Hey, if I can get out of bed these days without something hurting, I'm good.

Batteries

Shorai 6V Batteries in Parallel

If you ever need to run parallel Shorais for more capacity (these are two Shorai 6V for a ’48 Panhead).  I had to help a customer out today to help him achieve more capacity to lengthen his time in between charges.  I thought I’d share.

This is the best way to do it.  I truly recommend using a balance charger (like the BMS01) however, to balance them occasionally.   Balance chargers will charge each cell individually to  3.6V each (the Shorai batteries are multiple cell, prismatic to be exact) but they are wired 2S for the 6V and 4S for the 12V).  When you charge via the terminals and either your charging system is out of whack, or your battery voltage maintenance (guilty here!) is pretty poor, sometimes your cells can get out of balance.)

I do NOT recommend using the parallel method to improve performance or run lights at idle on vintage bikes due to low output at low rpms regardless of 12V or 6V.  You really should update your generator if you are having issues maintaining good idle voltage output.  If you use parallel configurations as a Band-Aid for your output, the battery will fail prematurely.  Dropping super low in V and then hammering it with high output at higher rpms is not good for any battery.

WARNING: Parallel is positive to positive, negative to negative.  If you do the opposite you will short your battery and fireworks will ensue, plus you will probably weld the connecting bars together.  One word of advice, DON’T.

These set ups require a dual polarity set up (one battery must be opposite polarity from the other ).

Front to Front Configuration
This set up will fit battery boxes/wells that are:

  • 3.5″ in height (plus a little extra room for terminal cables and important things like protective positive boots!!)
  • 4.56″ in width (plus a little room for the adhesive foam as the connectors do not make the battery fit absolutely flush front to front)
  • 4.45″ in length

Top to Top Configuration 
This is more similar to the 6V batteries that you often see for some HD vintage 6V, the CH-2 (or H2) that is H= 8.5″ x Length= 4 5/8″ x W=4″).  This set up will fit battery boxes/wells that are:

  • 7.5″ in height. (This will also require adhesive foam between the two batteries as the connectors do not allow the battery to fit absolutely flush top to top).
  • 2.28″ in width (width being front to back; but you will require a bit of adhesive foam to keep the two backs of the battery in line with one another. If you don’t, the connectors may bend, see pic 2 and 3.  Better to have it and not need than…you get the picture.)
  • 4.45″ in length (length being + terminal to – terminal, basically)

I hope this helps!

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