Motorbike battery for small boat - which one?

[VicS]

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.

I have a small Lidl one.

It charges a normal 12 v car battery at 3.8 amps until the volts reach 14.4 V. Then it reduces the output to 0,8 amps and continues until the volts again reach 14.4 V then it reduces the output further to a "retention" charge of 0.05 amps.
If the volts fall below a certain value, which I forget, it will kick back into 3.8 / 0.8 amp mode until recovered.
In the unlikely event of 15 volts being exceeded (very unlikely at 50mA, but I had it happen once with a brand new battery) It returns to standby mode.

It has a separate settings for small, <14Ah, batteries which it charges at 0.8 amps and for cold conditions or AGM batteries where it charges to 14.7 volts

It will recognise a 6 volt battery.

The major downside of the Lidl and Aldi chargers is than they do not restart after a power outage/ disconnection , they default to standby mode. The superior, and more expensive, CTEK chargers will restart without intervention.

 

[ShinyShoe]

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?

I don't know. How much water do you get in your bilges?
Are you manually pumping while racing? That feels like (a) you will be taking longer to do it, which slows you down and (b) you are probably light handed so automation may be helpful.

But actually, in the marina / mooring would be my main reason for a bilge pump - keeping the bilge dry when you are not there. Depending how you charge, will depend how that affects things.

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).

I've yet to see Portable Nav Lights that were Astonishinly Good! Don't fancy crossing the channel with them!
HH VHF may well work fine for you in that race environment there will be others around who can relay for you.

So to add to your potential power consumptions - consider adding USB chargers and HH VHF charger for all of the above (I see some of the newer VHFs have USB chargers).

That LiIon charger pack is tempting. Not using it in a marine environment does not feel quite right to me as a reason. Your tablet & your phone aren't designed for marine use either. And neither is a Motorbike, Car Battery or Alarm Battery!

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

Dully noted. Muchous apologies for my sexist assumptions.

 

[pvb]

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

Not sure you're allowed to say that anymore!

 

[Sailingsaves]

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

This looked interesting until I read:

"Product Output: DC 5V/2.1A 12V/2A 16V/3A 19V/3A"

Does that mean one can only select the 12V output option and not draw more than 2 Amps?

However, the specs also state:
"Start Current: 300A Peak Current: 600A (3s)"

So can one draw more than 2 amps at 12.7 Volts ? without having to add dc to dc buck converters or whatever (if using the "jump start" output method (that will provide 300 Amps apparently)?

Thanks in advance if you can reply.

 

[Yellow Ballad]

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.

As someone who's in the bike trade Motobatt are a bit hit or miss (we've stopped selling them now) but I wouldn't recommend a bike battery on a boat, they don't like standing and really you need to charge them weekly on a smart charger to keep sulphation at bay. A small budget car battery will be better and cheaper then a yuasa bike battery, if you want something small then as mentioned some sort of "alarm" battery would be better.

 

[ShinyShoe]

My understanding is the "jump leads" have no current protection on them. It you were to attach them into a 12V boat circuit (fused) you could power up the system.

Some things to be aware of. It is rated at 18Ah, but thats not at 12V, most likely at 3.7V which translates to 66Wh, which is 5.5Ah. But unlike a Lead Acid, you can probably use most of that rather than half of it, you could probably factor in using say 4Ah at 12V. So we might expect 8 hours use.

You can't usually charge a Li battery while using it. So a solar charger wont work.

You may find the other sockets are disabled when the jump lead is plugged in. You may also need a battery on the jump lead to get it to start (think that varies between models) - some may do some polarity checking which might need a small voltage present...

 

[pvb]

It is rated at 18Ah, but thats not at 12V, most likely at 3.7V which translates to 66Wh, which is 5.5Ah. But unlike a Lead Acid, you can probably use most of that rather than half of it, you could probably factor in using say 4Ah at 12V.

So it's a 4Ah battery for £60?

 

[ShinyShoe]

So it's a 4Ah battery for £60?

Yes... and no! Firstly I said you could use 4Ah - so more like a 8Ah Lead Acid battery.

If you took a 7.5Ah Lead Acid and tried to start a 3 litre diesel engine it probably wouldn't even get the starter to move, you certainly wouldn't get it to actually start from cold unless you were very very lucky and you wouldn't manage it 22 times.

