Good Electrical Lesson Learned

[Harrysea]

I knew I had a battery issue after a failure to start while bottom fishing a while back. No problem, changed the battery switches and everything worked normally. I made sure all the cells were wet and hooked up to shore power as usual to charge batteries when I got back. I checked my batteries with a multimeter next time out and all four batteries looked good. Then I had the same starting problem next time out. So I picked up a $25 battery load tester and checked my batteries after they’d been fully charged. All were showing proper voltage, but when I checked each one with the load tester, one battery‘s output under load immediately dropped to the bottom of the range. Time for a new battery. It was a good lesson for me.

 

[JJF]

Curious: how old was the battery?

 

[Harrysea]

I haven’t pulled it out yet and didn’t look for a date when I load tested. I bought the boat with these batteries already installed a year and a half ago, so I don’t know the history. I would have removed the battery already, but it’s in the worst location and I’ll have to remove at least one other battery and probably move the generator coolant reservoir to get it out.

 

[JJF]

ok; as an FYI, I believe certain types of batteries are supposed to replaced all at the same time (seems silly to me, but I seem to recall reading about it somewhere).

 

[DennisG01]

If the two batteries are part of one "bank" (in parallel) then definitely replace as a set. If they're separate then it's not anywhere near as important

 

[Harrysea]

I have a Pro Tournament Quad onboard charger. Do I need to replace both batteries in the bank to keep from degrading a new battery placed in the same bank with an older one during charging, or will my charger maintain all four batteries individually? I stay connected to shore power (batteries charging) whenever the boat is back on the lift.

 

[Hookup1]

If the batteries are in parallel they should be replace at the same time with identical batteries. Otherwise both batteries won’t charge the same and you could overcharge one of them.

 

[DennisG01]

I have a Pro Tournament Quad onboard charger. Do I need to replace both batteries in the bank to keep from degrading a new battery placed in the same bank with an older one during charging, or will my charger maintain all four batteries individually? I stay connected to shore power (batteries charging) whenever the boat is back on the lift.

See the post directly before yours!

You'd have to check the specs on your charger, but it should be charging individually. But that's not the issue. It's when you're off the charger that it matters.

 

[loubeer]

I again just swapped out all four of my Deka DC27's after 4 1/2 years. Everything electrical was working fine and some of you may think I'm way too cautious...... but I've never been stranded 60 miles from home .

 

[Hookup1]

5 years seems to be the magic number for me with battery life. Maybe the Duracell AGM's will be better. We'll see.

 

[DennisG01]

Just an interesting point... Deka is contracted by Duracell to "sticker" some of Deka's batteries with the Duracell sticker. I'm not sure if Duracell contracts with other manufacturers, but Hook, if you have a "Deka" Duracell, that's a GOOD thing!

 

[Harrysea]

As I understand it, the problem with replacing only one battery is that when batteries are part of the same bank, the charger will read the weakest battery and can overcharge the other battery in the bank and damage it. If my charger operates as explained to me by ProMariner tech support, it assesses each battery independently and won’t overcharge any of them. I can, in fact, see which one of my four batteries is bad by looking at the four status bars on the charger when I first activate it after using the boat. Buying an extra battery certainly won’t break the bank, but why would I want to replace a strong serviceable battery just to replace them in pairs, especially if I load test them periodically and always hook up to shore power for my smart charger when back at the dock? The partner to my bad battery is only two years old and load tests strong. If I’m way off base here, please tell me so. Most of what I know (or think I know) about the situation I’ve described is what I’ve learned in the past week. I know safety is always paramount, but I feel pretty good about having four batteries that can be reconfigured as needed with switching. I always keep at least one motor or my generator (charging batteries) running when offshore, and I carry a portable jump starter for emergencies.

 

[DennisG01]

Harry, did you read my post #8?

Think of it this way... fill one cup all the way up and another only half way. Set them next to each other and poke a hole near the bottom of each cup and connect the holes with a hose. What happens to the "full" cup?

 

[Hookup1]

As I understand it, the problem with replacing only one battery is that when batteries are part of the same bank, the charger will read the weakest battery and can overcharge the other battery in the bank and damage it. If my charger operates as explained to me by ProMariner tech support, it assesses each battery independently and won’t overcharge any of them. I can, in fact, see which one of my four batteries is bad by looking at the four status bars on the charger when I first activate it after using the boat. Buying an extra battery certainly won’t break the bank, but why would I want to replace a strong serviceable battery just to replace them in pairs, especially if I load test them periodically and always hook up to shore power for my smart charger when back at the dock? The partner to my bad battery is only two years old and load tests strong. If I’m way off base here, please tell me so. Most of what I know (or think I know) about the situation I’ve described is what I’ve learned in the past week. I know safety is always paramount, but I feel pretty good about having four batteries that can be reconfigured as needed with switching. I always keep at least one motor or my generator (charging batteries) running when offshore, and I carry a portable jump starter for emergencies.

If the batteries are in parallel the leads from the charger will be in parallel. The two banks of the charger will both see the same parallel battery "bank". The charger can not tell the batteries apart.

A strong battery will try to charge the weaker battery. This is true without a charger. If they don't reach equilibrium the battery will continue to try. Add the charger and it will also keep charging until the battery is fully charged. If one battery is weak the charger will never stop trying. This is especially the case with smart chargers. They go thru a finishing phase that get confused with marginal batteries.

For 24 volt systems two batteries are in series. One charger bank is connected to one battery. The second bank is connected to the second battery. Each charger bank sees only one battery. This is NOT how GW configures two batteries.

 

[Fishtales]

I agree with the 5 year rule or if you start to have issues as well as doing them per bank when you do. It seems to me that marine/auto batteries are not what they use to be especially if not used consistently in either application. I have a marine, auto and tractor batteries that are not used consistently like my daily driver auto and the batteries even if charged via trickle or standard charger every year just don't last more than 4-5 years.