Battery size / capacity

[Superaquarama]

Hi Guys,

Can anyone suggest what size battery would be necessary for a 50 hp 2 stroke Yamaha ? Presumably deep-cycle would be better than car type ?

As a rule the larger the better, but there are physical size constraints.

Thanks

 

[VicS]

Hi Guys,

Can anyone suggest what size battery would be necessary for a 50 hp 2 stroke Yamaha ? Presumably deep-cycle would be better than car type ?

As a rule the larger the better, but there are physical size constraints.

Thanks

I take it this is primarily for starting the engine ?

If so a car starter battery is what you'll need.

You dont say exactly what model engine but you will find a recommendation for the size of battery i in the owners manual. .. 380 CCA ??? Probably around 60Ah

If you are going to power much on board equipment maybe a leisure/dual purpose battery.

Only consider a true deep cycle battery if its not for starting the engine

 

[Superaquarama]

Thanks for the reply.

Yes, it's primarily for starting. There are lights and a vhf, but usually only when the engine's running anyway.

I thought deep-cycle and leisure were the same, but sounds as though I was wrong ! I imagined a leisure battery may be better than a car type as it would hold a charge better if not in regular use, but perhaps I'm wrong about this too ?

 

[ianj99]

A cheap 50-60ah car battery is more than adequate for a 50hp outboard if little power is required when the engine is not running. After all, most motorcycles have a tiny (12-16AH) or so battery.

As far as holding charge goes, no LA battery is good at this so buy a small solar trickle charger to keep the battery topped up. £20 will buy one suitable for a 60ah battery.

 

[VicS]

Thanks for the reply.

Yes, it's primarily for starting. There are lights and a vhf, but usually only when the engine's running anyway.

I thought deep-cycle and leisure were the same, but sounds as though I was wrong ! I imagined a leisure battery may be better than a car type as it would hold a charge better if not in regular use, but perhaps I'm wrong about this too ?

A leisure battery is very similar to a starter battery.... thicker plates if you are lucky I believe, otherwise maybe only the label, and should be treated in the same way.
A deep cycle battery is designed to withstand frequent discharges to a much lower level than a starter battery but it is not designed to supply the high current required by a starter motor.

A cheap 50-60ah car battery is more than adequate for a 50hp outboard if little power is required when the engine is not running. After all, most motorcycles have a tiny (12-16AH) or so battery.

As far as holding charge goes, no LA battery is good at this so buy a small solar trickle charger to keep the battery topped up. £20 will buy one suitable for a 60ah battery.

But the owners manual for the engine recommends 380 CCA minimum. .

 

[ianj99]

A leisure battery is very similar to a starter battery.... thicker plates if you are lucky I believe, otherwise maybe only the label, and should be treated in the same way.
A deep cycle battery is designed to withstand frequent discharges to a much lower level than a starter battery but it is not designed to supply the high current required by a starter motor.



But the owners manual for the engine recommends 380 CCA minimum. .

The CCA isn't the same as the AH.
Here's the spec for a £33 50AH battery from tayna.co.uk
As you can see its more than big enough and in fact you could use a 40ah battery.

Technical Specification
Terminals Positive Front RightStandard
Voltage 12 Volts
Technology Wet
Capacity 50 Ah
CCA 480 A
Length 210 mm
Width 175 mm
Height inc. terms 190 mm

Ian

 

[Superaquarama]

Okay, many thanks,everyone.

I don't know offhand what the c.c. of the Yamaha 50 is, presumably about a litre, so if you think in terms of a Mini (old type) then they have a pretty small battery.

That said, I suppose the more reserve capacity the better, so I'll perhaps get something that's higher capacity and will fit in the box (I always find a Peugeot 205 diesel battery's a nice compact one with good capacity), which is only just over 175mm wide inside and forget about leisure batteries.

But those small solar panels, Ian - do you not also get into the realms of voltage regulators too, or are they not necessary with a very small panel ?

 

[ianj99]

Okay, many thanks,everyone.

I don't know offhand what the c.c. of the Yamaha 50 is, presumably about a litre, so if you think in terms of a Mini (old type) then they have a pretty small battery.

That said, I suppose the more reserve capacity the better, so I'll perhaps get something that's higher capacity and will fit in the box (I always find a Peugeot 205 diesel battery's a nice compact one with good capacity), which is only just over 175mm wide inside and forget about leisure batteries.

But those small solar panels, Ian - do you not also get into the realms of voltage regulators too, or are they not necessary with a very small panel ?

You only need a very small panel which doesn't need a regulator since you are only trickle charging the battery. If you were using the engine once a month or more then the battery would be okay but for what it costs, a small panel is worth it for peace of mind sake. (& to keep it healthy over the winter)

EG http://www.maplin.co.uk/p/solar-powered-12v-15w-battery-auto-trickle-charger-l58bf

 

[VicS]

Okay, many thanks,everyone.

I don't know offhand what the c.c. of the Yamaha 50 is, presumably about a litre, so if you think in terms of a Mini (old type) then they have a pretty small battery.

That said, I suppose the more reserve capacity the better, so I'll perhaps get something that's higher capacity and will fit in the box (I always find a Peugeot 205 diesel battery's a nice compact one with good capacity), which is only just over 175mm wide inside and forget about leisure batteries.

But those small solar panels, Ian - do you not also get into the realms of voltage regulators too, or are they not necessary with a very small panel ?

You only need a very small panel which doesn't need a regulator since you are only trickle charging the battery. If you were using the engine once a month or more then the battery would be okay but for what it costs, a small panel is worth it for peace of mind sake. (& to keep it healthy over the winter)

EG http://www.maplin.co.uk/p/solar-powered-12v-15w-battery-auto-trickle-charger-l58bf

A commonly quoted rule of thumb regarding the need for a regulator is that up to a ratio of 1 watt per 10Ah of battery capacity does not require a regulator (although a regulator is advised for all panels in excess of 10 watts.) so if you choose a battery of the minimum recommended CCA rating with a capacity around 50 or 60ah you will be able to use a solar panel up to about 5watts without a regulator.
My experiences with small batteries and a 5 watt panel would suggest that the above ratio is about right.

Be aware that the low power panels like the one in ianj99's link are intended to placed on a car dashboard top or inside a caravan window. They are not always totally weather proof so not suitable for exterior mounting. Check that the one you buy is totally weatherproof if it is to be exposed to the elements.

 

[ghostlymoron]

Solar regulators are very cheap nowadays so don't be put off. I bought a simple on/off type from ebay for £5 but have since upgraded to a pwr for £7.

 

[Superaquarama]

Thanks for the further help, everyone - regulator comments all noted !