11DCV too much for automotive 12 volt starter 10

[frankiee]

I have heard that 12VDC auto starter batteries put in cars are designed to operate at 9 to 10 volts and that if a person puts too much battery in the car, the starter can go and not be covered under warranty. He said that the company said that cranking voltage of 11 volts was too high and his warranty was void. He then put the smaller recomended battery back in and he did not have any broken starters after that.
Is there any body that could confirm that starter motors are designed around 9 to 10 volts DC

Thanks

 

[Skogsgurra]

Tough marrying makes for a smooth marriage. Believe me...

Gunnar Englund

http://www.gke.org

 

[ScottyUK]

Hi Pete,

I love Scotland - it has the finest mountain country in Britain, especially up to the far north-west. Even though it rains nine visits out ten, the tenth time will make it all worthwhile. It is kinda hard to keep that thought going during the other nine!


----------------------------------

I don't suffer from insanity. I enjoy it...

 

[UKpete]

Scotty, of course no slight on Scotland was intended! It only rained occasionally and as we don't do proper walking it wasn't really a problem. In the bits in between it was exceptional. West is best I think (e.g. train journey Malaig to Glasgow via Fort William, one of my all-time favourites).

But Brighton's definitely warmer and less damp.

 

[bklauba]

Gosh, I wonder what the OP thinks about the circuitous route this thread has taken: golden opp to rib a frequent participant (who shows signs of addiction to eng-tips, as many of us do), marriage, Scotland. What next?

Anywho, nothing to prevent scammers, such as those who dealt a mighty blow to the OP's wallet, from plying their trade. (Oh, except knowledge.)

BK

 

[itsmoked]

And now philosophy..



Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[jraef]

Never found the problem... Put it back together.. No knock.

Works for me every time. I even end up with extra parts when I'm done!


I spent my honeymoon at a beach resort on the Baja coast. Rented a car, and specifically asked for air conditioning, knowing it gets really hot in Baja. Got the car, drove off on a trip in the early AM to see the Bajia de Concepcion where the Grey Whales go for their honeymoons. When it warmed up, I tried the AC. Nothing but fan. Got out and looked under the hood, no belt to the compressor. Naturally, we had only 2 small water bottles with us (another mistake). New wife and I must have perspired 2 quarts of water each, spent the next day sick from dehydration. To top it off, a whale had beached and died a few days earlier, and the stench went on for miles and miles as we drove near and around the Bajia, but because of no AC we had to keep the windows down. Later found out that the belt had broken months ago and they didn't have the right size, so they sacrificed the AC. I yelled at the hotel rental car agent about why he failed to mention that earlier, and he said "But you can roll the windows down sir"! I learned that you must be very specific about what you ask for in Mexico, i.e. working AC, and no matter where you go outside of the hotel, take a case of water with you.

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[itsmoked]

Mexican car rentals... heheheh yeah...
Toyota van I rented in Mexico City had a rod knock that was so loud you had to shout over it.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[bklauba]

Did anyone notice?

BK

 

[OperaHouse]

All my boats have 6V starters and 12V batteries. I haven't had a problem in 20 years. Maybe they just made better starters in the 30's and 40's.

 

[ruggedscot]

'Fraid the gentleman is right about battery size and its all down to internal resistance.

If you get a large capacity battery say from a F250 truck and connect it into your Suzuki Swift with duff ignition and try to start it you will end up with one knackered starter. If the suzuki started on the key then you would get away with it but as soon as you start to try to draw significant current then the starter will fry its guts as its not designed to deal with what large battery can supply.

If your talking perfect world then it would fry but were not were talking large capacity heavy cranking duty batteries.

 

[Skogsgurra]

Did you run a systematic test on that Rugged?

Or is that what happened when you tried to make that "near death" Suzuki make a last spin?

I don't know what the nominal voltages of the two systems involved are, but my guess is that they are not the same. F250 winning hands down.

Gunnar Englund

http://www.gke.org

 

[ScottyUK]

rugged,

Got to disagree. A few years ago, in one of our more creative moments, we jump started the site pickup with its 12V electrics by tapping off from six cells in the 110V turbine battery to give us a 12V source. The cells are each rated 2V / 1430AH and weigh about 200kg each. By the theory expounded earlier, the starter motor should have gone into meltdown.

Perhaps if the engine was totally siezed then some damage would arise, but it would be open to debate whether the motor shaft would shear off, the flywheel gear break, motor pinion strip its teeth, or the wiring would catch fire. But not on an engine free to rotate.

----------------------------------

I don't suffer from insanity. I enjoy it...

