Max Voltage Question got Mach2GTO/GTOCP5


quinnfamily@...
 

Folks,

I have two 12 volt lead acid batteries in series with the intent to operate the mount at 24 volts in the field.  The measured voltage on the power pole connector is ~25.66 volts.  Will the ~25.66 volts damage the GTOCP5/Mount?

Super clear skies forecast for tonight in Central FL!

Thanks,  

Shawn


michaeljhanson@...
 

Hi Shawn,

25.66 volts is fine.  It will not damage anything.

Regards,
Mike Hanson


Greg McCall
 

Hi,
Does anyone know what the specified voltage range is for the Mach2?
If, for example, you have a 24v LiFePO4 battery, the charge voltage is around 28.8 to 29.4v

So if you have a setup where you need to charge the 24v battery while it is connected to the Mach2, is that charge voltage within the Mach2 specification?

I seem to remember reading that was not allowed but I can't put my hands on where I saw that.

cheers
Greg


michaeljhanson@...
 

Greg,

That's a great question.  The charge voltage overlaps with the low end of the tolerance band in which the CP5 transient suppression could begin trying to protect the unit.  So running the CP5 off a 24V battery charger is risky.

Regards,
Mike


Greg McCall
 

Hi Mike
Do you have the specification for the CP5 voltage range? I can't seem to find where that spec as it's not in the manual.

Also, I wasn't suggesting actually running the CP5 from a charger but rather a 24v battery that has a charger connected. I know just a minor difference but it's something someone might do if they think running the mount off a 24v battery is OK. At some stage, they will need to charge that battery.

I was wondering about 24v in a portable situation but I could not find a 12 to 24 converter of suitable power (I always do portable)
Mix and matching batteries of varying LiFePO4 battery voltages with associated different chargers and power monitoring also seemed not really practical.
cheers
Greg


michaeljhanson@...
 

Greg,

I am not finding any published spec for voltage range either.  One issue with specs is that they will account for the widest possible range operating conditions, "one size fits all", with margin.  So they are not always useful in answering targeted questions.  It is unlikely that a max input voltage spec, spec'ed as a single number, will support use of a battery charger while the CP5 is powered.  An analytical value for max input voltage might be about 28V.

However, taking off the "specsmanship hat" for a moment, one observation is that the breakdown voltage of a TVS device will have a positive temperature coefficient.  This means that if a TVS device begins to conduct and heat up, the breakdown voltage will increase causing less conduction.

So, if someone wants to make sure it is OK to power a particular unit from a battery while being charged, suggest the following:  With the unit powered and the battery charger off, disconnect the motor cables from the CP5, and measure the CP5 input current.  The battery should be near full charge for this.  The measurement can be done with a multi-meter, or with a device like this:
https://www.astro-physics.com/cabppwm
Then, turn on the battery charger and verify the CP5 input current is not any larger, even though the voltage is.  As long as that is the case, you will not harm the unit with a battery charger.

The CP5 input current will ordinarily decrease with increasing voltage, until the TVS begins to conduct.  Then, current will rise exponentially with voltage.

Regards,
Mike


ROBERT WYNNE
 

I am under the impression it is never a good idea to run any device while it's batteries are being charged due unpredictable charge current especially when the batteries are close to 0. -Best, Robert 

On 01/11/2021 1:25 PM michaeljhanson@... wrote:
 
 
Greg,

I am not finding any published spec for voltage range either.  One issue with specs is that they will account for the widest possible range operating conditions, "one size fits all", with margin.  So they are not always useful in answering targeted questions.  It is unlikely that a max input voltage spec, spec'ed as a single number, will support use of a battery charger while the CP5 is powered.  An analytical value for max input voltage might be about 28V.

However, taking off the "specsmanship hat" for a moment, one observation is that the breakdown voltage of a TVS device will have a positive temperature coefficient.  This means that if a TVS device begins to conduct and heat up, the breakdown voltage will increase causing less conduction.

So, if someone wants to make sure it is OK to power a particular unit from a battery while being charged, suggest the following:  With the unit powered and the battery charger off, disconnect the motor cables from the CP5, and measure the CP5 input current.  The battery should be near full charge for this.  The measurement can be done with a multi-meter, or with a device like this:
https://www.astro-physics.com/cabppwm
Then, turn on the battery charger and verify the CP5 input current is not any larger, even though the voltage is.  As long as that is the case, you will not harm the unit with a battery charger.

The CP5 input current will ordinarily decrease with increasing voltage, until the TVS begins to conduct.  Then, current will rise exponentially with voltage.

