car battery on a boat

[prv]

I agree that some sailors are quite obsessive about batteries and charging and spend more time checking their BM1 than their wind instruments. Not a problem for me, I've got neither.

Of course, the other end of that scale is to "obsess" once when designing and installing the system, and thereafter not have to worry about it

When we bought Ariam the batteries couldn't keep the autopilot going for one Channel crossing; even departing from Cherbourg marina after a couple of days plugged into the mains, the pilot tripped out on low voltage several miles south of the Isle of Wight. I don't think we were running much else - no plotter or radar, no lights, I think we even turned the fridge off halfway across.

That winter (as had always been planned) I completely rebuilt the electrical system; we now use power fairly freely but still spend most of our time above 80% state of charge. We don't have power at our home berth, and I often don't bother to plug in when we visit marinas for one night as it's just not necessary (if staying a second, I do plug in just to keep the water hot). I've never run the engine just for battery charging; my parents did once after leaving the fridge on for a week when the boat was left in Falmouth between visits. But otherwise, with the big alternator and smart regulator, the normal running in and out of harbour (plus the occasional day with no wind) keeps things topped up.

Pete

 

[Heckler]

Again somebody tries to convince me that car batteries (much cheaper) work just as well as marine batteries. What was the story again?
Erik

I put Numax leisure 110 amp hour batteries on Sacha for the domestic bank 8 yrs ago! I bought them from the local farm shop, used for electric fences. they were £80 odd each. My view? expensive batteries aint worth it!
Stu

 

[Mistroma]

I put Numax leisure 110 amp hour batteries on Sacha for the domestic bank 8 yrs ago! I bought them from the local farm shop, used for electric fences. they were £80 odd each. My view? expensive batteries aint worth it!
Stu

Depends on how they are going to be used and relative prices. I bought T105s in 2012 because I expected to spend 6-7 months on the boat each year and most of that would be at anchor. T105s cost about £105 and leisure style were around £90 so it was a no-brainer.

I imagine that prices have gone up but think I could still buy a T105 for £116 so would still stick to Trojan vs. Numax at £80+. I'd obviously re-think if I used the batteries less or the price difference was a lot greater.

 

[Quiddle]

Leisure batteries are only modified starter batteries..... In some cases I suspect the modification is little more than a different label

I'm also inclined to this viewpoint. One useful tip (I think from Plevier on here?) is to compare weight, which is what costs. I found differently labelled and priced products from the same manufacturer shared the same mass and dimensions but came with different warranties, so you are effectively paying extra for a form of insurance. And having attempted to claim on battery warranties in the past, this is definitely not a good investment.

 

[William_H]

Yes essentially the size (weight) of the battery is the key to just how good they are. In the case of specialised car batteries the aim is for the most cranking current for the minimum weight. Likewise for motor cycles etc.
Batteries for deep cycle will have a lot more lead so are much heavier. Generally for boats a big deep cycle battery has plenty of current capability for small engine start, and of course plenty of capability if engine gives trouble starting. Indeed you might have to consider starter motor overheat.
However if a car battery is available at a low price (second hand) then it can be used for light ongoing loads. Just try not to flatten it too much. If you kill it no great loss. good luck olewill

 

[prof pat pending]

I put Numax leisure 110 amp hour batteries on Sacha for the domestic bank 8 yrs ago! I bought them from the local farm shop, used for electric fences. they were £80 odd each. My view? expensive batteries aint worth it!
Stu

so why did you pay so much :encouragement:

 

[VicS]

so why did you pay so much :encouragement:

One of the perils of being a local politician. You have to support local businesses in order to get their votes.

 

[lw395]

I recyled a Motorbike battery for use as a starting battery. All went well until I had a short run of starting problems. Basically it couldn't cope with more than four attempts to start the little SOB before dying. I currently have an old (>10) 80 amp "leisure" battery as a starting battery and an Exide 85ah "caravan" battery as a service battery. Maplin solar panels keep them high when I'm not on board. Bought on price per AH.

Motorbike batteries often have short lives at the best of times, so any use you get from a recycled one is a bonus.

 

[contessaman]

Interesting to see this thread at the moment. Clearly lesuire /deep cycle batteries are the way forward for your domestic bank. However, as I'm currently fitting a new engine and not sailing and have my boat in a berth without power, I removed the circa £1200 worth of gell battery from my boat and stored safely in my garage on a float charge. I went to the scrappy and had 4 very decent 60ah car batteries of a reputable make and got all four for 65 quid. I've paralleled them up and got a 20watt solar panel connected across them with just a diode and a fuse. I'm getting to the boat probably one day in 10 and giving the eberspacher D5 a damn good run not to mention all the cabin lights on (they are all warm white led though). So far this arrangement has kept up with the demands placed on it. Am I wrecking these batteries? Probably. Do I care! 65 quid for 240 ah.... No!

 

[boatmike]

The point is that "leisure" batteries are neither. They sort of claim to occupy a position in between starting batteries and deep-cycle batteries, but the suspicion is that in at least some cases this is mostly marketing. Certainly even the ones that are specially-made are a lot closer to the "car battery" end of the scale than the "golf-cart battery" end.