 

[fsmyth]

Methinks much of the hoopla here involves the
difference between real starter motors and
toy starters such as are usually installed
in (smaller) motorcycles and some smaller cars.
I personally equate foreign and domestic small
car electronics with the IEC offerings in
motor control gear - adequate if used as
rated, but not nearly as robust as U.S. made
equivalents (SquareD vs. Siemens, for example).
<als>
P.S. you can leave such as Jag and BMW out of
the category, but Mercedes seems to now use
the same type of aluminum-housed crap. And
probably some of today's domestics (dunno,
been out of it too long).

 

[IRstuff]

Seems like there a lot of speculation but little in real facts. My copy of Chilton's repair manual states that a 12V starter draws typically 60 A to 120A while the voltage droops to 9 V. The battery capacity is usually sized to provide some multiple of the starting current. If you use the low current value, you get a battery ESR of 0.05 ohms for the battery, and a start resistance of 0.15 ohms. Using the high value, you get a battery ESR of 0.025.

If you use the low ESR battery on the smaller starter, you get about 68 A of starting current vs. the nominal 60 A, hardly a catastrophic event. Doing it the other way, you'd wind up with 96 A starting current, less than nominal.

An even smaller starter would a correspondingly higher battery ESR. Setting the battery ESR to zero results in 12V/9V=1.33x nominal starting current, which seems to be something that should be designed for in the starter motor, since a jump start migh be with a much larger capacity battery and resultant lower ESR.

TTFN

 

[waross]

I must point out that there are two kinds of starter in common use now.
One is the old standby, series wound starter that has been with us for about a hundred years.
Some small motors such as lawn-mowers and outboard motors are using permanent magnet motors. The characteristics are quite different from series wound starters.
However, they will operate at a full 12 volts safely and, to my knowledge, are not used in automobiles.
The standard series starter is a series motor. Check the characteristics of a series motor. The faster it goes the less current it draws. The more voltage is applied the faster it goes. The starting surge is greater with higher voltage but is mostly disipated as voltage drop in the cables. I have seen a few starters fail because of low voltage but never because of over voltage.
I don't have any problem accepting that a failing starter
may well have drained a battery and the application of a good battery proved that the starter had failed. But, proving that a starter has failed is not the same as causing it to fail.
respectfully

 

[ruggedscot]

waross you reminded me of what I was thinking - series wound motor - faster it spins more back emf and less current flow through the motor. That was what I was thinking on!

Now you have a reasonable battery hook it up when you try to start the battery voltage drops to say the crank voltage of 9v and the motor is cranking you get the current flow going through. Bigger battery and a goosed engine slower crank speed lower back emf and more juice going through kills the starter.

I guess its one of those things that no body is wrong and no body is right. A stronger battery = more juice.

Rugged

 

[waross]

Hi skogsgurra
In North America The Suzuki will have a relatively small 12 volt battery. The F-250 will have one large 12 volt batterie or possibly 2 large 12 volt batteies in parallel, but both systems are 12 volts.
Cheers
Hi ruggedscot
When I get home, I have to change the ground cable on a truck I recently bought. The cable is too long and too small. If the (small diesel) engine doesn't start right away, it won't start at all. The cable overheats and the starter overheats and the cranking speed falls to almost stopped. At that point, with the overheated starter and partly drained battery, if I connect both of my jumper cables in parallel with the small battery cable the engine starts right up. Less cable resistance = more voltage at the starter.
There have been many starters damaged and destroyed by low voltage but almost none by high voltage. Most automotive starters will take double voltage safely for a year or more of normal starts.
respectfully

 

[UKpete]

waross, I agree. I think you are less likely to damage the motor with a higher voltage because it will start more quickly.

Incidentally, back in the old days I could judge the condition of my battery by listening to the starter. On my latest car when the battery was fading there was no warning - suddenly the electronics wouldn't let the starter even try. I thought I had an electrical fault until my neighbour pointed out that was what happened on modern cars when the battery voltage was low.

Even more incidentally, just coming off the drawing board are cars with stop-start. When the vehicle comes to a rest the engine automatically stops to save fuel, restarting when you touch the accelerator. The integrated starter-alternator (usually mounted on the crankshaft between the engine and the gearbox) is more powerful and can turn the engine at over 1000rpm, starting it in about 200ms. The old starters could only turn at about 300rpm and took over a second to start the engine.

 

[Skogsgurra]

Yes, and they usually have (or will have) a 42 V battery, too. I guess it would be a bad idea to connect that battery to a 12 V starter. So the old "Don't jump-start" warning gets a whole new meaning...

Gunnar Englund

http://www.gke.org

 

[itsmoked]

Naw skogs.. The 12 volt starter will just start the engine in 1ms!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com