Battery Replacement

Whole in the Water

Well-Known Member
Not quite sure what to do. I have 2, 5 year old Interstate deep cycle batteries that have worked flawlessly on my boat using a 3 way battery switch selector. At rest one reads 12.60, the other 12.45 volts. According to the state of charge graphs 12.60+ volts is 100% charged state and 12.45 is about 75% charged.

So, should I replace just the lower charged battery and keep the other one for another season, or replace them both. I know that replacing them both is best, but I am trying to see if I can save some $$$ and I can keep them isolated with the battery switch.

Any recommendations?

Long live wild salmon!!!
><))))>
 
I'm by no means an expert...but if they're both holding a charge of >12 volts and are working flawlessly, why would you replace them? (maybe I'll learn something when some of the heavy hitters respond)
 
A new 12 V lead acid battery should read approx. 12.75 VDC in peak condition. This is the voltage a battery in excellent condition should maintain. Some may be slightly higher, some a little lower.
As your battery gets older it will loose a little every year.
Readings on a 12 V battery can be misleading to the unfamiliar. A 12 V battery reading 12.25 VDC on a digital multimeter is, for all intensive purposes, DEAD.

Testing a battery immediately after disconnecting it from a charger will also give you a misleading reading. This is not a true indicator of the batteries charge. Actually , if you connect a meter you can watch the numbers drop over a short period of time. The battery, if in good condition should become stable, depending on age, at a reading over 12.5 VDC. If your battery is close to the limit and is 4 or 5 years old, you might need to consider a new battery.

If you haven't used your boat for a period of time,
A good test is charge it up take a reading and let the battery sit for the day or overnight without charging then take another reading in the morning. If the voltage has continued to drop below 12.45 VDC replace your battery. Canadian Tire will test your battery for free if you are in doubt.
 
Everything I read on the topic indicates that if you have two deep cycle batteries, they should be the same type, manufacturer and age. Either keep both until they are both a problem, or replace both now.

Alternative is to replace both with 2 x 6v golf cart batteries instead and wire them in series. They will typically last longer and provider greater amps.

TenMile
<'((((><
 
I allways replace the batteries in pairs. Go to Anchor Marine Electric, and get yourself some Trojan batteries. The standard issue black "dealer brand" batteries that float around this town are no screaming hell. If you can hold a group 27 battery out at arms length, it's "mediocre" at best. Try it with a Trojan, I know I can't.



Last Chance Fishing Adventures

www.lastchancefishingadventures.com
www.swiftsurebank.com
 
you cant test a batt with a volt meter alone.

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Fill the dam tub!
 
quote:Originally posted by LastChance

I allways replace the batteries in pairs. Go to Anchor Marine Electric, and get yourself some Trojan batteries. The standard issue black "dealer brand" batteries that float around this town are no screaming hell. If you can hold a group 27 battery out at arms length, it's "mediocre" at best. Try it with a Trojan, I know I can't.



Last Chance Fishing Adventures

www.lastchancefishingadventures.com
www.swiftsurebank.com

agreed.

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Fill the dam tub!
 
Depends what is more important to you - saving a hundred dollars or starting your boat as you are being pushed towards a rockpile by 3 foot waves and a 20 knot wind. [}:)]

Seriously - Replace both batteries now - you are buying security and peace of mind - cheap at twice the price.

As others have previously noted - buy good batteries. For the few dollars you save on cheap batteries, it's not worth it.

Also, as Dave IFL said, you can't test a battery by voltage alone. You need to do a load test and that takes a special meter. Every decent mechanic should have one.

Essentially, you charge the battery fully, let it sit for a day, and then load test it by loading it up with a heavy drain - the battery should maintain a certain voltage during the test. If it falls below that level, then replace the battery(s).

Also, don't ever run the batteries combined except for starting the motor in emergencies. If you combine a good battery with a bad battery you don't get two good batteries - you get two bad batteries.



Jim's Fishing Charters
www.JimsFishing.com
http://ca.youtube.com/user/Sushihunter250
 
quote:Originally posted by Sushihunter


Also, don't ever run the batteries combined except for starting the motor in emergencies. If you combine a good battery with a bad battery you don't get two good batteries - you get two bad batteries.



