MPP LV6548 Build

[Sanwizard]

All you Solar gurus out there, I am currently designing my LV6548 system as I await the slow ship from China to deliver my Lishen 280AH cells and Heltec 200A 2A active balance BMS's. I was wondering if you folks could take a look at my design and let me know if you see any flaws, or have any suggestions to improve the design. I will be putting both 16S cell strings into a Truck Toolbox case, and making cutouts for the terminals and AiLi Shunt monitors. Any pointers or ideas welcome!

 

[Bleedingblue]

Are you putting in a circuit breaker on each mpp from the batteries?

 

[Lt.Dan]

Make your own thread. This is not the correct place to ask your questions.

 

[Sanwizard]

Are you putting in a circuit breaker on each mpp from the batteries?

Nope. Just fuses and switches. The breakers are on the PV inputs.

 

[JoeHam]

Beautiful work @DanF but check the spec sheet on that BlueSea switch.

I believe it’s good to 48v and you will obviously exceed that while charging.

 

[Sanwizard]

Make your own thread. This is not the correct place to ask your questions.

You mean make another MPP LV6548 Build thread? Wouldn't that be redundant? I am new to these forums. Are these threads owned buy the original poster, or viewed as places to share information and ask questions?

 

[Sanwizard]

Beautiful work @DanF but check the spec sheet on that BlueSea switch.

I believe it’s good to 48v and you will obviously exceed that while charging.

Thanks for pointing that out! You are correct, they are 48V max, but rated at 300 amps continuous. Maybe I should return them and use breakers instead?

 

[JoeHam]

Thanks for pointing that out! You are correct, they are 48V max, but rated at 300 amps continuous. Maybe I should return them and use breakers instead?

I would.

No one “owns” a thread but it’s kind of a dick move to hijack one, just sayin ?

Especially a show and tell thread about a well done system.

 

[Sanwizard]

I would.

No one “owns” a thread but it’s kind of a dick move to hijack one, just sayin ?

Especially a show and tell thread about a well done system.

Understood. Ok, I will start a new one. By the way, as an FYI. I called BlueSea, and they agreed that using their switches in a high amp slightly higher than 48V environment is not recommended due to the possibility of arcing. I will be returning the switches for a Gigavac switch.

 

[DanF]

Thanks for pointing that out! You are correct, they are 48V max, but rated at 300 amps continuous. Maybe I should return them and use breakers instea

Beautiful work @DanF but check the spec sheet on that BlueSea switch.

I believe it’s good to 48v and you will obviously exceed that while charging.

Thanks for catching that Joe, I totally missed that one. Appreciated!

 

[ArthurEld]

It would be easy to miss. Especially since some people claim they handle 60V.

Amazon.com: Battery Disconnect Switch 12V 24V 48V 60V Battery Master Cut Off Isolator Switch Waterproof for Marine Boat Auto Camper RV ATV UTV Vehicles, Military Quality On/Off Position : Automotive

Buy Battery Disconnect Switch 12V 24V 48V 60V Battery Master Cut Off Isolator Switch Waterproof for Marine Boat Auto Camper RV ATV UTV Vehicles, Military Quality On/Off Position: Battery Switches - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[JoeHam]

Yup, the off brands have claims and Blue Sea has a spec sheet ?

 

[Sanwizard]

It would be easy to miss. Especially since some people claim they handle 60V.

Amazon.com: Battery Disconnect Switch 12V 24V 48V 60V Battery Master Cut Off Isolator Switch Waterproof for Marine Boat Auto Camper RV ATV UTV Vehicles, Military Quality On/Off Position : Automotive

Buy Battery Disconnect Switch 12V 24V 48V 60V Battery Master Cut Off Isolator Switch Waterproof for Marine Boat Auto Camper RV ATV UTV Vehicles, Military Quality On/Off Position: Battery Switches - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

So this is a false claim? I just ordered two of those based on the specs of 300a and 60V!

 

[DanF]

So, the first run went well. I got about 267ah on the first real scenario run on the new system and everything was balanced pretty well (fell out a bit near discharge).
Then I went into charge mode from the grid. All was well until about 3.4v/cell (This is when charging starts to pick up) as this happened my cell balance couldn't keep up. The faster the bank went up, the faster the cells went bonkers out of whack. By the time I hit 3.5v/cell average I had to shut down the charger(charging from the mains). I was off by .6 volts from the highest to the lowest cell!
I'm not sur what is going on now. Giving the cells a rest, shut er down and letting the active balancer do it's thing overnight and will start back in the morning.

Other notes. NOT happy with the Victron 500a shunt. (Drops out on bluetooth, barely any distance as well). My Chinese JK active balance does a wonderful job! SO, I got to thinking.. Why after finding out what your battery capacity is do you even need another possible problem in the system?
My JK balancer tells me all I need to know, and the inverters do the rest.
The Victron will be going back and removed from my system. Then after @JoeHam pointed out my Blue Sea disconnect really isn't rated for a 48v system (Another bottle neck) That one is going back as well! I kinda have to agree with Will here on the fact that do you actually need it? Being an electrician it's common practice to always provide a safety switch, breaker, fuse or some sort of shut off for safety, but he is right in my opinion.. Once connected properly, if you ever have to work on it.. Disconnect one wire and your done. You know even if you have a disconnect, you have all that open bus that can still do damage. I do however understand the convenience of having one for possible work on the system don't get me wrong, but mine will be Deleted.

The point is.. Every joint, or connection you make to your system is a point of failure. We have to be safe, but be smart! Every situation is different.

Thanks to everyone in the forum here. Without all you guys I couldn't have made it this far. Absolutely love this!


Be Safe!,
Dan

 

[DanF]

I have to add this... when studying a way to protect my investment in my batteries, the weakest point was the BMS in line expensive Daly's etc. that claim amperage that is wrong for the wire size they provide. That's why I chose the separate balancer that isn't in line with the batteries (another point of failure or fire). The balancer does a fantastic job on it's own. The inverter settings does the rest.

I worked a job for AEP where we connected lithium battery banks together that in series were over 800v (not sure about the current), but the BMS system was all done in #14awg wire. Not a Daly 10,000a in series BMS.. lol. anyway, you get the picture.

 

[Lt.Dan]

@DanF what will you be using as a breaker/disconnect between your inverters and the PV Panels?

 

[ArthurEld]

I suspect using that on/off switch is better than not using one.
The only time you will get an arc is if charging / discharging big amps.

I don't turn my switch off or on without turning down the amps.

And not using a switch I assume you would turn down the amps before disconnecting anything otherwise you are going to get an arc.

But I would like to hear about safer alternatives.

 

[Sanwizard]

GIGAVAC DC switches were recommended to me by BlueSea customer support.

 

[Lt.Dan]

I just received a LV6548 as well and am debating on using this Disconnect Switch i found on Amazon. Reasonably priced and will handle more than the LV6548 can.

 

[Sanwizard]

Looks good. I wanted an outdoor rated disconnect, so I bought this one: https://www.invertersupply.com/index.php?main_page=product_info&cPath=1304_425_426&products_id=29941