Small Boat BMS/LFP with backup

[Goboatingnow]

Yes domestic whole house RCBOs are cheap mine is mounted beside the breakers on the AC panel.€15 from my local electrical wholesaler

 

[rgleason]

Thanks for the description and photo it is helpful to visualize what is needed. Unfortunately our layout is the classic port and starboard cockpit lockers with no pilot berth. I am uncomfortable putting the LFP and BMS in those lockers due to potential to get wet if innudated from the stern. That would be closer to the engine and alternator, but it is too risky. So I simply have to pick the best cabinet or under berth location.

1. The port side berth slides out to a double, so access from the top is difficult. I have considered making a two access panels (which dadoed to fit in a rabbit to stay locked in place and not drop through). To get through the second layer of plywood, I would have a slightly smaller panel, also with dado and rabbits. This is a little bit complicated but would allow access from the top, which I think is necessary. One of the drawers would lost and just become a fake and also provide access.
2. It would be simpler to use the first under berth drawer area on the starboard so the top access would be just on dado/rabbited access panel. It is further from the alternator by about 3'
3. One of the shelves or cabinets on the port side could also be used if it is large enough.

 

[Goboatingnow]

Thanks for the description and photo it is helpful to visualize what is needed. Unfortunately our layout is the classic port and starboard cockpit lockers with no pilot berth. I am uncomfortable putting the LFP and BMS in those lockers due to potential to get wet if innudated from the stern. That would be closer to the engine and alternator, but it is too risky. So I simply have to pick the best cabinet or under berth location.

1. The port side berth slides out to a double, so access from the top is difficult. I have considered making a two access panels (which dadoed to fit in a rabbit to stay locked in place and not drop through). To get through the second layer of plywood, I would have a slightly smaller panel, also with dado and rabbits. This is a little bit complicated but would allow access from the top, which I think is necessary. One of the drawers would lost and just become a fake and also provide access.
2. It would be simpler to use the first under berth drawer area on the starboard so the top access would be just on dado/rabbited access panel. It is further from the alternator by about 3'
3. One of the shelves or cabinets on the port side could also be used if it is large enough.

I often taught a “ slide out “ tray system under the saloon berth would be ideal.

 

[svsagres]

I often taught a “ slide out “ tray system under the saloon berth would be ideal.

The downside is having to cable manage all that slack to allow it in and out. There are pluses and minuses to everything. In our case, top access was sufficient.

 

[svsagres]

I often taught a “ slide out “ tray system under the saloon berth would be ideal.

The downside is having to cable manage all that slack to allow it in and out. There are pluses and minuses to everything. In our case, top access worked well enough, and we didn’t need to deal with all the slack.

 

[Goboatingnow]

The downside is having to cable manage all that slack to allow it in and out. There are pluses and minuses to everything. In our case, top access worked well enough, and we didn’t need to deal with all the slack.

Cable chains can handle that. But it needs careful design. It’s just I’m tired of dark inaccessible holes on boats with things stuffed in them.

 

[Goboatingnow]

Cable chains can handle that. But it needs careful design. It’s just I’m tired of dark inaccessible holes on boats with things stuffed in them.

And trying to move people and their “ stuff “ on the saloon berth when I need to access the void beneath.

 

[rgleason]

For access from the top, I could provide an access panel under the cushions, that is lapped or dadoed and rabbited which might be the best approach. The cushion would have to be set to the side (glad we got 3 cushions!). On the port side we would need two access panels (one smaller so it can be removed) on the starboard it would just be one access panel. I think this would be similar but a little tighter than svsagres pilot berth.

 

[rgleason]

And trying to move people and their “ stuff “ on the saloon berth when I need to access the void beneath.

I agree, but it is a small boat! Perhaps a cabinet or shelf would be better?

 

[Goboatingnow]

For access from the top, I could provide an access panel under the cushions, that is lapped or dadoed and rabbited which might be the best approach. The cushion would have to be set to the side (glad we got 3 cushions!). On the port side we would need two access panels (one smaller so it can be removed) on the starboard it would just be one access panel. I think this would be similar but a little tighter than svsagres pilot berth.

Agree. My current battery bank and associated controls is under the port saloon berth. This is adjacent to the DC distribution panels.

Still like a “ tray “ system but hey it’s a boat.

 

[rgleason]

I've written Phillipe at TAO BMS and he has kindly responded in detailed manner which answers many of my questions about use of the TAO BMS. It appears there is another iteration which may remove the need for CerboGX and ColorGX, while still providing a status display and operation through a Bluetooth app, which also controls all the chargers. This does show that there are many ways to achieve these goals.

Additionally he suggests that the switching over to SLA Emergency could be done automatically by the BMS. This is an interesting idea because the boat would not be left dark, however manual control is possibly affected.

I think it might be useful to do a version of this with TAO BMS and estimate the cost. What do you all think?

 

[Goboatingnow]

I've written Phillipe at TAO BMS and he has kindly responded in detailed manner which answers many of my questions about use of the TAO BMS. It appears there is another iteration which may remove the need for CerboGX and ColorGX, while still providing a status display and operation through a Bluetooth app, which also controls all the chargers. This does show that there are many ways to achieve these goals.

Additionally he suggests that the switching over to SLA Emergency could be done automatically by the BMS. This is an interesting idea because the boat would not be left dark, however manual control is possibly affected.

I think it might be useful to do a version of this with TAO BMS and estimate the cost. What do you all think?

Switching by bms is fine and dandy but it’s a reliance on a piece of electronics. After my lightening strike. Im converted to manual bypasses. !!!

 

[svsagres]

I've written Phillipe at TAO BMS and he has kindly responded in detailed manner which answers many of my questions about use of the TAO BMS. It appears there is another iteration which may remove the need for CerboGX and ColorGX, while still providing a status display and operation through a Bluetooth app, which also controls all the chargers. This does show that there are many ways to achieve these goals.

Additionally he suggests that the switching over to SLA Emergency could be done automatically by the BMS. This is an interesting idea because the boat would not be left dark, however manual control is possibly affected.

I think it might be useful to do a version of this with TAO BMS and estimate the cost. What do you all think?

The thing you lose when doing away with the Cerbo is the larger ecosystem. BMS is just a piece of it. The wakespeed reads directly from the BMS, but it is monitored by the Cerbo. The cerbo also controlling the solar controllers, monitoring loads. Plus, I use it to monitor my tankage (Fuel, Potable Water, Sewage, Bilge), monitor my boat sensors remotely (Is it worth sailing today? lets check SignalK and see what the wind sensor is reading!).

And all of this is remotely accessible through Victron's website, which allows me to remote control it and monitor things while I'm not on the boat. It's a very much worth it in my books.

 

[Goboatingnow]

The thing you lose when doing away with the Cerbo is the larger ecosystem. BMS is just a piece of it. The wakespeed reads directly from the BMS, but it is monitored by the Cerbo. The cerbo also controlling the solar controllers, monitoring loads. Plus, I use it to monitor my tankage (Fuel, Potable Water, Sewage, Bilge), monitor my boat sensors remotely (Is it worth sailing today? lets check SignalK and see what the wind sensor is reading!).

And all of this is remotely accessible through Victron's website, which allows me to remote control it and monitor things while I'm not on the boat. It's a very much worth it in my books.

Yes the Cerbo/Venus is good

 

[rgleason]

See this post for some price and feature comparisons, REC Active BMS + CerboGX + Touch50 vs TAO BMS + TAO Monitor. Also Phillipe (TAO BMS) answered all my questions about TAO BMS use in this diagram, and I believe it could be substituted quite easily. See his Post #2 in his forum, and his following responses.