Notice:
The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.
How long should we expect our factory battery to last? Boat was delivered new in July 2002. Battery seems to hold a decent charge from the outboard's alternator, after running awhile, but not super strong, judging only by the brightness of the cabin lights. I once checked the water level and added some distilled water, but that the only maintenance on it. Is DIY battery testing difficult? Or should I pay a mechanic like I do with our cars?(I admit to being a total novice in such matters.) Also, if we install a radio/CD player, will a single battery provide enough power with factory lighting and a depth sounder also being used?
I monitor my battery 'life' / charge via an inexpensive digital voltmeter (Wal Mart) that is plugged into a 'cigarette lighter' socket. My battery is a 2005 'vintage' and no signs of an issue yet. However I do check and fill the battery electrolyte at least once a month particularly during the summer months. I frequently run a CD / XMRadio and depth finder while I sail and you would be surprised how much power a 'loud' stereo can consume. So, the question is: how long do you want to run the radio and lights? My guess with my setup would be a weekend if you are careful with the volume level but you best monitor if you want to be sure of lights all night.
It is a good idea to build an "energy budget" for your boat. Your battery will say on it how many AMP Hours (Ah) it provides. That is your capacity. Then add up the AMPs that your equipment uses each hour and how many hours you use the equipment. That will tell you the drain on the battery over time. Try not to drain more than 50% of the battery AMPS (Ah) on a wet cell battery like the one that came with your C250. Also calculate the AMPs that your outboard is putting back into the battery, again by multiplying its charging AMPs by the hours it runs. Based on all this data determine if you should have a second battery.
We use two AGM batteries. These batteries supply 79 AMPS each and AGM batteries can be drawn down well below 50% and they require no maintenance at all. They are more expensive though.
The West Marine catalog has lots of useful information about batteries and boat electrical systems.
Once you install a stereo you may find that the outboard charging is not enough unless you motor quite a bit. You may need an onboard battery charger.
Charging with just your outboard will never get the battery fully charged and will shorten its life very much. Read the Ample Power Primer which you can download at www.amplepower.com, and learn how to take care of your batteries.
FWIW, I replaced my wet Group 24 battery with a gel sealed, no maintenance Group 24 two years ago and hooked it to a 5 watt solar trickle charger that I rigged aft of the starboard catbird seat. It constantly registers 13.4 on my 9 buck Harbor Freight voltage tester and never drains. Of course my electrical needs are very basic, just the running lights, cabin LED's, and engine starter.
I'm with Randy and Arlen on your experience with your battery. Typical battery life is no more than 6 years, however the battery I got when I bought Passage was almost 10 years old, and still running! It was installed by Dave Bristle who always does everything top notch.
I have found that battery voltage, reported by a digital voltmeter, is the best indicator of battery charge or remaining power. The article identified by Randy on "12 Volt Way of Life" for RVs is thorough and gives you the info you need without all the theory.
Fully charged around 12.6-12.8V, half dead at 12.1 - 12.2V and you are warned never to discharge your battery beyond 1/2 way. For standard group 24 lead acid batteries with 70-80 AH, you can run one amp for forty hours, two amps for twenty hours or four amps for ten hours before you have to recharge the battery.
Its important to note that battery voltage measurements are highly influenced by loads (bigger loads make the voltage appear lower, but once the current is turned off, the voltage will recover) and by time (voltage may read lower for up to an hour after discharge but will recover upward) and (voltage may read higher after recharging for up to one hour, but can sag downward after that).
In the latter case, keep charging the battery until it reaches 13.5V while charging, then let the voltage settle back. It should go back to approximately 12.6V - 12.7V, but if it settles back to 12.4V, the battery is still not fully charged and you should continue charging it.
Bruce, WADR, 13.5 is too low a voltage to obtain a true bulk charge. Given the information in almost all recognized battery charging references, including WM Advisors, Ample Power and the instructions that come with true three stage chargers and regulators (like Xantrex, Freedom Inverter/Chargers, Balmar, Links, etc.), the bulk, absorption and float stages are BULK: 14.2 to 14.4 V, ABSORPTION: 13.5 to 14.4 and FLOAT: 13.3 to 13.5 V (the varying voltages are different based on different battery types).
