Starter battery capacity

[hoppy]

A couple of years ago I replaced my 3 100ah batteries (1 starter & 2 house) with 4 Victron 110ah AGM batteries (1 & 3). I'm now thinking about possibly increasing the house bank to 4 batteries.

It seems logical that to increase it I should move the starter battery over to the house bank and buy a new smaller starter batteries as I will have space issues.

I am not sure how small I can go.

I looked up the Yanmar manual and the starter is 12V 1.2kw, so I guess that means it will draw 100amp when starting. I can't figure out how much I can reduce the capacity?

The guy who installed my solar tried to show me a "neat trick" by doing some rewiring which should allow the starter motor draw power from both the starter and hose banks for "extra kick" but still keep the starter isolated from the house usage. Unfortunately when he did that, the instrument panel started screaming. He said it could be done if I replaced whatever the unit the wires were connected to in the engine bay. I have totally forgotten what it was called but several of the large battery wires connected to it. Anyone know what I'm talking about?

If I stick to the Victron AGM, reducing to the 90ah will not help me size wise as it is longer than the 110. The 66 ah could be "perfect" I think but it is a hell of a lot smaller capacity

[On y va]

hoppy, I am at the same point as you and want to use the available two battery spaces with 2x2 100Ah service batteries. This means moving the starter battery elsewhere.

I am considering two options: on a shelve and a battery box above the exhaust hose or in a battery box in the bottom of the shelved part of the cupboard unit in the port rear cabin. The latter has my preference, as it is just easier.

Two years ago, I have changed my 100Ah lead acid starter battery for a Optima Bluetop 75Ah spiral AGM battery, as this battery has the same "properties" as a 110Ah lead acid battery, but these things last forever and have 1125Amps cranking at 0 degrees celcius.
It´s a little smaller than a lead acid battery too. Worth looking at this battery.
Alternatively, and or space wise, you could install 2 45Ah red tops. The can be installed any way you like and are small, but very powerful. Also last forever. I had this (one) red top on my bowthruster for 11 years!

[hoppy]

Jan 27, 2015 9:43:32 GMT On y va said:

I am considering two options: on a shelve and a battery box above the exhaust hose or in a battery box in the bottom of the shelved part of the cupboard unit in the port rear cabin. The latter has my preference, as it is just easier.!

I was thinking starboard cupboard, but only because the starter battery is already on that side

Jan 27, 2015 9:43:32 GMT On y va said:

Alternatively, and or space wise, you could install 2 45Ah red tops. The can be installed any way you like and are small, but very powerful. Also last forever. I had this (one) red top on my bowthruster for 11 years!

I think the blue 75 is about the same length as my current 110 Victron's but lower. I get the feeling that it wont be possible to put any battery big enough in the cupboard limited to 1 side. Maybe 2 x 45ah might be the way to go and just maybe using two batteries might give the possibility of putting them somewhere else that is less inconvenient for "passengers"

[dbostrom]

It's surprising how small of a battery you can use for a starter, given that your engine is healthy.

I'm a mentor in a FIRST high school robotics team. We're mandated to use a 17AH 12V gel lead-acid battery for robot power supply. During competition use it's not uncommon for these batteries to supply loads of 750W (our own maximum has been ~900W) or more (main breaker is mandated at 100A, 1.2kW). Granted, the length of a competition round is short (2'15") but starting an engine is of course an even shorter process, or should be. We have a number of these batteries that are 2-3 years of age and still useful, despite this clearly abusive application.

Not recommending a 17AH battery, just pointing out that there are options for sizing down, if you're confident about your engine maintenance.

[On y va]

Jan 27, 2015 11:33:40 GMT hoppy said:

Jan 27, 2015 9:43:32 GMT On y va said:

I am considering two options: on a shelve and a battery box above the exhaust hose or in a battery box in the bottom of the shelved part of the cupboard unit in the port rear cabin. The latter has my preference, as it is just easier.!

