Car Battery for Simple Electrics?

[Little Rascal]

I have a reasonably new car battery in the shed that was salvaged when my last car gave up the ghost. I also need to get my electrics set up on my trailer sailer. Is there any reason why I can't use the car battery for a season until I get a proper one sorted?

The battery is 60Ah and I would be running the echosounder, anchor light and possibly nav lights off it.

 

[ostell]

No reason why not. The leisure batteries are still the same lead acid type.

How are you planning to charge it?

 

[pteron]

It will work be be aware that a car battery is not designed for deep discharge (it generally has to give loads of amps for a short time rather than a few amps for a long time), so keep it topped up with charge.

Is it sealed? You don't want battery acid slurping around.

 

[noelex]

It is not a battery intended for deeper discharge so it life will be short if you discharge it much. It should still last a year of intermittent use, if you can keep the discharge down. Try and charge it up as often as you can. The echo sounder will use very little. Led nav lights only use a small amount, but their incadencent cousins use a lot.
Make sure it's well tied down and fused correctly even if it's a tempory step.

 

[John the kiwi]

Keep the charge up!

I am sure lots of experts will tell you why not, but what else were you going to do with that battery? If the answer was not much then you are better off using it. I know some trailer sailors who use a car battery and actually run said battery in a the car except when they hoick it out and into the boat for the weekend expedition.

Deep cycle batteries are designed for being heavily discharged and have heavier plate construction to cope.
Car batteries actually don't discharge much unless your motor is stuffed and needs huge cranking time. what they are optimised for is high current short over a short burst, but mostly at or near full charge.

So go ahead! just try and avoid deep discharge and recharge as often as possible. LED lights are your new best friend.

 

[VicS]

I have a reasonably new car battery in the shed that was salvaged when my last car gave up the ghost. I also need to get my electrics set up on my trailer sailer. Is there any reason why I can't use the car battery for a season until I get a proper one sorted?

The battery is 60Ah and I would be running the echosounder, anchor light and possibly nav lights off it.

No problem at all. It is what i have mostly done although I do now have a Leisure battery.
In theory a leisure battery will be better for supplying a current for prolonged periods ( eg nav lights or anchor light all night).

I sometimes wonder if it's only the label that's different


Be sure to avoid discharging below 50% and to recharge it straightaway after use. I assume that trailer sailing mans that you will be taking the boat home after use ... if not a small solar panel is a good investment. I have a 5 watt one and that keeps the battery nicely topped up.

 

[prv]

I sometimes wonder if it's only the label that's different

Mm. A Halfords "leisure" battery is definitely not a proper deep-cycle battery, and I suspect any differences from a car battery are relatively minimal.

Pete

 

[Little Rascal]

Thanks thats good.

Make sure it's well tied down and fused correctly even if it's a tempory step.

I'm not really sure how I would fuse it correctly? (Being a thoroughly IMpractical boatowner when it comes to all things electrical) Can anyone point me in the direction of a wiring diagram?

I want to run the sounder (with an on off switch), anchor light and 10W tricolour, plus I have a 12v mobile charger with a cigarette lighter type socket for my phone. Could you wire in a 'female' socket?

I was thinking of a small solar charger for use while cruising (worth it?) but the battery could come home between trips.

 

[halcyon]

I sometimes wonder if it's only the label that's different
.

They were at one time, in the old days, 1980, we had lead acid batteries, then they bought out flash starter batteries for cars. The marketing departments then had loads of production capacity for old type batteries, so thay called them leisure batteries, changed the label, put the price up, and wrote a good bit of blurp to cover price rise.


Brian

 

[noelex]

Thanks thats good.



I'm not really sure how I would fuse it correctly? (Being a thoroughly IMpractical boatowner when it comes to all things electrical) Can anyone point me in the direction of a wiring diagram?

I want to run the sounder (with an on off switch), anchor light and 10W tricolour, plus I have a 12v mobile charger with a cigarette lighter type socket for my phone. Could you wire in a 'female' socket?

I was thinking of a small solar charger for use while cruising (worth it?) but the battery could come home between trips.

Something like this
http://bluesea.com/category/105/27/productline/118

Would be a good solution.
Female cig sockets are readily available.

Solar can be a very good solution, but if you take the battery home to charge it may not be needed for your limited electric needs. How long do you want to cruse for?

 

[Little Rascal]

Thanks, I may go for this which would combine the charger socket too.

Cruising for a week or two so charging in the meantime shouldn't be an issue. Would marinas be likely to let you use a plug socket for the night do ya reckon?

 

[noelex]

Thanks, I may go for this which would combine the charger socket too.

Cruising for a week or two so charging in the meantime shouldn't be an issue. Would marinas be likely to let you use a plug socket for the night do ya reckon?

