Making a cheap BMS ABYC compliant

[newhaul]

Originally Posted by rgleason

This is a good idea, but the BMS you referenced only supports

"Discharging current: 30A, Charging current: 15"
although this particular one is 48v is it enough for a decent sized alternator?


I am wondering what the best way to actually implement this is, perhaps for 12vdc

https://www.ebay.com/itm/Daly-SMART-...edirect=mobile
There ya go 200 amp unit like mine. Except smarter

[s/v Jedi]

Originally Posted by rgleason

This is a good idea, but the BMS you referenced only supports

"Discharging current: 30A, Charging current: 15"
although this particular one is 48v is it enough for a decent sized alternator?


I am wondering what the best way to actually implement this is, perhaps for 12vdc

The BMS current is only used to power a relay/solenoid. The primary DC circuit skips the BMS negative connections, going straight from battery negative to the busbar.

[newhaul]

Found it and the price is good as well.
https://shop.pkys.com/Balmar-APM-12-...RoC46cQAvD_BwE

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.

[s/v Jedi]

Originally Posted by newhaul

Found it and the price is good as well.
https://shop.pkys.com/Balmar-APM-12-...RoC46cQAvD_BwE

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.

These protectors are based on a MOV (Metal Oxide Varistor). These can be sacrificial if the surge is bad enough and the nice thing is when they have a circuit that checks if they still work.

As nice as they are, this is a last resort method, like a fire extinguisher, which means it should not be used to handle battery disconnect events. It’s something to have when primary method fails, which is the cell voltage high warning being used to shut down the alternator.

[goboatingnow]

Originally Posted by s/v Jedi

These protectors are based on a MOV (Metal Oxide Varistor). These can be sacrificial if the surge is bad enough and the nice thing is when they have a circuit that checks if they still work.



As nice as they are, this is a last resort method, like a fire extinguisher, which means it should not be used to handle battery disconnect events. It’s something to have when primary method fails, which is the cell voltage high warning being used to shut down the alternator.

TVS diodes are better then MOVs and have multiple repeatable characteristics and a sharper “ knee “the LP02 range from ST micro being very applicable.

[newhaul]

Originally Posted by s/v Jedi

These protectors are based on a MOV (Metal Oxide Varistor). These can be sacrificial if the surge is bad enough and the nice thing is when they have a circuit that checks if they still work.

As nice as they are, this is a last resort method, like a fire extinguisher, which means it should not be used to handle battery disconnect events. It’s something to have when primary method fails, which is the cell voltage high warning being used to shut down the alternator.

Anything is sacrificial if the surge is bad enough. It is a in my opinion a good low cost last resort. Even if running to a lead bank .stuff happens

[s/v Jedi]

Originally Posted by newhaul

Anything is sacrificial if the surge is bad enough. It is a in my opinion a good low cost last resort. Even if running to a lead bank .stuff happens

I am installing these as well: https://www.amazon.com/gp/product/B09KBRXXXR

[goboatingnow]

Originally Posted by s/v Jedi

I am installing these as well: https://www.amazon.com/gp/product/B09KBRXXXR

To what purpose ?

[newhaul]

Originally Posted by s/v Jedi

I am installing these as well: https://www.amazon.com/gp/product/B09KBRXXXR

That's a grat idea I've never ( yet) but friends have lost controllers due to near strikes.
Great cheap insurance for a couple hundred worth of electronics kit

[goboatingnow]

Originally Posted by newhaul

That's a grat idea I've never ( yet) but friends have lost controllers due to near strikes.

Great cheap insurance for a couple hundred worth of electronics kit

Won’t likely save you from lightening

[Jammer]

Originally Posted by s/v Jedi

In my preferred setup, I charge the AGM start battery with the alternator and the lithium battery with the dc-dc converter. If I experience a similar BMS failure, everything keeps working. This is an example of inherent reliability, something of high importance on boats when you want to venture out to uninhabited areas of the world.

What happens when you get a shorted cell on your AGM start battery?

[newhaul]

Originally Posted by goboatingnow

Won’t likely save you from lightening

Actually it would protect electronics like my MPPT . As to a direct strike well that's what my arresting gear is for .

[newhaul]

Originally Posted by Jammer

What happens when you get a shorted cell on your AGM start battery?

Limited chance for a shorted cell in a good condition lead based battery

[goboatingnow]

Originally Posted by newhaul

Actually it would protect electronics like my MPPT . As to a direct strike well that's what my arresting gear is for .

In my case the lightning strike propagated up the battery line and took out the mppt mosfets. A PV feed breaker would not have saved the controller

None of those mechanical devices will save electronics anyway

[newhaul]

Originally Posted by goboatingnow

In my case the lightning strike propagated up the battery line and took out the mppt mosfets. A PV feed breaker would not have saved the controller

None of those mechanical devices will save electronics anyway

Well I have confidence in one specificly my lightning arresting gear of my own design .
It involves a plate of copper on my keel and a heavy wire from my rigging