Author Topic: New Batteries  (Read 1231 times)

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Offline MadScientist267

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New Batteries
« on: December 31, 2015, 01:54:48 pm »
I've actually had them for a couple weeks or so now, but I've been so busy that I haven't had time to update anything. Here's a short quip and the pic...

4997-0

4 x 6V @ 215Ah, configured 2S2P for 12V nominal @ 430Ah.

The two "extra" connections at the bottom are for "close as you can get" for measuring jumper delta. Whole slew of reasons to do this... Safety, balance, longevity, etc. It will catch (and already has actually) connection issues at any point up to the bus bar on the power board. Very easy to implement if you have a spare differential ADC channel to donate to it, and well worth the while.

That's all I got for now... till next time...

Steve
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Offline MadScientist267

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Re: New Batteries
« Reply #1 on: December 31, 2015, 02:04:39 pm »
A tack on... the delta plot...

4999-0

Almost 24h ago now (far left), can see where they were trending away from each other due to a weak connection.

Following this where it spiked to 0 is when I did the calibration.

Then, as you can see, after the connection was tightened, they headed back into balance.

Steve
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Offline MadScientist267

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Re: New Batteries
« Reply #2 on: September 07, 2016, 05:53:27 pm »
Well obviously this needs to be updated... sheesh :o

Didn't want to do it with one of my hard picture hit and runs but... nutshell story here centers around the thermal gradient effects across the bank imposed by strong cooling on one side of the box. Left to right in the above pic they're 1-4 as referred to by the delta ("departures") plot, the main "end result"... The rest are the conditions it occurred in.

6116-0

6117-1

6118-2

6119-3

6123-4

6120-5

6121-6

And finally, the one that at first glance might seem like a misfit of sorts... But is included because the condenser temp provides a bit of insight as to the conditions the hot side of the Peltier is experiencing... There's a carefully designed array of passages and fans that manipulate the airflow thru them... It indicates (with a little interpretation) what's going on whether the fridge is running or not. Only the transitions from one state to the other disrupt the hidden data underneath. Big thing here to note is that while the Peltier was pumping harder because of its direct feed from the sun during the day, overall conditions weren't nearly as dramatic as the ones later in the evening, yet had a much greater effect. Combined with the battery box temps, it's pretty clear that there was plenty more margin to pour heat thru, yet the batteries in float are mostly unaffected. I confirmed that this was thermal again in the near future, and not the usually "unprovoked" weebles and wobbles that happen from time to time under charging or discharging conditions.

6122-7

It's been too long a day to go much deeper into all this than that, but there's the basics on why gradients should be avoided as possible within a bank. Left unchecked, they create unfavorable conditions with a positive feedback loop against the lifespan of the bank as a whole. Obviously those with single cells accessible can do some compensation if so inclined electrically... those of us with GC2 and the like have our hands tied a bit tighter...

Till next time...
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Offline bj

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Re: New Batteries
« Reply #3 on: September 08, 2016, 07:53:30 pm »
   Interesting Steve---kind of knew about the effects, but didn't really comprehend the full
effect.
   Just going through my head about changing my ventilation on the new battery/generator
room to accommodate more air around  the batteries.  No big to do, and can't hurt.
  Thanks for sharing.
"Even a blind squirrel will find an acorn once in a while"
bj