Connect CAN-bus or not?

[MrSwede]

Hi,
I have built a couple of DIY packs and I don't really know if i whant to connect them via CAN-bus to my Victron GX device.
Seems like if that pack (master pack) that connects via can-bus to my system has an issue and turns off, my whole system shutsdown (3x Quattros) when it no longer have coms with the BMS.
I'm thinking of just connecting the packs plain dumb, without any coms, to my Lynx Power terminals. And use the Lynx shunt and enable DVCC.

Does anyone have any advice for me in this? How are you Victron users doing with DIY batteries?

Kind Regards
MrSwede

 

[Culchee]

Hi,
I have built a couple of DIY packs and I don't really know if i whant to connect them via CAN-bus to my Victron GX device.
Seems like if that pack (master pack) that connects via can-bus to my system has an issue and turns off, my whole system shutsdown (3x Quattros) when it no longer have coms with the BMS.
I'm thinking of just connecting the packs plain dumb, without any coms, to my Lynx Power terminals. And use the Lynx shunt and enable DVCC.

Does anyone have any advice for me in this? How are you Victron users doing with DIY batteries?

Kind Regards
MrSwede

I don’t have loads of experience.. but I reckon it’s always best to keep things simple... if the bms do their job... that should be enough... makes me think of Chinese whispers...

 

[Culchee]

Hi,
I have built a couple of DIY packs and I don't really know if i whant to connect them via CAN-bus to my Victron GX device.
Seems like if that pack (master pack) that connects via can-bus to my system has an issue and turns off, my whole system shutsdown (3x Quattros) when it no longer have coms with the BMS.
I'm thinking of just connecting the packs plain dumb, without any coms, to my Lynx Power terminals. And use the Lynx shunt and enable DVCC.

Does anyone have any advice for me in this? How are you Victron users doing with DIY batteries?

Kind Regards
MrSwede

Dumb is good...

 

[Culchee]

Hi,
I have built a couple of DIY packs and I don't really know if i whant to connect them via CAN-bus to my Victron GX device.
Seems like if that pack (master pack) that connects via can-bus to my system has an issue and turns off, my whole system shutsdown (3x Quattros) when it no longer have coms with the BMS.
I'm thinking of just connecting the packs plain dumb, without any coms, to my Lynx Power terminals. And use the Lynx shunt and enable DVCC.

Does anyone have any advice for me in this? How are you Victron users doing with DIY batteries?

Kind Regards
MrSwede

Maybe check out Andy’s Off Grid Garage YouTube channel... I think he runs Victron multiplus without coms from his diy packs...

 

[houseofancients]

I don’t have loads of experience.. but I reckon it’s always best to keep things simple... if the bms do their job... that should be enough... makes me think of Chinese whispers...

Comms is a safety feature, and it helps Your pack to stay balanced.
Last thing you want in an emergency is a cascade of BMS overloading, possibly damaging all your bms'es.

 

[houseofancients]

Maybe check out Andy’s Off Grid Garage YouTube channel... I think he runs Victron multiplus without coms from his diy packs...

There is s reason he is trying to switch his "dumb" jk bmd's to communicating...
Safety being a big one

 

[Culchee]

There is s reason he is trying to switch his "dumb" jk bmd's to communicating...
Safety being a big one

I believe he’s thinking of not having coms ... I’m wondering why Andy doesn’t either.. unless he’s changed his approach... there always seems to be problems with coms..

 

[houseofancients]

Live and learn, besides, Andy slowly found out his Victron equipment behaves differently to comms than most modern aio equipment...
This is also the reason he couldn't get comms working with pace , seplos V2 and many other bms's

 

[Culchee]

Live and learn, besides, Andy slowly found out his Victron equipment behaves differently to comms than most modern aoi equipment...
This is also the reason he couldn't get comms working with pace , seplos V2 and many other bms's

Does Victron only want Victron products to be able to communicate with each other I wonder...it’s a shame.. I see GWL reports success with some of their newer battery packs and Victron.. I originally looked at forklift batteries because this eliminated all of these problems... but then they have their own drawbacks... so whichever battery chemistry people opt for.. they all have pros and cons..