Pete

Oh dear! I tried to keep it simple but the thread obviously drifts...... ALL batteries are marketed to do more than they are generally capable of and frankly you get what you pay for. Batteries marketed as "leisure" span a price and quality range that will generally, when considered for deep cycle use be as good as a top quality car battery in one extreme or give better deep cycle life on the other, but will never be as good as proper deep cycle batteries costing a great deal more. What has not been said is that deep cycle batteries don't like high cranking loads. They also don't like fast charging generally either so often for light duty, especially on a MoBo which is probably on charge more often and longer than a sailboat a reasonable quality leisure battery is often a cost effective compromise. The engine starting battery however, especially on boats with big engines to start, should always be a cranking battery of reasonably high Amp/Hours. Lorry batteries as someone said are great for this purpose. Often missed is that lead acid "leisure" batteries can tolerate high volt charging where deep cycle (often gel types) won't.

 

[vyv_cox]

Leisure batteries are only modified starter batteries..... In some cases I suspect the modification is little more than a different label

Vic, I know you enjoy internet research (!) so perhaps you might like this one. I have read that one of the differences between leisure and starting batteries, other than possibly the size and number of plates, is that the leisure ones are taller to allow spent lead oxide/sulphate to fall down without shorting out the cell. I assume this might be evident from the height of the two types, unless of course they just place the plates higher in the cell and make them shorter.

 

[macd]

Often missed is that lead acid "leisure" batteries can tolerate high volt charging where deep cycle (often gel types) won't.

I think that's a bit misleading. Yes, gel batteries need a charging regime which avoids gassing but my distinct impression is that they're not 'often' found on yachts. Flooded are surely the most common deep-cycle jobs (followed by AGM?) and accept high charging voltages: 14.8V in the case of Trojan T105s.

 

[VicS]

Vic, I know you enjoy internet research (!) so perhaps you might like this one. I have read that one of the differences between leisure and starting batteries, other than possibly the size and number of plates, is that the leisure ones are taller to allow spent lead oxide/sulphate to fall down without shorting out the cell. I assume this might be evident from the height of the two types, unless of course they just place the plates higher in the cell and make them shorter.

A quick attempt to compare my Varta leisure battery with similar style Varta car batteries of the same capacity is inconclusive. I found one the same height and one less by 15mm but both were less lengthwise by 4mm.

 

[KellysEye]

>The point is that "leisure" batteries are neither. They sort of claim to occupy a position in between starting batteries and deep-cycle batteries, but the suspicion is that in at least some cases this is mostly marketing. Certainly even the ones that are specially-made are a lot closer to the "car battery" end of the scale than the "golf-cart battery" end.

I don't understand that 12v CCA batteries, which are usually gel, are completely different from 6V deep cycle batteries, such as Trojan, which are lead acid, and are wired in series.

 

[vyv_cox]

I don't understand that 12v CCA batteries, which are usually gel, are completely different from 6V deep cycle batteries, such as Trojan, which are lead acid, and are wired in series.

I suspect you may be confused. CCA stands for 'cold cranking amps' a characteristic of all batteries that measures its ability to turn an engine over.

 

[prv]

I don't understand that 12v CCA batteries, which are usually gel, are completely different from 6V deep cycle batteries, such as Trojan, which are lead acid, and are wired in series.

12v cranking batteries aren't usually gel, and in any case all the batteries being discussed are lead acid. But yes, cranking batteries and deep-cycle batteries are different as you say.

The point is that so-called "leisure batteries" are often identical to cranking batteries (see other posts in this thread about sticking on labels) and at most might be lightly modified from cranking batteries. They are not deep-cycle batteries, but tend to be misleadingly sold as if they had deep-cycle properties.

Pete

 

[ghostlymoron]

The last Leisure battery I bought was from Hankook. I can't remember the model number but I chose it on the basis that they didn't quote a CCA so I surmised that it was a genuine deepish cycle one. This could have been just a marketing ploy though. I've since sold it with my old boat so have no idea of its performance.

 

[Andrew_Trayfoot]

I have been running two £30 large car batteries bought second hand from the local car breaker 3 and 4 years ago...
No problems so far and I am quid's in.

 

[Tammany]

I'm the same as most and have a 55AH car battery for the engine and a 125AH leisure battery for running the boats electrics. Leisure batteries are designed for repeated discharge & re-charge cycles as in powering your lights & instruments and car batteries don't like deep discharges although modern ones are better as they more or less use the same technology nowadays. Both my batteries are the same make and both use the same sealed calcium technology. The only difference with the leisure battery is it has 2 sets of connectors instead of the single round posts of the car battery. I'm pretty sure it's the same inside. I charge them with the alternator and a VSR circuit and also with a dual solar controller. I'll eventually fit a show power charging system in too at some point.

 

[prv]

Leisure batteries are designed for repeated discharge & re-charge cycles
[...]
I'm pretty sure it's the same inside.

Which?

Pete