Mysterious battery drain... where to begin?

[Bleemus]

If i recall correctly some reported subpar performance from the Duracell labeled 6v batteries. Wait to hear from someone with direct experience before making the plunge on them.

[Symphony]

Originally Posted by Maine Sail

I currently have about a half dozen GEL banks over 12 years old (Prevailers & East Penn) with one bank turning 17 this coming May...

Wow. I thought i did well- 17 years life bring the annual cost way down. Congrats.

[tkeithlu]

As long as your battery charger (shore power/genset) and alternator/voltage regulator (engine) can handle the load, no problem. The problems, at least in my experience, arise when the alternator has to run wide open to handle the load of charging too many batteries. In that case, the alternator is never able to reach the 14.7 volts you need in bulk charging. My problems disappeared with the addition of a heavy duty alternator and a sophisticated programmable voltage regulator (Balmar in my case) that could take care of my house batteries the same way my sophisticated battery charger could.

[OrangeCrush]

Originally Posted by tkeithlu

As long as your battery charger (shore power/genset) and alternator/voltage regulator (engine) can handle the load, no problem.

Yeah I guess this is my question. How would I figure out if my alternators are appropriately sized for a bigger bank? I have two 90amp Balmar alternators and a Balmar Max Charge MC-612 regulator. The highest current I saw it produce last season was 150 amps. This "seems" like plenty to me but that is not an educated assumption on my part. I will spend almost no time on shore power during the sailing season.

[Stu Jackson]

Originally Posted by tkeithlu

As long as your battery charger (shore power/genset) and alternator/voltage regulator (engine) can handle the load, no problem. The problems, at least in my experience, arise when the alternator has to run wide open to handle the load of charging too many batteries.

This needs to be clarified.

For any given daily load or draw, let's say 100 to 120 ah, there is substantially NO difference in charging time or load between a 200 ah house bank and a 1,000 ah house bank, when recharging daily.

One has to replace what has been removed.

Now, if because of a larger house bank the skipper does not begin to recharge for more days, different story.

[Sailuke]

You may just have old batteries. They wont be able to hold a charge if they're old and well used.

[OrangeCrush]

Originally Posted by Stu Jackson

Now, if because of a larger house bank the skipper does not begin to recharge for more days, different story.

I'm with you so far, Stu, but can you elaborate on the 'different story' part?

If I start with full batteries and I use 50ah, then it doesn't matter how big the bank was, I have the same deficit either way and it will take 50amp hours worth of charging (plus inefficiency) to recharge them.

But the main purpose of having a bigger bank would be the ability to use more amp hours on "special occasions" without getting them low enough to do damage. For example, say I run autopilot on an offshore passage and drain a bank of 690ah down to 60%. The same usage would have drained a smaller bank of 440ah down to well below 50%, presumably doing some damage. But will I be unable to charge a bank back up if again if it is too big, or will it just take longer?

Similarly, if I start with 690ah and use only 5%, will my measly 200 watts of solar be able restore them from 95% to 100% or will the bank be "too big" to take a charge?

I understand the math regarding amp hours, I guess the part I don't get is how to know if a charger will be able to reach the required voltage to put the amp hours back into bigger bank.

[DeepFrz]

If you have a larger bank and you only use the top 10% then you don't need a large alternator or solar bank to recharge the bank as you are only replenishing a small deficit. However, most people have a larger bank for two reasons.

1) as you have stated above to give them a reserve on passages or during rainy periods.
2)so they don't have to run the engine to charge the bank every day.

just thought of another reason

3) so the bank doesn't get completely discharged if left for a few days and the solar controller stops working.

I don't think that having a large bank is economical if you consistently use only the top 10 or 20%. If you have a smaller bank and are on passage and need to replenish your power then you can run the engine to top the bank up enough to get you to your destination. Then you can use the engine or other charge source to charge the bank to 100%.

If you have a large bank and you do not recharge it every day then you may need a larger alternator. That, however, depends on how much and how efficient your solar array is. A smaller alternator charging a large, 50% depleted, bank will have to be dialed back in order to preserve the alternator. That means longer engine run times. That could be a big problem during rainy periods or if your solar charger lets the magic smoke out. You can also complement your alternator with a small generator which would come in very handy if your alternator goes up in smoke.

This only means that you have to look at your whole electrical system as a SYSTEM and build it from that perspective.

[DeepFrz]

When I last sailed solar arrays were not in widespread use on boats. I never actually saw one. There has been tremendous advances in battery technology and charging technology in the past 20 yrs. This means we really need to step back and re-evaluate our electrical systems.

