Motorbike battery for small boat - which one?

MissFitz

MissFitz

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I'm planning to put an electrical system into my Sonata this winter. I don't need to run much off it (nav lights, depth sounder, log, VHF) so several people have suggested a motorbike battery. Unfortunately I hadn't realised they come with such a very wide range of specs. Also, the ones in Halfords seemed insanely expensive compared with some of the options online. Can anyone help with a bit of guidance on what type and/or make would work best for a small boat?
 
not much bigger and cheap is a 063 car battery. They often come with a carrying handle unlike a bike battery, and the terminals are less fiddly
 
What you need to do is add up the consumption you need in Amp hours.
E.g. depth sounder, GPS and log use say 0.5A, you want to run for 24 hours thats 12Ah. 0.5A is a total guess but some small plotters are surprisingly greedy.
Nav lights how many hours? etc All night or just a bit of the evening.
VHF might be on but rarely transmitting.
So you know how many Ah before you can recharge. Double that for a battery size.

Then look for a sealed battery, perhaps the sort sold for burglar alarms, you want something that won't spill.
Look on ebay for 'Sealed Yuasa Battery'.
Yuasa is the No1 make, Exide, Varta, and others worth a look.
The ones I use on my bikes are dearer, but they are all about cranking an engine with very big pistons.
HTH
 
pvb said:
You've been badly advised. Motorcycle batteries have very low Ah ratings, which means they'll run flat very quickly. You should be looking for a small car battery or a small leisure battery. Perhaps something like this - https://www.tayna.co.uk/Numax-LV22MF-Sealed-Leisure-Battery-P7672.html - which would run your electrics for many more hours than a motorcycle battery.
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Possibly so, but I know people running a GPS and instruments off alarm batteries. A solent race is one set of needs, round Britain another.
 
pvb said:
You've been badly advised. Motorcycle batteries have very low Ah ratings, which means they'll run flat very quickly. You should be looking for a small car battery or a small leisure battery. Perhaps something like this - https://www.tayna.co.uk/Numax-LV22MF-Sealed-Leisure-Battery-P7672.html - which would run your electrics for many more hours than a motorcycle battery.
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solent clown said:
not much bigger and cheap is a 063 car battery. They often come with a carrying handle unlike a bike battery, and the terminals are less fiddly
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I agree, small car battery is the way to go.
 
One other thing to consider is how are you are going to recharge the battery, along with, as lw395 says, how you will use it.
 
MissFitz said:
I'm planning to put an electrical system into my Sonata this winter. I don't need to run much off it (nav lights, depth sounder, log, VHF) so several people have suggested a motorbike battery. Unfortunately I hadn't realised they come with such a very wide range of specs. Also, the ones in Halfords seemed insanely expensive compared with some of the options online. Can anyone help with a bit of guidance on what type and/or make would work best for a small boat?
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FirstAway said:
One other thing to consider is how are you are going to recharge the battery, along with, as lw395 says, how you will use it.
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+1

A battery will have a very short lifespan if it it not recharged after use.

The charging output from a small outboard is unlikely to be sufficient unless you motor for a good amount of time ......... got the tee shirt on this one!

A small, permanently mounted,solar panel ....... mine is only 5 watts ... saves the day.

You might also look at golf cart and mobility scooter batteries as these being deepcycle/traction batteries, may be more suitable for use which does not include engine starting. They may be expensive, however.
 
Sorry, I should have been clearer about my charging capabilities. I only have a small outboard & definitely won't use it enough to charge a battery. I have shore power in the marina but quite like the idea of a battery that's small enough to take out & charge at home/ashore. I'm also keen to get a solar panel, although I worry slightly that it might get damaged in the rough & tumble of racing. Does anyone have one on a race boat?

Also, just one question on the 063 car battery - will this tolerate being run right down or does it need to be kept topped up?
 
MissFitz said:
Sorry, I should have been clearer about my charging capabilities. I only have a small outboard & definitely won't use it enough to charge a battery. I have shore power in the marina but quite like the idea of a battery that's small enough to take out & charge at home/ashore. I'm also keen to get a solar panel, although I worry slightly that it might get damaged in the rough & tumble of racing. Does anyone have one on a race boat?

Also, just one question on the 063 car battery - will this tolerate being run right down or does it need to be kept topped up?
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You cannot keep running the battery dead flat, be it a car battery or a motorcycle battery.

An 063 is light enough to take home and usually has a handle for doing so, as previously mentioned. You could also fit quick release connections.

Better yet would a the small solar panel previously mentioned. If it's no more than 1w you shouldn't need a controller with the car battery. If you are worried about damage during racing make it removable.
 
lw395 said:
Then look for a sealed battery, perhaps the sort sold for burglar alarms, you want something that won't spill.
Look on ebay for 'Sealed Yuasa Battery'
Click to expand...

