Leisure battery for engine starting?

[tugboat]

A friend has a boat with a single cylinder Volvo which is always difficult to start and needs a proper service. However part of the starting problem is due to the cranking speed being too slow. The starter battery is a 'Leisure battery type 677, 75 Ahr.'
Now I'm of the opinion that a battery defined as 'leisure' is a deep cycle jobby and not suitable for engine starting. I understand the meaning of the 75Ah but for starting you need cranking amps doncha? i.e. lots of amps bunged out over a short period as opposed to a leisure type which is designed to drizzle out low amps over a long period and can be discharged deeper. Am I correct so far?
Are some so-called leisure batteries OK for engine start? I had been thinking along the lines of getting a portable power pack to parallel the start battery in case it faded, but having today seen the installed battery for the first time, I'm thinking it needs replacing with a proper start battery with decent cranking amps.
There is another leisure battery on the boat for lights etc.
The starter battery shows 12.4 volts after a long period resting. This drops to about 11 volts while cranking.
I'd be glad of advice from you electrickery types. Cheers.

 

[Sinbad2222]

Some modern high tech(eg calcium/lead) batteries are claimed to be equally suitable for deep-cycle and cranking. See here:
http://www.barden-uk.com/delphi-deep-cycle-batteries.html

 

[RobinA]

Read a recent article on this subject. It would seem that a starting battery needs maximum surface area on the plates to produce cranking amps, whilst a deep discharge needs stronger plates and hence thicker meaning less of them and less surface area.

In short leisure batteries are also starting batteries but have slightly stronger plate mountings. They are not deep discharge. They may last slightly longer than a starting battery given the off season abuse that they typically receive. However the extra longevity is unlikely to be more than 10%.
In reality I believe its merely commercial. If you look in Halfords the leisure batteries have 2 year guarantee whilst starting batteries have 5 years (if I remember correctly). I suspect this is because they know that boat and caravan owners are likely to ignore their batteries through the winter.

In short leisure batteries are fine for starting - I've been starting using leisure types for years.

If your planning on liveaboard cruising for many years and you have plenty of space and don't mind the weight, you may want to consider true deep discharge batteries otherwise known as traction batteries. But they only make financial sense if your going to use them over many years.

 

[RobinA]

P.S. forgot to mention, 12.4 volts is somewhat discharged. Somewhere I have seen a table showing voltage against charge level. I believe that 12.6V is fully charged and 12.4% would be 50% discharged.

 

[William_H]

I would suggest that 11 volts while cranking is pretty good. (high)
Try the same test onyour car and I think it will be alot lower.
Anyway an easy check is to paralell the starting and service battery for starting . This should equate to a new starting battery to acheive good cranking speeds.
If not then perhaps the stater motor needs some work.
Or maybe it is just the engine needs work.
olewill

 

[SvenglishTommy]

Most 'Leaisure' batteries are fine for engine starting. Firstly because the plates are not that different from standard wet cell batteries, and secondly because they are usually high AH which naturally produces more CCA.

Although 12.4 is not a fully charged battery, it is perfectly normal for a battery that just gets charged with a normal alternator and regulator.

Your battery should state the CCAs, even if it is a leisure battery. But pretty much any 75A battery should be able to start a single cylinder engine. Is it a 1-2-both system? If so, have you tried starting in the both position? One possibility is the cable size is too small and inducing a voltage drop.

I have a similar phenomena on my boat. I have a start bank consisting of a brand new 75AH start battery which rests at 12.8volts, going through a length of 50mm2 cables that keep the voltage drop to less than 2%. Despite this I find that if the engine is not in a good mood, it will turn over faster and start much better if I add the two 80AH house batteries in parallel.

 

[sailorman]

low cranking on a cold engine could be down to oil too thick, using a 10 / 40 might help

 

[ShipsWoofy]

Ring the irish chap at Sterling and talk about deep cycle batteries for starting and when he stops laughing he may impart the knowledge that they are one and the same yada yada yada.

I gave up in the end as the conversation turned into a competition and I got bored.

 

[davidbains]

I agree with Svenglish. I find my Yanmar2gm starts so much better with the two batteries parralleled that they are now permanently connected, to give a 210AH combined start and service battery. This with a trickle charge solar panel gives peace of mind . I also cleaned and oiled the starter bendix which helps. If necessary jump leads can be brought from another windlass battery, but it's never been necessary!
I know battery salesmen will not agree, but I really question whether small yachts need seperate starting batteries.

 

[SvenglishTommy]

I dont think the issue was ever really to have a different type of starting battery, but to have one battery that was left fully charged rather than being run down by the domestic loads. When I had a 1-2-both setup with 2 batteries, I would always start the engine on both, and then switch to one or the other when the engine was switched off. This way I had a house and a starting bank, but which was which would vary. The reason for this was to allow the batteries to share the deep cycles and hence live a longer, happier life.

In my new setup I have isolated banks, so it was just cheaper to stick a car battery in as the starter bank, so the salesman would not have gained anything.