Yes that would be fine.
Some of the switch panels are very cheaply made, so it's better if you can see it in the flesh before committing. I would prefer to go with a name brand product for this kind of thing, once you have cut holes to mount it it's hard to change if fails.
The cig lighter socket is often best just on a flying lead ( jut a long length of wire) so it can used in various places like the cockpit.

Two weeks is too long even on your limited electrical demand so you will probably need a solar panel. Shore power is usually not a problem, but some marinas charge and given the trouble and danger of AC power leads, unless you have things set up well it may not be worth the hassle, but keep that battery as charged as you can.

 

[VicS]

If you go armed with a suitable portable battery charger you may find one of these
http://www.towsure.com/product/Mini_Mobile_Mains_Unit
or
http://www.towsure.com/product/Camping_Site_Mains_Supply_Unit_3_Outlet

useful to connect to the marina shorepower when available. Both incorporate an 2 pole mcb and an RCD

 

[ostell]

I tried to use one of those panels on another boat and wasn't impressed (the meter calibration was terribly wrong, < 1.5V for full scale!). Check meter before you fit. Marinas will give you a mains connection but you may/will need a lead with a 16 A plug on the end, such as this one. You can then make up a 16A plug to 13A socket adapter.

The plugs and sockets are readily available, you can make your own up.

As long as your charger output is fully insulated you should not have a problem as long as you are careful with the mains lead. Tie the boat end firmly down before you plug in to the marina.

 

[Mirror Painter]

Thanks, I may go for this which would combine the charger socket too.

Cruising for a week or two so charging in the meantime shouldn't be an issue. Would marinas be likely to let you use a plug socket for the night do ya reckon?

I've just fitted one of those panels to my tiny cabin cruiser. The primary reason was to fulfill my four year old son's desire for 'more controls'. So it's O.K. BUT, there's nothing special about it and the battery test is just a moving coil meter with a 1/4 W resistor in series. I.E. anything from 8 to 14V is well in the green on mine. PLUS those fuse holders are horrible because they require a tiny screwdriver to change the fuse - just the sort of tiny screwdriver you won't have when you are afloat and need to change a fuse. I swopped mine for some screw-caps jobs but if you are going to start doing that you might as well buy a cigar socket, switched and fuseholders and make your own.

 

[BERT T]

If possible change all your bulbs to led type, it may cost you £30 to £40 to do so but it is well worthwhile and will reduce the drain on your battery very considerably. A lighter socket is available from ebay item no (140681292340) I've just bought one and they seem to be decent quality.

 

[electrosys]

I have a reasonably new car battery in the shed that was salvaged when my last car gave up the ghost.

You say 'a new car battery' - just to check, how long has that battery been sitting in the shed ? If it's more than (say) 3 months, the first thing to do is to get it on charge ...

24hrs later - what voltage reading do you have ? Hopefully it's >13 volts. Then connect a load (I find old car headlights are good for this kind of thing), and burn a few Amps for a few hours, but don't let the battery go below (say) 11v. That will give you some idea of the battery's existing working capacity in practice (as opposed to the theory). Then re-charge immediately.

Now you know the working capacity of the battery, you can do your sums with the sounder and lights. Go LED if at all possible. Likewise a single all-round white if possible.

A car battery in reasonable condition will certainly be ok for day-sailing - whether it's ok for several days will depend (obviously) on how much you pull out of it, and whether you are able to re-charge it 'as you go along'.

As long as you remember to put the battery on charge just as soon as you get the boat home (even if you're cream-crackered, and just want to flop onto the sofa), it should be a viable system to use.

However, for the first time out - until you test the rig 'for real', I'd be inclined to take an extra torch or two with a few spare batteries, just to be on the safe side.

 

[Little Rascal]

You say 'a new car battery' - just to check, how long has that battery been sitting in the shed ? If it's more than (say) 3 months, the first thing to do is to get it on charge ...

24hrs later - what voltage reading do you have ? Hopefully it's >13 volts....

Well I finally got round to checking the battery: after 9 months in the shed it had 12.5V. I charged it for 8 hours on a cheap 4amp charger and it got up to 13.5V but this slowly dropped off to 12.9V this morning (14hrs later).

Is this a problem?

 

[VicS]

Well I finally got round to checking the battery: after 9 months in the shed it had 12.5V. I charged it for 8 hours on a cheap 4amp charger and it got up to 13.5V but this slowly dropped off to 12.9V this morning (14hrs later).

Is this a problem?

If that is 12.9 after standing idle with no charging for 14 hours it is well charged. Anything over about 12.7 would have been good.

It does not necessarily mean the battery is good but it's a very promising start
It may not hold its charge and it may not be capable of delivering a high current.

12.5 after 9 months is not so bad either. It suggests it was holding its charge well

 

[nigelmercier]

Thanks, I may go for this which would combine the charger socket too...

Looks fine, but don't rely on the battery test function. At best it will tell you it is connected, at worst it will give you a false sense of security.