New Battery Voltage ?

[Blind Bobber]

Bought two new group 27 deep cycle marine batteries from Costco. Initial voltage reading was 12.6 & 12.7. Did a two amp charge over night and had initial readings of 13.2 & 13.4. Six hours later back down to 12.6 & 12.7. I thought new batteries should be 13.2. Am I wrong? Should I just put the volt meter away and be happy? What are good numbers here? Thanks much.
BLIND BOBBER:cool:

[baitsauce]

It sounds fine to me. I may be wrong but I was always told anything between 12 and 13.7 volts was good. If it starts the boat whats the problem? :shrug:

:twocents:

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[Hawk JJ]

After a charge overnight let the batt rest for a few hours, then test with voltmeter.

new 12volt battery at 100% should be 12.76 volts...

[dixiefisher]

I bought those same batteries about 3-4 years ago and 12.3-12.5 is my normal reading when not being charged by the main engine. I say go ahead and shelve the meter and rest easy...

[Cliff D.]

All good, 12.6-12.8 at rest.

[Smj]

Don't use a "Deep Cycle" battery for a starting battery. If your going to be using an outside charger for a "Deep Cycle" battery make sure that the charger is delivering 14 plus volts to the battery. A "Deep Cycle" battery will fail way before it's time if it's repeatedly re-charged with less than 14volts. Really!

Smj

[teelduck]

agree with smj.had a deep cycle in my duckworth, didnt last.not made for starter batteries.made for lights,trolling motors ect. that draw slow.

[fishkisser]

Havn't you guys ever heard of a deep cycle starting battery ?

Using a deep cycle battery as a starting battery

There is generally no problem with this, providing that allowance is made for the lower cranking amps compared to a similar size starting battery. As a general rule, if you are going to use a true deep cycle battery (such as the Concorde SunXtender) also as a starting battery, it should be oversized about 20% compared to the existing or recommended starting battery group size to get the same cranking amps. That is about the same as replacing a group 24 with a group 31. With modern engines with fuel injection and electronic ignition, it generally takes much less battery power to crank and start them, so raw cranking amps is less important than it used to be. On the other hand, many cars, boats, and RV's are more heavily loaded with power sucking "appliances", such as megawatt stereo systems etc. that are more suited for deep cycle batteries. We have used the Concorde SunXtender AGM batteries in some of our vehicles with no problems.

It will not hurt a deep cycle battery to be used as a starting battery, but for the same size battery they cannot supply as much cranking amps as a regular starting battery.