 

[tugboat]

[ QUOTE ]
Most 'Leaisure' batteries are fine for engine starting. Firstly because the plates are not that different from standard wet cell batteries, and secondly because they are usually high AH which naturally produces more CCA.

[/ QUOTE ]

Is that right? My understanding has been that AH is the potential storage capacity of the battery, I wasn't aware that it also affected the cranking amps (or speed of delivery for want of a better expression).

[ QUOTE ]
Your battery should state the CCAs, even if it is a leisure battery. But pretty much any 75A battery should be able to start a single cylinder engine. Is it a 1-2-both system? If so, have you tried starting in the both position? One possibility is the cable size is too small and inducing a voltage drop.

[/ QUOTE ]

Unfortunately the only info on the battery is Leisure type 677 75AHr. No mention of cranking amps at all. Also, the 2 batteries are separately switched, so I'd need to use jump leads to parallel them. This leads me back to a portable power pack as it'e easy to remove and take ashore for charging. If both boat batteries get flattened life becomes more complicated.

I fully realise the engine needs a good overhaul, it was supposed to be done but there was a comms breakdown. The boat is now afloat and my friend, who is a lady senior citizen hanging on to her sailing despite increasing odds, is looking to me to get her through this season. Now I'm au fait with her situation I can help ensure the engine gets sorted next winter.

Thanks to all of you for the replies so far.

 

[lw395]

I suspect that the highish voltage during cranking indicates resistance in the starting circuit.
Try measuring the cranking volts at the starter motor. If the cables and switches are dropping more than a volt, that will not help!
The resitance can be internal to the motor, i.e. worn or sticky brushes.
The cranking current of a battery is quoted to so many volts per cell, can't remember the number offhand, but I don't think you are pulling anywhere near maximum current.
Best to sort this as you are giving the motor a hard time.
Good luck,
Chris

 

[tugboat]

Thanks, yes I'll do that. The cables are the diameter I would expect and the battery is very close to engine so there shouldn't be a lot of voltage drop, but there could be a poor connection somewhere increasing resistance.

 

[SvenglishTommy]

No, it is not completely 'right'. Your understanding is correct that AH is just a measure of the theoretical amps the battery could supply for an hour. In reality this is usually measured over a 10 or 20 hour period until the voltage drops to 10.2V, and will vary depending on the current being drawn. You will get more AHs at low current than high.

The actual power output is determined by the surface area and density of the plates, so you would expect a battery designed for high output to have thin plates to provide large surface area, and deep cycle batteries to have dense plate to provide the cycling ability.

The fact is that most leirsure batteries we buy are only slightly different in construction to the car start batteries and so are also capable of delivering high CCAs. Only real traction batteries with very dense tubular plates would casue a CCA issue.

The reason for my comment is that more AH means more lead, which usually also means more surface area, and hence more CCA. If you look at batteries of the same construction, you will see that CCA goes up with AH capacity. Big 100+ AH 'Leisure' batteries will usually be capable of putting out at least the same number of CCAs as a 70AH car battery.

The bottom line is that I dont think you have a problem with your battery, and although a new starting battery may help a little, it probably wont give out that many more CCAs, so the power pack may well be the best solution.

 

[duncan]

in the style of Monty Python - this battery is dead, is has ceased to function properl, it is no more, it is not resting (@12.4v) it is comatose. It doesn't matter what it was in life (leisure or whatever) is is now deceased.

Halfords, Macro whatever - £30 will get a battery of the same dimensions and terminal layout with a CCA figure on it that will do the job fine. Any other issues with the SM etc can then be resolved if they present themselves.

 

[Chris_Robb]

Battery is finished - get a new one. - problem solved.

 

[KREW2]

I have always used one of my 110 ah leisure batteries for starting a VP2002. I have now banked them together and, installed a 600cca starter battery it wizzes it round much quicker.

 

[duncan]

yep...............that will do it nicely a little ott but so what

 

[Searush]

OK, I may be teaching you to suck eggs, but, as a tightwad, I have many years of starting old engines with knackered batteries or even manually.

First, open the decompressor & apply the increased fuel setting if there is one. Then spin the engine (by hand if possible) to prime with fuel. Even a clapped out battery will spin an engine with the decompressor open. Then, when spinning fast, flick the decompresor closed. There is a strong chance the engine will fire pretty quickly. A warm engine will hand start this way.

If it doesn't start after a couple of goes, get your injectors checked & change the battery! Good luck, I have started engines with batteries as low as 11V this way!
/forums/images/graemlins/cool.gif

 

[tugboat]

Thanks for that, I have tried the decompressor trick and to be honest it doesn't make a helluva lot of difference to the cranking speed. Maybe that's a sign that the compression is crap anyway? On this engine the cold start procedure is to operate the engine stop control before cranking, which I have done. Also when the engine does eventually fire it takes perhaps a minute before the revs start to increase, which suggests to me either a fuel problem or the compression increases as the engine warms up a bit. Valves, rings? I remember an old Petter I had years ago had a facility to inject some oil into the cylinders to help the compression for cold starting. This little Volvo has a hand start facility but it can't be used because of the companionway boxed steps permanently fixed in the way! /forums/images/graemlins/mad.gif