Batteries

[workinprogress]

In an attempt to minimize weight, I have been planning on running my j16 accessories (bilge, 2 reciculation pumps, livewell intake pump, lights, and gps) from a single battery. The one I have is rated for 670cca at 32deg, and weighs 55lbs. I am kind of uneasy about not having a dual battery setup, because I don't want to wind up dead on the water. I just today thought it might be a good idea to go with 2 smaller batteries instead of one large one. I think this may be the best alternative.
http://www.odysseybatteries.com/battery/pc925series.htm
24lbs!! I could have 2 batteries and still have less weight. I'm a little confused about the power rating on these Odyssey batteries. This battery is officially rated at 380cca, but Odyssey spends a lot of time trying to say that rating is misleading, and it is basically a 925cca (the 5 second rating) battery. Can anyone clarify this for me? I could always step up to this size.
http://www.odysseybatteries.com/battery/pc1200series.htm
Even with dual bats I would only increase weight by 20lbs.
Are there any other batteries that are noted for being lightweight?
Would you guys pursue the dual battery idea?

[Shakespeare]

workinprogress, you've got two things to consider. (1) CCA - cold cranking amps and (2) AH - amp hours.

You have to have enough CCA to crank your motor. That's a momentary load. If you're not motoring but sitting still, then you rely on AH to keep power on your gear. The more AH then the longer you can keep things powered up. The specs on those smaller batts only has 28AH... that's roughly enough power to cover 2.8 amps for 10 hours. Just divide the AH by your loads and that'll give you a rough idea of how long that battery is going to last. IMO I'd be a heck of a lot more concerned about those smaller batts than one large one. If you take good care of your battery ie. keeping it charged and out of deep freezes, then it'll take care of you.

Here's a link to an FAQ that my help you understand some of this.

http://www.exide.com/faq/faq_marine.html

You got a trolling motor on that boat? If so that can be your emergency backup.

Mike C.

[workinprogress]

Yeah Mike, I've got a trolling motor that has it's own battery mounted under the front deck. I can use it as a backup, I just want to make sure I set this up right. Thanks for your input.

[workinprogress]

Mike, you are the man on the technical info. The link you gave gives a very comprehensive explantion of how deep cycle batteries work. I can't come up with any specs for the amp hours rating on my battery, but the reserve capacity is 160 minutes. According to the info I just read that means it can supply 25 amps for that 160 minute time period. I am guessing, based on the amp rating on my accessories, and the fact that they won't all be running all the time, that I will pull about 5 amps/hour. Is there anything incorrect about deducing 25 amps/160 minutes = 5 amps/800 minutes-or a little more than 13hrs. Even considering starting the motor several times will take away some of this charge, I still think I should never have a problem. Is my application of the reserve capacity rating to my requirements correct? Thanks.

[Shakespeare]

I failed to state that amp hours only apply to deep cycle batteries. Sorry for the confusion. There are dual purpose marine batteries for starting/deep cycle applications and I was on that trail.

I agree with your calculation that a reserve capacity of 160 minutes should deliver 5 amps for 160 minutes X 5 (13.3 hours). This is a maximum rating and I wouldn't suggest gambling on it... just use it for a guideline.

009 After thinking about your question for a few minutes let me change my answer. The reserve capacity defines the number of minutes a 25 amp load can be imposed on the battery withour major degradation. To infer that a lesser load can be applied for a longer period of time may be incorrect. I better not make any claims on this until I do a little more research. Sorry :(

As far as battery consumption during motor starting, the alternator will recharge the battery in fairly quick order, but I can't say exactly how long as it depends on several factors. Just think about the nature of a fishing expedition. You don't generally sit in one spot for 10 hours straight and are more inclined to hop between several spots during a fishing day. The amount of time spent traveling from one spot to another determines how much recharge you get on the batts. If you get close to a full recharge then you essentially wipe the slate clean... partially clean on short hops. If you figure your battery capacity based on worst case, then you shouldn't have any problems... keeping in mind that a battery has a life expectancy in months and that should be respected.

Mike C.