Added to that, its got inbuilt USB etc, it is a lot more functional than just a 7.5Ah Lead Acid would be, especially for a boat that sounds like it wont have USB charging points pre-installed etc.

I'd make an interesting option for an alternative to 1+2 installs. Install a 120Ah Leisure plus this. Charge this from the Leisure circuit. Charge Leisure from the engine Alt +/- other sources.

 

[PaulRainbow]

Gordon Benett !!

Talk about complicating things. Fit a small car battery, which is as suitable for marine use as any other wet lead acid battery. Stick a 10w solar panel on to keep it charged and to extend the available power. If you want to add a small mains smart charger, why not.

Going offshore with only a handheld VHF might not be the best idea. At 5/6w max power and a very low antenna height the range is about 5 miles on a good day. I'd fir a fixed DSC VHF.

 

[pvb]

Yes... and no! Firstly I said you could use 4Ah - so more like a 8Ah Lead Acid battery.

If you took a 7.5Ah Lead Acid and tried to start a 3 litre diesel engine it probably wouldn't even get the starter to move, you certainly wouldn't get it to actually start from cold unless you were very very lucky and you wouldn't manage it 22 times.

But the OP doesn't seem interested in starting a big diesel, simply using lights, VHF, GPS, etc, in which case a cheap small car battery would be fine and would have much more endurance.

 

[PaulRainbow]

Most jump packs that i've come across will only start a diesel engine if a partially charged battery is fitted.

 

[ShinyShoe]

Most jump packs that i've come across will only start a diesel engine if a partially charged battery is fitted.

This is not a normal jump pack! This is the next generation of jump pack. I've seen them used - they do actually work. It can thow out 600amps!

But the OP doesn't seem interested in starting a big diesel, simply using lights, VHF, GPS, etc, in which case a cheap small car battery would be fine and would have much more endurance.

Oh I don't disagree! And I pointed out you can't usually charge these while using them. That is a MAJOR disadvantage to me. Can't use it for any kid of shore supply, or top up the battery from the solar panel while out.

Going offshore with only a handheld VHF might not be the best idea. At 5/6w max power and a very low antenna height the range is about 5 miles on a good day. I'd fir a fixed DSC VHF.

He is doing so as a race. 5 miles may well be close enough, especially as that would only be for use if the battery dies. But I completely agree, you'd get a reconditioned one (60Ah) delivered to your house for a third of the price of the LiIon unit from fleabay. Solar panel costing even less, and chuck a £6 charge controller on (probably not really needed) - pick the right one it will give you voltage info and a couple of USB charge ports for the backup 'lectrics.

 

[Sailingsaves]

To ShineyShoe,

Great info there, thanks
The Amazon video DID state that the 'crocodile clip' outlet (the 300Amp side) of the Li-Ion pack would not initiate unless it 'sensed' a reading of LESS than 7 Volts, so possibly could be connected to a boat's distribution as you say, BUT I am no longer interested (sincere thanks to you for saving me a load of money) because it won't start a car battery unless it senses less than 7 volts (about 12 minutes into the video) and I would like it to kick in at about 10.8 Volts-ish at least.

I did not factor in the low amp hours as you have pointed out. If it WAS 18Ah at 12V, then it would be ok for small trips on a boat (although I'd have a lead acid too) AND the inability to charge it whilst using it is very limiting too.

It would have been good for me for starting the old car that has an elderly battery to get to the boat in Winter and useful on the boat in case the batteries on boat were not healthy (boat has good charging system (when it is afloat), but as it is long keel and sits on mud when tide is out, batteries are at 45 degree angle and solar panel in shade possibly). It still would probably do most of the above, but not worth the money for me.

So thanks.

To the OP:
Good and light (epoxy based board) and cheap solar panel here for £29:
https://www.ebay.co.uk/itm/Very-Light-20w-Solar-Panel-12v-Battery-Charger-c-w-4m-cable-BLOCK-Diode-Clips/302260147470?hash=item46601bd50e:g:r6gAAOSwal5YCQpr

and charge controller here £7.55
https://www.ebay.co.uk/itm/PWM-10-20-30A-Dual-USB-Solar-Panel-Battery-Regulator-Charge-Controller-12V-24V/112564741868?ssPageName=STRK%3AMEBIDX%3AIT&var=412966512112&_trksid=p2057872.m2749.l2649

Stick it on a small cheap car battery as lots of people have pointed out (£35 delivered from many sources) and you are good to go. Happy racing. (You can set the charging voltage on the controller so you don't over-gas the battery and because you are afloat, the lead plates will always be covered with electrolyte). The battery could last years that way and solar panel and controller should last much longer.

