Realtime LED Based Subpack Monitoring

[uhtrinity]

I was browsing through the Forkenswift website and videos http://forkenswift.com/ and came across this http://www.evconvert.com/article/led...attery-monitor

The best visual example is this You Tube video http://www.youtube.com/watch?v=cHlq1J5dbb4 Setting up this through the stock connector will allow visual monitoring of all 10 subpack pairs under load, or in my case 20 subpack pairs. This would allow quick identification of weak (out of balance) subpack pairs under load. If you wanted to you could even double the number and monitor every subpack. He does give instructions for rescaling the pack size (6 volts vs 12 volts). For our usage we would have to rescale for 7.2 volts or 14.4 volt packs, as well as determining what upper and lower ranges you want displayed. Total pack values would most likely be 180 volts as a high and 120 volts as a loaded low. That would give a 0.6 volt per led resolution per 14.4v sub pack pairs, or 0.3 volt resolution for individual subpacks. A single display for an entire pack would give 6 volt resolution for that same range.

Here is the original National Semiconductor pdf for the lm3914:
http://www.national.com/ms/LB/LB-48.pdf

Too much fun

[Roger Crier]

I like that. In fact, I like that a lot! Just imagine a bank of 120 of them

You would never get time to look through the windscreen with that lot to look at!

Rog

[uhtrinity]

Well, I built up the first one on a bread board, and finally got all the values figured out for 14 volts (1 led) up to 17.5 volts (10 leds). After that I built the first one on a proto board, which took about 1.5 hours) and it worked the first time. This allows it to run right on the C connectors coming off the battery packs, and the battery pack actually runs it. Power draw seems to be about 18 mA in single dot mode for one board. This also takes into account the two 180ohm limiting resistors that are integrated into the packs (which were a pain to figure out). Only 19 more to go for my 20 subpack pairs. I also found a good surplus deal on pcb mount relays at 20 cents each, so in all this project won't break the bank. I'll set the relays to turn on with the key. I will post schematics and resistor details after I check this board against 2 subpacks for a full cycle.

[IamIan]

I don't know if 0.6 V per 12 cells or even 0.3 V per 6 cells is enough resolution....

Let us know what you find.