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Old 09-10-2014, 16:12   #1
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Very Light Weight Battery.

I removed my 60 pound battery from my 23 ft cruiser racer last spring to get rid of weight. Now we are finishing in the dark and I need to run the 12VAC lights.

I don't know how many ah I need to reasonably run the mast and running lights plus maybe two or three small dome lights in the cabin. Also what chemestry of battery if it matters. I'm seeing ads for maybe 5 ah batt for $20 that weighs 5# what have a tab terminal rather than posts. Are these sufficient? Better ideas?

Thanks,
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Old 09-10-2014, 17:31   #2
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Re: Very Light Weight Battery.

I have flashlights with LED lights that have 3 AA batteries and last 300 hours.

So that sort of thing could be the go. Remember, people who read Colregs correctly realise theres no law about having lights way up your mast. All nav lights can be done with portables at, or near deck level to no higher than you can stand.
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Old 09-10-2014, 17:39   #3
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Re: Very Light Weight Battery.

Depends on what kind of lights. If you have 5 bulbs that use 1 amp each you would use up a 5ah battery in 1 hour. If you have 5 LED bulbs that burn 100ma each thats 1/2 an amp so 10 hours out of the 5ah battery.

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Old 09-10-2014, 17:50   #4
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Re: Very Light Weight Battery.

I hate disposable batteries, but if light weight and ease of removing when not needed are the criteria (and you can accept AAA batteries - either disposable or rechargeable):

Attwood LED Bow & Stern Light Combo ATT-141807, Portable Navigation Lights

LED Battery Operated Stick On Tap Light (Pack of 4)
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Old 09-10-2014, 21:34   #5
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Re: Very Light Weight Battery.

Consider getting a NiMH battery pack. 12v, 10ah, 4lb, about $100, $140 with charger.

12V Battery Packs from 10Ah to 52Ah
This is just one of a number of suppliers. Prices are fairly consistent.

If you pull up to shore power every night you are good to go. If not then you will want a solar panel. The problem with that is the charging. A NiMH charger for solar panel feed runs about $250. What I would do instead is get a cigarette lighter inverter ($30-70 for 75-150w) to feed the standard charger. So the setup would be:

Panel-->Inverter-->Charger-->Battery.

The extra step in the middle will decrease potential efficiency in exchange for cost savings. Given that NiMH charges more efficiently than lead-acid batteries of any type, you will be even or perhaps a bit ahead.

Given the standing rule of thumb that 25% of panels rated watts is what you can expect in amp-hours I would get 40-45w of solar panels for one battery pack and 75-90w for two packs. With more than 2 packs you want to think about getting a multichannel charger.

Because of the differing chemistry NiMH batteries can be discharge down to 100% DoD vs 50% for LAs. 80% DoD will probably increase the number of cycles you get significantly.

That covers the supply side.

On the demand side of the system:

House lights need to become LED or florescent.

Running lights for sailing need to be LED. The best deal I have found is:
Misc: NASA Marine Instruments
I do not vouch for its durability, or it meeting minimum brightness requirements. It combines a Tricolor and an anchor light and draws about 0.2a. Price is about $250 in the US.

Motoring presents a problem. The best situation is that your motor has a generator and you run normal incandecent running and steaming lights. If not then you need to think about LED running and steaming lights and maybe the tricolor is not such a deal.

If you really are just running the minimal lights, one pack with a solar panel will get you along. If you toss in a VHF, or FM radio, you'll want 2. A CD player or fans will push you still higher.
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Old 11-10-2014, 14:52   #6
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Re: Very Light Weight Battery.

Wish I knew the Ah of the little incandescant bulbs used on the 80s vintage boat. They probably are marked and I should simply look at them. The mast lights are a tubular affair with contacts on each end, but running and interior dome lights are like camper bulbs. I can't imagine one of these little guys using an amp, I have a real battery for cruising but have been mostly racing lately. That 60 pounder is presently in a power (ugh) boat.

There's not problem taking it home for a rechage after each use if needed, if it only weighs five pounds or so, or maybe I could charge it in the car. I have a small solar panel, but those seem to take eons to apply a charge. Maybe better for a little battery.

Thank you for the suggestions.
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Old 11-10-2014, 16:16   #7
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Re: Very Light Weight Battery.

Quote:
Originally Posted by cptmclark View Post
Wish I knew the Ah of the little incandescant bulbs used on the 80s vintage boat. They probably are marked and I should simply look at them. The mast lights are a tubular affair with contacts on each end, but running and interior dome lights are like camper bulbs. I can't imagine one of these little guys using an amp, I have a real battery for cruising but have been mostly racing lately. That 60 pounder is presently in a power (ugh) boat.

There's not problem taking it home for a rechage after each use if needed, if it only weighs five pounds or so, or maybe I could charge it in the car. I have a small solar panel, but those seem to take eons to apply a charge. Maybe better for a little battery.

Thank you for the suggestions.
Pull the bulbs and check the bases. The wattage is normally stamped on the base. Go from there. You might find that a single Group 24 105 AHr deep cycle battery is the best compromise between cost/weight/endurance and life cycles.

FWIW...
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Old 11-10-2014, 18:36   #8
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Re: Very Light Weight Battery.

