Balmar Alternator Protection Module (APM)

[rgleason]

Balmar just announced release their APM for 12v and 24v systems starting February.

Mounted conveniently on the rear of any alternator, the Balmar APM is designed to absorb voltage and current spikes that commonly occur in many onboard electrical distribution systems from intermittent connections, disconnects and over-voltage events. Lithium battery adoption has introduced a new problem if a battery disconnects due to an internal fault or issue. A battery-initiated disconnect during charging can induce a voltage surge which will damage the alternator’s rectifier diodes or internal regulator and render the unit inoperable. The Balmar APM excels in both short duration and longer duration spikes, where other products fail.

The APM-12 will clamp up to a 60 volt spike and sustained over voltage conditions beginning around 20 volts. The APM-12 can absorb multiple surges of such energy to continually protect an alternator and other devices on the electrical distribution network. Visual and audible alarms indicate if the device has been compromised and needs replacement.

The Balmar APM family meets ISO 16750-2 for Load Dump Protection and ISO 7637-2 for Surge Protection. The APM can be deployed to protect either Balmar or other manufacturer’s charging systems.

“The APM family provides an extra level of protection against electrical system anomalies.” explained Chris Witzgall, Balmar Product Manager. “Proper grounding practices and solid connections are still the best protection against unintended damage to electrical components. Our lab testing demonstrates that it is very difficult to damage unprotected Balmar alternators, yet we know these events can occur in many installations and use cases. The APM adds another level of fault protection against unforeseen events.”

https://balmar.net/product/apm-12/

[d design]

Wont the correct rated capacitor do the same thing?

[jordanbigel]

Meanwhile, I'm looking at this PDF which shows how to connect it (https://balmar.net/wp-content/upload...PDS-APM-12.pdf) - it looks like it just attaches between the B+ and B- of the alternator. Seems too simple. Is that it really?

I also notice this admonition:

DO NOT PLACE EITHER CONNECTOR
UNDER THE BATTERY CABLE LUGS

So, that just means put them on top of the battery cables, not below. Why would that be important exactly? (not that its a problem for me, I will gladly comply, I'm just curious why).

[goboatingnow]

Originally Posted by d design

Wont the correct rated capacitor do the same thing?

No. You need active devices to respond fast enough and deal with the long duration transients which a cap can’t handle

[goboatingnow]

Originally Posted by jordanbigel

Meanwhile, I'm looking at this PDF which shows how to connect it (https://balmar.net/wp-content/upload...PDS-APM-12.pdf) - it looks like it just attaches between the B+ and B- of the alternator. Seems too simple. Is that it really?

I also notice this admonition:

DO NOT PLACE EITHER CONNECTOR
UNDER THE BATTERY CABLE LUGS

So, that just means put them on top of the battery cables, not below. Why would that be important exactly? (not that its a problem for me, I will gladly comply, I'm just curious why).

Because In effect the full battery current could be conducted through the ring terminal to the original battery cable , hence you place it on top


And yes it’s that simple to connect, it’s basically a couple of big TVS diodes

It would be worth opening it if possible and taking a picture of the circuit board

[d design]

Originally Posted by goboatingnow

No. You need active devices to respond fast enough and deal with the long duration transients which a cap can’t handle

Ok that makes sense

[GordMay]

Zap Stop - Fact or Fiction? ➥ https://www.cruisersforum.com/forums...tml#post315702

The Zener Diode ➥ https://www.electronics-tutorials.ws/diode/diode_7.html

[goboatingnow]

Zener diodes are not suitable for this type of application. Specific avalanche diodes capable of handling very high brief surge currents are used , mainly derived forms the automotive industry

[witzgall]

Hi, Chris from Balmar here. This issue is not with the APM specifically. You don't want small connectors under the battery cables anywhere. This would force the current from the cable to flow through the smaller connector, and they are not designed to do this. It is mentioned in the ABYC E-11 standard.

Chris

Originally Posted by jordanbigel

Meanwhile, I'm looking at this PDF which shows how to connect it (https://balmar.net/wp-content/upload...PDS-APM-12.pdf) - it looks like it just attaches between the B+ and B- of the alternator. Seems too simple. Is that it really?

I also notice this admonition:

DO NOT PLACE EITHER CONNECTOR
UNDER THE BATTERY CABLE LUGS

So, that just means put them on top of the battery cables, not below. Why would that be important exactly? (not that its a problem for me, I will gladly comply, I'm just curious why).

