Battery CCA Rating / Torque Effect

[Alan]

Up until now I have always used Odyssey Batteries in my J230.  However, I have just found my local battery shop is quoting a 2 months supply delay, so I went looking at alternative lead/acid batteries.

Now the Odyssey battery is quoted as 200CCA, some of the batteries I have come across advertise 300CCA.

Given the starter ring is at the back of the motor and the flywheel (prop) is at the front, should I be concerned for the starter ring attachment, crank shaft, etc as a result of the extra torque?

 

Alan

[old man emu]

Just like sports car manufacturers brag about how much horsepower their engines have, battery brands tend to do the same thing with their performance attributes. Enough brands and companies have told people over the years that "more is better" when it comes to cold cranking amps, that a lot of folks now believe it always the case. While more may be better, it may not be necessary and it may be more expensive.

 

One of the performance attributes is how many cold cranking amps (CCA) a battery can generate.

So how is this determined? Since "Cold" is in the name, they put a battery in a cold environment (0°F/-18°C) and measure the discharge load in amperes that a new, fully-charged battery can deliver for 30 seconds, while still maintaining terminal voltage equal to or higher than 1.20 volts per cell.

 

Why did they pick a cold environment? Ask anyone who lives in a cold climate with a high-mileage diesel truck- it takes a long time to start some vehicles, whether that is due to high compression engines, extremely cold temperatures or both. Does a J230 in Australia operate in these conditions?

 

A good starter will draw amps under load (while cranking the engine). So if the battery can deliver can deliver 200 amp when it is is chilled to -18C, it will produce more than that at our usual air temperatures. Buying a 300CCA battery would be overkill, unless you want to run a full glass panel, air conditioning and cabin entertainment system at the same time.

 

Getting to the point of your question, the 300CCA battery will not generate extra torque.  It will just provide power for longer. And keeping a starter motor cranking for extended period of time will overheat it and burn it out. 

[onetrack]

The only two ways you can increase starter torque is by increasing the cable and connector sizes - or by increasing the battery voltage. Battery voltage drops to about 10V at the starter when cranking, normally.

If you utilise a larger battery you may see a slight increase in battery voltage at the starter when cranking, but I personally don't think you would see any substantial increase in starter torque. A slight gain, perhaps.

 

CCA is really quite a poor measurement for our climate. It's an industry standard set in, and for, North America, to determine a batterys cranking ability on their bitterly cold Winter mornings. 

The Nth American Winters get down to -10° and -20°C, and at those temperatures, battery performance really suffers.

For us, unless you're in an Australian Alpine location, we don't often get any lower than about -2° to -5°, and that is usually only for a short period, unlike America, where it can be -10° or -20C°, all day.

There is a battery measurement for our climate, and it's termed HCA - Hot Cranking Amperes. But you will find it difficult to get that figure from manufacturers, as CCA is the "recognised figure".

 

If the battery you're looking at is Chinese, take the CCA rating with a degree of scepticism. Chinese electrical ratings are always over-rated. I'd be more concerned about increasing battery weight in an aircraft, by going to a bigger battery.

 

The Odyssey battery is a deep cycle Absorbed Glass Mat battery, and deep cycle batteries are not recommended for use as starting batteries - even though people do often use them for that purpose.

A dedicated starter battery can produce the high amperage needed in short bursts, such as starter motor power demand.

An AGM battery is designed to produce a smaller amperage current supply, over a longer period of time - and to be able to be cycled a lot more often, between a fully charged state, and a discharged state.

 

Accordingly, I'd suggest a dedicated starter battery be fitted, rather than another AGM battery. But at the end of the day, it's your choice.

[Bruce Tuncks]

My Jabiru kit came with a motorbike lead-acid battery which was not good enough to start the engine, well after I left it on a small solar charger for months. It was replaced with an Odyssey, which performed well for more than ten years. It is still going, that battery, these days on a farm buggy. I am sure Onetrack is correct, but I didn't know that stuff at the time.