 

[houseofancients]

Does Victron only want Victron products to be able to communicate with each other I wonder...it’s a shame.. I see GWL reports success with some of their newer battery packs and Victron.. I originally looked at forklift batteries because this eliminated all of these problems... but then they have their own drawbacks... so whichever battery chemistry people opt for.. they all have pros and cons..

Doesn't have anything to do with chemistry , nor vendor lock-in in my opinion, rather with the separation of components..

In a aio, the mppt, charger and inverter are separated , but on the same DC bus.
Therefor when a BMS tells the charger to stop charging, or slow it down it only affects the charger, and not the inverter or mppt.
Loads will still be powered by the mppt to inverter.

In a separated system, the mppt and chargers are separated, therefor when the BMS tells the charger to stop charging , the inverter won't receive any dc power from the mppt , causing battery micro cycling

 

[Culchee]

Doesn't have anything to do with chemistry , nor vendor lock-in in my opinion, rather with the separation of components..

In a aio, the mppt, charger and inverter are separated , but on the same DC bus.
Therefor when a BMS tells the charger to stop charging, or slow it down it only affects the charger, and not the inverter or mppt.
Loads will still be powered by the mppt to inverter.

In a separated system, the mppt and chargers are separated, therefor when the BMS tells the charger to stop charging , the inverter won't receive any dc power from the mppt , causing battery micro cycling

I suppose the point I’m making about battery chemistry is there is no technology involved in lead acid... no bms as such .. making for a much simpler system... but of course there are drawbacks..

 

[Ampster]

Comms is a safety feature, and it helps Your pack to stay balanced.

I see it the in a similar fashion but not because it helps my pack to stay balanced. I use a separate balancer with no comms to balance my pack. My BMS still is the last fall back of pack safety for me to shut off my battery if one cell or the pack go outside my limits. I disable the BMS balancing because the active balancer can balance at 2 Amps and my BMS can only do milliAmps. Comms is an acuracy and data issue for me. The value of Comms is that I get more acurate SOC and voltage values and before a cell exceeds the voltage setting the BMS tells the inverter to ramp down currrent. You could argue in that sense it indirectly helps the pack stay balanced because the pack spends more time at lower current while charging and therefore giving the active balancer more time.

 

[MrSwede]

Comms is a safety feature, and it helps Your pack to stay balanced.
Last thing you want in an emergency is a cascade of BMS overloading, possibly damaging all your bms'es.

Could you eloborate more on that?
Do you mean that when cell- or total voltage is above a setpoint, an alarm is triggered and charging for that pack is limited to10A?
I don't understand why coms would help the cells stay balanced otherwise.

I have external balancer, not using the balancer on the BMSes. So i was thinking of doing like Andy's 2.0 build. Whats the safety reason he's moving from dumb packs to coms?

 

[houseofancients]

Could you eloborate more on that?
Do you mean that when cell- or total voltage is above a setpoint, an alarm is triggered and charging for that pack is limited to10A?
I don't understand why coms would help the cells stay balanced otherwise.

I have external balancer, not using the balancer on the BMSes. So i was thinking of doing like Andy's 2.0 build. Whats the safety reason he's moving from dumb packs to coms?

Cascading shutdowns with the potential of damaging mosfetts because of sudden overloads would be one

And yes, on my case ( and also with the pace BMS) when a certain set point is reached the charging will slow down to 10a for the whole battery which gives even a passive balancer the chance to bring cells into balance, provided they are good cells and a top balance was done

 

[Culchee]

Cascading shutdowns with the potential of damaging mosfetts because of sudden overloads would be one

And yes, on my case ( and also with the pace BMS) when a certain set point is reached the charging will slow down to 10a for the whole battery which gives even a passive balancer the chance to bring cells into balance, provided they are good cells and a top balance was done

Thinking about the cascade effect...for example .. two battery packs in parallel... completely dumb.. no coms with anything... bms on both packs shut down.. what happens to the mppt...?