It is now possible to have multiple types of battery charge sub-systems.

LED lighting technology, as an example, has reduced the power requirements needed for all the lighting sub-systems on the boat.

Other advances, such as multiple computers, longer computer usage, etc. will be a larger drain on the battery sub-system.

These changes can mean that we can get by with smaller, lighter battery banks with smaller lighter alternators. Can being the operative word.

[Cadence]

Originally Posted by OrangeCrush

Hello,

My new-to-me boat is hauled out for the winter and it seems that the house battery is draining on its own somehow. The battery monitor shows zero amps of draw when the house switch is turned off, but after two weeks or so the voltage drops from 12.8 to 12.0 or lower. The only thing I know that is hard wired is the bilge pumps which are both off.

The previous owner said that the batteries would hold a charge through the winter without being disconnected. In general the wiring is in good shape and most of it was redone 3 years ago. The batteries are 4 AGMs for 440 amp hours total. I'm sure it's not good for them to get so low, but a month ago when I was sailing they were able to maintain their charge through pretty heavy usage over the course of a weekend, so I don't think they're shot (yet). The starter battery is charged with an echo charger and is staying full. The only switch I've been leaving on while the boat is unplugged is the Main AC double breaker because the PO said he never turned it off. Could that be a factor? The battery monitor itself seems to stay on but I can't imagine that draws much nor do I know how to turn it off.

I've got a multimeter and I'm ready to crawl into whatever nook I need to crawl into, but I don't know where to start. If the battery monitor shows zero draw, I don't see how pulling fuses or disconnecting wires will help me find the source of the draw.

Here is a picture of my panels (while on shore power) Any advice is most Attachment 136469greatly appreciated!


Sent from my iPhone using Cruisers Sailing Forum

Had it dawned, he may have been blowing smoke up your butt. Batteries will decay by themselves. The older the quicker. Left unmaintained over the winter?

[OrangeCrush]

If you guys don't mind revisiting this very helpful thread, I've got a follow up question.

To recap: I'm replacing the existing 4 12v AGMs with 6 6v golf cart batteries connected in series-then-parallel. The 6 golf carts just barely fit in the same footprint as the 4 AGMs. They're a tad taller so I'm modifying the existing plywood enclosure to add some extra height.

The problem I see right now as I convert from AGM to FLA is spill protection. There isn't enough room in the enclosure for 6 individual battery boxes. One long box could work, but I don't know where I'd find a 43" x 11" acid-proof plastic trough. I could use a thick sheet of flexible plastic tacked to the plywood enclosure, which would be easy to install but sounds a little sloppy and would probably get punctured eventually. There's something called Randolph's Acid Proof Paint, but I'm not sure if that is really best for this sort of application (it's meant for metal not wood, and I would have to seal up the area better before painting it anyway). Other people seem to have had limited success with spray on bed-liner.

Then again, it seems like some people just put down a mat with baking soda and check it frequently for spills.

Do any of these sound like the right approach? Any pointers or experiences are much appreciated.

[skipgundlach]

We had a fiberglass box and shoebox lid built from fiberglass...

[DeepFrz]

Seal and coat the interior of the box with West System Epoxy.

[ranger58sb]

Originally Posted by OrangeCrush

To recap: I'm replacing the existing 4 12v AGMs with 6 6v golf cart batteries connected in series-then-parallel. The 6 golf carts just barely fit in the same footprint as the 4 AGMs. They're a tad taller so I'm modifying the existing plywood enclosure to add some extra height.

If you haven't bought yet... I understand from A64's posts that the Lifeline 6V AGM GPL-4CTs are slightly shorter than most GC2s...

-Chris

[OrangeCrush]

Originally Posted by ranger42c

If you haven't bought yet... I understand from A64's posts that the Lifeline 6V AGM GPL-4CTs are slightly shorter than most GC2s...

-Chris

Thanks, Chris, but after a lot of thinking I decided against AGMs because my boat is kept at a mooring and will rarely be connected to shore power so won't be brought up to 100% charge frequently enough. My solar array is not huge, and I think the GC2s will tolerate my less-than-ideal charging conditions better than AGMs. Plus the GC2s are a 3rd the price of those lifelines. Plus yes I bought them already.

As for the boxes, I found these on Hamilton Marine which I think will be perfect. (Fingers crossed that they fit): https://shop.hamiltonmarine.com/prod...ack-22943.html. If I can't make them fit, I will return the boxes and glass in the entire battery compartment.

Thanks for the help as always!