petersto
Well-Known Member
About to buy new batteries for my Centaur, engine MD11C 23HP, 17Kw manual say 70AH(max) but no mention of cold cranking figure. Any ideas?
Cold Cranking.
- Thread starter petersto
- Start date
philip_stevens
Well-Known Member
No idea of cold cranking, but I did change my engine starting battery during the winter, from a leisure battery to a dedicated engine start battery.
It was worth doing, as rge engine turns over better than it did with the leisure battery.
The same physical sized engine start battery had a higher cold cranking amp output than the leisure battery.
It was worth doing, as rge engine turns over better than it did with the leisure battery.
The same physical sized engine start battery had a higher cold cranking amp output than the leisure battery.
vyv_cox
Well-Known Member
All the Yanmars up to at least the 3GM30 have a starter CCA requirement of 200A, if that is any help.
PhillM
Well-Known Member
This is what I bourght last month as a dedicated engine start for my MD7a.
JAGUAR X TYPE 12V 80Ah 700 AMPS VARTA CAR BATTERY HEAVY DUTY BATTERIES 12 VOLT
http://bit.ly/Mv8f0G
I tend to charge from a charger and I think the 60 aha from the manual refers to the altinator capability.
Only problem was that it was bigger than my battery box so had to install a new one!
JAGUAR X TYPE 12V 80Ah 700 AMPS VARTA CAR BATTERY HEAVY DUTY BATTERIES 12 VOLT
http://bit.ly/Mv8f0G
I tend to charge from a charger and I think the 60 aha from the manual refers to the altinator capability.
Only problem was that it was bigger than my battery box so had to install a new one!
wotayottie
Well-Known Member
been toying with the same idea of adding an engine only battery. my engine is a 3 cyl 29 hp volvo so presumably the same CCA as a yanmar. but is CCA and the voltage the only criteria to specify? ie no need to worry about amp hours capacity.
I'm thinking of using a motorcycle battery. For example this is small and has sufficient CCA
I'm thinking of using a motorcycle battery. For example this is small and has sufficient CCA
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petersto
Well-Known Member
Thats exactly the kind of thing I am looking for Phillm and my sort of price. I want two of them not interested in leisure batteries havent got a lot to run, keep it simple use No1 one day No 2 the next day through change over switch. Have lead acid now lasted 9yrs and they came with the boat, so who knows how old. Thanks very much for all comments I would still like to know the cold cranking though.
VicS
Well-Known Member
Any decent 70Ah car starter battery will be adequate
I do not know the reason why VP specify a maximum Ah. I have a theory but that is all.
My 70 Ah (Exide) battery is 540 CCA ( it starts a 2.1 litre petrol engine ) but you will easily find them upto 760 CCA ( maybe more) if you want
KellysEye
Well-Known Member
We have an MD17C and a 100amp cranking battery for 35 HP. Obviously you can go lower.
lw395
Well-Known Member
The cranking amp rating of a battery tells you what it will do when ideally charged and brand new.
The cranking amps requirement of an engine tells you what it needs the day before you go and buy a new battery.
I have a Ducati with a little 19Ah battery on it, these are spec'd for 200Amps cranking.
I think I have measured a peak of about 90Amps, using a clamp ammeter on 'max hold'.
These batteries do not tend to last nearly as long as car batteries, despite the fact that we look after them probably better, using float chargers etc.
I suspect you want a big margin between CCA rating and what the motor actually draws.
CCA can be spec'd in several different ways, but it is a) at a cold temperature and b) the current that will pull the battery down to some quite low voltage in some quite short time.
One spec is 0 degreesF, to 7.2V in 30 seconds.
Obviously reducing the voltage to 7.2 has reduced the power enormously. And you have cable losses on top of that.
The cranking amps requirement of an engine tells you what it needs the day before you go and buy a new battery.
I have a Ducati with a little 19Ah battery on it, these are spec'd for 200Amps cranking.
I think I have measured a peak of about 90Amps, using a clamp ammeter on 'max hold'.
These batteries do not tend to last nearly as long as car batteries, despite the fact that we look after them probably better, using float chargers etc.
I suspect you want a big margin between CCA rating and what the motor actually draws.
CCA can be spec'd in several different ways, but it is a) at a cold temperature and b) the current that will pull the battery down to some quite low voltage in some quite short time.
One spec is 0 degreesF, to 7.2V in 30 seconds.
Obviously reducing the voltage to 7.2 has reduced the power enormously. And you have cable losses on top of that.
lw395
Well-Known Member
Do you understand the difference between Amps and Amp-hours?
CreakyDecks
Well-Known Member
Good luck with that. I've never had a battery on my bike last more than two years yet. Quite annoying when you see how much more expensive they are than small car batteries with much more material in them. Supply and demand I suppose!
savageseadog
Well-Known Member
I've measured cranking currents on small diesels and it's about 200-250A. I suggest a battery at least twice that. I suggest it's better to have a dedicated start battery with a high CCA and low cranking marine/leisure type batteries for the domestic bank. Reason is the high CCA batteries don't like deep discharge and deep discharge batteries don't like high cranking currents, horses for courses.
PhillM
Well-Known Member
The previous dated 2003 and had a Cold Cranking rate of 540. I had one flat batery experence when at sea - the only time the engine has not started first time so far and I used the leisure to start, so I wanted to fit as big a battery as I reasonably could, hence this one.
I also liked the price. Although having to fork out another £15 for a battery box to fit it and it taking half a day to switch them over, sort of took the shine of the experence.
sailorman
Well-Known Member
i have3 domestic & 1 engine batteries all the same 115 Ah sealed so called heavy duty .
works for me
petersto
Well-Known Member
First job when the rain stops is to measure the battery box. Just changed all cabin lights to led so its only vhf, clipper duet and on long trips chartplotter, tiller pilot only used when engine running. Thanks
vyv_cox
Well-Known Member
I fitted a Red Flash 900 as a starter battery, very small and has sufficient CCA but its capacity is quite small, 13Ah. It will start the engine when fully charged, the engine starts first turn of the key anyway. I imagine that if the engine was at all reluctant the battery would not cope. It was an experiment that was not totally successful. Next time I will go for a battery about twice the size of the 900.
savageseadog
Well-Known Member
Depends on what "heavy duty" means. There is a range of battery types spanning leisure batteries and starting batteries, they will all do a job but batteries are designed to do certain jobs well, compromise is compromise.
sailorman
Well-Known Member
reeac
Well-Known Member
Here's an alternative approach: I have two ca. 7 year old leisure batteries totalling 180Ah. capacity and switch to "both" for cold starts of my VP2002. That way each battery supplies about half the required current and so, I think, they'll last longer. As back-up I carry a jump start pack but I've never had to use it yet.
savageseadog
Well-Known Member
in sailing, one has to compromise, doesn't one
Quite.