Batteries

[tm3]

Need to replace two of my six 6v house batteries. The two were installed in 1999. The other four were installed in 2001.
Told that I should replace all six at the same time.
Reason given was that if any of the four not replaced are low they will tend to draw power from the new ones and thus lessen the life of the new ones.
Thoughts please!
Also, what is the difference between using three 12v batteries vs six 6v?

[jbanta]

You were told right a weak battery will "drag" a freash one down to it''s level.
And your also is that 6 volt batteries tend to have more reserve hours than do 12 volt batteries. if you are set up for a 6v system I feel you should stay with it you have the best system now.. Why is it you need so much power?

[tm3]

Jim,
Battery set up was on the boat when purchased. Six 6v batteries used as the house load and two 12v batteries wired together used for a dedicated starter.
On the 12v vs the 6v batteries I am just looking for info. and reasons.
Thanks.

[jbanta]

I have been rewiring my boat since the water levels have made sailing all but imposible. I was looking at new batteries and saw that the reserve hours for a 6 volt battery is twice what you find in a 12 volt. Wiring two of them togeather does NOT increase those reserve hours, but you need tow per circuit to get 12 Volts. When you put two 12 volt batteries togeather it does increase your reserve hours. This is because of the way they must be connected. The 6 V are in series while the 12 V are installed in parallel. You can get by without buy all new batteries if you have a good battery combiner. If all this sounds like a foreign language to you may I recomend a book called the 12 Volt Bible. It will explain all this and show you pictures of how it''s all installed. To explaine all the properties of eletricity to you would require at least a 12 month course. I have spent YEARS working with voltages 12 and less of all sort of eletronic equipment. I know a Radio transmitter isn''t a boat but the way DC moves in that equipment is the same way it moves through your boat. Series and parallel
circuits follow very differnt rules. You have both 12 Volt batteries (parallel) and 6 volt batteries (series). You''ll need to learn how to deal with both.

[tm3]

Thanks Jim. Have that book and read it twice sometime ago. Will re-read and go from there.

[fer@fer]

I understand that you have 2 6v bat wired in series for starting. Are those the ones to replace? If that is the case, you don''t need to replace the other ones.

If all batteries are connected together in paralel, you should.

Are the 6v batteries deep cycle? For starting, such 6v batteries are not the best choice. Starting batteries require huge quantities of Ah in a very short period of time. The opposite is for housing purposes, usually provided by deep cycle bat.

Regards

Fernando

[tm3]

Starting batteries are two 12v wired together.They are okay. Batteries to be replaced are 6v house bank. All six 6v house batteries are wired togethr. Four were installed in 01. The two that are the problem in 99.
Will probably replace all the house bank batteries.

[jbanta]

If they are seperated with battery combiners you don''t need to do the newer ones. It might be more cost effective to install the combiner since 6 volts batteries are a bit expensive.. But if you have lots of $$$$ go ahead..

[tm3]

Not to sound "duh" but what is a "combiner?"
All six 6v batteries are wired together.

[jbanta]

You can find them on West Marine at the following url

http://www.westmarine.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&langId=-1&catalogId=10001&productId=29828

Here is the discription if you don''t want to look them up...

The Pathmaker allows you to charge two or three battery banks automatically from a
single charge source, whether it be an engine alternator, shore-power charger, wind generator,
or whatever. Then, when the charge device is turned off and the battery voltage drops, the Pathmaker
opens the circuit to isolate the batteries from one another.