The reason for replacing it in the plane  was because of weight. A LiFePO4 was 5kg lighter! and much cheaper too, from a chinese hobby online shop. ( without the charging electronics and the case which looks like a regular car battery)

These lithium batteries are not as robust as the odyssey, and I am on my second lithium after about 5 years, on account of buggering up the lithium battery by leaving the master on. ( I had done this with the Odyssey, and it came good again... one tough battery, huh.)

My advice is  not to change to lithiums unless you are quite expert. There are types which are dangerously flammable, their voltage is not compatible with   simple charging systems and they cannot stand terminal voltages outside a narrow range. In particular, don't be sucked in by a " lead acid equivalent" figure.

[kgwilson]

I have a Motobatt MBTX20U AGM battery which is 21Ah with 310 CCA that has been going well for 5 years so far. Never had a problem on freezing cold mornings. It cost about $110.00 but they are about $150.00 now I think. Heaps cheaper than Odyssey which are overpriced IMO. It weighs 6.5kgs so no lightweight.

[Old Koreelah]

 

Bruce has mentioned Lithiums, which because of their much lower weight, are attractive for aircraft.

I tried small AGMs for several years and found them only just up to the job, especially in winter. When I fitted a LiFePO4 (which claimed a 400 CCA rating) I also fitted a PowerMate regulator which seems to have mated up well with this battery. 

As Bruce says, a lithium may not be a drop-in replacement for a LA battery; the charge regime is different and their much lighter weight may cause you CoG issues.

 

Besides its very light weight and ability to keep its charge for months even in the cold, Lithiums are attractive because of how they deliver their power; on cold winter mornings my Li battery cranks incredibly slowly, like its flat. After a few seconds the cranking rate picks up as it warms.

That gentle start is kind to Jabiru flywheel bolts, but re-starting when it’s hot is not. 

[RFguy]

 I have made a soft start for the Jabiru.

 

It works by simulating a flat battery . It gets the starter engaged at low voltage- as once it is engaged it does stay engaged down to a few volts.... then winds up the voltage...

 

Going  to install on mine next week, have been messing with a starter motor (same as Jab )  on the bench.

Will make up some kits..... Goes in series with your starter pos cable from the solenoid...

 

[RFguy]

you could do it actually, in a crude but effective sort of way with an extra starter solenoid in series with the starter cable, and a time delay relay.

 

The 2nd starter contactor has a small loop of wire across the contacts.

 

Initially the starter is engaged with the 2nd contactor 'open' so the starter is connected via that length of wire, which acts like a resistor taking a couple of volts off your battery. 

 

After one second the time delay relay times-out and the 2nd contactor pulls in, shorting the loop wire, giving your battery full voltage.

 

You could substitute  a resistor and capacitor for the time delay relay also, just becomes a little more sensitive to battery voltage.

[kgwilson]

It will need to have enough power to throw the pinion out to fully engage the ring gear. You could also install a car style starter with a pre-engage mechanism. The problem with this is presumably a weight disadvantage.

[keith.b]

On 25/06/2021 at 3:54 PM, kgwilson said:

I have a Motobatt MBTX20U AGM battery which is 21Ah with 310 CCA that has been going well for 5 years so far. Never had a problem on freezing cold mornings. It cost about $110.00 but they are about $150.00 now I think. Heaps cheaper than Odyssey which are overpriced IMO. It weighs 6.5kgs so no lightweight.

Tried one of these in my J200 recently(after reading your post) as the odyssey battery couldn't cope with the winter cold starts... So far so good, with temps below 0 deg The Mottobatt starts it first go no problems..  Cost me $175 delivered. The two way terminals is a good feature too.

[kgwilson]

16 minutes ago, keith.b said:

Tried one of these in my J200 recently(after reading your post) as the odyssey battery couldn't cope with the winter cold starts... So far so good, with temps below 0 deg The Mottobatt starts it first go no problems..  Cost me $175 delivered. The two way terminals is a good feature too.

I hope it lasts as well as mine has. Never thought about the 2 way terminals but depending on location that is a handy feature.