Hi Ben,
Sorry to hear you are having these sorts of issues - I'm in a very
similar situation, including the miniBMS. Fortunately for me, I have a
friend at work that is very good with batteries and such, and is helping
me build a battery tester - it uses a 0.1 ohm resistor and a strong
MOSFET (transistor) and a 16-bit ADC to determine the resistance of the
battery. Once I get something I can assemble, I can send you the PDF of
the schematic and such. However, that's not for a week or so.
Your idea of the dyno is not a bad one - especially if you can see all
of your batteries (or at least the BMS). So if you can keep the Jeep
running until you get the fault, then the battery that is soft will be
missing the green light.
Note to BMS designers - put something in there to indicate that the
battery has had a fault recently. Red would be a good color.
Cheers,
Peter
On 1/24/13 7:52 PM, Ben Jarrett wrote:
So my Jeep is becoming almost non-functional.
It used to be I would get a low voltage alert occasionally on the =
highway when going 60+ mpg
(where I tended to sustain 300+ amps for more than a few seconds when =
accelerating)
Now I get low voltage alerts from my BMS and from the Soliton for very =
moderate acceleration
and at much lower speeds (like 35 mph).
I had someone test a few of my batteries, and they test came back pretty =
good.
I haven't measured all of my batteries (I have mini-bms so it's hard to =
know the exact state of things)
but I feel that all of my batteries are basically sagging (vs having 1 =
voltage drop in my system somewhere.)
I'm not sure if I need a new battery pack or if there's something else =
going on. My pack voltage drops
from 160V to 120V during decent acceleration. This seems too much. It =
seems unlikely that all
of my batteries are bad though.
What I would like to do is put my jeep on a full vehicle dyno and test =
the voltage drop at various
places to see if something else is awry. Not sure if this is possible, =
but I'm not sure
what other options I have (besides hooking up a few multimeters to =
various spots, driving around, recording
data, then moving the connections and trying again.)
Any other ideas?
thanks!
-ben
www.evalbum.com/4001
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