I was thinking starboard cupboard, but only because the starter battery is already on that side

Jan 27, 2015 9:43:32 GMT On y va said:

Alternatively, and or space wise, you could install 2 45Ah red tops. The can be installed any way you like and are small, but very powerful. Also last forever. I had this (one) red top on my bowthruster for 11 years!

I think the blue 75 is about the same length as my current 110 Victron's but lower. I get the feeling that it wont be possible to put any battery big enough in the cupboard limited to 1 side. Maybe 2 x 45ah might be the way to go and just maybe using two batteries might give the possibility of putting them somewhere else that is less inconvenient for "passengers"

Yes, 2x 45Ah will fit in the space above the exhaust hose, before or after the waterlock.

[hoppy]

I was thinking that if I go smaller, maybe I can keep a set of jumper cables or whatever to allow me to add the house bank if the motor is having issues and has started to stress the battery

[hoppy]

BTW do you know what generator you have fitted? I noticed in the Yanmar manual they mention 55A and 80A optional. I have no idea what mine is

[On y va]

Here another option from Optima. 2x 55ah 6 volts! They are very small and when wired in series to make 12 volt, you have good starting capacity taking up very little space. Then they would really fit in the space above the exhaust hose.

(sorry website is in spanish)

[electricmonk]

Just been round this loop, Yanmar's recommendation is 100AH, knowing the Yanmar starter motor is a known weakness and it likes lots of power and a low internal battery resistance (it has a high cranking under load VOLTAGE requirement) I would go with 100AH.

[so36idavid]

When spec'ing a starting battery the Ah capacity of the battery is not terribly important. That tells you how many unsuccessful cranks you could give the motor before running the battery down. Usually if it doesn't start within a few seconds you know you've got other problems and go sort them out. Continuing to crank indefinitely will ultimately back up the muffler and destroy the engine. (If you must keep cranking then close the raw water inlet valve).

The important spec is the number of amps that the battery can put out in a short period of time. In the US these are defined in units of Cold Cranking Amps (CCA), i.e. how many amps they can put out in a burst when cold. House batteries are usually bad at this, they're made to put out a relatively low number of amps over a long period of time. Some batteries are sold as both house and starting, which means they're not terribly good at either of these things, but if that's what you have so be it.

I recently looked into changing my starting battery and the process boiled down to figuring out what kind of starter you have on your motor. Then find the specs for that starter. In my case I have a Yanmar 3ym30. I couldn't find the relevant specs on the starter so I contacted Yanmar and spoke with a tech there. He looked it up and said pretty much "anything with over 600 CCA", which covers most starting batteries.  If you live in a very cold place then you'd want to upsize so you have some margin. 

Finally, you should probably stick with the same battery technology for both banks. Most charging systems can't be adjusted to charge different banks at different voltages. So don't, for example, have a bank of flooded cells and a bank of gels. 

David

[Don Reaves]

In the context of marine engines, the relevant parameter is MCA (Marine Cranking Amps). It's just like CCA except it's specified at freezing rather than well below freezing (0 degrees F).

Don

[hoppy]

Ok, new info to absorb

Just checked and my current started is rated at 800 CCA (no MCA quoted)

The Yanmar manual was no help but I found on this site a figure of 300 CCA for my 4JH3E

My motor is in good condition and even after being idle for winter starts very quickly, so I'm starting to wonder if I should go for something like this 44ah Optima Redtop www.eurobatt.co.uk/optima-red-top-rtr-3-7-8035-255-rtr3-7-rts3-7r-agm/ or which ever model best fits the boat.

I can always keep some jumper leads or rig up some wiring/switch that will allow me to include the housebank in the starting if necessary.

Until I'm back onboard and have the tape measure out I can't exactly decide on anything for now

[On y va]

I find 300 CCA for a 4JH3E very low. Whose to say that guy of that website actually has it right?
I would go for at least double that. If there is one thing you do not want to fail, it is your engine starting.
Same for 1 red top only. It is rather marginal to have 45Ah available as a starter battery for a 56HP marin diesel engine.
As I suggested before, if space is an issue, you could go for 2x 45Ah 6volt red tops in series. They are small and will fit anywhere and in any position too.