Quote:
Originally Posted by cptmclark View Post
Wish I knew the Ah of the little incandescant bulbs used on the 80s vintage boat. They probably are marked and I should simply look at them. The mast lights are a tubular affair with contacts on each end, but running and interior dome lights are like camper bulbs. I can't imagine one of these little guys using an amp, I have a real battery for cruising but have been mostly racing lately. That 60 pounder is presently in a power (ugh) boat.

There's not problem taking it home for a rechage after each use if needed, if it only weighs five pounds or so, or maybe I could charge it in the car. I have a small solar panel, but those seem to take eons to apply a charge. Maybe better for a little battery.

Thank you for the suggestions.
If you go with the NiMH you have to get LED or fluorescent lighting.

The mast light probably is a 25w bulb which is what is required to meet visibility requirements. That's just over 2 amps of draw.

I just looked up the incandescent bulb wattages for a typical PERKO fixture. They are 11 and 17w depending on fixture size and brightness. That's about 1a and about 1.5a draw respectively.

The one bulb on the mast running at the same time as one cabin light will have about 3 hr of run time on a 10 a-hr battery. Just the mastlight gives you 5hr. Two batteries double the run time, etc....

If you want to get rid of the heavy battery you have to invest in the rest of the system.

Did you get rid of the battery because of the weight on the boat or the weight involved in pulling it out and recharging it?
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Old 11-10-2014, 18:39   #9
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Re: Very Light Weight Battery.

Quote:
Originally Posted by svHyLyte View Post
Pull the bulbs and check the bases. The wattage is normally stamped on the base. Go from there. You might find that a single Group 24 105 AHr deep cycle battery is the best compromise between cost/weight/endurance and life cycles.

FWIW...
I don't think she/he wants to pull a 60lb battery and replace it with a 45lb battery.

On the other hand if there isn't a willingness/ability to invest in alternatives, it probably is the best alternative.
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Old 11-10-2014, 21:38   #10
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Re: Very Light Weight Battery.

Quote:
Originally Posted by Adelie View Post

The one bulb on the mast running at the same time as one cabin light will have about 3 hr of run time on a 10 a-hr battery. Just the mastlight gives you 5hr.
If you want to get rid of the heavy battery you have to invest in the rest of the system.
These numbers are way off because you are assuming 0% soc and also with such high loads on a tiny battery peukert curve comes in and reduces the battery a lot

2a draw on a 10ah battery would probably last about 1.5-2 hours
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Old 11-10-2014, 22:04   #11
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Re: Very Light Weight Battery.

Quote:
Originally Posted by smac999 View Post
These numbers are way off because you are assuming 0% soc and also with such high loads on a tiny battery peukert curve comes in and reduces the battery a lot

2a draw on a 10ah battery would probably last about 1.5-2 hours
You are just making my point better. A smaller battery only works if the demand side is reduced.
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Old 11-10-2014, 22:35   #12
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Re: Very Light Weight Battery.

A Lithium battery is going to be about as light as it gets.
As I mentioned in another thread on trolling motor dinghy,
you can get a 40ah 12v battery that weighs about 13lbs,
and you can pretty much use all 40ah.
Can charge it via a car alternator or most lead-acid chargers.

Not real cheap though, $160-200.

If all you need is 20ah, I've got some of those, about 320 of them..
A 12v pack would be about 6lbs.
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Old 12-10-2014, 19:32   #13
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Re: Very Light Weight Battery.

Thank you for the replies.
I didn't expect so many to want to help. Tonight I had to go claim a trailer parking spot for the winter, and while there pulled a bulb from the red/green fwd position light fixture. It is a cylindrical affair that is held in place with springs forcing it between the two terminals. As best I recall that's the same style of bulb used in the mast lights.

Thinking myself smarter than having to pull an acutal bulb (three screws) from a cabin light fixture I instead popped the fuse from one of the circuits. Well, it's a fuse all right, but I'm not sure I can read it properly. One end says 250V then the UL symbol. The other end reads BUSSAGC3. Does that mean 3 amps? I'm used to plainly marked fuses and this one ain't. Or my old eyes can't see it.

About the mast and postion lights, I'm thinking they are standard items and somebody knows and probably sells a gadzillion of them. 7/16 in diameter and 1 3/4 inch long. Conventional wire filament. Metal terminal ends have dimples to accpet the contacts. This has to be a super common bulb used on gadzillions of small (23') cruisers everywhere.

The idea i'm getting from the several replies is that it's not reasonable to have a small battery that will run the three position lights and maybe a cabin dome light for a few hours. I can tape small flashlights with colored film over them to the deck and use them for many years. Those are less voltage of course, but much brighter than needed. Friendly sarcasm intended.

Thanks again for the help and ideas.
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Old 12-10-2014, 21:03   #14
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Re: Very Light Weight Battery.

AGC3 is an AGC style fuse with 3 amp rating. AGC is a common fuse size.
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Old 13-10-2014, 07:46   #15
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Re: Very Light Weight Battery.

What Dan said.
BUSS AGC-3 are Fast Acting Glass Tube Fuses 1/4" dia. X 1-1/4" long, rated 3 Amp (max 250V), with a typical cold resistance of 0.045 Ohms, as manufactured by Bussman.
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