Low Battery level and engine starting

Refueler

Refueler

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This I find an interesting subject and when looked at online has a world of different results.

Just a short example : My pal has a Yanmar 1GM on his boat .... his battery can be pretty low ... as low as 12.2v ... and as long as engine is not strone cold - will start. But try that on my 4-107 and you'll just hear the solenoid click ..

Many online talk about anywhere from 12.2 to 12.5v is lowest level ... hit button and see that drop to less than 10v if it turns over. Last couple of days because batterys ran down - I could not get my 4-107 to start ... even though both batts showed ~12.6v.
I accept that one I use for domestic (#2) is not so good ... but will start non cold engine when full charged. #1 will start engine as long as has decent charge level in.

Yard owner had sailed his Banner 33 to Ventspils for the Regatta ... with my intention to drive to Pavilosta where his yard and my boat is - I gave him a lift back so he could collect his car. I was going - so I could 'jump' my engine with a new battery ...

We arrived and both went down to Superanne ... and just out of interest - checked voltage .... being a low rate charger through a solid state Kemo splitter - the batterys were slow charge about 36hrs. The volts showed reasonable - so tongue in cheek - pressed the start button .... she started.

The new battery is now sitting in the boat just in case and has a trickle maintainer connected ....

Portable 12V/1A Car Boat Motorcycle Smart Battery Charger Maintainer Trickle ho | eBay

These really are good .... fully connect and forget ...
 
Probably silly of me to say and you’ll likely know already…but if you have two batteries onboard, for example. One of them fairly healthy and decent cca rating…then link it to another battery of perhaps even slightly less health or cca ability, by means of a battery switch or selector. It usually results in a situation where the lesser battery tends to draw from ( in a parasitic, even detrimental fashion) the other battery in an attempt to level out residually between them. Technically and occasionally meaning that you’re worse off in terms of starting ability, than you would be with them isolated from each other. If you take the presumed voltage reading when both are adjoined, it’s not really a true reading of each battery, you’ll know too. It’s a reading reflecting the voltage supplied from the healthy battery. If you watch the gauge for long enough, you’ll most likely see the figure dropping, as a result of the weaker battery feeding from the other. Anyway. Boring stuff, but true story.
Finally and just quickly. A gauge on the dash and in anyway linked or common fed to and by other gauges or ancillary items around or local to it…usually reads a little lower than actual voltage at the battery itself. No by much, but certainly and often a few 10ths lower can be assumed. Perhaps that might explain the example given around the smaller friends engine and voltage available. All the best.
 
I am of the opinion (perhaps with out real knowledge) that a batteriy's ability to provide high current (start an engine) is not necessarily related to it's charge state but rather it's condition re delivering high current. So I have had a battery absolutely fully charged fail to start the car after a long run. But have seen a battery totally flat recharged with a very limited number of AH able to start an engine. (car battery flattened with lights left on, jump start then run engine for a few minutes then found able to start engine). Of course if a battery is struggling to start engine a recent charge will perhaps help a bit.
So in my opinion the best test of battery condition re high current delivery is the engine start. The best test of actual capacity is low current long time discharge. The 2 are not necessarily related. If a battery won't reliably start engine then chuck it. Likewise if it won't give you useful supply as a service battery chuck it. ol'will
 
William_H said:
I am of the opinion (perhaps with out real knowledge) that a batteriy's ability to provide high current (start an engine) is not necessarily related to it's charge state but rather it's condition re delivering high current. So I have had a battery absolutely fully charged fail to start the car after a long run. But have seen a battery totally flat recharged with a very limited number of AH able to start an engine. (car battery flattened with lights left on, jump start then run engine for a few minutes then found able to start engine). Of course if a battery is struggling to start engine a recent charge will perhaps help a bit.
So in my opinion the best test of battery condition re high current delivery is the engine start. The best test of actual capacity is low current long time discharge. The 2 are not necessarily related. If a battery won't reliably start engine then chuck it. Likewise if it won't give you useful supply as a service battery chuck it. ol'will
Click to expand...

I agree ....
The matter is down to Internal Resistance. With high IR - the battery may be good for light domestic work and provide reasonable duration or power. But try to start an engine and it soon rebels.

As another says - BOTH together .. a good and bad battery can create a poor ability to turn over an engine .. in extreme cases it can actually create damage to gear...

I try to replace batterys singularly ... basically having a VG battery as starter ... and a moderate / good battery to power domestics and can usually still start engine when full charged, when it fails to start engine after charging - then its time on board is temporary till I get a new battery. The starter battery then moves to #2 and new battery is set as engine starter. I really do not see point as a motor sailer to swap both batterys same time. Having motor on for up to 50 - 60% of sailing time ... means even the lesser battery is looked after.

We have a similar situation with Lithiums for models .... When we find IR increases and no longer delivers high power needed for some models .. the LiPo gets relegated to a lesser demand model or to replace battery in a drill / flashlight etc. Once it fails in that function - then its binned.
 
The Yanmar is a single cylinder engine that like my Feryman will have a small starter motor which will require less current that the starter motor on your Perkins like my Perkins 4 236

The bigger the starter motor the more current it will draw and will pull down the battery voltage due to internal resistance of the battery
 
rogerthebodger said:
The Yanmar is a single cylinder engine that like my Feryman will have a small starter motor which will require less current that the starter motor on your Perkins like my Perkins 4 236

The bigger the starter motor the more current it will draw and will pull down the battery voltage due to internal resistance of the battery
Click to expand...

Well aware of that .... my point was that online - there are too many generalisations about the required voltage / condition of a battery to start an engine.
Its not unusual for such figures to be quoted in posts on these and other forums ... but the fact is that it can or not work based on size of engine to turn over.

A Yanmar 1GM in fact could use a Lawntractor battery quite easily ... but that battery would likely buckle plates trying to start my 4-107.

Also - we see comments about Leisure Batterys used for starting engines ... that one pot Yanmar and other small stuff - yes - fine. But again put a Leisure battery to my 4-107 and that will be last job it ever does. (TRUE Leisure battery - not the compromise ones that are often quoted).
 
Hi Nigel. I loved the video. But really sorry you had to damage SuperAnne to get the video. Don't beat yourself up over it. None of us are perfect sailors. (Shit happens) I occasionally see boats running aground or on rocks in Swan River. Sometimes I can even expect it from a distance. Love the way the stern goes up and the mast top tilts forward. Classic. Sadly inn one case it was my own boat I was watching from shore. I had lent the boat to a friend as his was broken for sailing lessons. I told him where the rocks were just west of swing mooring and always approach from east. He forgot. No more harm done than usual every season. He neveer mentioned it after so I did not either. Anyway I hope you can get the canvas repaired and find the leaks. Probably around the keel attachment. best wishes in all. ol'will
 
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