New house batteries for Tom Cat??

[Gene Morris]

I've talked about this subject before. Reefmadness has only one 55AH AGM battery to run the house. The battery is not adequate for our use. The standard charger on the Tom Cat is a 10/5/5 with 10Amps to charge the house battery. After a full charge it's OK for about an hour then I have a battery alarm @ 10.9V. Then the on board charger will only get me about 15 minutes, running only the Nav Electronics, Stereo & Refer running, then the alarm sounds.
I believe that I will install two golf cart batteries that have 220AH and 202 mins reserve each. I will also have to install a 40Amp charger. I was told this would be equal to 404 mins reserve.
Comments would be greatly appreciated.
Thanks
Gene

[Dreamer]

Gene,

Some may call this overkill, but it works nicely for us. 2 AGM 275 amp hour 8-Ds and a 2000 watt Outback inverter. the inverter has a 80 amp battery charger and quickly charges the batteries with a Honda 2000w generator. The inverter will run the coffe maker, hair dryer, toaster oven, computer or TV. 3.5 MMUs total.

[journey on]

I installed 2 ea. golph cart batteries in the aft lazerette of Journey On, with a 1000 watt Xantrex inverter and a Xantrex 40 amp battery charger. Has worked great for the last 2 years. If we spend more than 1 day anchored, I use the Honda 1000 to charge them.

Some comments. I would love to have 2 8-D's , (~500 ah-hr vs 180,) but I'm getting old and can't lift them. And a C-25 doesn't have the space, nor can it take the weight. A Tomcat obviously can. In charging the golph cart batteries, 40 amps is used for about 5 min and then it tapers off to <20 amps. This allows me to use a Honda 1000. As you can see I'm worried about weight, since Journey On is already overloaded for cruising. I appreciate the sine wave inverter, especially if one has a microwave.

Boris

[SEA3PO]

Our boat always lists to Starboard....and I only have the standard batterys that came with the boat .....if I put those mondo batterys I probably would turn turtle... I was looking in Cabella's and they have some light weight high capacity marine batterys ....
(Nathan my son now works at the Cabella's in Reno)

Now darn it....be nice...I know I am a tad overweight...the boat lists even when I am not on board.....

Joel
SEA3PO

[Dora~Jean]

Joel, my 25 lists to starboard also. It lists less now that I moved one of the two batteries to the port side. I'm pretty sure it's the cables (throttles, controls) and wiring that all run along the starboard side of under the gunnel. Copper can get very heavy, especially as you add accessories every year. On my boat there's also the extra structure for the bathroom.

But actually a little starboard list works out fine for my boat. When we have dinner and sit at the table, 2-4 people balance it out nicely and actually lists to port a little.

[thataway]

Gene a few things to remember. First, you should never discharge ANY battery more than 50%. For lead acid or AGM batteries this is about 12.2 volts! If you discharge to 10.9 volts you are damaging the battery.

I have never personally liked the 8D batteries, because they are so heavy (I have owned boats with them)--but I have prefered the golf carts.

Figure that two golf carts--you only have 200 amp hours and 200 Reserve minutes because they are 6 volts in series, and equal to one 12 volt battery with these ratings.

Correct that the standard battery charger is in-adequate for cruising. At least 20 and better 40 to 50 amp battery charger is desirable. AGM batteries are good if you are putting them inside of the boat. Also if they are put in on their sides, you cannot get to the batteries to check the electrolyte level.

The Tom Cat lends nicely to two or three group 31 AGM's--one in the aft hanging locker and two under the aft dinette seat. You will want to put in adequate wire, and fuse it properly for the 45 amps which each engine will put out (90 amps).

If you have room aft, for the golf carts, they are certainly more cost effective and very rugged. We have been running our long distance cruising boats (where everything is dependant on 12 volts and a charging time of only a couple of hours a day at 150 to 200 amps)--on Golf Carts for 30 years. I also run the Golf carts in my RV's.

Sears has recenly released the "DieHard" platinum series in AGM--susposedly they can tolerate a charging current up to 15 volts. Some folks believe that AGM's cannot tolerate over 14.2 volts. I don't believe that, and have found no problems with 14.5 volts for a number of years. True Gel cells are sensative to any voltage over 14.1 volts.

Another feature of AGM's is that they will take a charge twice as fast as a lead acid battery--and this again is a good feature for a cruising boat.

You pays your money and takes your choice.

