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ContinuousWave: Small Boat Electrical
Optimax BlueTop Battery Life
|Author||Topic: Optimax BlueTop Battery Life|
posted 07-11-2007 03:31 PM ET (US)
I have had my 15' Striper long enough to report on the life of at least one component. An Optimax BlueTop battery. After a least five years of abuse it refused to accept a charge this spring. I use my 15' about 20 to 25 hours per season. This hour figure is based on an hour meter purchased from West Marine. I believe that there is some residual draw in my electrical system, and the battery would always be nearly dead after winter storage. I have a 5-6 amp charger which claims to accommodate the Optima charging requirements. At the start of each previous season, it would always top up the battery with one night of charging. I have not found a clean and simple "cut-off" switch to isolate the battery during periods of inactivity. I am satisfied with the life, and the zero maintenance of the battery is also a big plus. If you disconnect the cables at the end of each season I would expect that your life might exceed what I experienced. The replacement BlueTop was about $150 at Costco.
posted 07-11-2007 04:53 PM ET (US)
Optima is a sprial wound AGM battery, I believe.
All marine batteries self discharge at some rate. A coventional flooded lead acid battery self discharges at about 1% per day. I think AGM batteries are about 0.5% per day.
That's if they just sit. If you have a small current draw (like the station preset memory in a radio) they will go down faster. So if you let your battery just sit for a few months, its going to be at 50% or below.
The life of a battery is proportional not to the time that it is used, but to the number of discharge cycles and the depth of the discharge cycles. The deeper the discharge cycle, the fewer you get. For example if you down to 50%, you may get twenty discharge cycles, if you go down to 20% you may get ten, if you go 0% you might just get one or two. If you can keep a battery topped up and only go down to say 80% charge, you may get hundreds or even thousands of cycles. (The number of cycles will vary with battery type, these numbers of for illustration purposes only.)
My point is that if you let your battery go flat each winter, you are killing it. I think the reason you got five seasons is that you started with a very good battery. A lesser battery would have been dead at the start of season two.
The best thing to do is to have a high quality multistage charger, or a newer maintenance smart charger%, or even a small solar panel, and leave your battery on that for the entire off season. Avoid the old 'trickle' chargers, they can overcharge the battery, which leads to a whole different set of problems.
What you might use is something like this: http://www.thebatteryminder.com/agmoptimabatteryminderplus-p-62.html
I'm not recommending this one particularly, its just the first thing I found in a Google search for Battery Maintenance Charger AGM. Note that AGM batteries need a different charge profile than gel or flooded lead acid batteries.
posted 07-11-2007 07:38 PM ET (US)
I am aware that using a "Battery Tender" or similar product would possibly extend the life of the battery. There is no electrical outlet in my storage location. Removing the battery from the inside of the console is a project that I am unable to perform twice a year (once in and once out). I did look for a high quality, compact and simple disconnect for the battery. I stopped in at the local West Marine but was not impressed with their suggestions. All of them were panel mounts, and I am out of panel space. I was hoping to find some sort of in-line option. So call the battery police, I confess, I have abused my BlueTop... I am please with the life of my first BlueTop. Optima claims a fully charged new BlueTop will have about 12.5 volts after 200 days of storage. In fact, after year one, as I recall, it would have started the motor. My Tohatsu is a great starter, as I have rope started it several times when the battery was low. In the case of my BlueTop application, it is the residual draw that is slowly killing mine.
posted 07-11-2007 10:28 PM ET (US)
I monitor and manage two large UPS units which contain 80 VRLA AGM batteries. My experience with the useful life of a typical high quality VRLA AGM battery which is under constant floating charge and maintained at moderate room temperatures is:
--after two to three years we see cells begin to decay with excessive rise of internal resistance;
These batteries have a five year warranty. (Compare this with some popular boating AGM batteries which have a one year warranty.) We have never gone more than five years before replacing all cells. Again, this is for high-quality cells under a constant and well-regulated floating charge which experience only occasional discharge, never below about ten-percent of their full-charge rating.
posted 07-12-2007 08:44 AM ET (US)
I installed this switch on my Montauk. There are cheaper ones available. http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/ 10001/244583/377%20710%201641/0/Batteries%20/Primary%20Search/ mode%20matchallpartial/0/0?N=377%20710%201641&Ne=0&Ntt=Batteries%20& Ntx=mode%20matchallpartial&page=CategoryDisplayLevel1&isLTokenURL=true& storeNum=null&subdeptNum=null&classNum=null sorry for the long url.
posted 07-12-2007 09:26 AM ET (US)
Nice switch, but it is a panel mount.
posted 07-12-2007 09:32 AM ET (US)
Have to admit that 5 years life under your conditions is pretty impressive. Can't you just remove the ground cable from the wing nut terminal when storing? That is a pretty easy disconnect and would definitely preserve your battery capacity. If it must endure periods of deep discharge then next time try a dual purpose AGM battery.
I am in my fourth season with an Optima blue top. I have a battery disconnect switch and pull the battery in the Fall. I replace it in the Spring without a charge and it cranks the motor like new.
posted 07-12-2007 10:22 AM ET (US)
My Blue Tops are at six years and counting. I have dual batteries with the one, two, both, off arrangement.
The batteries have been deeply discharged only once due to me testing the GPS the evening before a fishing trip and failing to turn the thing off properly plus failing to turn off the batteries. It was late and I was tired. My usual MO for an aw shucks to happen.
I charge the batteries fully the day before any use of the boat and I carry a portable jump battery as back up. Belt and suspenders, don't you know.
So far the batteries have shown no hint of performance loss. If they continue to perform well I'll probably replace them in about four years. Ten years for Optimas sounds about right to me. :=)
I'm considering installation of an onboard fixed charger to simplify the charging process but do not plan to leave it connected to AC.
posted 07-12-2007 09:38 PM ET (US)
I have a covered battery box buried in the center console. The box is then strapped down in a wooden frame. It is almost impossible to access. The only activity that was more challenging than the battery installation was the rub rail replacement... And it was close.
posted 07-16-2007 12:52 AM ET (US)
Jefencino: Leaving the GPS on overnight won't drain the
battery. The GPS is < 1 amp. Battery is typically > 60 AH.
Do the math.
posted 07-18-2007 02:20 PM ET (US)
This might be worth a try .....
posted 07-20-2007 03:44 PM ET (US)
Thanks for the comment.
I don't disagree with your statement. But in the case mentioned the engine would not start the next morning without a jump. A couple of factors may have contributed. First, the engine is a FICHT with electric injectors that require a lot of juice to operate. Second, the GPS was a combination GPS, Map, Sounder which may have drawn more than <1 amp.
Perhaps my statement that the batteries were "deeply discharged" was erroneous. If so, I extend my apologies.
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