Battery Protect now can customise setpoint via BT

[john61ct]

New version Victron Battery Protect have bluetooth, custom program the LVD and return V
https://www.victronenergy.com/batter...attery-protect

Essential for use with LFP cells, tweak for changing conditions.

If only they also made an OVD version. . .

[rgleason]

Originally Posted by john61ct

New version Victron Battery Protect have bluetooth, custom program the LVD and return V
https://www.victronenergy.com/batter...attery-protect

Essential for use with LFP cells, tweak for changing conditions.

If only they also made an OVD version. . .

Thanks John. Excellent. Maybe they'll just improve the device to be selectable ovd/lvd?

[john61ct]

Or even better one device that can do both.

Good for those with a single buss for both loads and charging anyway, like users of combi style charger / inverters.

[nebster]

Originally Posted by john61ct

Or even better one device that can do both.

Good for those with a single buss for both loads and charging anyway, like users of combi style charger / inverters.

Unfortunately, no. Battery Protect is an asymmetric FET, so it can only interrupt current in one direction. One of these cannot be used as the safety isolator in a homebrew battery monitoring system.

[john61ct]

Yes I just meant "if it could" be improved

or a new device developed by Victron

to act as such, not be so limited

that "would be nice".

But certainly as is, I think this is still a great improvement,

more suitable than before as part of a DIY LFP

for those with separate charge and load busses.

[nebster]

Originally Posted by john61ct

Yes I just meant "if it could" be improved

or a new device developed by Victron

to act as such, not be so limited

that "would be nice".

I see. Yes, that would be nice.

But certainly as is, I think this is still a great improvement,

more suitable than before as part of a DIY LFP

for those with separate charge and load busses.

...and with (small) loads guaranteed to be lower than the rating (which itself is underspecified... "peak" for how long?).

FET arrays tend to fail quietly and infuriatingly: they cascade short and turn into wires.

Contactors have a distinct advantage here. For a given nominal rating, good ones can handle substantial overcurrent transients for periods well into seconds, and at the same time their primary failure mode (contact arc welding) occurs during breaking events rather than in normal use.

Put another way, if your Battery Protect is "on" in a system running normally, and you inadvertently apply something north of the peak transient current for 20ms, you may well now have a BP that won't P! (That peak is marketed as 2.5x the rated continuous, by the way.)

On the other hand, if your contactor is closed "on" in a system running normally, inadvertent transient currents well in excess of 10x the rated continuous are unlikely to do a thing. The device won't melt, and the contactor doesn't have a gap to arc over. It will still happily break a nominal current, later, in a shutdown event.

In large systems, substantial transients can be created as inverters with big buffers are switched into the system. (Ask me how I know!)

I'll stop there, and just summarize: don't use Battery Protects as pack disconnects in high-power lithium systems. They look cool on paper, but they're not robust enough for the job.

They're probably fine for small systems with light, unidirectional loads. Make sure you understand their drawbacks before proceeding.

[witzgall]

Originally Posted by john61ct

Or even better one device that can do both.

Good for those with a single buss for both loads and charging anyway, like users of combi style charger / inverters.

Victron told me that you cannot use a Battery protect on an inverter charger. This was after mine stopped working, installed in such a manner. It only lasted a few minutes. I was drawing 50a at 24v, running an air conditioner. I do not recall the reason given. It was the non bt version.

[Tornadosailing]

I bought a Victron Multiplus for my soon to be home brew LFP setup. Would have done it later, but my battery charger died a month ago.

I now own the batteries (12 Sinopoly 200ah cells to run 3P4S) and I bought a 123Smart BMS in part because I can enable or disable charge and invert on the Multiplus independently with it.