Jim's Fishing Charters
www.JimsFishing.com
http://ca.youtube.com/user/Sushihunter250
What about when your running, is it a good idea to put the battery switch in the both position(combined), that way your charging both batteries while your running.

And remember....Keep your tip up!!!
fish.gif
 
OK, I hear you on replacing both batteries.

Should I replace them with 2 deep cycle ones like I had and seemed to work well. Or should I get a cranking battery for starting the engine only and a deep cycle one to run my downriggers and electronics only?

What do most of you guys use?

Long live wild salmon!!!
><))))>
 
ALWAYS one for cranking and one as a house battery. You shouldn't use a Deep Cycle battery for cranking as it's not designed for the heavy initial load. You should also not use a start battery for your electronics needs. Get the right battery for the right purpose.

My suggestion is to get one of the heavy duty Trojans or an AGM battery. One for the house system and one for starting.

Also pick yourself up a Blue Sea "Add a battery" Automatic Charge Relay. It combines and charges both batteries when your boat is running or a charger is plugged in, and isolates your house and starting system when they are not charging. Protects all your electronics from the surge from your starter. No more need for a 1, 2, Both system.

TenMile
<'((((><
 
When using two house batteries and one cranking battery do you tie all the grounds together or do you isolate the house from cranking?
Cheers
 
quote:Originally posted by Sea Ranger


What about when your running, is it a good idea to put the battery switch in the both position(combined), that way your charging both batteries while your running.

You can do that, but...

Here's the problem - IF you needed to tie both batteries together to get started, then you obviously have a problem battery.

My way of dealing with this situation is to get started, and then after a few minutes on BOTH, I will switch to the dead battery. The hour or so cruise out at 3800 to 4000 RPM should charge it up enough to get you started again. As soon as I slow down to start fishing, I switch to the other battery and run off of that for the rest of the day. That means draining it to run the motor, radar, radio, fishfinder/gps and downriggers etc. It is then charged up on the run back to the dock. The next trip out, I will reverse the process.

Also, not a bad idea to have a battery charger at the dock to keep your batteries topped up.

On another subject: Go over-size on your main battey cables. A few years ago, I bought a cable crimper and make up my own battery cables - wish I could remember the cable size number, but it is big! About 3 X the size of standard car battery cables.

Use them to run to the starter and for all ground cables and to the switch.

Unless you are running a big cruiser for over-night camping trips, I would avoid deep-cycle batteries for boats. They are not designed for starting motors. They do not release large amounts of energy quickly enough. Oh, the will start your motor... for a while. They will burn out your starter after a while, especially if they are not fully charged when trying to start. They also take longer to charge.





Jim's Fishing Charters
www.JimsFishing.com
http://ca.youtube.com/user/Sushihunter250
 
quote:Originally posted by Sea Ranger
[brWhat about when your running, is it a good idea to put the battery switch in the both position(combined), that way your charging both batteries while your running.
I did agree up until this last post, sorry Jim.
I think, I am starting to sound like a broken record but, I have towed a lot of fishing boats in due to “dead” batteries!

First, I do agree that most sport fishing boats really do not have the need or require a “deep cycle” battery? For “most” smaller boats, it is just an added expense and really not that much of an added benefit; however if there is a need for the extended continual discharge of the battery that would be deep cycle. A deep cycle battery is designed to provide a steady amount of current over a long period of time. They are rated by both number of discharges and amps. There are deep cycle batteries with adequate amps for starting - I had three of them on my Diesels. Normal starting batteries are not designed for that deep discharge and they will fail - due to the thinner plates. Only the end-user knows which is best... and I “need” the “deep cycle” and they are rated to start my engines!

Running the battery switch in “BOTH”… IS A “VERY” “VERY” “BAD” IDEA! Eventually – you will lose!

