http://evolveelectrics.com/displays/tbs-e-xpert-pro/
Jay Summet via EV wrote:
Thanks for the link, yes, that would work.
This looks like a rebranded Xantrex LinkPro meter. The original was the Cruising Equipment E-meter. They were bought out by Heart Interface and it become the Link-10. Then Xantrex bought them, and it became the LinkPro. I think Xantrex outsourced it to someone (Mastervolt?) and it changed names again. These meters are all fairly well made; not the usual throwaway indoor-only crap.
It does use an external DC/DC and 1:5 prescaler, as well as an in-line shunt (I assume), but I could work with that (and the $300 price) if it's the best (only) option for the 2" mounting hole.
You should also be able to find any of the earlier versions on eBay etc. for much less. I've bought them for $50-$100. Just be sure it works (so you're not buying someone's broken one).
I do like the ability to monitor my 12 volt battery on the same gauge, I could potentially remove the Pack/Accessory voltage meters I have now in the center console and reclaim that space.
In fact, Heart Interface also had a 2-battery version, called the Link-20. All the same functions, but it monitored *two* battery packs. One drawback, though... the two shared a common ground. But that's fixable; keep reading. :-)
These meters all basically need an isolated 12v power source (provided by an external isolated DC/DC converter). Then, they have 4 input wires; +pack and -pack to sense voltage, and +shunt and -shunt to sense current. The -pack and -shunt wires need to be at the same voltage; treat them as if they are tied together.
The current draw on the sense wires is very low -- far less than 1 ma. This eliminates problems with voltage drop in long wires. It also means you can isolate it very easily. Switch a capacitor back and forth between the isolated voltage, and the meter's voltage. Switch position A charges the capacitor to the isolated pack voltage. Position B connects the capacitor to the meter, which reads the voltage. A second capacitor across the meter inputs holds the voltage while the switched capacitor transfers back and forth.
You can use real relays, and switch them maybe once a second. A circuit I saw from the 1950's simply used two relays wired as a self-oscillating flip-flop. Or optocouplers with FET outputs, switched by a 555 timer.
-- Knowledge is better than belief. Belief is when someone else does your thinking. -- anonymous -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
