Boat Battery

[jmac]

I have been getting my boat ready the next step is to buy a battery for it. It is a 4.5 metre fibreglass runabout with a 50hp 2 stroke Mercury.

This is the first time I am buying a battery for a boat. I have investigated on the internet and there seems to be two main types being deep cycle and starting batteries. I probably only need a starting battery as most of the electrics would only be on while the outboard is on except for when I put lights on the boat and go out in the night.

I have also seen there are some batteries that are both starting and deep cycle. Should I use one of these (don't know how much they are compared to the normal starting or deep cycle) or should I possibly consider using two batteries and getting a deep cycle when I go out at night.

I also have no idea what size cranking amps I will need to start my outboard.

Any recommendations for size, makes,models, etc will be appreciated.

Joe

[rayke1938]

Feral has a contact at wacol . It is a firm that sells deep cycle batteries that have been used as computer standby power systems. These batteries are usually replaced at 2 or 5 year intervals and have another 5 - 8 years life in them.They give a warranty ( 3 Months it think).

A deep cycle battery will do everything that a marine battery does plus it is built stronger with better quality plates etc. A deep cycle battery has a design life of 10 years .

Feral will probably pick up this thread tonight,

Ray

[Brian D]

Mate no doubt that Feral and Ray know their stuff here.

But what I did is go for a slightly over sized cranking battery. I refer you to my posts on boat refit and electrics. I have a similar size boat and slightly bigger motor. Like you I had concerns with lights draining battery for starting.

The main purpose is to make sure you have enough cranking battery left to start the motor. The lights are a seperate issue. Main priority is turning over the motor to get home.

So what I have done is wired in a twin fluro cabin light direct to the battery that has an independant light switch. I also have the nav lights and all round anchor light wired through the switch board, again with independant switches.

As a precausion I use a seperate stand alone AA battery lattern as my main cabin light. THis is a overkill I know but it has zero worry about cranking.

Cranking Batteries go in sizes like 50 to 70 hp, then next size up is 75 - 110 etc. So the 50-70 should be good for your 50hp. But buy the best you can afford.

I suggest if you want lots of extras (lights, live tanks) get a seperate deep cycle and wire all your gadgets to that.

[Guest IcEkNiGhT]

Post edited by: IcEkNiGhT, at: 2007/02/12 12:59

[Feral]

I'd go deep cycle, you need to go about 40% over rated to get equivilent cranking amps. (IE if your boat manual says you need 100cca, go a 140amp hour deep cycle and you will get same cranking performance) This does not really matter that much with a boat though, they use bugger all amps compared to cars.

Speaking of which DO NOT get a car battery. The pounding will kill it. If you go a cranking battery make sure it is a marine unit.

If you interested in a deep cycle second hand unit, give Batrec at Wacol a call and see what they have available.

ph is 38794507 business hours. Lady in Office is Sandra. tell them you were recommended on AFO site, probably wont get a discount, but if a few people do it, they might start to offer one in future.

Also gives Angus another potential sponsor if they get a bit of business from the site.!

[Brian D]

Feral wrote:

I'd go deep cycle, you need to go about 40% over rated to get equivilent cranking amps. (IE if your boat manual says you need 100cca, go a 140amp hour deep cycle and you will get same cranking performance) This does not really matter that much with a boat though, they use bugger all amps compared to cars.

If you don't have a manual go to a place like Bias Boating and they will ask you your motor, then they look at a chart and say \"take this one\". Depending on budget either do what Feral says above (best option) or go the one they show you and keep a seperate system for gadgets (hard wired or battery).

The problem with the Feral option for me is that I fish for long periods and don't want fear of motor not cranking. But I am paranoid from previously abusing substances. You might not have same problem.:woohoo: :whistle:

[jmac]

Thanks for all the information.

I see that some of the marine batteries are sealed maintenance free. Are these worth getting? I think that the main reason to get them would be to avoid spills.