But....it's up to you.

[electricmonk]

All I would add is that the Yanmar service manual for the 4JH3E states 100AH or greater. Its all about volts guys; volts at full load, amps will as other have said take care of themselves, practically anything will supply enough amps, but enough volts and amps is a very different proposition. As I stated before the Yanmar starters are a bit of a weakness LOW VOLTAGE kills them.

[allegria]

Hi Hoppy,

I totally agree with David's assessment in his latest post.
In relation to your jumper leads solution, I would recommend the switch option.
I have wired an Emergency Parallel switch for that very purpose with the switch hidden away to avoid it being turned on by neophytes. Never had to use it as yet but the idea that it's there is reassuring.
There are plenty of well documented pages on the net for this and it is really easy to setup.
I don't like the idea of looking for jumper leads and opening the battery compartments in an emergency situation...

Good luck with your choice,
Cheers,
Allegria

[so36idavid]

Feb 2, 2015 19:46:59 GMT electricmonk said:

All I would add is that the Yanmar service manual for the 4JH3E states 100AH or greater. Its all about volts guys; volts at full load, amps will as other have said take care of themselves, 

Monk,

This is kind-of correct, actually what counts is watts (Amps x Volts). You need a certain amount of power out of the starter to turn the engine which means you need at least that much flowing into the starter. Simply talking about volts and Ah ignores how the battery is built. There's a good reason why starting and deep cycle batteries are different things! There is a limit to how many amps a battery can supply, it's not infinity. The limit is governed by internal resistance in the battery which in turn is due to its design and construction. Starting batteries have many thin plates in parallel that can deliver a lot of amps with very low resistance. Deep cycle batteries have fewer, thicker plates that can withstand sulfation and many deep discharge cycles without damage. If your deep cycle batteries are in good shape then sure they will start your engine. However if they're not well charged or are in marginal condition then they simply won't supply the amps you need when you turn the key. There is a voltage drop internal to the battery which limits the amps that it can supply. Think of this as a resistor in series with your circuit. The more amps you pull the more volts will be dropped over the internal resistor, leaving fewer for the starter motor. Starting batteries have lower internal resistance and can supply more amps at a given voltage.

Furthermore there is a voltage drop in the wiring between the batteries and the starter so the volts that the starter sees can be significantly lower than the voltage at the battery terminals.

David

[On y va]

Feb 2, 2015 19:46:59 GMT electricmonk said:

All I would add is that the Yanmar service manual for the 4JH3E states 100AH or greater. Its all about volts guys; volts at full load, amps will as other have said take care of themselves, practically anything will supply enough amps, but enough volts and amps is a very different proposition. As I stated before the Yanmar starters are a bit of a weakness LOW VOLTAGE kills them.

All very well, but the battery is 12volt.

The CCA is important for starting power and the amount of Amps how many times you can start before the battery says "do it yourself". CCA is actually not that important to us boaties, unless you like sailing the poles, as they are measuren at -18 dgrs Celcius.
Therefore, there is also the MCA, (Marine Cranking Amps) which are measured at 0 dgrs Celcius. (Even that is out of the comfort zone of most).

What is important is how this power is delivered and as important, over time too. so36idavid already says something about this, indicating the difference about deep cycle and starter batteries.

Spiralcell batteries are specifically made for starting (although they are also prefectly ok for deep cycle). They have heavy duty cast straps connecting the spiral cells, which allow for a much greater flow of electricity than the welded straps typically found in traditional flooded batteries. These straps are a real difference-maker in terms of long-term performance and will allow the batteries to keep providing the maximum amount of amperage for the maximum amount of time. 
Hence I got the 75Ah Optima Blue top as starter battery, as this outperforms the by Yanmar specified 100Ah standard battery any time. It is approx 75% more expensive, but will last double if not triple in its life span.

[vasko]

OPTIMA® BlueTop® 75Ah seems like really good battery... although very expensive - about 3.5 times more then - LFD75 Varta Professional 

[On y va]

Depends where you buy it. But they are not cheap no. But very reliable and long lasting.

