Cooked Batteries

[Alan Wheeler]

Thanks Delmarrey. The lower link is just a battery combiner/isolater relay. It wouldn't work.
Your first link to the C-charger is what I already have, to link the alternator to the house bank and start bank. But they only split the charge while maintaining isolation of banks. They don't isolate from individual batteries in one bank. Remember, each battery is connected via a very heavey cable, thus making the individual batteries one. Plus, as there is a voltage drop, the charger would have an eroneuose reading and thus not charge through it's three steps correctly, which is what I believe caused the fault to begin with.
I don't know if a product exists, nor what it would cost if it did, but I imagine a huge installation like a submarine would have one if it did exist. But it would need to be some sort of relay device, capable of switching the entire battery current. So maybe upto 1000A's. It would have to electronicaly monitor the battery in both charge and discharge and if something was out of the normal, it would then drop the relay to isolate that battery from the rest of the bank.

[delmarrey]

So what I hear is your batteries are hooked up in series. Rather then three batteries, I think I would buy one large one to take the place of three.

I have three batteries also but they are on combiners. Each batt. charges only what it needs.

My house batt. is hooked to the altenator thru a combiner with a switch to the second batt. that also stays charged by another combiner. So I can run on one batt. or two.
The third batt. is up forward for the winch use only and is also on another combiner. If one battery is low it doesn't draw off any of the others. And if the house batt. get too low then I switch over to two batteries.

The combiners have a little green LED that lights up when that batt. is charging. I know I need a one new batt. this year because one of the combiners is always on, which means it's having trouble getting up to voltage.

Here's a site that might be of interest..................................._/)

Yandina

[Alan Wheeler]

No the three batteries are connected in Parrellel. Three 12V 200Ahr batteries in Parrellel equals 12V @600Ahrs. If three were in series, you would have either 36V or you would need three 4V batteries to get 12V. The other side of the coin is that I would doubt you could get one 600Ahr battery, nor would I want to try and lift the thing if you could. The 200Ahr battery is just about as much as I want to lift. They must be 60KG(150lb) each or so.

Yes I have seen that circuit you posted a link to. It is a common circuit and idea to do such a job. There are draw backs with that though. The thought is that the charge to the batteries are from the alternator only and it doesn't matter to much if you have a slight voltage drop across the splitter diode to the battery. But in the case of a voltage monitoring multi stage charger, that voltage drop becomes criticle. The charge works by bringing the voltage upto I think 14.8V. At that point, the current is decreased substantially and the voltage is raised to something like 17V or so. This is called the absorbtion stage. A battery will never accpet a full charge at a lower voltage higher current, so the higher voltage coaches the battery into taking on more charge. Some chargers even get into pulse modulation etc. Then once the battery reaches the next level, the voltage is droped back down to a float level. It's not a crued trickle charge, it is slightly different. But the float level maintains the battery at about 13.8V
These different voltage levels are criticle and having a splitter diode in line simply mucks up the sensing and thus when the charger should be going from one stage to the next.

[Chris Sheridan]

Do all boats work on a 12V electrical system, or do some work on a 24V or higher system?

[GordMay]

Yes - some boats utilize 24 Volts.
At some point, we may begin to see more 42 Volt (36V Nominal) systems, as the 42V PowerNet standard comes into more common automotive use.
The higher DC voltages have the advantage of lowering Amperages, hence reducing required wire size and/or voltage drop.
Current varies Inversely with Voltage (I = E/R)

[Alan Wheeler]

I could be argued that 24V and higher is better. As Gord pointed out about less power loss and smaller wires. The main issue that tends to steer most away from anything higher than 12V is the price. 24V items tend to be twice the price. Just why I don't really know. Some would argue that there is more 12V equipment produced, so costs are reduced. Some would argue that there is more wire in 24V motors so it's more expensive. Well maybe true, but 12V is using heavier wire. And the cost of the wire is negligible to the overall price difference. what ever the reason, 24V equipment tends to be expensive. Electronics these days are able to take a range of voltage, so that area has changed.
It is more common to find 24V systems on large engines. My Perkins for instance was originaly a 24V system. The original owner changed it over to 12V. Why I just don't know. I wish it was 24V still. It would solve so many issues. One of them is the way you can use and charge batteries. In series is much safer than in Parrellel. I wouldn't have had an issue of over charging due to a cell dropping out if they were in series. Of course, I may have lost all voltage if one goes OC, but that is in itself a safety feature.
My advice, if you can go 24V, go for it.

[BC Mike]

The Leyland Hippo I drove had four 6 volt batteries for 24 volts.
It had a large engine.
Michael

[capt lar]

I will be replacing batteries and wonder which is "better", traditional flooded such as Rolls, or ACM.
Please try to use some version of English when responding.