Those are also the preferred battery for powering instruments in gliders. Only problem is the charging regime, they need a dedicated charger, not a car battery one.
 
If you go down the motorbike route these are well liked:

http://www.motobatt.com/index.php?r...nufacturer_id=39&category_id=65&model_id=1133

Available on the 'Bay for about 60 quid in the larger sizes. The terminals are particularly robust and some models have two sets which is handy. You will need a motorcycle battery charger but the smart chargers are designed to be - plug in and leave - so that is good. With a small, wet, car battery you can use your ole Grandad's charger from down the shed but you should not leave it for long without attention.
With marina power there should be no need to ever have to move the battery off the boat.
 
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doug748 said:
Available on the 'Bay for about 60 quid in the larger sizes. The terminals are particularly robust and some models have two sets which is handy. You will need a motorcycle battery charger but the smart chargers are designed to be - plug in and leave - so that is good. With a small, wet, car battery you can use your ole Grandad's charger from down the shed but you should not leave it for long without attention.
With marina power there should be no need to ever have to move the battery off the boat.
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But even the larger sizes are only about 15-16Ah. For £60 you can get a small car battery with much more Ah capacity. And a small smart charger could equally be used for a car battery, so no problem leaving it. And if there's no need to take the battery off the boat, the extra weight of a small car battery wouldn't be an issue.
 
I use one of these Lithium based jobbies. 18Ah but much better for repeated discharging and charges usb devices, charge indicator built in, small and light. It comes with mains and 12V charging adaptors and really does work as a car start battery.

I use it for an echo sounder constantly, top up my 'phone, can use it to recharge my hh vhf, tiller pilot for short spells and for next year some led nav lights. The longest that I've used it is for two days, and the lowest charge remaining has been about 45% (but I'm fairly sure that I'd forgotten to charge it before that weekend). I won't name him, but a local boat electronics supplier/installer who crews for me was surprised and impressed by it.

https://www.suaoki.com/g7.html
 
Did we get a required power consumption?

Yes we got that he wants to race rather than cruise. But is that 1 hour on Wednesday nights with 20mins out and 20mins back in so 2hours is "enough" power, or is that 3 races Saturday, 3 races Sunday, perhaps 12 hours on the water?

No bilge pump on the list of kit?

VHF usually quote 90% standby-5% receive - 5% transmit. You will draw something like 5A during transmission, So you are probably using something like 0.5Ah with the VHF. BUT - if you want the VHF to work on Sunday afternoon when you break something significant on the way back in I'd personally want to have perhaps 90 minutes of reserve power with 25% transmit, 25% receive 50% standby. So a spare 3Ah. With spare Lights etc too. The time to run out of battery is not when other things are failing.

I find Alarm batteries next to useless for running kit. I use them because that is what comes installed in things like small UPSs. But I have to replace them every 2-3 years when they just stop charging without notice. Yet to have that happen on a "proper" lead acid.
 
LadyInBed said:
If you have marina shore power then a small Aldi / Lidl smart charger would do a job.
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Depends. Some cheap battery chargers will continue pumping in charge even after the battery is fully charged, unless you are on hand to disconnect once "volts in" exceeds about 14.6 or thereabouts. If you leave one of these on while unattended (not a good idea in any case) you might finish with a fried battery.
 
anoccasionalyachtsman said:
I use one of these Lithium based jobbies. 18Ah but much better for repeated discharging and charges usb devices, charge indicator built in, small and light. It comes with mains and 12V charging adaptors and really does work as a car start battery.
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I remember you mentioning this at the start of the season, very interested to hear it's worked out well. One experienced sailing friend poo-pooed the idea, though, on the grounds that this type of battery isn't designed for either constant use or a marine environment. Clearly yours has already lasted a season, which is pretty good. Does anyone else have any thoughts on this option?
 
ShinyShoe said:
Did we get a required power consumption?

Yes we got that he wants to race rather than cruise. But is that 1 hour on Wednesday nights with 20mins out and 20mins back in so 2hours is "enough" power, or is that 3 races Saturday, 3 races Sunday, perhaps 12 hours on the water?

No bilge pump on the list of kit?
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No power consumption figures as yet, still working on that. And only manual bilge pump at the moment - do I really need an electric one on a small boat?

Racing for me means inshore & offshore - so anything from 1.5 hours round the cans on Sunday to cross-Channel or down to Weymouth. (And yes, I realise I may not be able to meet the Cat 3 specs for racing, in which case I'll just go anyway!) But I'm not too fussed about running out of battery power as I have astonishingly good portable nav lights, handheld VHF, handheld GPS, & Navionics on phone & tablet (with which I've already sailed the boat back from Brixham to Brighton).

Oh, & just for the record, he's a she :)
 
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