batteries under V-berth

[Fulvio]

Has anyone installed a second battery bank under the V berth?  The space just forward of the hanging locker (stbd) and the drawer locker (port) seems a good candidate, with one battery on each side.

Fulvio Casali
Seattle WA
Soliton
#929 (1989)

[pklein]

I have two group 27 batteries and one Group 24 battery in the stock battery compartment.  The 27's are turned 90 degrees from the normal position dictated by the molded partitions in the compartment and are side by side outboard.  The group 24 drops in on the inboard side and makes everything snug. I "sort of" have them tied down.  I know I'm at risk in the event of a knockdown, but Lake Michigan and I understand each other. It almost looks like there's room for a 27 instead of the 24.  The two batteries are connected the the 1-2-All switch and the third battery is only connected to negative (black).  It's strictly for emergency starting and if needed it's a 60 second job to move a positive connector from battery 1 or 2 to the spare. I check the charge state of the spare about every 6 weeks.  For the $50 cost of the battery, it's cheap insurance and I don't mind that it never gets used and needs to be replaced after about 3-4 years.

BTW I replaced the ferro-resonant charger that came with my '89 and have never had battery problems since.

Phill Klein
Andiamo #977
Montrose Harbor - Chicago

[jentine]

I agree with Ron.  It is a long way from the power panel.  The only battery I would put forward is one for the windlass.  You don't want to put too much weight forward of the mast because the boat narrows too much and there is little buoyancy at the pointy end.
I have done as suggested and put four golf cart batteries in the compartment under the settee and a starting battery in the compartment with the holding tank, above the macerator pump.  The cables pass through the compartment there and make for an easy connection.
Jim Kane

[Fulvio]

As for distance, I thought it's just a matter of running thick enough cables (to minimize resistance, and therefore voltage drop).  But the bouyancy factor is a different story.

Regarding the 440 AH in the battery compartment:  that sounds great, but isn't it risky to cram so many batteries so close together, considering thermal runaway?

Thanks for your suggestions, I appreciate them.

Fulvio Casali
Seattle WA
Soliton
#929 (1989)

[jentine]

Please define thermal runaway.  Some theories are just that.
Jim

[Ted Pounds]

Thermal runaway can be a problem in NiCad batteries like those used on aircraft.  I don't believe it's a problem with lead-acid batteries because if they overheat during charging the electrolyte boils off shutting down the charging.  Of course, if you are still concerned about it, a good charger like the Satpower with a temp sensor should put your mind at ease.  I too use the 4 golf cart batteries under the dinette seat.  I got mine at Sam's club, $45 each.  I've been very happy with their performance.

Ted

[Fulvio]

I quote from "Boatowner's Mechanical and Electrical Manual" (2nd Ed.):
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>  Additional features: Different regualators have numerous additional features, in particular:
[...]

• Temperature compensation, which lowers the regulator's voltage set-point if the battery temperature rises.  When coupled to large alternators, the high currents produced by multistep regulators will cause a battery to warm up, which in turn will increase the battery's charge acceptance rate (the warmth accelerates the chemical reactions needed for charging).  Unless the voltage regulator setting is lowered, the battery will steadily absorb more current, further raising its temperature, until damage occurs (note that the fitting of Hydrocaps to wet-cell batteries exacerbates this problem).  In extreme conditions a battery can get into a condition known as thermal runaway.  This will destroy the batteryand can even cause it to blow up!  The maximum safe battery temperature is 125°F (52°C).  Battery charging can be accelerated only until this temperature is reached;  the rate of charge must then be tapered off to ensure no further rise in temperature takes place.
  Without temperature-sensing equipment, how can you guard against this?  Anytime a battery case becomes warm to the touch, it should be suspected that the internal temperature is dangerously high.  (Battery temperature can be determined more accurately by using a digital thermometer on the battery post or withdrawing a sample of electrolyte using a hydrometer with a built-in temperature gauge.
  [...]
  <HR></BLOCKQUOTE>
  
  
  I also remember reading somewhere (or maybe I heard it from Nigel himself), that for a similar reason multiple batteries constituting a single "bank" should not be placed in spaces with radically different temperatures.
  
  But I'm starting to split hairs.
  
  The 400 AH golf cart solution in the standard battery compartment sounds good to me.
  
  Fulvio Casali
  Seattle WA
  Soliton
  #929 (1989)

[jentine]

It sounds like Nigel Caulder has too much time on his hands.  Thermal runaway!!!!!!!!!  Please cite some real examples of this being a problem on Catalina 34 or any other boat.  I (just for the heck of it)felt the battery in my car after driving 100 miles.  Guess what1!  It was warm.  Should I be concerned?  I think not.  The battery in my motorcycle gets warm when run for several hours.  Is this a problem?  NO!!!!!!!!!  The regulator keeps the charge rate within acceptable limits.  If it does not, the problem is not with the battery, it is with the regulation system.
 :eek: