Two items of possible interest to the group :)

 If your group has any interest in either of these things I'd love to hear b
ack from you.  If you've got suggestions on these ideas I'd really love to  
hear those.

A coworker of mine has been making these and is thinking about making a bus
iness of it:
https://www.kickstarter.com/projects/1214410980/garden-circles-a-new-raised  
-garden-bed-for-every-g?ref=nav_search

The other items is a battery management system - it allows the hooking of a
ny batteries into a smart bus that optimally charges each battery while mak
ing the potential of that battery available to the bus.

Normally such systems put batteries in banks and some batteries tend to get
 damaged by the resulting imbalances, this system is immune to that.

Here are what they look like right now:
https://goo.gl/photos/A8wyGunbpGWWFFDr9  
https://goo.gl/photos/ymt8MsFXeRoePCbx5  

(These are shots from my test bench) - final runs will look a little differ
ent, but not much.  I could really use ideas and feedback on these boards i
n terms of capabilities and feature sets.  I've got a pretty solid idea wha
t I think they should do, but it is in my best interest to include the func
tionality that potential customers want. :)

Feel free to hit me up with additional questions.. I really should try to p
ut together a proper document detailing the capabilities and usefulness of  
such a board.

  If your group has any interest in either of these things I'd love to  
hear back from you.  If you've got suggestions on these ideas I'd  
really love to hear those.

A coworker of mine has been making these and is thinking about making  
a business of it:
https://www.kickstarter.com/projects/1214410980/garden-circles-a-new-raised-garden-bed-for-every-g?ref=nav_search  

The other items is a battery management system - it allows the hooking  
of any batteries into a smart bus that optimally charges each battery  
while making the potential of that battery available to the bus.

Normally such systems put batteries in banks and some batteries tend  
to get damaged by the resulting imbalances, this system is immune to  
that.

Here are what they look like right now:
https://goo.gl/photos/A8wyGunbpGWWFFDr9  
https://goo.gl/photos/ymt8MsFXeRoePCbx5  

(These are shots from my test bench) - final runs will look a little  
different, but not much.  I could really use ideas and feedback on  
these boards in terms of capabilities and feature sets.  I've got a  
pretty solid idea what I think they should do, but it is in my best  
interest to include the functionality that potential customers want.  
:)

Feel free to hit me up with additional questions.. I really should try  
to put together a proper document detailing the capabilities and  
usefulness of such a board.

======================

I've been studying and experimenting with how to optimally charge 12V  
lead-acid batteries, flooded and AGM. The details of the suggested  
charging algorithms depend on the battery's internal temperature,  
capacity and designed use, differ among manufacturers and change as  
the battery ages.

How do you adaptively determine the maximum bulk charging current and  
the proper absorption and float voltages, and decide when and how much  
to equalize?

I read the label and look up the data sheet online. My universal  
charger is a Variac-controlled transformer, rectifier and capacitor  
with digital voltage and current meters, but no active regulator which  
makes it immune to loss of AC power while connected to a battery. The  
rectifier output automatically tapers down the current as the battery  
voltage rises, so it can be left unattended, or bumped up as needed  
when I walk by.

DC-DC converters with the SEPIC topology can efficiently raise or  
lower individual battery voltages to a common level but they aren't  
cheap at higher currents.
https://en.wikipedia.org/wiki/Single-ended_primary-inductor_converter  

John de Armond once referenced a good paper from the Bureau of  
Reclamation on battery maintenance.

--jsw  

 
http://www.chargingchargers.com/tutorials/charging.html  
"You talk to different engineers, even at the same company, you get  
different answers."

After a week's trial I'm pretty impressed with the $
0 Uni-T UT210E  
clamp-on ammeter's 2A DC range, with reasonably stable 1mA DC  
resolution. Being a clamp-on it can safely measure low charging or  
leakage current in battery circuits that could easily fry a DMM's  
current shunt, or are troublesome to reset after disconnecting such as  
a newer vehicle.
http://www.eevblog.com/forum/testgear/a-look-at-the-uni-t-ut210e/  

--jsw  

 
The current link:
http://www.usbr.gov/power/data/fist/fist3_6/3-6.PDF  

--jsw