For those interested, you might want to start here?
http://www.sportfishingbc.com/forum/topic.asp?TOPIC_ID=14902&SearchTerms=battery

By using that “both” switch, you are in fact “paralleling” those batteries. If doing that the batteries “absolutely” need to be matched; to include, type and “age”! Mismatched batteries will indeed create problems, more sooner than later. If you have one battery fully charged and the other battery fully discharged, if that switch is in “both” those batteries “will” equalize, period! Meaning, if both batteries “are good”, you will end up with two batteries half-charged. If you are trolling on a 6 amp kicker, in “best” case scenario, you will have 3 amps “per hour” going to those batteries? NOT GOOD! Also please note: Most electronic starting systems require around 12 volts to start the main engine! More NOT GOOD – you will lose!

In the “both” position again, best case scenario, it will take twice as long to charge two batteries running on your main, as the charging AMPS will be split between two batteries. If the batteries are mismatched (including age), they will accept the charge at different rates and can create an “over charging” condition of one of the batteries. That equates to “bad” battery, period. If there is a “bad” battery, that battery will continue to drain the good battery. Again – NOT GOOD! If there is a “bad” battery, even with the alternator/stator putting out “max amps” it will still try to charge that bad battery and won’t be able to put enough charge to the “good” battery, it will discharge! And again, since they are trying to accept the charge differently that could also create an overcharging situation causing the good battery to go bad. Trolling with one discharged battery in the “both” position - you “WILL” “FLAT OUT” “LOSE!

Depending on how much equipment you are running – “DO NOT” assume any battery is being charged, regardless of that switch position? At an idle, you will be lucky to put 17-amps charge to the battery, using your main. Using a small kicker more like 4-6 amps. So a good question is, how many amps are you using?

Starting out with a “good” discharged battery (meaning something like anchored at night and I run it down) I “start” on the “reserved” “charged” battery – that is the point of having two batteries! I give that one enough time to put the amps back to it. Then I would “highly” recommend switching to the “discharged/dead battery and run off that the “entire” time – hoping to charge it up? And save the good battery for when I need it – someday you “will” need that reserved battery! If you have a 40 amp stator (which I do), and you run at cruise, it should put 40 amps charge back to the battery in an hour’s run. Sorry, that does not define the actual “state” of that battery or the remaining amps - just that you put 40 amps charge to it. That’s not taking in consideration the amps your other equipment is using/used in the one hour run? Two Scotty downriggers use 15 amps/hour - Don’t even think about an anchor winch? I wouldn't even be thinking of turning off my main under those conditions, without knowing I had a "good" battery in reserve!

Regarding the wire size… that really depends on the length of the run. Longer the run – bigger the wire, but there can be too much of a “big” thing. They have charts for that, stay with the charts and you will be fine.
 
I have a couple of those Blue Sea battery minders that burned up on me, I can't say they do very well under stress. I have your standard issue two batteries in the back of the boat on a switch. I have a pair of group 27 deep cycles. Yes, they are not starting batteries, but I have nice cute little 4 banger outboards that pull maybe 60 amps if they really are cold, so that's ok. Then, up front, under my drivers seat, I have a standard issue Canadian Tire battery that runs all of my electronics radio, heater, etc etc on an isolated switch.

When my Blue Sea battery minder is busy getting burned out, I simply use a small switch beside my seat to flip the things that really drain my batts over from the big ones in the back, to the small one under my seat. The "under seat" battery just gets replaced annually thanks to a very generous warranty program from a local retailer. So that way I can really kick the hell out of a cheap battery from all of my electronics, heater and radio that pulls near 10 amps with the radar running, and the big batteries in the back will ALLWAYS get me started. Deep cycle is ok for starting small outboards, just go one size bigger then what you normally would use (Group 27). For a grouchy old V-8, stick to a starting batt.

I tried the "Echo Charger" too, but when that poor thing tries to only give 15 amps to a really dead battery, they burn out too. The Blue Sea ones are OK if you don't run your batteries down hard, but when you have a thirsty battery, they won't last that long feeding it.

And yes, I have some very fat battery cables going to it.

My $0.02 ..

Last Chance Fishing Adventures

www.lastchancefishingadventures.com
www.swiftsurebank.com
 
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