Solar dump.

[Tony1]

6 hours ago, IanD said:

When the ISO rule referred to above comes into effect, I'm pretty sure that the BSS will have to incorporate this into the regulations because of the RCD -- if only because insurers are likely to require it.

 

by the way ISO/TS 23625:2021 is also ratified and will be approved standard for RCD boats . in Europe the RCD has the force of law unlike ABYC

 

Unless it only applies in the EU and not the UK -- could this *finally* be a Brexit benefit? 😉

 

P.S. The full up-to-date ISO document costs about £60, here's an earlier version -- don't know what has changed, but this one doesn't seem to distinguish between LFP and other more dangerous chemistries... 😞

 

https://cdn.standards.iteh.ai/samples/76438/9f817478349b4f4f8770642cb1748902/ISO-TS-23625-2021.pdf

 

I get the impression that a lot of the features required by this spec will be included in modern lithiums that have a good BMS. 

Although it does mention balancing as well, which I'm not sure is that common even on new lithiums.

Buyers of bare cells, or of batteries without a comprehensive BMS, may have difficulties. 

 

In my case, I can meet many of the new spec's BMS requirements with my disconnect switches that are controlled by BMV712s, but one thing I don't have is a disconnect that will act when the battery is charged at below 0 degrees (or 5 degrees, say).

In fact I dont yet have a temp sensor that will disconnect the chargers if the battery gets too hot, and that will be needed regardless of the new spec. 

 

But Victron BMV712s will work with temp sensors, so folks with DIY BMS setups might be ok.

I think I'll need one BMV712 to manage the low temp disconnection (of the charger), and because of the way they work with the relays, I might need a second BMV to control the high temp disconnect. 

I actually have three BMV712s already, so I think its possible to add temp sensors to two of them, and connect the 12v signal from the BMVs to my battery protect unit. 

The battery protect currently acts as a high voltage disconnect for the chargers, so as long as I can wire in two extra 12v control wires to its input socket, I should be ok. 

 

So even with my rudimentary understanding, I think its possible for DIYers to use BMVs, motorised switches, and temp sensors to add in the control and BMS elements that are needed for the new spec, at battery level. 

But if these features are required at cell level, I'm personally going to struggle to meet them. 

 

@nicknorman, might I possibly prevail upon your knowledge of these beasties? can I use the victron temp sensor to control the relay in a BMV712, or can it only do an audible alarm?

And if I can, would you use a relay that is NO, or one that is NC, for this sensor? 

https://www.victronenergy.com/live/temperature_sensors

There isnt even a datasheet for the sensor, but I know from a youtube video that its resistance value falls as temp increases, if that helps?

 

My first need is for a high temp disconnect for safety reasons, and I have a BMV712 already in place to disconnect the charger in the event of high voltage. The relay is not inverted, and its set to NO. Is that suitable to use with an auxiliary temp sensor for high temp disconnect?

 

I think I have a feasible alternative strategy I could use, which is to use the remote BMS input on my B2B chargers. A 12v signal from the BMV712 triggered by a high temp event could switch the B2Bs and the MPPTs off, so no need to use the battery protect device for the high temp disconnect.

Whether the BSS people would be happy with a remote charger switch off instead of a direct battery disconnect I'm not sure....

 

 

 

Edited July 20, 2023 by Tony1