[electricmonk]

"Monk,

This is kind-of correct, actually what counts is watts (Amps x Volts). You need a certain amount of power out of the starter to turn the engine which means you need at least that much flowing into the starter. Simply talking about volts and Ah ignores how the battery is built. There's a good reason why starting and deep cycle batteries are different things! There is a limit to how many amps a battery can supply, it's not infinity. The limit is governed by internal resistance in the battery which in turn is due to its design and construction. Starting batteries have many thin plates in parallel that can deliver a lot of amps with very low resistance. Deep cycle batteries have fewer, thicker plates that can withstand sulfation and many deep discharge cycles without damage. If your deep cycle batteries are in good shape then sure they will start your engine. However if they're not well charged or are in marginal condition then they simply won't supply the amps you need when you turn the key. There is a voltage drop internal to the battery which limits the amps that it can supply. Think of this as a resistor in series with your circuit. The more amps you pull the more volts will be dropped over the internal resistor, leaving fewer for the starter motor. Starting batteries have lower internal resistance and can supply more amps at a given voltage.

Furthermore there is a voltage drop in the wiring between the batteries and the starter so the volts that the starter sees can be significantly lower than the voltage at the battery terminals.

David "

Read more: jeanneau.proboards.com/post/20094/quote/3607?page=1#ixzz3R5NTIMov





I do agree to some extent. BUT if the battery is not capable of supplying sufficient volts at full load the amperage will go sky high (ohms law is not applicable here, the load is inductive not resistive). In my experience manufacturing and reconditioning diesel engines and all sorts of other electro mechanical stuff burnt out/molten starter motors are not uncommon. The usual cause (there are many) is a flat battery, or a battery that is unable to meet the specified duty. The starter will only draw 100 - 150 amps, most lead acid cells will supply 300 - 400amps more than enough to melt the armature.

There are other causes, but a high resistance in the wiring or terminals will not cause a starter to melt, it just wont work.

The deep cycle battery vs starter battery argument is a wonderful myth propagated by battery manufacturers, eager to differentiate lead acid batteries; pretty much they change the configuration of the mechanical properties of the plates, the change in the battery characteristics is in the grand scheme pretty insignificant, lead acid is lead acid is lead acid. Well made ones last longer. You can ask me how I know this but again it involves my hands on experience making the things. . . .

cheers


David

[On y va]

Feb 7, 2015 18:50:43 GMT electricmonk said:

"Monk,

This is kind-of correct, actually what counts is watts (Amps x Volts). You need a certain amount of power out of the starter to turn the engine which means you need at least that much flowing into the starter. Simply talking about volts and Ah ignores how the battery is built. There's a good reason why starting and deep cycle batteries are different things! There is a limit to how many amps a battery can supply, it's not infinity. The limit is governed by internal resistance in the battery which in turn is due to its design and construction. Starting batteries have many thin plates in parallel that can deliver a lot of amps with very low resistance. Deep cycle batteries have fewer, thicker plates that can withstand sulfation and many deep discharge cycles without damage. If your deep cycle batteries are in good shape then sure they will start your engine. However if they're not well charged or are in marginal condition then they simply won't supply the amps you need when you turn the key. There is a voltage drop internal to the battery which limits the amps that it can supply. Think of this as a resistor in series with your circuit. The more amps you pull the more volts will be dropped over the internal resistor, leaving fewer for the starter motor. Starting batteries have lower internal resistance and can supply more amps at a given voltage.

Furthermore there is a voltage drop in the wiring between the batteries and the starter so the volts that the starter sees can be significantly lower than the voltage at the battery terminals.

