TVS load dump protection

[BobR]

I am looking for information on design and construction of a load dump clamping device for a 24volt marine installation. Or the source for a device to purchase.

I have just started looking into these; I understand they are used in electric autos.

I don't know enough yet to ask the proper questions

 

[svsagres]

Balmar makes/sells them (Alternator Protection Device) but if your design things correctly, with a properly integrated regulator and BMS, you will never experience a disconnect.

 

[BobR]

Balmar makes/sells them (Alternator Protection Device) but if your design things correctly, with a properly integrated regulator and BMS, you will never experience a disconnect.

The Balmar and Sterling alternator protection devices are a resistive load and have limited ability to protect electronics on board a boat. I am looking for protection for $5000.+ worth of navigation etc. electronics.
Such devices are being developed for electric vehicles to protect their electronic controls.

I have found some information but nothing that helps with my limited knowledge of electronics.

Here is one: https://www.maximintegrated.com/en/design/technical-documents/app-notes/7/7084.html

 

[BobR]

Balmar makes/sells them (Alternator Protection Device) but if your design things correctly, with a properly integrated regulator and BMS, you will never experience a disconnect.

Never is a strong word

 

[BiduleOhm]

The simplest and cheapest will probably be a bunch of TVS diodes (they're like zener diodes but made exactly for that purpose; https://en.wikipedia.org/wiki/Transient-voltage-suppression_diode) in parallel.

But outside of protection designed for this did you consider just putting a lead-acid battery in parallel? they're cheap and should be enough to absorb the energy of the transient before voltage rises too high (but require testing IRL to be sure).

 

[BobR]

I have considered the lead acid battery; finding room is always a problem.

 

[BiduleOhm]

Ok, then I recommend the TVS diodes solution

 

[Goboatingnow]

I am looking for information on design and construction of a load dump clamping device for a 24volt marine installation. Or the source for a device to purchase.

I have just started looking into these; I understand they are used in electric autos.

I don't know enough yet to ask the proper questions

Firstly you must define what you want

What’s the maximum clamp voltage that’s can be allowed.

What’s the timing of the “ over “ pulse , protecting a device for 50 uS is way different to 250mS

What devices are you specifically looking to protect.

TVS diodes represent the best solutions but you must look at the details of the clamping action , clamp timing and energy dissipation

Otherwise it’s just a Bandaid and may do little

 

[Goboatingnow]

The Balmar and Sterling alternator protection devices are a resistive load and have limited ability to protect electronics on board a boat. I am looking for protection for $5000.+ worth of navigation etc. electronics.
Such devices are being developed for electric vehicles to protect their electronic controls.

I have found some information but nothing that helps with my limited knowledge of electronics.

Here is one: https://www.maximintegrated.com/en/design/technical-documents/app-notes/7/7084.html

The application note covers all the bases if you can follow it.

The big problem is what you are trying to protect.

To survive a 24v electronic device needs to be able to handle 40v over voltage as a TVS clamp is not perfect. Modern car systems now are designed to handle 80v. This gives the protection devices some headroom to work.

So if you have a 24v system and you want no excursion over 25v that’s really hard to do where the currents and timing are high.

In fact in most cases you need active disconnect stage it’s rather then clamping

I designed car qualified electronics and in my recent boat lightening strike all my own electronics survived whereas all the expensive commercial stuff failed.

 

[Goboatingnow]

The Sterling unit uses a TVS as does the balmar I believe.

Without response graphs and detail timings graphs it’s impossible to detail these devices.

Then are marketed as alternator protectors but that does not mean they will equally protect non alternator electronics.

 

[svsagres]

Never is a strong word

It's been nearly a year now, have yet to come even close to a disconnect. Alternator, Inverter/Charger, Solar, all coordinated and feeding into my LiFePO4, and it's all worked cleanly as I have cycled the batteries.

 

[Goboatingnow]

I have considered the lead acid battery; finding room is always a problem.

A battery won’t stop certain fast spikes.

 

[Goboatingnow]

It's been nearly a year now, have yet to come even close to a disconnect. Alternator, Inverter/Charger, Solar, all coordinated and feeding into my LiFePO4, and it's all worked cleanly as I have cycled the batteries.

I agree the obcession with lithium HVC disconnect is totally overplayed

 

[BobR]

There are more things that can cause a voltage spike on a boat than just a shutdown from a bms.

 

[Goboatingnow]

There are more things that can cause a voltage spike on a boat than just a shutdown from a bms.

Like what

 

[BobR]

Proper wiring practices will control most of these to a reasonable voltage.
Poor wiring practices make them worse as will a device malfunctioning.

