Placement of 4 Group 27 Batteries

[H33CRich]

The PO installed two grp 27 batteries forward of the engine (standard location) over the sump area, plus another two in the starboard cupboard under the half-bunk. These were used primarily to power a TV and VCR. There is a separate battery charger for them with a 150 watt inverter. I have read Paul F's modification about converting the shower sump to a dual 6V battery holder. Where would you recommend placement of my second pair of grp 27s? Is there a recommended 4 battery switch to tie all 4 together?

I am not totally thrilled with their current location and use.

 

[Paul F]

I have been playing around with the battery arrangement and battery switching for years. This is the latest "Plan" which has been in place successfully for a few months. While I have 2 6 volt house batteries and one 12 volt starting battery. This plan will work with your 4 12 volt batteries as well.

On the Hunter 33 I would recommend putting two in the shower sump with a cover board above them to hold two more batteries. In other words stack the batteries on top of one another. I have done this with my one starting battery for years. All the batteries should be held to the boat so that they will never come loose. I take the top battery off twice a year to check the water in the batteries below. There has never been much water used over a six month period.

Now the wiring and switching, first take a look at the rough diagram below. The four batteries are on the left with two switches on the right. The objective of this plan is to isolate the engine starter from the electronic instruments. On other plans the gps, radio and other instruments turn off when the engine is started. This plan separates the starter battery from the house battery so that the two power sources do not interfere with each other.

Your 12 volt house bank is wired in Parallel. Connecting all the positive (RED) terminals together adds the amps of all the batteries together and keeps the voltage the same at 12 volts. The Starter battery, only one, is not included in the bank and stands alone. It's only job is to start the engine.

On my boat all the batteries are charged with one alternator and one shore power charger by the use of a combiner. I actually hook it up to the terminals in the large 1-Both-2 switch. Attaching the wires to the 1 feed for the starter battery and the 2 feed for the house bank. This equally charges all of the batteries at the same time. There are many more expensive charging systems out there but this has worked for me for many years.

O.K. when getting the boat ready to go sailing this is what is done. The large 1-Both-2 switch is set to "2" (House Bank). The small second On-Off switch has a red key that I keep by the back of the boat near the engine water valve so that I remember to turn the water valve on. I turn this small switch on to start the engine. You can see that once these two switches are set there is no need to touch them until the sail is over.

This last week I was coming back in from a sail and the engine would not start. The 5 and a half year old starting battery had failed. To start the engine I simply turned the 1-Both-2 switch to Both and started the engine with the house bank's batteries.

I hope I haven't made mud out of battery wiring and switching with this example and plan. It works very well and was tested last week, l

 

[H33CRich]

Most excellent response Paul, Thanks. I have one question which may seem silly. Do you use your shower and does this setup interfere with the draining and pump out of the shower drain discharge? It might be silly because you would not configure your batteries this way if it did interfere.

 

[Paul F]

A good question Rich, The shower is not operational. In fact I have replaced the sink faucets without a shower water fitting. A shower is available in the cockpit with a fresh water connection there. In Florida the water is always warm and the outside shower works well in the morning or after swimming.

If you wish to continue using the shower in the head, you could make a battery base four to six inches off the bottom of the shower sump and use the shower along with gaining added battery storage space. Shower water will not effect the batteries in anyway. As long as you run the shower bilge pump when showering there will be no interference in using the space for both purposes.

 

[Stephen Trapani]

I have my batteries set up pretty much like Paul with a shelf, and I have the shower sump functional as well. Bit of a hassle if you want to clean the sump or service the lower batteries, but it hasn't really been much of an issue over the years. I have the upper battery strap fastened to the forward piece of cabinetry because the shelf itself just sits in there loose (held down by the battery) for easier removal.

 

[Steve W]

Rich, I did something similar to what Paul describes on my old '33 (I'm on a newer 376 now). The biggest difference is that I was looking for a much larger house bank since I had installed refrigeration. The answer was to install a pair of L16 6-v batteries on that tray over the shower sump and add a starting battery (G-27). The two L16's have a similar footprint as the original pair of G-27s and fit nicely there. The biggest difference is the L16s are almost 17" high and weigh about 120 lbs each. The tie down was a length of strong metal channel covered in rubber where it rested on the battery tops. The L16s were 380 amp hours each so rigged in parallel, they gave me a 12-v 389 aHr house bank. I then put the G27 Starting battery in the aft most underseat locker on the starboard side (Just forward of the storage drawers). The start battery, for the most part, was kept fully charged using an Echo Charger.

Worked like a charm. The photo shows the tops of the L16s before I installed the tie-down rod and also the Xantrex TruCharge20 3-stage charger I installed with them. The schematic shows how it all tied together except I ended up going with the L16s in parallel instead of 150 aHr batteries. I also installed an 80W Solar Panel to keep everything charged when I was away from the boat. (I never installed a wind charger).

The bottom line is I always had plenty of juice to the extent that I could leave the refrigeration on unattended Monday-Friday and still have plenty of battery when we'd get to the boat Friday evenings!

 

[Sylvain]

"a pair of L16 6-v batteries on that tray over the shower sump... were 380 amp hours each so rigged in parallel, they gave me a 12-v 389 aHr house bank."

How did you get 12 V out of two 6 V in parallel?
Your diagram shows them in parallel as well.

 

[Steve W]

My Bad - I meant Series - and that was an older sketch I put up by accident stemming from when I first added the starting battery and got was using a pair of G31s as the house bank.

That sketch was in response to someone asking how I rigged up the 80W solar panel to trickle charge while I was off the boat during the week.