Thursday, September 15, 2005

Batteries, Batteries, Batteries

Update:  finished the job and now have everything mounted in the engine room including:

1.     TrueCharge 40+ as the main house charger, or to charge four of the house bank batteries when they are split apart.
2.     TrueCharge 20+ as a backup charger, or to charge two of the house bank batteries when they are split apart.
3.     Optima starting battery for the GenSet.  Which is recharged by the GenSet alternator.
4.     Optima starting battery for the Perkins engine, which is recharged by the Perkins alternator.
5.     Six 6VDC golf cart batteries.  4 mounted in the original Morgan battery box alongside the port side of the engine, and two more mounted in battery boxes in the bilge between the Perkins and the Genset.  These are tied together with a 2 bank battery switch.

My question now is should I tie the house bank back into the Perkins alternator, or simply rely on shore power or GenSet power to recharge the batteries?

I came to a decision on what to do with Pelican's batteries.  I have not liked how the previous owner set up the battery loads, so I am going to take the time in September to get it fixed.  Right now here is pretty much how it had been set up:

Generator -- 12 VDC lead acid battery, tied to genset alternator and a TrueCharge 20+ battery charger

2 6VDC Trojans in aft cabin -- refrigerator only, tied to Perkins alternator and TrueCharge 40+ battery charger

4 Exide 6VDC batteries in engine room -- for all house except fridge, plus starting, plus windlass on 30 foot cable, tied to Perkins alternator through 2 way switch.  One set of 2 is tied to TrueCharge 40+, the other to TrueCharge 20+

TrueCharge 40+ is mounted in aft cabin on bulkhead next to Betsy's pillow.
TrueCharge 20+ is mounted inside engine room.

Problems with current set-up are:

1.   Starting Perkins from golf cart batteries which
   a.   causes electronics to turn off when starting the motor
   b.   is risky with house draw plus windlass draw on same set of batteries.

2.   Location of genset battery requires a maintenance free battery because it is hard to access from aft head.

3.   Fridge will deeply discharge a single set of two batteries over the weekend.  Prefer to see a more shallow discharge to extend battery life.

4.   Overall system is inefficient use of battery resources, hard to understand, and risky sharing starting batteries with house and windlass.

New Setup will be:

1.   Optima maintenance free 34M marine starting battery tied exclusively to genset.  (Yes, they are twice as much as cheaper marine starting batteries, but trouble free, could be mounted upside down or sideways if I wanted, and they have a 3 year warranty)

2.   Optima maintenance free marine starting battery tied exclusively to Perkins.  (OK, so now I'm spending 4 times as much, but really want to get this right.  This battery will be mounted in front of the genset, I estimate I need about an 8 foot cable run from the battery mounting to the engine.  Really not any longer than the current system going to the battery switch and back.  Oh, and the Optimas put out 1000MCA / 800 CCA vs. the cheaper option 550 CCA.

3.   The Exides will serve as a bank of 4 house batteries, still using the 4 way switch.  They will run the fridge, but no longer start the motor or run the windlass.  I believe I can still tie the Perkins alternator into these batteries to recharge them while under motor (?)

4.   The TrueCharge 40+ battery charger will be remounted inside the engine room.  Initially it will exclusively charge the house bank only.  I have the option of charging up to 3 sets of batteries with this system and can easily add the two optimas in the future if I desire.  (The Optimas are also sealed lead acid batteries so this will work.  You can't mix battery types with the TrueCharge.

5.   The 2 Trojans in the aft of the boat will be relocated to the engine room and tied into the four battery bank with the existing 2 way battery switch..  

6.   The TrueCharge 20+ will remain in the engine room.  It will exclusively be used to charge the 2 Trojans.  This way I have the option of charging all six batteries with either the 20 amp or 40 amp TrueCharge, or to split the bank of six into banks of 4 and 2 golf cart batteries and run both chargers at the same time, giving the system up to 60 amps per hour recharging.

7.  The Windlass will continue to run off of the house banks.

I think this will be a pretty good system.  All of the reading I have done and the participation in chat discussions points to it being a good idea to have separate starting and house banks.      


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