > a PC via an RS-232 serial port. I have a QuickBASIC program that logs, > plots, and prints the data. > > The "controller" is an old Manzanita Micro "Rudman Regulator". It has an > output that switches a relay to select between charge and discharge, and > trimpots to select the max and min voltage at which to switch between > charge and discharge. This setup has been documented in the EVDL archives. > > I also built my own stand-alone battery tester/cycler, which includes the > charger, constant-current load, and metering for volts, amps, amphours, > temperature, etc. It is documented at > > http://www3.telus.net/nook/balancerland/cycler/index.htm > > This stuff is not exactly "hard" to build yourself, either from scratch or > cobbled together using whatever you have on hand. But it does take a fair > amount of time and effort to sort it all out and figure out how to use it. > -- > A designer knows he has achieved perfection not when there is > nothing left to add, but when there is nothing left to take away. > -- Antoine de Saint Exupery > -- > Lee Hart's EV projects are at http://www.sunrise-ev.com/LeesEVs.htm > _______________________________________________ > 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) > > -- Put this question to yourself: should I use everyone else to attain happiness, or should I help others gain happiness? *Dalai Lama * Tell me what it is you plan to do With your one wild and precious life? Mary Oliver, "The summer day." To invent, you need a good imagination and a pile of junk. Thomas A. Edison <http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> A public-opinion poll is no substitute for thought. *Warren Buffet* Michael E. Ross (919) 550-2430 Land (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google Phone (919) 631-1451 Cell (919) 513-0418 Desk michael.e.r...@gmail.com <michael.e.r...@gmail.com> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20141107/65c7de7c/attachment.htm> _______________________________________________ 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)