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Old 26-02-2009, 15:58   #16
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Originally Posted by Sam Plan B View Post
Concerning flat batteries, I have considered buying a small gas powered generator. The idea is, store the generator until needed and then bring it up on deck. Plug in the shore power cable and start it up. The generator would provide power for the onboard battery charger and so charge up the battery bank allowing one to start the engine. Comments please.
That is exactly what I'm doing which is why I leave my switch on both. I haven't had to use the generator to start the engine yet. I want to add a battery because the only time my batteries get fully charged is if I'm in a slip or motor most of the day. After a while the output on the charger drops so low it doesn't make sense to keep running the generator. My thinking is an extra battery gives me more opportunity to 'bulk charge' for a while and have enough juice to last the day. Of course, I know little on the subject, so I could be completely off base.
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Old 26-02-2009, 16:11   #17
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My thinking is an extra battery gives me more opportunity to 'bulk charge' for a while and have enough juice to last the day.
The larger your house bank, the less you have to draw down, so you will be operating your batteries at a higher charge, which is a good thing. Most cruisers operate their batteries between 50% and 90% charge, with a full charge at least once a month. The last 10% charge takes a long time as you said. You are on the right track by adding another battery.

Did you ever get your battery monitor connected and working properly?
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Old 26-02-2009, 17:27   #18
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I remember my first trip down the ICW... I had two batteries, a start and a house, and God did I kill that house battery! I didnt understand the whole concept killing a battery by drawing it down past 50% too many times. I'm sure I didnt get 50 cycles out of it before it booted, pooped and died. Best reason ever to add more capacity...
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Old 26-02-2009, 19:32   #19
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Good on you Paul I had a good laugh.

Good engineering is a compromise between what should be done and what can be done. What is done in land-based installations may not be achievable in a pleasure craft. Massive 2-volt cells have no place in pleasure craft and to see one explode covering a vast area with acid is scary. Today’s electrical installation in pleasure craft can be as complex if not more than a land-based power station, which is operated by an array of professionals, you will hope. There is no reason why safety procedures that are associated with land-based installations may not have a place in pleasure craft.
Yes batteries need sometime to be carefully paralleled (a full battery connected with a faulty battery can have serious destructive consequence) and, at best, for only that time that it is required to do so if no other method of preventing self-discharge is used.
Some boat owners to prevent water sloshing back into their cockpit install suitable non-return valves on their cockpit drainpipe. To prevent electricity from sloshing
from a battery to an other battery an electronic non return valve (a blocking diode) can be installed. At charging or at starting time, a suitable switch is operated to by-pass the diode. The charging process can be automated by the use of a relay controlled by a voltage sensing device who’s logic can be programmed to cut in when the load on the charging device diminishes. The wiring should be suitably protected by current limiting devices (fuses, CB, fusible link, etc) suitable for it’s location (ignition proof, waterproof, etc), correctly sized and chosen by taking into consideration the need for essential spare parts (fast DC fuses).

35 years ago when I was sailing in the Timor Sea and the Indian Ocean on my 43 ft RASTA I had nickel cadmium alkaline cells (advantage; they can be totally discharged, disadvantage; cost and caustic (nasty stuff)) to run my HF DSB (which was as big than the bulkhead) and navigation lights. Weather permitting I would bring on deck my home made charger, which consisted of a Briggs & Stratton engine and a Morris Messenger generator. The boat had no engine. All the other lighting and cooking was with kerosene. I had a DF, a neon sounder and a sextant and the sea was as enjoyable as it is today.

Accidents do happen. When a coroner is involved, he can make clueless recommendations. Then the legislators move in. In some countries, Law’s already exist and have stiff penalties attached to them, but are rarely enforced (shortage of inspectors). However legislators have better tools at their disposition they are called insurers. When an insurer for reasons of risk refuses to insure, then for the one who cannot do without an insurance that may be the end of the sailing season. Already some insurers are refusing to insure home made steel boats with a good survey.
Let’s play safe and we will sail longer
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Old 27-02-2009, 03:55   #20
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1/2 both with a twist

Hi, 1/2/both switch is exactly the setup i found on my boat when i bought her. This setup is quite outdated now and all modern boats have a relay that controls starter versus domestic battery bank charging.

Rewiring everything can be expensive and daunting so here is my suggestion (it's what i did on my system).

You have two positive wires going to your 1/2/both switch. One comes from the domestic, one from the starter battery. From the 1/2 both switch screw where the domestic positive is attached, wire a short cable to a simple on off switch then wire all your electrics to this switch (i.e. take the power from here to the control panel. Normally you would be taking the power from the common pin on the 1/2/both switch.

