Battery Question

C

cjeccher

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Apr 29, 2010
RO Number
32109
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107
I have two Dekka 27 Dual Purpose and one Dekka 24 for genset stored out of the boat for winter. They all take a full charge to 12.6 on Shumacher smart charger but then they all drop to about 12.45 after a few days sitting with no load. The specific gravity of each cell is at least 1.275 and all batteries three passed a load test.

It only take a few minutes to charge them back to 12.6 and the battery charger has a desulfation mode that can detect sulfated battery and can go into a special mode which I assume is an equalization charge, but it hasn't done that.

The Batteries are going on 5th season but I baby them. I am just concerned that they fall to 12.45 volts with no load It is time to replace them?
 
When you say no load are you considering most bilge pumps are connected with battery switches set to off? I have also seen some assesories that need a memmory +12VDC be wired on the battery side of the switch. If you can not leave your charger on when docked and away you might want to think about installing a solar panel and 2 battery charge controller. You don't need a large panel system like I have for trickle charging <65 watts of solar will work.
Bill
 
The batteries are still in winter storage, out of the boat and not connected to anything. I keep the batteries inside over the winter and charge them every 30 days. The batteries have a surface charge of about 13 +/- volts as soon as they come off the charger and slowly drift down to about 12.4 over 4 days sitting not connected to anything. Maybe this is normal for 5 year old batteries, I just remember the batteries holding a 12.6 volt charge at least for a few days.

There is no setting on my charger to perform a manual equalization and it will not go into that mode automatically, telling me the batteries might not need it.
I think they do not go down much past the 12.4 even after 30 days between charges, it is just that they do not seem to hold the full 12.6 or even 12.5 voltage like they used to.
I am going to launch this week and see how they do after using them and charging by alternator and Charles Charger.

I know batteries normally discharge a small percent while in storage, but Does anyone know if it is normal to not keep a full 12.6 volts for more than a week sitting in storage?
 
IMO, that voltasge drop doesn't mean they need to come out right now, but it does indicate that your batteries are reaching 'the end.' At 5 years you got your money's worth. I'd perform a load test on them, rather than relying solely on voltage as the health indicator. If they passed a load test I'd likely use them for one more season and plan to swap them out before it splashes in 2014.

My .02
 
Just a thought, As the temperature of the battery drops, so will the fully-charged voltage reading. I have found a lot of conflicting information about this phenomenon, but it seems to be safe to say that for each 10 degrees F drop in temp, you can expect to see the voltage drop about a tenth of a volt. (.10 volt) That means that a battery at 32 degrees F with a no-load voltage reading of 12.35 volts is fully charged.
 
Ypu are not testing with the charger connected are you?? They will drain the batteries.
What CPSS said. Voltage is temperature related so is gravity. Gravity and voltage will both be higher after a charge than after they sit for a while. Additionally they will self discharge and if the tops are not clean that will happen sooner. Try washing off the tops with a little baking soda and water then a good rinse. Dry and retest If all cells reach 1.275 I would not worry about it.

Here is everything to know about batteries, really good stuff from the experts.

http://www.trojanbattery.com/BatteryMaintenance/Testing.aspx
 
I would also recommend you get 'smart' maintenance chargers for winter storage. They automatically keep a trickle charge on the batteries, cutting on and off as needed. Doing a flash charge every month and then letting them sit for 29-30 days disconnected and running down in-between charges is not good for the batteries. At five years, they are near the end of their useful lives. If it were me, I would replace at least one of the batteries immediately and plan on replacing the other two at the beginning of next season. That way, you're less likely to find yourself with three weak or dead batteries. Hy
 
It seems the batteries are acting like they should, being that they are 5 years old. I would expect them to be worse next year and the years after that. The question becomes 'when is it time to replace them'. I don't think that time is today. Put them back in the boat and monitor them every couple of months to see how they hold a charge. If they start to deterioate, then start looking for a sale on batteries. They may have one year left or several years. As they age the amp hrs of the battery will diminish and accelerate the demise of the battery. If the battery was 100 A/hr new and you pulled 40 A/hr out of it, then it would only be discharged 40%. If the battery as it aged is only capable of 70 A/hr (still enough to start the engine), then depleting by 40 A/hr will now discharge it 57%. The increase in the depth of discharge will increase the degradation of the battery leading to battery failure.
 
I agree with Pa Mikee on his explanation of the slow deterioration of a battery. However, i still believe that at least one of the batteries should be replaced now. That way, you can be fairly certain that you will not be stranded with batteries too weak to start an engine. Assuming you've got battery cross-over switches, you could start each of the engines on the one new battery. As to the smart charger: Cjeccher indicates that his batteries quickly reach charge level. That suggests that the chargers are not maintenance chargers, but rather full-power chargers. The use of maintenance chargers for off-season storage helps batteries last longer by avoiding the the extreme levels of discharge and fast recharge. They maintain a steady, low-level of charging, which is far less damaging to the battery structures. That's why I had recommended a different type of battery charger for maintenance. Hy
 
You should have 3 of the same size batteries, all 27. You should replace all of them with 31, I new someone who tried to get 5 years on the batteries and almost burned up his boat. Batteries are very dangerous especially in a enclosed area. If you have one battery with a weak cell the charger will still charge witch it will over charge the good ones.
 
quote:
Originally posted by Salvatore356

You should have 3 of the same size batteries, all 27. You should replace all of them with 31, I new someone who tried to get 5 years on the batteries and almost burned up his boat. Batteries are very dangerous especially in a enclosed area. If you have one battery with a weak cell the charger will still charge witch it will over charge the good ones.

Click to expand...

I have to agree when it comes time for replacement batteries I would upgrade from 27 series to 31 series. The additional AH's are well worth it for a slight increase in cost.
Bill
 
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