 

[anoccasionalyachtsman]

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?

I have it in a waterproof box because I don't have a roof on my boat, but it would be fine on a protected chart table etc..

 

[anoccasionalyachtsman]

This looked interesting until I read:

"Product Output: DC 5V/2.1A 12V/2A 16V/3A 19V/3A"

Does that mean one can only select the 12V output option and not draw more than 2 Amps?

However, the specs also state:
"Start Current: 300A Peak Current: 600A (3s)"

So can one draw more than 2 amps at 12.7 Volts ? without having to add dc to dc buck converters or whatever (if using the "jump start" output method (that will provide 300 Amps apparently)?

Thanks in advance if you can reply.

I use it (from the DC jack socket) at 12V and don't think that I've tried a load of 2A on it. I'll have a play sometime tomorrow/tomorrow evening.

 

[anoccasionalyachtsman]

To answer the other points. Like MissFitz I have no way of charging onboard, so the fact that I can't charge and discharge a battery simultaneously doesn't matter.

As far as using a handheld (dsc) vhf is concerned, well, it's an open boat so nowhere to put a full set, I don't go offshore, and for this year I've got a masthead aerial to fit, so range should be much better. It is utterly useless at the minute.

 

[William_H]

An alternative to the car battery is a set of 3 Lithium 18650 cells in series. Connect a charge/ discharge controller for 3S and you have a charge controller for solar or any higher than about 14v plug pack and the controller will cut load if voltage falls too low. You can add 18650 cells in parallel to increase capacity and certainly light weight and cheap.
https://www.ebay.com/sch/i.html?_od...0+lithium+ion+rechargeable+batteries&_sacat=0
https://www.ebay.com/itm/3S-11-1V-1...013044&hash=item2f0e85e0c7:g:P~sAAOSwE-laAvq4
https://www.ebay.com/itm/5-Pcs-Blac...741456&hash=item2830daab86:g:~G4AAOSww3tY6j97
olewill

 

[Sailingsaves]

Below is a review.
No more than 2 Amps via dedicated 12v outlet.
If I were to buy one, I would try by-passing the voltage sensor thing on the crocodile clip.
But £53 is too much when one could build one as William_H shows.
1000 cycles is specified too. Li-Ions have come a long way (think of cordless drills etc), but I think I'll stick to lead acid and gel batteries for a while longer.

I used one of these to power nav lights and bits and pieces in a cruising dinghy for years and it is still going strong (rests at 12.8V)

Click to the right here http://cpc.farnell.com/camdenboss/bel120120/battery-agm-lead-acid-12v-12ah/dp/BT02674?CMP=KNC-GUK-CPC-GEN-SHOPPING-CAMDENBOSS-BT02674&gross_price=true&mckv=sW1G2G2fo_dc|pcrid|72935638217|kword||match|| plid||pid|BT02674|&gclid=EAIaIQobChMIot3gp_a71wIVqLztCh0u2AVvEAQYASAB EgJl7fD_BwE

 

[jac]

Gordon Benett !!

Talk about complicating things. Fit a small car battery, which is as suitable for marine use as any other wet lead acid battery. Stick a 10w solar panel on to keep it charged and to extend the available power. If you want to add a small mains smart charger, why not.

Going offshore with only a handheld VHF might not be the best idea. At 5/6w max power and a very low antenna height the range is about 5 miles on a good day. I'd fir a fixed DSC VHF.

This is the answer of choice so far IMHO.

Meets all the OP's requirements, is a good basis to expand later on if she wants.

IF she wants to add USB points then plenty of those that are available to add later on if required but no need to overdo this.

With a small battery + solar she can go off on Sunday with a discharged battery, and then come back the next weekend to a charged battery.

 

[billcole]

AS an alternative to lithium batteries then a lead acid mobility scooter battery would be a suitable choice, as , unlike bike, car, and alarm standby batteries, they are expected to be deep discharged on a regular basis. Made and sold in large quantities so good value to buy.