Battery life - time for a fresh pair?

[reverie]

Hello all,

Here's a auestion about the capacity of my 2 house batteries in my 2004 SO35, and whether it's time to replace them:

I participated in a 11 hour race last Saturday (great fun despite pea-soup fog and zero wind for the first 5 hours...).

During the the vast majority of the first 10 hours, we were using the following electronics:
- The autohelm
- 2 GPS/chartplotters (Raymarine A50, and Raymarine 425). (And please don't ask why we were using two. Hey, the fog was thick!).
- The VHF radio
- The stereo system (in FM radio mode)

Nothing else - ie. no refridgerator, no lights.

We left the dock with fully charged house batteries. After 10 hours of running the electronics listed above, my A50 blinked out. We checked the house batteries and discovered we were down to ~10.5volts.

The two house batteries are original equipment from 2004 (boat was purchased and launched in 2005). They've been carefully maintained, and the battery tester this spring showed they were both in good shape.

Is this sort of power life about what I can expect from a pair of typical original manufacturer house batteries, or is it time for a fresh pair??

PS..no issues with the engine battery at all.

Many thanks,

John

[Zanshin]

The autohelm is the joker in the equation. In heavy seas and with a lot of weather helm it could account for enough energy drain to chew up 200 Amp hours (I'll assume your 2 house batteries are 110Ah and round down to 200 for simplicity). Capacity is measured at a 20 hour rate so that means you will have 200Ah when using 10Amps. If you use more then you capacity will be less, at double the drain rate it will be significantly less.

Back to your race, the VHF (when not broadcasting), stereo and 2 charplotters probably drained around 10Ah - I'm guessing a big drain from the screens of the chartplotters. That would leave you at 50% capacity but your 10.5v shows a completely drained battery.

I would suggest that you try a load test. You will need a voltmeter to do this. Charge the batteries completely (the voltage should be over 13Volts. Turn off all switches/breakers/loads and the charger. Measure voltage - if less than 12.6V (or so) then you have a dead cell or a dead battery.
If your voltage is above 12.5 then turn on all your lights and electrics and autohelm at the dock and see what your on-board Ammeter reads and measure the voltage at the battery at the same time. You want to put as much load on the batteries as possible, optimally using a battery tester to reach 1/2 of the battery CCA. If you have help then operating the windlass would add load.
If the voltage drops below 9.5 or so (see google for accurate charts) then you've got a dead battery.

If you have access to the batteries, take them out and bring them to any car shop, they all have load testers which will do the above test accurately, compensated for battery type and temperature and can tell you within seconds whether or not you need to replace them.

Any time you go below 50% of the rated capacity you will be causing some (small) amount of harm to the batteries. Considering your small capacity and heavy equipment drain I would hazard a guess that your house bank is nearing its end-of-life and retirement age.

For just over $100 you can get a battery monitor such as the Link10 which will give you a good indication of battery charge and drain. I consider that my little monitor more than paid for itself within weeks of installation, mainly due to letting me know when I'd run the genset or engine long enough to charge them or to the point where I was getting little charge (Peukert's law)

[Deleted]

I replaced my 2003 SO 35 house batteries after 4 years when I noticed my fridge shutting off in the middle of the night, something that's never happened when they were new. I replaced my starer battery only last year. I believe the OEM batteries are better starting batteries than house batteries. Given your situation, I don't think it's unreasonable to think it's time to replace them.

- James

[reverie]

Many thanks for both your posts, guys.

I think I'll limp through the rest of the season, and put in a new pair. I'll also do some digging on the Link10, James. Sounds like a fairly useful bit of kit to have on board.

John

[MartyB]

4-5 yrs is pretty good for house batteries. Not sure if Jeanneau puts a combo start/Deep cycle or just a deep cycle 12V battery.

Also when you replace, look at potentially going to 2 6V batteries of equal size to a 12V, you get about 25-50% more AHrs generally speaking, and they will last longer, have more charge cycles before going haywire.

If this will not work, some 12V batteries have more lead in them. When I replaces my size 24 2 yrs ago, I found batteries with anywhere from 70-85 Ahrs in this size.

Marty

[Don Reaves]

My batteries (and boat) are the same age as yours, and I had to replace my house batteries this year. I had a dead cell in one at the end of last year, and it dragged down the other, since they were wired in parallel.

I've gotten 6-8 years out of batteries in the past, and was disappointed at only getting four seasons out of the original batteries on my SO35. Part of that may be the parallel wiring. Part may be the quality of the batteries.

I did as Marty suggested, buying two 6V golf cart batteries and putting them in series. Their total capacity is quite a bit greater than the original batteries. Getting them to fit wasn't much of a problem. They were a bit taller, and all I had to do was cut a 1.5" hole in the cover above two of the terminals. Since this was under the aft berth, where there are already similar cutouts for other service items, I wasn't concerned.

So far, the new batteries are doing very well, and I'm glad I switched to a higher capacity set. Of course, my engine battery is now showing the first signs of its demise, so I need to keep a close watch on it.

Don

[reverie]

Thanks, guys.

The 2 x 6volt in series route seems like a good way to go.

Don - did the battery charger in your SO35 work fine under this configuration, or did you have to make any modifications there?

John

[Don Reaves]

John,

My new battery capacity is not so much larger that I had to make any changes in the charger. Note that I keep the charger on pretty much all the time, so it has plenty of time to get the batteries well charged.

Don

[so40gtb]

My house batteries were both replaced before the 2008 season after one died late the prior year. These were originals on a 2001 boat, so no surprise at their demise.

The starter battery, which was previously replaced by a prior owner at a year unknown, died when starting the engine to motor to winter layup last fall.

I replaced all with Optima AGM batteries, deep-cycle for the house and starting for the other.

My OEM charger died in early June. It's on my workbench to diagnose and repair, but I put in a Charles Industries unit to replace it. That charger, like most modern mid-range types, has programmable charging characteristics that you select to your battery type, a good idea if running AGMs or gel cells. I relocated the charger to the front side of the nav station seat, outside the box of the latter, so it can "breathe". The original Jeanneau placement within the box would shorten the charger's life, I would think, due to the lack of positive ventilation.

--Karl

[sailingpages]

Hi,
Just a note on my experience with the factory supplied batteries on my new 36i. The boat came with 2x 70 Ah House batteries and 1x 70 Ah Engine battery. All batteries were identical, and were flooded cell Tudor Technica car batteries. They were not deep cycle, nor specifically designed for marine use at all. We had a lot of problems with these batteries delivering anything near their ? rated power 70 Ah, 20 h rate.

Before the boat was 12 months old, I replaced these with 2x Lifeline AGM GPL-31T (210 Ah total) house batteries, and a Lifeline AGM GPL-1400 as an Engine Battery. No maintenance, very good charge acceptance, very little risk of hydrogen gas while charging (there may be some diffusion of hydrogen gas from the batteries over a long term so still need to be somewhat ventilated). Highly recommend AGM batteries!

Cheers,
Geoff.

[reverie]

Hello Geoff,

Yes, those are exactly the same batteries I removed from my 2004 SO35 last weekend.

It's remarkable that the previous owner sufffered them as long as he did. Obviously he did not cruise much.

My view is that the SO35 is a well built boat, and we continue to be thrilled with her. But some of the shortcuts that Jeanneau took are disheartening. Clearly the choice of batteries is one such issue. And so was the bagged out, potato sack Sobstad genoa that came with the boat.

John