Batteries and chargers

[higgs]

I have a system where there are two house batteries on a 1/2 switch and a starting battery on its own separate on/off switch.

In the battery compartment it appears to my eye that the starting battery is isolated. All three batteries are connected on the negative side.

I am going through house batteries rather quickly - 1 to 2 years life on 27s. I am suspicious of my Charles smart charger, which is normally on at the slip. I do have have meters, but they read high even when the charger is off, so it is tough to rely on the meters, yet they read full charge at 17 volts - too high, if the meter is accurate. I also have found electrolyte in the wood battery supports. I am suspicious that I may be overcharging even though the water levels are not low.

I am considering putting a new smart charger in and want recommendations. With my setup as described above how many banks do I need to pan for? I have a reefer, but very little 12v beyond that. How many amps do I need?

 

[Steve Dion]

Joe, check out the new Xantrex units.

Joe:

Check out the new line of Xantrex chargers (XC). One major advantage is the charger allows you to have different chemistry in each of the 3 banks.

The general concensus is to make your house bank large enough to handle your requirements based on the amount of time you spend away from the shore power for no more than a 50% discharge. This may mean that you need to run your engine if you are going to be out on the hook for a couple of days.

You probably need to do some calc's to determine your actual power requirements so you really know your loads.

 

[Nice N Easy]

Batteries

If you are reading 17 volts, your meter is obviously off. Get a good digital and get an accurate reading. You can buy one for less than 20 bucks that will do the job. But there are a couple more questions that need answering. How low do you run your batteries. A couple of Group 27's isn't a lot of amp hours, and if you are running a fridge very much, you are probably draining them below 50%, which will make their life span pretty short. Also, if you charger has two outputs, and your start battery has a normal life span, then it is probably not the charger. Figure how many amps. your reefer draws, and how much it runs. I think that 30% is a pretty good average number for reefer run time. It's pretty easy to listen and time it if you want a more accurate number. Do the math, and you will get the answer whether or not it is the batteries or the charger. My first guess is that you are taking the batteries down below 50%, and they just don't have a long life when you do that.

 

[Capn Dave]

Let's not get rid of the volt meter

just quite yet. If your getting electrolyte in your battery boxes sumthin is wrong. Trust your instruments. Borrow a digital VOM (volt,ohm meter) and check your batteries voltage. If they are reading 17 vdc your cooking your batteries. Without any charging voltage going to your batteries you should be reading 12.5 to 12.7 vdc after about an hour rest.
If your charger is not a 3 stage charger, I would replace it with one as suggested in other posts. I would also combine the house bank batteries to make one large house bank. This helps battery life by not discharging them ad deeply. Put the house bank on one position of the selector switch and the start battery on the other position. One less switch to worry about. Why you could get a combiner and you wouldn't have to remember to switch to all when the engine is running. It will sense the voltage of the battery bank and will switch automatically to the bank that needs charged. Great little black boxes until they fail.

Good luck and fair winds

Cap'n Dave

 

[Stu Jackson]

higgs, try this link

http://c34.org/bbs/index.php?topic=4352.0

 

[Maine Sail]

One..

One large bank for house (possibly your two 27's combined) & one start emergency bank is all you need! Separating your house batteries just shortens their life expectancy..


17v is frying your batts but double check it with a DVM! They are dirt cheap these days and a must have item on a boat!!

 

[Stu Jackson]

Here's an energy budget form for you

http://c34.org/bbs/index.php/topic,3976.0.html

 

[Cap't Ron]

Good Info

Here and for some basics on electrical check out

" The 12 Volt Bible for Boats" Miner Brotherton.

" Living on 12 Volts" is also good copy too.

Steve, are you in Delta Marina right next to "The Pier" restaurant where they have the end tie and famous 'Champagane brunch'?

 

[higgs]

Using a meter

My meter is reading 15 volts at the battery terminals when the charger is on.

 

[Stu Jackson]

Dump the charger, higgs, it's killin'

your batteries. Take our advice and go for the Truecharge or its newer replacement units.

What charger did you say you had?

 

[higgs]

Thanks

I appreciate the help from all.