David "

Read more: jeanneau.proboards.com/post/20094/quote/3607?page=1#ixzz3R5NTIMov





I do agree to some extent. BUT if the battery is not capable of supplying sufficient volts at full load the amperage will go sky high (ohms law is not applicable here, the load is inductive not resistive). In my experience manufacturing and reconditioning diesel engines and all sorts of other electro mechanical stuff burnt out/molten starter motors are not uncommon. The usual cause (there are many) is a flat battery, or a battery that is unable to meet the specified duty. The starter will only draw 100 - 150 amps, most lead acid cells will supply 300 - 400amps more than enough to melt the armature.

There are other causes, but a high resistance in the wiring or terminals will not cause a starter to melt, it just wont work.

The deep cycle battery vs starter battery argument is a wonderful myth propagated by battery manufacturers, eager to differentiate lead acid batteries; pretty much they change the configuration of the mechanical properties of the plates, the change in the battery characteristics is in the grand scheme pretty insignificant, lead acid is lead acid is lead acid. Well made ones last longer. You can ask me how I know this but again it involves my hands on experience making the things. . . .

cheers


David

I am sorry David, but now you are talking rubbish. There most certainly is a difference between lead acid and lead acid. What you are saying is that a man is the same as a woman, because they breath.

This is one of the reasons I don´t actually like forums.....  

[On y va]

Feb 7, 2015 22:07:31 GMT On y va said:

Feb 7, 2015 18:50:43 GMT electricmonk said:

"Monk,

This is kind-of correct, actually what counts is watts (Amps x Volts). You need a certain amount of power out of the starter to turn the engine which means you need at least that much flowing into the starter. Simply talking about volts and Ah ignores how the battery is built. There's a good reason why starting and deep cycle batteries are different things! There is a limit to how many amps a battery can supply, it's not infinity. The limit is governed by internal resistance in the battery which in turn is due to its design and construction. Starting batteries have many thin plates in parallel that can deliver a lot of amps with very low resistance. Deep cycle batteries have fewer, thicker plates that can withstand sulfation and many deep discharge cycles without damage. If your deep cycle batteries are in good shape then sure they will start your engine. However if they're not well charged or are in marginal condition then they simply won't supply the amps you need when you turn the key. There is a voltage drop internal to the battery which limits the amps that it can supply. Think of this as a resistor in series with your circuit. The more amps you pull the more volts will be dropped over the internal resistor, leaving fewer for the starter motor. Starting batteries have lower internal resistance and can supply more amps at a given voltage.

Furthermore there is a voltage drop in the wiring between the batteries and the starter so the volts that the starter sees can be significantly lower than the voltage at the battery terminals.

David "

Read more: jeanneau.proboards.com/post/20094/quote/3607?page=1#ixzz3R5NTIMov





I do agree to some extent. BUT if the battery is not capable of supplying sufficient volts at full load the amperage will go sky high (ohms law is not applicable here, the load is inductive not resistive). In my experience manufacturing and reconditioning diesel engines and all sorts of other electro mechanical stuff burnt out/molten starter motors are not uncommon. The usual cause (there are many) is a flat battery, or a battery that is unable to meet the specified duty. The starter will only draw 100 - 150 amps, most lead acid cells will supply 300 - 400amps more than enough to melt the armature.

There are other causes, but a high resistance in the wiring or terminals will not cause a starter to melt, it just wont work.

The deep cycle battery vs starter battery argument is a wonderful myth propagated by battery manufacturers, eager to differentiate lead acid batteries; pretty much they change the configuration of the mechanical properties of the plates, the change in the battery characteristics is in the grand scheme pretty insignificant, lead acid is lead acid is lead acid. Well made ones last longer. You can ask me how I know this but again it involves my hands on experience making the things. . . .

cheers


David

I am sorry David, but now you are talking rubbish. There most certainly is a difference between lead acid and lead acid. What you are saying is that a man is the same as a woman, because they breath.

[weinie]

What is a "Deep Cycle" Battery?

[so36idavid]

Feb 7, 2015 22:07:31 GMT On y va said:

Hey On Y Va,

Just FYI it wasn't me who said that, I think it was ElectricMonk, some confusing formatting in the way the post was quoted. FWIW I agree with you on all of this, particularly the men and women part .

David

[abgreenbank]

all you need to know about batteries



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