[GordMay]

Originally Posted by witzgall

Hi, Chris from Balmar here. This issue is not with the APM specifically. You don't want small connectors under the battery cables anywhere. This would force the current from the cable to flow through the smaller connector, and they are not designed to do this. It is mentioned in the ABYC E-11 standard.
Chris

Thanks for the Excellent explanation, Chris.

The cable carrying the highest current should always be the first one on the terminal. Cables carrying lower currents are then stacked in order, above this first cable. This is to prevent currents from the high current cables from flowing through smaller lower current lugs in the stack, that may not be rated for it, and introduce additional resistance.

The order of lug, washers, and nut, on a threaded stud, is also very important. Many washers and nuts are stainless steel, which has a higher resistance than copper, and can lead to overheating conditions, if installed in the wrong order, in high current paths. The cable lug goes on first, tight against the bus bar or terminal device, followed by flat washer, lock washer and nut. Never put any washers between a lug and the bus bar or terminal device. Similarly when connecting cabling to a terminal device (such as a high amperage fuse holder) with a bolt, the order is terminal device, cable lug, washer, lock washer, bolt.

However, I don’t recall seeing any reference in E-11 - can you cite a specific paragraph?

ABYC E-11 - AC and DC ELECTRICAL SYSTEMS ON BOATS [2003]
➥ http://www.elettronavigare.it/files/...0americane.pdf

11.16.4.1.11. No more than four conductors shall be secured to any one terminal stud. If additional connections are necessary, two or more terminal studs shall be connected together by means of jumpers or copper straps.
11.16.4.1.12. Ring and captive spade type terminal connectors shall be the same nominal size as the stud.
11.16.4.1.13. Conductors terminating at panelboards in junction boxes or fixtures shall be arranged to provide a length of conductor to relieve tension, to allow for repairs and to permit multiple conductors to be fanned at terminal studs.

See also “Proper Stackup”
➥ https://www.cruisersforum.com/forums...up-144309.html

[jordanbigel]

Originally Posted by witzgall

Hi, Chris from Balmar here. This issue is not with the APM specifically. You don't want small connectors under the battery cables anywhere. This would force the current from the cable to flow through the smaller connector, and they are not designed to do this. It is mentioned in the ABYC E-11 standard.
Chris

This makes total sense.

Oddly, even though I did not know this, I always instinctively stack connectors by size anyway, for aesthetic reasons.

[NPCampbell]

I'm still curious as to how this works.

It seems like load dump protection should work like a choke filter rather than just an input capacitor filter. I know this device doesn't use a capacitor but it is effectively shunting the spike across the output leads, just like an input capacitor filter would do.

What is protecting downstream electronics? Without a choke-like component in series with the output leads then downstream electronics will see the same voltage spike that the in-parallel APM does. No?

Maybe my misunderstanding is due to not dealing with the internal resistance of the source of the spike. I dunno, I'm hoping someone can enlighten me.

[goboatingnow]

Originally Posted by NPCampbell

I'm still curious as to how this works.



It seems like load dump protection should work like a choke filter rather than just an input capacitor filter. I know this device doesn't use a capacitor but it is effectively shunting the spike across the output leads, just like an input capacitor filter would do.



What is protecting downstream electronics? Without a choke-like component in series with the output leads then downstream electronics will see the same voltage spike that the in-parallel APM does. No?



Maybe my misunderstanding is due to not dealing with the internal resistance of the source of the spike. I dunno, I'm hoping someone can enlighten me.

The normal approach boils down to two active approaches.

The most basic is high power TVS diodes simply placed across the dc supply from the alternator. With proper component selection these diodes break per at a particular voltage , usually several volts above normal operating points. For 12v these would be 18 -20V

These diodes short the alternator output for a limited time , they can handle the current , however the new ISO test dumps are very challenging , and you can fry TVS diodes if they are subject to repeated shorting actions.

Other solutions can deploy mosfets to disconnect down stream devices etc.

It’s important to realise that the down stream equipment must survive the initial voltage rise , to 20v , some cheap electronics can’t survive this.

Here’s a typical automotive qualified TVS



These can handle over 1000A for 20uS.

[rgleason]

Maybe Chris will explain what is in the black box? Apart from that someone could take one apart.

[SoonerSailor]

Originally Posted by rgleason

Maybe Chris will explain what is in the black box? Apart from that someone could take one apart.

I opened mine. A TVS (avalanche diode) with supporting circuitry to indicate it is intact with a flashing LED. I don’t recall the part number, it was Littlefuse brand, unipolar, 15kW peak pulse capability, with a stand-off voltage around 20 or 22 Volts, I don’t remember which.