Third Battery on a 26C

[Tom Schoenhofer]

Where would you put a third battery in a 26C? I'd like to avoid putting it in the engine compartment or the lazarette because this area is used for other things already (maybe I should get rid of some of the junk?) but I see no other option.

I have two batteries in the stock locations. One under each of the aft berths in their own little compartments. 

There isn't room for a 3rd battery in these compartments because the hull slopes up here and there is not enough vertical clearance I believe.

I'm using Walmart group 31 marine batteries which have worked well and are +10 and 8 years old. The +10 year old one came with the boat and should be replaced soon. 

These are sealed but I don't want to put them on their side and they are in battery boxes anyway. 2 group 31ns on their sides would fit in one compartment and I think the AGM batteries can be put on the side but I don't want to pay for these.

Extra battery is for a planned additional load of a NovaKool and autopilot. One battery is always saved for starting. 

Tom

26C #28 North Star 

W13

Penetanguishene

 

  

[caped...@gmail.com]

I really like the Optima AGM batteries because the are very small for their ability and they can be put on their side, but I would not mix battery types, so if you have lead acid I think you should stay with those.  A small group 24 could be reserved for starting.

Tim in STL

[Thor Powell Mariner's Cat V - 26C - North Channel]

I have 3 batteries on board. A pair of Trojan 6 V golf carts in a box in the starboard lazarette and yes there is now only room for 6 fenders and the shore power cord.  

There is a battery box for the start battery in the port lazarette and it is on a small box further down in that cave than the Trojans.  I lose little space here due to the battery and it is a good spot for the start battery as it is close to the starter. 

I have mused that perhaps behind the cross member aft of the shaft would be a good spot for AGM or Gel batteries, getting them in there would be a PITA but since they need little maintenance maybe a small price to pay.

T

[Tom Schoenhofer]

Thor, do you have a Classic or Ultra? I will have to measure the space but I can't see fitting two golf cart batteries side by side in the 26 C lazarette without taking up all the space.

My battery charger has separate leads for two batteries and you can set dip switches to charge two different types. I may have to get a new charger when I go to 3 batteries but I see these also all have switches so you can mix battery types. It's when you are using the engine and everything gets 14.0 volts that the batteries have to fend for themselves. They are diode isolated so won't discharge into each other but that diode I believe is why the batteries never get a full charge from the engine.

The Optima AGM batteries are very good I agree. But one Optima costs twice as much as two group 31 marine Walmart batteries and one Optima has less capacity than 1 Walmart battery. I've been deep discharging my one house battery every summer weekend for 8 years and it still charges up nicely. The charger is a 10 amp and takes a long time, several hours, to charge it back up. I have no issues with the quality of the Walmart battery. 

Tom

[Mark Powers]

Tom,

I have two group 31 batteries installed under the starboard side quarter berth  and one Optima under the port side quarter berth. I have set the two  up in an "L" pattern. I have also installed a small pony wall for the bus bars. Here is a photo of the set up.

The two house batteries are 11 years old. 

Most split diodes cause a voltage drop and effects to ability of the alternator to bring the batteries to full charge. Westerbeke has instructions on wiring the split diode so that the alternator senses on the battery side rather then the alternator side thereby overcoming this problem however as the batteries come up to full charge their acceptance rate drops and it probably will take 4 hours of engine run time to put in the the last 5-10% of the charge so the loss in voltage through the diodes is generally not the limiting factor but rather the amount of time you are prepared to run the engine. 

Mark Powers

La Reina 26C

Vancouver, B.C.

 

  

[Tom Schoenhofer]

Hi Mark

Thanks for the picture. This is great and I'll try it this way. It's using up otherwise wasted space.

Do you use one three bank battery charger? My boat has a rather small 10 amp 2 bank charger. It is wedged in front of the holding tank. Do you think it's an ok idea to move it (or the new 3 bank charger) back into this space with the 2 batteries?

The boat next to mine has 3 batteries and the owner wired up a nightmare of battery switches. In your case do you just use the standard A or A+B or B switch where B is the house bank of two batteries in parallel? I'm trying not to complicate it.

Tom

[caped...@gmail.com]

Who manufactures the Walmart batteries?

Tim in STL
On Thursday, March 9, 2017 at 11:30:43 AM UTC-6, Tom Schoenhofer wrote:

[Mark Powers]

Tom, I am a little reluctant to get into technical discussions after my brain infarction yesterday on the day marker issue that Thor raised, however I will give it a shot.

I installed a 3  bank 30 amp charger. I wired two of the banks together to feed the house bank. There was not enough room or cooling air in the battery compartment for the charger so I installed it on the forward bulkhead of the starboard cockpit locker along with the galvanic isolator. I have attached a picture.

Originally I had a four position battery switch, Off, A, B or Both along with a split diode for charging. After reading too many articles and talking to too many people I went with a 3 position, Off, On, and Combined switch with an automatic charge relay (ACR) from Blue Seas. I have a second two position switch for the engine. In hind sight I would have stayed with the four position switch and split diode. I would use the "A" terminal for the larger bank and run both starting and house loads off of that. I would keep the smaller bank for emergency only and run it off of the "B" terminal. In this way I could keep the banks fully isolated. Under the current setup if I use the "Combine" setting the batteries act like one bank and a bad battery can pull down the good battery.

Compass Marine Inc. has a good article on installing a battery charger.  http://www.pbase.com/mainecruising/installing_a_marine_battery_charger

[Thor Powell Mariner's Cat V - 26C - North Channel]

I have a Classic and yes the box the two golf carts take most of the space.  I don't have photos unfortunately. The box is on a shelf so the top is about a foot down. There is space behind and aft but all I can get in there is 6 20 inch fenders 4 flat foam fenders and the shore power cable. The start battery is on the other side but the top is only about a foot off the bottom so does not take much space.

The diodes will fool the regulator.  One of the side effects of diodes is that there is a voltage drop associated with them. This drop is not constant and varies from around 0.6 volts to 1.1 volts depending upon how much current is flowing through them. At very high charge currents the voltage drop can actually be as much as 1.6 volts. The higher the current, the higher the voltage drop. This means that the output voltage of your alternator at say 14 volts is not being presented to the batteries. The batteries will only be "seeing" between 12.9 and 13.4 volts depending upon the charge rate. Obviously this drastically reduces charging capability. The charge voltage on the batteries is simply too low.

AGM and gels are nice offer quick charge rates and flexible placement  but they remain  expensive.  I have used Trojan wet cell  golf cart batteries and for what do they have lasted 8 - 9 years.  No refrigeration so they are not heavily taxed.   We need 10 to 15 days between full charging  and so far they have been fine. I use a 120 amp alternator with a separate regulator  that is restricts charging to no more than  to 80 amps due to the belt.

[Rick Oppegaard]

Hi Guys.
I have 4 6V house batteries and a 12v start battery in the stbd laz. of my 26C. It for sure takes up most of the room but I can still fit a few things in there. I had to cut out the plywood that separates the laz into two compartments, and build a stout platform to hold the batteries securely.

Rick.
84 26C
Puget Sound