[journey on]

Bob, my comments here on battery voltages is more of a discussion. Now, we've had several type of "deep discharge" batteries. There was an Interstate 4D, which was good for 300 cycles and it was 50% discharged at 12.3 vDC, and full charge was 12.8 vDC. This was less than 1 yr. of use by the way (cycled once per day.) We also bought a real deep discharge battery in Tahiti. This would go down to 12 volts, and would float at 12.5 vDC. And the golf cart batteries also float at 12.5 vDC, and still look good at 12.1 to 12.0 vDC. And they've lasted for several years. I'm convinced that the golf cart type batteries just operate ~ 0.3 vDC less than the regular, Interstate RV type of deep discharge.

By the way, you haven't lived until you buy a battery in Tahiti. It wasn't free. And the parts were made in Torrance, Ca. Another thought: 2 ea. small golf cart batteries are the same size as 1 ea. 4D battery.

Boris

[thataway]

Boris, I agree, and the 12.2 volts is a generalization. The AGM's tend to have a higher terminal charge voltage at test--I find that 12.8 is common, and many of the lead acid flooded are in the 12.6 range. For the 50% 12.3 is often quoted for the AGM's as 50% discharge. If you are using Surgette or Rolls batteries, with very heavy lead plats, you can most certaily discharge them down lower than the lighter "marine all purpose" batteries.

I use this 12.2 volts because I see so many folks who talk about drawing the battery down to 11.5 volts or where ever the cut off is for an inverter or the electronics fail. The repeated draw down below a certain level will shorten the life of any battery. If it is a battery rated for 1000 cycles, it may only get 300 and if it is reated for 300 full cycles it may only get 100 before it begins to detiorrate. That is why I closely moniter my battery voltages. But, if you are running an inverter and find the voltage temporally dropping to 12.0 volts, that may not cause harm, because as soon as you turn off the high current draw item, the voltage will come back up. There is a surface charge--which will make the battery voltage appear to be higher right after charging--and will appear to make the battery voltage lower during a high current draw.

Incidently before heading down the Coast from Washington and thru the Panama Canal to Florida, I replaced all of the batteries, except the gen start battery (The house and starting banks were 5 years old and we would be dependant on the batteries as we sailed--the generator battery was only 2 years old)--of course the Generator battery failed in Zihuatanejo. I purchased a Mexican battery, thinking it would last a year or so. 5 years later, I checked out all of the batteries--and the best one was the Mexican locally made battery.

Regards,

[drjohn71a]

Dr. Bob, Boris, et. al., I appreciate your sharing the detailed aspects of battery choices.

I am no expert on the batteries themselves, but want to share that we users need to be aware of the "invisible" things on our boats that can drain those batteries rapidly if left on all the time.

I often anchor out for a day or so, but sometimes forget to shut off the radar scanner, the depthfinder, or even the gps/autopilot, TV inverter (small), etc..
My house batteries can go to dead in a few hours of all that running. I sometimes use heated 12v coffee cups also. So, I am just wanting all to remember that, if you want to go a long time between charges, you need to be careful about all those little things that draw the batteries down unnoticed.

Thanks for your help!

John

[SEA3PO]

Sue and I are planning on some long trips next winter once she starts retirement..... I plan on installing fresh batteries just prior to that...but also I am buying a 1000 watt Yamaha generator just in case we run the batterys dead in some remote spot.... sure would hate to call SEA TOW just for a jump start...

Joel
SEA3PO

[thataway]

There are alarm devices which will sound when the battery drops to a pre determined voltage. There are also devices which will cut power the to the main bus when the battery drops below a pre-determined voltage.

I prefer to either moniter the battery voltage or to moniter the battery amp drain with a device like the Link 10 or 20 moniter. I also have a set of switch pannels to shut off the electronics--and shut down the radar, depth finder, chart plotter etc--when I shut off the engines.

[Dora~Jean]

Every night before hitting the sack, I have got in the habit of checking the current draw on the batteries thru my Link 10's. More than once I've found something inadvertantly ON! You should go through whatever routine or checklist that works for you.

[Gene Morris]

Ok I ordered two Discovery AGM EVGC6A-A batteries and a Xantrex True charge 40+ battery charger. Roger (Dreamer) sent me a diagram of his battery set-up. I am not going to have an inverter and need help with the set-up.
What if I left the standard charger on the boat to charge the motor batteries and used the 40Amp charger just for the house bank? Does anyone see a problem with that?

Gene

[journey on]

If your Xantrex 40 is like my Xantrex 40 (and take that any way you want,) it can charge up to 3 12vDC battery banks. This would simplify the wiring, since you need large wires to get the high current flow. Also if you dump the 5 amp Guest charger that came with the boat, you can use that space for the Xantrex.

Where did you get Discovery batteries?

Boris

[thataway]

Gene,
That is basically what I do. The origional 5,5,10 battery charger is attatched to the starting batteries, and the origional "house" battery. The Xantrex is dedicated to the AGM batteries. Works very well.