Larry

[Alan Wheeler]

Well seeing as I have just gone through this.... I went back to a Deep cycle flooded. Main reason was cost. But it was also cost versus longevity. From the manufactureres mouths, all said that the flooded has been found to outlast a Gel or AGM, PROVIDED that the flooded has good maintanace.
The advantage of sealed or Maintanance free batteries( other than being mainatance free) is that they have no acid that can leak out should you have a roll over.
At least for me here in NZ, it was going to cost me NZ$2500 to go to 6V cells. This would have given me 800Ahrs, but I had no choice on that and didn't need 800ahrs. the next was to go to a AGM and have the 600Ahrs. But this was going to cost me $1800. So in the end I went to the flooded, which cost me $320 each. I have started with 2 batteries to get me started. The third will be added a little later in the year when I can afford it. So I will end up with my 600Ahrs for just a little under a grand.
The interesting thing is, with the old batteries, after a night on the hook, I would have 10V left int he bank. Compleately drained. Now in the morning, and with only 400Ahrs, I still have 12.3V. That was staggering. The old batteries must have been stuffed a long time and I didn't realise.

[Alan Wheeler]

Oh and I should have added, the other thing that sold me, the batteries I have are NZ made. They come with a Two year warranty. If one should fail in that two years, they will replace the entire bank of them, provided all are ruffly the same age. Hence I don't want to wait to long before I get my third in.

[southernman]

we have gel batteries that are 3 years old and still getting good results from them. Interesting reading your volt readings - what are you running while on the hook to suck that much juice from your batteries? We only have 200 amp hrs which is light but I'll be doubling that this year. We find that in a typical 24 hr period we start at 14 volts fully charged and they drop to 12.4 volts.

I worked out our typical 24 hour period use was 153 amp hours but that is not using the autopilot as we use the wind vane. You can add another 48 amp hours for the tri light (12 hrs x 4 amps) but I'm replacing that with an LED one this weekend.

On the charge side we get 6 amps from solar on a good day and have a tow generator and an air x windturbine which gives us very good charging. Add to that a big body 100amp alternator on a cruzpro charge controller.

We generally charge using the alternator as our main freezer is driven off the compressor on the engine anyhow.

Interested in your feedback on the battery bank size - and voltage readings? Do you think we should increase the battery bank size? Also at what voltage would you start recharging? IE. when are the batteries dead?

[Alan Wheeler]

This is quite a complex issue. Not that it is complex to understand, it just has a lot5 of side issues that need consideration. Like here is just one to think about..., you may use 100Ahrs in a 12hr (overnight)period. But you may only have charging available to replenish 50Ahrs before your next 12hr overnight period. So you are on the back foot already. So what ever your bank size is, is not so much the issue. The main issue is, can you replace what you have used.
OK, if you click back one to get yourself to the threads under this Power heading and go down to the bottom of the page, you will see some tabs that allow you to go back to topics in the past. It maybe that all you have is the last 30days or 100days. Click on "the begining" and click go. Then scroll through and clickn on subjects about batteries. There are some very clever guy's that have participated some great info in those threads and if you are like me, there are hours of great reading to go back over and digest. trust me, it will cover all your questions and more. However, If you can't find an answeror something brings up another question, please feel free to ask here.

[Alan Wheeler]

Oh I forgot to add. I have the following.
A 20W anchor light.
A fridge box=about 4Ahrs on average.
A fridge/freezer that draws 17A conituouse, but we run that on Gas to keep it out of the electrical system.
A 240V Freezer running off the inverter. It's about the same draw'ish as the fridge box.
House Lighting
Outside deck lighting if Kids are out fishing,or we want to attract fish at night around the boat just for fun.
TV
DVD
Electric toilet
Maybe a bilge pump may cycle in the night.
All in all, not a huge load.

[Alan Wheeler]

Dang, what's wrong with my memory
I forgot another point. The first night is not an issue. But if we are out for a weekend, we may not have had the engine and genset running long enough to fully recharge the bank. (See my first post in this lot of three ) So it is good to have extra capacity to hold you through another night, till you can run charging devices.

[NoTies]

Damn Alan, couldn't you just fit sails to your house?
At least you can run the power station on the steam out to the sailing ground.
It's going to be interesting to see how my system works out for us. I've gone with 1x 80W panel, 200a/h AGM batts, 25a charger to run off 1000W Honda EU. I'm going to make the panel "aimable" so hopefully won't have to dig out the genset too often. Fridge draw is 2A, pilot 1A @10% duty cycle, lighting will be converted to LED then there's the electronics.
Looks like I've got a date for return to the world. 25th of Feb. Yahoo.