How many voltage do i need to start my engine?
 

Hi,

I am planning to make a device that gives a signal (beep) when my
voltage drops at a level that i cant start my boat engine. I have to
know aproximaly what voltage is the minium to start.

I have an 4.3l V6 mercruiser inboard. What will be a save voltage to
program in the device?

I think that might be difficult to say. Among other things,
it will depend on the actual capacity of your battery
(likely to be less than when it was new) and the starting
requirements of your inboard. Other factors that might
influence the minimum starting voltage are engine and
battery temperatures. Worst case is cold battery and cold
engine.

You can certainly experiment (when you have access to a
battery charger) to determine the critical voltage, but
expect it to change. Prudence will doubtless require a
generous margin of safety in any case.

You could be much better off with a second "starting"
battery and isolator.

Good luck.

Chuck

Mvd wrote:
Hi,

I am planning to make a device that gives a signal (beep) when my
voltage drops at a level that i cant start my boat engine. I have to
know aproximaly what voltage is the minium to start.

I have an 4.3l V6 mercruiser inboard. What will be a save voltage to
program in the device?

My car has a feature that will automatically start it and charge the
batteries if the voltage drops below 11 volts. I haven't tested it
but apparently the designers felt this was a good figure.

Doug

"Mvd" wrote in message
om...
Hi,

I am planning to make a device that gives a signal (beep) when my
voltage drops at a level that i cant start my boat engine. I have to
know aproximaly what voltage is the minium to start.

I have an 4.3l V6 mercruiser inboard. What will be a save voltage to
program in the device?

"chuck" wrote in message
...
I think that might be difficult to say. Among other things, it will depend
on the actual capacity of your battery (likely to be less than when it was
new) and the starting requirements of your inboard. Other factors that
might influence the minimum starting voltage are engine and battery
temperatures. Worst case is cold battery and cold engine.


I agree. This is just to hard to predict.

The best way to ensure you have enough battery capacity to start your
engine, is to have a separate starting battery and an isolation switch.

Much simpler and more predictable.

A good practice would be to purchase a new battery each season and install
it as your starting battery, move the '1 y/o' from the previous season over
to aux/house battery service and take the '2 y/o' battery home for use in
your second car. Small investment but great insurance.

My opinion, FWIW.

Steve
s/v Good Intentions

"Doug Dotson" dougdotson@NOSPAMcablespeedNOSPAMcom wrote in message
...
My car has a feature that will automatically start it and charge the
batteries if the voltage drops below 11 volts. I haven't tested it
but apparently the designers felt this was a good figure.

Hopefully only when in Neutral or Park....... :-))

Meindert

"Meindert Sprang" wrote in message
...
"Doug Dotson" dougdotson@NOSPAMcablespeedNOSPAMcom wrote in message
...
My car has a feature that will automatically start it and charge the
batteries if the voltage drops below 11 volts. I haven't tested it
but apparently the designers felt this was a good figure.

Hopefully only when in Neutral or Park....... :-))

Mmm... I realize this might seem a silly remark, but here in Europe, most
cars have a manual gearbox and it is very common to leave the car in 1st
gear when parked, instead of using the parking break.

Meindert

Also Sprach Doug Dotson dougdotson@nospamcablespeednospamcom:

My car has a feature that will automatically start it and charge the
batteries if the voltage drops below 11 volts. I haven't tested it
but apparently the designers felt this was a good figure.

I hope that this is a feature which you must manually activate, and will
deactivate itself automatically after you put the car in drive or
something... I imagine a scenario where you forget the feature is on, park
the car in an attached garage, accidentally leave the door ajar, and then
the car automatically starts at 3AM when everyone's asleep and fills the
house with CO.

Dan


--
I have made good judgements in the past. I have made good judgements in
the future.

-- Dan Quayle

On 24 Mar 2005 06:46:37 -0800, (Mvd) wrote:
Hi,

I am planning to make a device that gives a signal (beep) when my
voltage drops at a level that i cant start my boat engine. I have to
know aproximaly what voltage is the minium to start.

I have an 4.3l V6 mercruiser inboard. What will be a save voltage to
program in the device?

===================================

Like everyone else has said, it depends. I'll throw some numbers in
the air however just to give you a starting point and provide target
practice for everyone else:

Battery under load is about 50% discharged at 11.5 volts, and the no
load 50% point is around 12 volts. Your engine should still start at
50% charged if you don't have to crank it for too long and
temperatures are not too low.

It's not good practice to let your battery go below 50% in any case.

Park only of course. Can't get the key out of the ignition unless it is
in Park.



"Meindert Sprang" wrote in message
...
"Doug Dotson" dougdotson@NOSPAMcablespeedNOSPAMcom wrote in message
...
My car has a feature that will automatically start it and charge the
batteries if the voltage drops below 11 volts. I haven't tested it
but apparently the designers felt this was a good figure.

Hopefully only when in Neutral or Park....... :-))

Meindert

This feature is not available with manual transmissions. Matter of fact,
this particular vehicle is not available in anything but an automatic
transmission.

Doug

"Meindert Sprang" wrote in message
...
"Meindert Sprang" wrote in message
...
"Doug Dotson" dougdotson@NOSPAMcablespeedNOSPAMcom wrote in message
...
My car has a feature that will automatically start it and charge the
batteries if the voltage drops below 11 volts. I haven't tested it
but apparently the designers felt this was a good figure.

Hopefully only when in Neutral or Park....... :-))

Mmm... I realize this might seem a silly remark, but here in Europe, most
cars have a manual gearbox and it is very common to leave the car in 1st
gear when parked, instead of using the parking break.

Meindert