Starter Battery How To Setup?

[brandenjg]

Hello all, I recently bought an outboard with an electric start and I've never owned one before.

I'm trying to work out firstly whether I attach the controller to my main 110ah dual purpose battery or if I have to buy a seperate starter battery?

Secondly, do I directly wire to the battery or do I need to wire through an isolator or in-line fuse?

The outboard is a Honda BF15 and provides 12amp charging.

Any advice appreciated. Branden

[tjg1677]

Hi Branden,

the Honda BF15 is a great engine and a wise purchase.  To answer your questions, the best practice is to provide a seperate starter battery and connect it to that via an isolator, no inline fuse required.

Less good practice but possible and workable is to connect to the dual purpose battery via its own isolator. This has pros and cons. The cons are that if you flatten your DP battery then you cannot start the engine electrically, although it is possible still to hand start.

Pros -  saves the space taken up by a second starter battery and will also charge up your DP battery whilst the engine is running, cheaper installation cost and is generally neater.

Just to complicate things further, it is possible to fit a two way battery isolator, where you can switch between one set of batteries or another or even have both in the circuit, gives more flexibility for battery usage and re charging.

 

hope this helps

trev

[brandenjg]

Thanks Trev. I'll go the the extra battery + isolator route rather than the 2 way isolator. Would I need another dual purpose battery or a starter specific battery E.g a car battery? Branden 

[Vaughan]

6 minutes ago, brandenjg said:

Would I need another dual purpose battery or a starter specific battery E.g a car battery?

For a separate battery it would be the starter type. All a question of CCA - cold cranking amps. I don't suppose a petrol outboard has a very big starter so you should be OK just with your DP battery.

Other than that, What Trev said!

[Viking23]

40 minutes ago, brandenjg said:

Thanks Trev. I'll go the the extra battery + isolator route rather than the 2 way isolator. Would I need another dual purpose battery or a starter specific battery E.g a car battery? Branden 

We have the earlier version of your Honda 15, square top. We started off with just one 75ah leisure battery, and we often discharged it so it couldn't start the engine. Hand pull start worked first pull every time.

What we have now are two identical  heavy duty leisure batteries, each about 96ah each has it's own isolator switch. So you choose one, or two or both.

It works well for us. Just for your reference, we have current shunts and voltmeters for each battery, and we know exactly what the state of charge of each battery is. Our Honda takes approx 100 Amps on starting. When the engine has been left for a month or so, I often pull the start cord to just turn the engine just a bit before electric starting, make sure it can turn lol However sometimes it actually starts with the minimum pull. It's not a bad idea to manually start the engine say a couple of times a year anyway, one day you might have to lol.

BSS require the batteries to be secured, ie less than 10 mm in any direction, and make sure the terminals are not exposed, iecwhat if a mooring pin drops in lol.

I can say a lot more, but see how you get on.

Richard  

[tjg1677]

I agree, either type of battery will do if it for stand on its own just for the engine, in fact a car starter battery may be cheaper as you will only need something like a similar type to a small engines fiesta etc.

however, that said, how do you propose to charge the dp battery that you already have on board, as if you connect a stand alone battery for the engine, the dp battery will not be in the charging circuit, hence what Viking says makes sense by putting in a dual isolator and gives total flexibility, I appreciate it adds to the cost but suspect it will pay off in the long run.

if you really don't want to fit a dual isolator, an alternative is to fit another dp battery of the same capacity, wire it in parallel to the existing dp battery and fit isolators between them, when the engine is running it charges both, when you shut the engine down, isolate the second battery, that way you always have the means to start the engine yet charge both.

trev

[brandenjg]

I don't have anything to charge my main battery onboard at the minute as it only powers lights and horn so very little power usage. When it's low I take it home and plug in to battery charger.

My 2nd battery takes the brunt of my power consumption. It powers the stereo, USB ports for phone charging, dc socket for spotlight and hoover. This battery is charged by solar panel and always has a good charge level. P.s it's only a 85ah.

The idea of charging off the engine is new to me. I like things to be obvious so isolator near switch panel for lights. Isolator near stereo for stereo and will be an isolator near engine bay for engine.

[Wildfuzz]

12 hours ago, tjg1677 said:

Hi Branden,

the Honda BF15 is a great engine and a wise purchase.  To answer your questions, the best practice is to provide a seperate starter battery and connect it to that via an isolator, no inline fuse required.

Less good practice but possible and workable is to connect to the dual purpose battery via its own isolator. This has pros and cons. The cons are that if you flatten your DP battery then you cannot start the engine electrically, although it is possible still to hand start.

Pros -  saves the space taken up by a second starter battery and will also charge up your DP battery whilst the engine is running, cheaper installation cost and is generally neater.

Just to complicate things further, it is possible to fit a two way battery isolator, where you can switch between one set of batteries or another or even have both in the circuit, gives more flexibility for battery usage and re charging.

 

hope this helps

trev

I had the last option on my previous boat, running the two batteries via a switchable isolator, even from the 40hp I found the charging to be very unsatisfactory due to the low output of the engine alternator.

 

On my current boat I am running a Suzuki DF15, similar to your Honda and a single 85ah battery, this runs every thing on the boat and the starter, never had a problem with running low even when Mrs Wildfuzz has been watching the TV, me the fish finder and lights and spot lamp all on together. I do start the engine by pull start every few weeks, just to check I can if I need to, current battery 3 years old and even in this cold spell no issues with a single unit.

 

Worst case scenario is a flat battery in the morning, then a simple pull start and we are off and charging. I like to keep it simple

[tjg1677]

hello again branden,

I didn't twig on to the fact you had two batteries, now I have, it is easy. Simply use your low output battery as the engine, starter, fit an isolator between the engine and battery, bingo, problem sorted and the engine will charge up the battery to save you having to take it home to charge. Simples!

 

trev

[brandenjg]

2 hours ago, tjg1677 said:

hello again branden,

I didn't twig on to the fact you had two batteries, now I have, it is easy. Simply use your low output battery as the engine, starter, fit an isolator between the engine and battery, bingo, problem sorted and the engine will charge up the battery to save you having to take it home to charge. Simples!

 

trev

I like it mainly because I don't have to buy anything else 

[ExUserGone]

When I had an outboard powered boat I had 2x 110ah batteries connected together as a single bank for both starting and domestic as the engine could always be hand started if need be (although awkward), a mariner 9.9 charged just fine with good running hours done.

Small outboards don't take a lot of starting.