I was planning to put the battery in a battery box. Any issues with that?

Feral the deep cycle batteries from Wacol are they marine or just standard. I have read that they are built a lot stronger then standard car batteries so they can probably handle the marine a lot better then a car battery.

Joe

[Guest IcEkNiGhT]

Post edited by: IcEkNiGhT, at: 2007/02/12 12:59

[rayke1938]

definatly recommend a battery box.

It reduces risk of dropping something across terminals and shorting out battery.

I will not use anything else except a sealed battery.

No explosive hydrogen gas emitted whilst charging.

No need to top up.

Only type of battery allowed on Baroon Pocket dam.

Deep cycle batteries are more sturdily constructed than marine battery.

If you are going to fish overnight and are worried about battery capacity I would recommend the use of 12 v fluorescent lights for general lighting and the fitting of led lights for your all round and navigation lights.

If your existing nav lights take festoon type bulbs you can buy led lamp inserts to replace the normal bulb.

If you have problems with the fluoro interfering with radio you can also purchase led down lights to use for your general lights.

Ray

Ray

[Feral]

IcEkNiGhT wrote:

we have replaced so many of the sealed calcium type are these the ones you talking about? i have always found you are just better to use what the manufacturer reccomends as its always the best, marine battries to my understanding have the plates fibreglass coated to prevent them falling apart when pounding,

As Ray said Deep cycle batteries are much sturdier than Marine, which is a fair bit sturdier than car units.

For example my 6volt 160amp hour deep cycle batteries weigh 38 kilo's each (I run 2 in series to get 12 volts). The same size car battery would be lucky to weigh 10 kilo's.

[Guest IcEkNiGhT]

Post edited by: IcEkNiGhT, at: 2007/02/12 13:00

[Brian D]

Good point here guys

Ray and Feral have practical hands on experience - they know their shit, learnt by experience, trial and error. one of my best friends (died of cancer) was this way inclinded - outside the box, saw things for use not sellability. That's proberby why I appreciate the 2 dags so much.

But only smart person or stupid fool goes against what the maker reconmends.

Me myself still struggles to go outside the box.

[Feral]

IcEkNiGhT wrote:

i just go on what mercury recommend, working at a dealership and all but u could be right i dont know, i just go on what they say

Nothing wrong with that, but they usually recommend minimum or slightly above, requirements. Going deep cycle is a much more robust solution. Particularly as any battery is expensive, a marine more so, then deep cycle horrendously so!

That is the beauty of 2nd hand industrial grade deep cycle batteries, they are relatively cheap, and as most industrial Grade deep cycle batteries are designed for 10 to 15 years life, as against 2 or 3 years for normal and up to 6 for marine batteries, very good buying. If they see out the 3 month warranty period, they will pretty much last forever.

The batteries I have in my boat cost me well under $200 second hand, the retail new price would have been around $1400. Two are only a year old, one 3 years old, one 5 years. All with a 10 to 15 year design life.

Here is a link for a pretty good battery FAQ if anyone is interested.

http://www.windsun.com/Batteries/Battery_FAQ.htm

Post edited by: Feral, at: 2007/01/31 22:15

[jmac]

Thanks for all your help guys. Karma to come to you all.

Firstly Feral that link you posted has been moved and I think it is now

http://www.solar-electric.com/deep_cycle_batteries/deep_cycle_battery_faq.htm.

Those used deep cycle batteries sound great but are heavy. I have given them a call and will go and take a look and then decide.

Also Feral...jumping threads again...thanks for the info on the size of your boat and how it goes with the 6HP. I did look under the other threads but I wasn't sure which boat was the Silver bullet and I think you have another one as well.

I have a 6HP Johnson that I will probably have to try on the new boat and if it goes well I could get rid of the dinghy that I also have and norammly use with the 6HP. Might need a long shaft though.

Joe

[Feral]

happy hunting!

The silver bullet thread is the 4th one in the top posts thread - \"my new project 4.9 tinnie\"