Windlass
Bow thrusters
Electric Winches
Electric Windshield Wipers (power boats mostly)
Engine Driven Refrigeration Clutch
DC Motors (these transients can occur on the negative side too)
DC Refrigeration
Water Makers
Load Dump of an Alternator
Inverters
Water Makers
Electric heads
Water & Washdown Pumps
SSB Radio
Bilge Blower
Battery Charger
Battery Switch
Relays, Solenoids & Combiners
12V/24 Appliances – Blenders etc.
Electric Oil Pumps
Bilge Pumps

From the Battleborn site:
“Voltage spikes have a variety of causes, most of which can be lumped into equipment malfunctions or users improperly operating a device. Something as simple as a switch malfunctioning or as complex as circuit failures can cause voltage spikes. There are also natural causes like lightning or electromagnetic pulses emitted by geomagnetic storms. "


Among the most common causes of voltage spikes is the decay of a magnetic field in an inductor. This occurs when motors, transformers, or other large devices with inductors go offline quickly. This is called a flyback transient and almost always induces a voltage spike.”

 

[Goboatingnow]

Proper wiring practices will control most of these to a reasonable voltage.
Poor wiring practices make them worse as will a device malfunctioning.

Windlass
Bow thrusters
Electric Winches
Electric Windshield Wipers (power boats mostly)
Engine Driven Refrigeration Clutch
DC Motors (these transients can occur on the negative side too)
DC Refrigeration
Water Makers
Load Dump of an Alternator
Inverters
Water Makers
Electric heads
Water & Washdown Pumps
SSB Radio
Bilge Blower
Battery Charger
Battery Switch
Relays, Solenoids & Combiners
12V/24 Appliances – Blenders etc.
Electric Oil Pumps
Bilge Pumps

From the Battleborn site:
“Voltage spikes have a variety of causes, most of which can be lumped into equipment malfunctions or users improperly operating a device. Something as simple as a switch malfunctioning or as complex as circuit failures can cause voltage spikes. There are also natural causes like lightning or electromagnetic pulses emitted by geomagnetic storms. "


Among the most common causes of voltage spikes is the decay of a magnetic field in an inductor. This occurs when motors, transformers, or other large devices with inductors go offline quickly. This is called a flyback transient and almost always induces a voltage spike.”

The presence of a large capacity battery acts as a capacitor of several farads.

This effectively damps any transients from the sources you mentioned. This can easily be seen by using an oscilloscope

Where mechanical disconnect occurs there is a certain inductive spike present at the equipment side. The motors ( windlass etc !) are designed not to be effected by this and the spike is damped by the effective series resistance

Hence spike transients on the battey feed are present but they are small and low energy. The input circuitry of attached electronics is typically designed with small energy TVS protection exactly for such reasons.

Hence in normal usage such spikes are merely standard and designed for. This of course does not cover induced spike from external faults or lightning , in such cases little connected electronics will survive anyway and little can be economically done to protect such circuits.

It has very little to do with “ wiring practices “

 

[BobR]

Here is a quote from Rod Collins on wiring practices:
"Batteries act as very good transient filters clamping the voltage down pretty quickly. It takes huge amounts of amperage in charge current to increase bank voltage a few tenths of a volt when charging large house banks. Transients can be extremely fast and can increase voltage in the system wiring quickly but as we get closer to the bank the transient range is greatly reduced. This is why one central take off point, as close to the battery bank as is possible, for your DC system, is best.

Unfortunately if your wiring for sensitive electronic items, such as marine electronics, is not as close to the batteries as is possible, or the supply feed for them is not close, you widen the risk of transient damage."

 

[Goboatingnow]

Here is a quote from Rod Collins on wiring practices:
"Batteries act as very good transient filters clamping the voltage down pretty quickly. It takes huge amounts of amperage in charge current to increase bank voltage a few tenths of a volt when charging large house banks. Transients can be extremely fast and can increase voltage in the system wiring quickly but as we get closer to the bank the transient range is greatly reduced. This is why one central take off point, as close to the battery bank as is possible, for your DC system, is best.

Unfortunately if your wiring for sensitive electronic items, such as marine electronics, is not as close to the batteries as is possible, or the supply feed for them is not close, you widen the risk of transient damage."

It’s not that sensitive. Firstly a high current device likely to create significant Energy transients will normally have high power dedicated battery feeds. hence the spikes will not propagate beyond that wiring

Other battery feeds hence will not be greatly affected. So low current devices on their own wiring feeds can be some distance away.