[workinprogress]

As far as battery consumption during motor starting, the alternator will recharge the battery in fairly quick order, but I can't say exactly how long as it depends on several factors. Just think about the nature of a fishing expedition. You don't generally sit in one spot for 10 hours straight and are more inclined to hop between several spots during a fishing day. The amount of time spent traveling from one spot to another determines how much recharge you get on the batts. If you get close to a full recharge then you essentially wipe the slate clean... partially clean on short hops. If you figure your battery capacity based on worst case, then you shouldn't have any problems... keeping in mind that a battery has a life expectancy in months and that should be respected.



I agree with everything you said here. 1st, I want to figure everything on the worst case scenario so I can be sure when I get on the water I only need to think about getting the Capri-Suns for my 4yr old and catching fish. The alternator on my Yami 25hp 2stroke only charges at 6amps, which I am not sure will keep up. So far as the life expectancy on the bat goes, if that becomes suspect, I will go get another one.

I can't wait to hear the results of your research on what I calculated--last time I decided 15amp breakers x 6 breakers meant a panel was rated to 90amps, you pointed out the panel was rated for significantly less. ( I think 40 amps-not sure about that)

This is like going back to school, and I thank everyone furthering my education.

[Shakespeare]

On a side note... I put a timer on my livewell aerator because I was concerned with it running full tilt while I was stopped for any length of time.

http://www.boatersworld.com/product/478707276.htm

Mike C.

[CFISHN]

I have seen "fail safe" "terminal mounted things" that will not let you drain past a starting reserve . I think they were around $100.00 west overtons ect
Craig

[boogieblues50]

Hi
I cant tell you how they figure their battery ratings any better than their web site...But I can give you some personal experiance with the Odessey battery...They are bullet proof and vibration proof...The military uses them in tanks and aircraft...because they can take a bullet thru them and do not leak and still work...They say they can sit on the shelf for two years with no charging and still start....Iam inclined to beleive this.I bought one for My Harley Road King..I got sick and almost Died...My harley sat for 11 months in the shed with no heat no charging nothing... I went out on a cold day figuring to charge up the battery...said what the heck lets try to start it up... The headlight comes on automaticly when You turn the key to start it...That dang battery cranked the motor for twenty to thirty mins on and off till I finaly burped all the old gas out and got her to fire up...never in that time did it feel like the battery was trying to give out...considering the small size of motorcycle battery's I dont know of any other brand that would be able to do that..It sold me on Odessey
They sold me so much I just purchase two 2150 size 31 for my boat...They have 200mins reserve each at 25 amps...4 year no prorated warranty...they just replace them and a service life of 8-12 years...the bad part..they are expensive I found them on e-bay for $280 each about $50-$60 cheaper than anyplace else...and the 2150 are heavy but so are most 31 group battery's...The good part once charged they will hold that charge well over a year...warranty...no spills..no leaks...no fumes..mounts any way except upside down...and at least twice or more service life than any other battery out there..Which means hopefully I wont have to do anything to them for at least six to eight years but plug them into my bank charger..I have had 5 or 6 boats and batterys have always been a pain in the butt but hopefully that has ended now....BoogieBlues

[Shakespeare]

Ok workinprogress... here's what I got; The general consensus is you multiply Reserve Capacity by .6 to achieve Amp Hours. So your 160 minute reserve capacity battery should be rated at around 96 amp hours. That means a 5 amp continous load will go for approx. 19 hours assuming a fairly new/fresh battery. I think you're good to go.

Have fun!

Mike C.

Here's a few web sites that may be of interest;
http://www.powertroll.net/deepcyclefaqs.html


A. Reserve Capacity or Ampere Hour Rating
The most important consideration in buying a deep cycle battery is the
Reserve Capacity (RC) or Ampere Hour (AH) rating that will meet or exceed
your requirements. RC is the number of minutes a fully charged battery at
80 degrees F is discharged at 25 amps before the voltage falls below 10.5
volts. Some deep cycle batteries are rated in Ampere Hours. To convert
Reserve Capacity to Ampere Hours, multiple RC by .6. For example, a
battery with 120 minute RC will have approximately 72 Ampere Hours. This
means that the battery should produce one amp for 72 hours of continuous
use. Since shallower the average discharge increases the battery life,
more RC is better in every case.