Leave the rest as it is. What you achieve is that your domestics can only draw from your domestic battery, so you no longer need to worry about forgetting the switch on "both" and draining your starter battery. The master 1/2/both switch will normally be left in the "all off" position. When you want to start the engine, select the starter battery then crank. Since it's 1/2/both, you still have the option to start off your domestic or off both if for some reason you need to. When the engine is running, you can use the 1/2/both switch to decide which battery you are charging but make sure your switch is of the "make-or-break" type, i.e. that when you rotate the switch there are no "gaps" where the current doesnt flow anywhere, you'll toast your alternator. Also make sure you never turn off switch to off with the engine running.

Initinally I had two 110amp batteries, domestic and starter, and given the setup, it was all a bit arbitrary as to which was domestic and which was starter. Now i've added a small 40amp cranking battery to be my starter battery (it's cheaper, weighs less and has more cranking power) while i put the other two batteries in parallel to become a 220amp domestic bank. Works a treat.

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Old 27-02-2009, 16:25   #21
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The larger your house bank, the less you have to draw down, so you will be operating your batteries at a higher charge, which is a good thing. Most cruisers operate their batteries between 50% and 90% charge, with a full charge at least once a month. The last 10% charge takes a long time as you said. You are on the right track by adding another battery.

Did you ever get your battery monitor connected and working properly?
I did finally get the monitor hooked up right. It took delving into it until I completely understood what was going on. My problem was I was only moving one wire at a time to the shunt. Now I have the neg going to the panel, the charger and the big one going to the engine all on the shunt and it's working properly. Still trying to get the % left dialed in but I have to wait until I'm 100% charged to reset it.

BTW, when you say 'equalize', that means charging to 100% right?
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Old 27-02-2009, 16:29   #22
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Originally Posted by Christian Van H View Post
I remember my first trip down the ICW... I had two batteries, a start and a house, and God did I kill that house battery! I didnt understand the whole concept killing a battery by drawing it down past 50% too many times. I'm sure I didnt get 50 cycles out of it before it booted, pooped and died. Best reason ever to add more capacity...
That is exactly why I'm using $80 batteries, Chris. I'm counting on destroying the first set before I get it figured out.
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Old 27-02-2009, 17:13   #23
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Glad you got the battery monitor sorted out.

There seems to be 2 common meanings for the term "equalize". One, often used by battery charger manufacturers is to cycle in a full charge cycle to already charged batteries. That is the charger cycles a bulk, acceptance and float phase.This type is usually automatically initiated every so often. The other term is used for a special low current, high voltage (15 or more volts) cycle lasting about 5 or more hrs. This cycle has to be applied to fully charged batteries that are offline. This type of equalize cycle has to be monitored carefully.

At least that is my understanding.
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Old 27-02-2009, 19:29   #24
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Glad you got the battery monitor sorted out.

There seems to be 2 common meanings for the term "equalize". One, often used by battery charger manufacturers is to cycle in a full charge cycle to already charged batteries. That is the charger cycles a bulk, acceptance and float phase.This type is usually automatically initiated every so often. The other term is used for a special low current, high voltage (15 or more volts) cycle lasting about 5 or more hrs. This cycle has to be applied to fully charged batteries that are offline. This type of equalize cycle has to be monitored carefully.

At least that is my understanding.

So, if I'm understanding this, I'm supposed to be running fully charged batteries through a full charge cycle? I don't know if thats even possible with my current equipment.
I'm looking at getting an Iota45. Is this charger 'smart' enough to equalize on its own? It would probably be a pain to do even then with my generator. What happens if you don't equalize?
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Old 27-02-2009, 21:12   #25
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You normally only equalize when you have shore power and then only when needed.

Some chargers have an automatic "equalize" cycle when the batteries are left for lengthy periods of time. I don't think it is a true equalize (as noted above).

Equalizing your batteries may extend their useful life if they have become sulfated. Proper maintenance of your batteries including charging, watering, being careful not to discharge beyond 50% will help prevent sulfation.

I don't think you have to worry about it to much with $80. batteries, because I doubt that they are true deep cycle batteries. However, I may be wrong about that.

More reading for you

Trojan Battery Company

Battery Tutorial | BatteryStuff.com
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Old 28-02-2009, 02:32   #26
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It's only sort of true. a common 12 volt battery is 6 - 2 volt cells in parallel. ......
Surely you mean in series rather than in parallel.

As to two similar batteries in parallel, I also would like to some tests that they are self discharging in less than twice the time of a single battery.
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