The Ample Power Primer discusses the actual battery requirements in great detail, and explains WHY these stage are required for battery health. It also discusses the need to understand amp hours (or kilowatt hours) as the "fuel gauge" for battery health in addition to just voltage, which is and has been a misnomer for years in measuring battery health. Add to that the specific gravity of the batteries for proper measurement of health and performance. Battery monitors, now much less expensive than just a few years ago, are a MUST for tracking your battery's health. Most suggest it should be a FIRST as part of your system. I put it off for too many years and found out something very important: I was spot on about how much was being taken out of my house bank because I did an energy budget, but I was COMPLETELY wrong about how much went back IN when charging because of the acceptance rate of batteries which drops off as they charge to full. This is a very important consideration when charging: you need to know when they're full and only a monitor can tell you that. I suggest you all consider getting one and learn to use it or else you just will never truly know.
You are correct about the impact of loads on battery voltage.
The reason I go into this occasionally in great detail on this MB is that I spent 12 years with our C25 from 1987 to 1998 when we bought our C34. I, too, was pretty basically ignorant about battery health until we got our more sophisticated electrical system because I just depended on "The 12 V Bible" for my information. That book, while a good starter, does not cover the more recent (read 10 or 15 years) of battery charging technology. It's a good start, but doesn't go into enough detail. I had one 95 AH gel cell with a 5 W trickle solar panel, and 5 A automotive charger (which I later learned was a battery KILLER!!!). Usually got five years out of a battery.
Sure, some have had batteries last a loooong time, and that's great. But it could be from either taking really good care of them, or excuse the phrase, just plain dumb luck with just using low loads and reasonable but maybe not proper battery charging.
I, too, had long lasting batteries, but found I was actually doing it ALL WRONG for years. Instead of continually trickle charging, I should have insisted on charging fully and letting the batteries rest at full charge. I am constantly amazed at how many skippers leave their boats plugged in all the time, many with inadequate and old and bad chargers, or even good ones with true three stage chargers. Then they wonder why their batteries die so prematurely.
And few equalize their batteries (for wet cells only).
I simply suggest that you read the available (and FREE!) information about how to REALLY take care of your batteries, regardless of how you use your boat and what kind of wiring and switching you may have. Outboard motors will NOT adequately or properly fully charge a bank because of the constant voltage output.
So, please, to eventually save lotsa $$ on batteries, read up while you still have your C25s and improve your understanding of electrical systems. You'll find, for instance, as many of us have, that old chargers (cheap, but...) will kill your batteries and the small investment in a new modern charger will provide an immediate payback in lengthening battery life. Put another way: spend $200 on a new charger and save the same amount or more on new batteries since your old ones will last a lot longer.
I hope you all can learn from my mistakes.
Edited by - Stu Jackson C34 on 02/14/2009 15:05:55
I had incorrectly reported elsewhere here that WM discontinued their energy budget worksheet. They moved it from the Advisors to the DIY Projects in the "Product Advice" tab on their homepage.
Stu - I hear you, and I apologize for not being precise enough when I was discussing the battery charging to 13.5V.
What I was really trying to say is using your Solar or Engine regulator, once the battery itself reaches 13.5V, not the charger, battery voltage will, over an hour or so, settle back to 12.6 or 12.8 volts (full charge). This should correspond to a specific gravity of 1.265 (per Don Casey).
It bears repeating - all in one place - each of the references you've cited between "Ample Power" and West Marine, among others. Would you put them all into one note for the benefit of the Forum?
Fred, I have an '03 and finally have to replace both last summer after the motor wouldn't start. I also have shore power. Piseas II is in a slip and gets lots up use all through the year. I took batteries out and had them tested. There were dead. If you do yourself and its easy, just use blue tape and pen to mark what goes where-before you remove. I got one of those digital voltmeters(made in China)from Wal Mart as mentioned. I am ashamed to admit it too. If you keep group 24, go to Kragen auto for best price. They have marine batteries. You can upgrade like some has mentioned but price jumps and sounds like you have basic needs. Steve A ps. Randy, btw, nice link, tks.
Steve - I like the cigarette lighter plug-in digital voltmeter, but I plan to install the following LED-based indicator to provide an "instant answer" on the battery and charging voltage in the cabin.
Pro-Mariner, carried by Defender, displays 6 LEDs from 11.5V to 15.5V allowing you to see the state of the battery day and night.
I plan to permanently mount it next to the control panel. Note that it has a magnetic strip on the back that should be removed to avoid compass deviation.
Notice: The advice given on this site is based upon individual or quoted experience, yours may differ. The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.