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What batteries to use?

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matta0413

Contributing Member
[FONT=&quot]I was working in the engine compartment yesterday and took a look at the batteries. I have only had this boat for one season so I have no idea how long these batteries have been on the boat. I am going to load test but I figured "Lets see what is on here now". Currently installed are West Marine AGM 8A31DT. I looked them up and they are Dual Purpose. Seems like a waste, shouldn't they just be cranking batteries since everything else runs off the house? What are you running for batteries?

Thanks for any replies.[/FONT]
 
not everybody's stuff is wired the same so what works for one configuration may not for another.

I don't see any issue with whatyou have as long as they still have adequate capacity....and the cables are in decent condition.

We have 4D AGM VRLA batteries installed - that was the best bang for the buck at the time...and the OEM had selected the 4D size as their standard. Yes it is oversized but has worked well for years....
 
If this boat is equipped with an MBSS ( main battery selector switch ) you will do well with a dedicated cranking/starting battery on #1, and a dedicated deep cycle battery (better yet 2 of these) on #2.

The MBSS should NOT be in the engine bay, and should be easily accessible from outside of the engine bay.

You will crank from #1, and then warm the engine up.
The AHs removed from cranking will be replaced in minutes!

You may then switch to bank #2 and enjoy the use of your 12vdc items.
(this keeps #1bank in reserve!)

Most any MBSS can be switched between banks w/ the engine running!
To be safe, DO NOT pass through the “OFF” position w/ the engine running!


Bluesea offers more complex systems if desired!



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Thanks guys for the responses.

Ricardo - my system has 2 - 2 batter banks. Each wired to it's own master switch which is simple on/off unless in an emergency there is a cut over switch but you would have to be in a pretty bad situation to have to use that. I am going to run through and check to see if there is anything else wired to that bank besides just the engines.
 
be careful with battery switches being moved with the engine running.....not all do it the same way and alternators don't tolerate removing their loads very well.
 
Yes, be sure that you have a "make-before-break" type of 1,2,BOTH OFF switch. Takes less than a tenth of a second to blow the diode pack on your alternator. There are much better ways of wiring up batteries nowdays.
 
matta0413 said:
Thanks guys for the responses.

Ricardo - my system has 2 - 2 batter banks. Each wired to it's own master switch which is simple on/off unless in an emergency there is a cut over switch but you would have to be in a pretty bad situation to have to use that. I am going to run through and check to see if there is anything else wired to that bank besides just the engines.
Click to expand...

Do yourself and your boat a favor, and bring it up to a modern day battery bank management configuration.

Also, for those of you who who are not quite understanding the MBSS, we would all be hard-pressed to find one of today’s MBSSs that is not “make-before-break”!



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RicardoMarine said:
Do yourself and your boat a favor, and bring it up to a modern day battery bank management configuration.

Also, for those of you who who are not quite understanding the MBSS, we would all be hard-pressed to find one of today’s MBSSs that is not “make-before-break”!



.
Click to expand...

under the premise that nothing is too obvious... "make before break" functionality is only present on the change from one battery to the other while transiting the "BOTH" position. Changing batteries while switching via "OFF" is a big NO- NO. And... the "BOTH" position is ONLY for trying to start an engine when NEITHER battery alone will crank the engine... NEVER run for a prolonged time (more than a few seconds) on BOTH. Leads to drastically shortened battery life.
 
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sandkicker said:
under the premise that nothing is too obvious... "make before break" functionality is only present on the change from one battery to the other while transiting the "BOTH" position.
Precisely.
In other words, while making a battery bank change from Batt #1 to Batt #2, the contacts will not let go of Batt #1 until Batt #2 has been connected.... thus the term "make-before-break".

Changing batteries while switching via "OFF" is a big NO- NO.
Yes..... unless you have one of the older MBSSs that offers an alternator field circuit.

And... the "BOTH" position is ONLY for trying to start an engine when NEITHER battery alone will crank the engine... NEVER run for a prolonged time (more than a few seconds) on BOTH. Leads to drastically shortened battery life.

Well, my take is this.
We want the charging system (be it the engine alternator or the OB Charger) to sense each battery individually as it predicates the charge rate.
When the MBSS is set to the BOTH/ALL position, it cannot do this.
Click to expand...
 
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