Regards,
Mike


Roland Christen
 

You are correct. A battery that is close to full discharge can easily go way above 13.8 volts, even 15 volts when a charger is attached. It no longer regulates or limits the voltage of the charger.

Rolando



-----Original Message-----
From: ROBERT WYNNE <robert-wynne@...>
To: main@ap-ug.groups.io; michaeljhanson@...
Sent: Mon, Jan 11, 2021 3:29 pm
Subject: Re: [ap-ug] Max Voltage Question got Mach2GTO/GTOCP5

I am under the impression it is never a good idea to run any device while it's batteries are being charged due unpredictable charge current especially when the batteries are close to 0. -Best, Robert 
On 01/11/2021 1:25 PM michaeljhanson@... wrote:
 
 
Greg,

I am not finding any published spec for voltage range either.  One issue with specs is that they will account for the widest possible range operating conditions, "one size fits all", with margin.  So they are not always useful in answering targeted questions.  It is unlikely that a max input voltage spec, spec'ed as a single number, will support use of a battery charger while the CP5 is powered.  An analytical value for max input voltage might be about 28V.

However, taking off the "specsmanship hat" for a moment, one observation is that the breakdown voltage of a TVS device will have a positive temperature coefficient.  This means that if a TVS device begins to conduct and heat up, the breakdown voltage will increase causing less conduction.

So, if someone wants to make sure it is OK to power a particular unit from a battery while being charged, suggest the following:  With the unit powered and the battery charger off, disconnect the motor cables from the CP5, and measure the CP5 input current.  The battery should be near full charge for this.  The measurement can be done with a multi-meter, or with a device like this:
https://www.astro-physics.com/cabppwm
Then, turn on the battery charger and verify the CP5 input current is not any larger, even though the voltage is.  As long as that is the case, you will not harm the unit with a battery charger.

The CP5 input current will ordinarily decrease with increasing voltage, until the TVS begins to conduct.  Then, current will rise exponentially with voltage.

Regards,
Mike


W Hilmo
 

I use a buck-boost converter between my batteries and devices to keep the voltage constant, even as the voltage at the batteries varies.  This works to keep the voltage up in cold weather, or as the batteries discharge, and it allows me to recharge the batteries using an optimal charge profile, without the elevated voltage reaching my devices.

 

I have been happy with the arrangement and would recommend it.

 

From: main@ap-ug.groups.io <main@ap-ug.groups.io> On Behalf Of Roland Christen via groups.io
Sent: Monday, January 11, 2021 1:55 PM
To: main@ap-ug.groups.io
Subject: Re: [ap-ug] Max Voltage Question got Mach2GTO/GTOCP5

 

You are correct. A battery that is close to full discharge can easily go way above 13.8 volts, even 15 volts when a charger is attached. It no longer regulates or limits the voltage of the charger.

 

Rolando

 

 

 

-----Original Message-----
From: ROBERT WYNNE <robert-wynne@...>
To: main@ap-ug.groups.io; michaeljhanson@...
Sent: Mon, Jan 11, 2021 3:29 pm
Subject: Re: [ap-ug] Max Voltage Question got Mach2GTO/GTOCP5

I am under the impression it is never a good idea to run any device while it's batteries are being charged due unpredictable charge current especially when the batteries are close to 0. -Best, Robert 

On 01/11/2021 1:25 PM michaeljhanson@... wrote:

 

 

Greg,

I am not finding any published spec for voltage range either.  One issue with specs is that they will account for the widest possible range operating conditions, "one size fits all", with margin.  So they are not always useful in answering targeted questions.  It is unlikely that a max input voltage spec, spec'ed as a single number, will support use of a battery charger while the CP5 is powered.  An analytical value for max input voltage might be about 28V.

However, taking off the "specsmanship hat" for a moment, one observation is that the breakdown voltage of a TVS device will have a positive temperature coefficient.  This means that if a TVS device begins to conduct and heat up, the breakdown voltage will increase causing less conduction.

So, if someone wants to make sure it is OK to power a particular unit from a battery while being charged, suggest the following:  With the unit powered and the battery charger off, disconnect the motor cables from the CP5, and measure the CP5 input current.  The battery should be near full charge for this.  The measurement can be done with a multi-meter, or with a device like this:
https://www.astro-physics.com/cabppwm
Then, turn on the battery charger and verify the CP5 input current is not any larger, even though the voltage is.  As long as that is the case, you will not harm the unit with a battery charger.

The CP5 input current will ordinarily decrease with increasing voltage, until the TVS begins to conduct.  Then, current will rise exponentially with voltage.

Regards,
Mike