[C320-list] Battery selection; Questions & Answers

[Warren Updike]

Following-up on Chris Burti's comments on the Exide Com-4D-P battery, I
posed several questions to Exide via their web site and was promptly
answered by Paul Korinek, Engineer.  

 

Q-- I'm replacing my two 4d batteries on my Catalina 320 sailboat. Here are
two Exide 4Ds I've found. I want to be able to discharge up to 50% for the
most number of cycles, however, my typical discharge is about 20-40%.  My
typical load is between 5 and 10 amps.  Total per day about 90A.  Could you
advise me as to which of these would best suit my needs?

NG4D                    RC250   AH160 (AH/RC=0.64)

COM-4D-P           RC320   AN205 (AH calculated based on 0.64RC)

 

A-- If you can adapt to the SAE terminal post, I would suggest the Com-4D-P
for your cycling app given that it has approx 30% more capacity which will
provide for a lower depth of discharge and extend life.  But if you must
have the marine terminal, the NG-4D has this.  Both have similar chemistry
for cycling purposes.  (WU-post adapters can be purchased to convert the
posts to bolt type marine posts.)

 

Q-- Do you recommend a periodic equalization of batteries under these
conditions?

A-- An equalization charge is a good practice but you have to be careful of
too much of a good thing.  Excessive equalization / overcharging will
dramatically shorten the product life due to grid corrosion and paste
shedding.

The equalization should not exceed 6hrs and water levels should be monitored
before and after.  I would not equalize the battery more than once per month
during use.  If the battery is performing OK and the charged voltage is >
12.8V when the acid levels are good, you don't need to equalize.  I would
equalize after you add water to mix the acid to avoid stratification which
can occur.  (WU-Others recommend that you monitor an equalization process
with a hygrometer to avoid over charging.)

 

Q-- Do you recommend several initial deep discharge/recharge cycles as a
break-in before placing in-service?

A-- Initial cycling is not a bad idea but not absolutely necessary for Exide
batteries.  An initial equalization charge is the most important thing to
bring the state of charge up to the 95%+ range.  Other manufactures
design/mfg their product such that it does require 10-30 cycles to reach the
rated capacity.  But this is not the situation with these Exide products.

 

I'm going with the COM-4D-P this spring.

 

Warren & Pattie Updike

1994 C320 #62 "Warr de Mar"