http://www.windsun.com/Batteries/battery_Glos.htm

Reserve Capacity (RC)
Reserve capacity is sometime used to rate deep cycle batteries. It is the number of minutes that a battery can maintain a useful

voltage (over 1.75 VPC) at a constant 25 amp discharge rate at 80 degrees F. Reserve capacity is probably a more useful measure

than AH for batteries that run heavy loads, although most batteries also have tables that show the AH capacity at different

discharge rates. AH is approximately equal to RC X .60


http://articles.mbz.org/electric/batteries/

A good yardstick for characterizing deep-cycle performance is the amp-hour (AH) rating, which describes how much current a battery

can continuously deliver over a specific time period (usually 20 hours) before the voltage drops to 10.5 (which is considered to

be fully discharged). The battery's AH rating is determined by multiplying the load current by the length of time it lasts. For

example, a battery capable of deliving 11 amps for 20 hours would earn a 220-AH rating.

Reserve Capacity is an similar, more modern specification that describes how long the battery will deliver 25 or 75 amps before

going dead. The idea behind reserve capacity is to provide an indication of how long a vehicle can be driven with a "dead"

alternator. To convert 25-amp reserve capacity to a roughly equivalent AH rating, multiply it by 0.6. Larger deep-cycle batteries

are rated at 75 amps; golf-cart batteries are usually rated in this manner. A 105-minute battery is rated to sustain a 75-amp load

for 105 minutes at 80 degrees F. A high-minute rating indicates high reserve capacity. To convert 75-amp reserve capacity to a

roughly equivalent AH rating, multiply the minutes by 2.0.

http://www.type2.com/library/electrip/battbas.htm


The maximum storage capacity of a deep-cycle lead-acid battery is
usually rated either in amp-hours, or in minutes of reserve capacity.
The amp-hour value refers to the number of amps a battery will deliver
over a specified period of time (generally implied to be 20 hours if not
specifically stated), before the battery has discharged to a useless
level (10.5 volts for a 12-volt battery).

The reserve capacity value specifies the number of continuous minutes
the battery can last while delivering 25 amps before dropping to this
same 10.5 volts. As a rule of thumb, for the smaller batteries you can
multiply the number of reserve minutes directly by 0.6 to arrive at an
approximate equivalent amp-hour rating for the battery.

Therefore, a 50 amp-hour battery (or a battery with approximately 83
minutes of reserve capacity) can be expected to deliver at least 2.5
amps for 20 continuous hours, or at least 1 amp for 50 continuous hours.
Note that at current drains much higher than those specified at the 20-
hour rate, however, the capacity of the battery starts to decline due
to internal losses and chemical inefficiencies at high currents.
Consequently, this same battery might only be able to deliver 5 amps for
nine hours (45 effective amp-hours), instead of the 10 hours (50 theo-
retical amp-hours) implied by the battery's amp-hour rating. In general,
bigger batteries can deliver higher currents without incurring this
effect.

[Slim to None]

i used a series 51 battery from a honda civic on my J16. had plenty of juice for all my electronics and motor. my trolling motor was wired separate, but could be used as an emergency backup. very small and light battery. 27 lbs Cranking Amps: 625 Cold Cranking Amps: 500.

http://www.interstatebatteries.com/estore/search.asp?details=1&searchtype=Y&mscssid=AJE22M2U5TR39H5PC34HENLSP1X61WBD&Ntt=mt51&N=0&Dx=mode+matchallany&part_number=MT%2D51&Nty=0&D=mt51&Nu=Part+Number&Ntx=mode+matchallany&part_desc=Mega%2DTron+%2D+75+Months+%2D+500+CCA&Ns=product+Type%7C0%7C%7CRank%7C1&Ntk=SearchGroup&js=1

[otter]

I use a maintence charger on all my batteries and they last five years or more and are always charged when I go to use the boat. Last one I bought will charge and maintain three batteries. It has three different banks and each battery is being charged and maintained separately. The charger was less than $200.00. It is permanently connected to the batteries and is permanently on the boat. It is water proof. All I do is plug it in when I return from a trip. Northern tool has some cheaper maint. One I have used successfully is $14.00 and the other is around $50.00. It takes them much longer to recharge the battery, but they are small and use gator clips. Hope this helps someone.

[workinprogress]

Extremely useful information. Thanks guys.