Which BMS should I use?

harpo

Good at many things, master of none
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Working on putting together my off grid small solar system with LifePO4 cells (280Ah cells, 4s}. I am purchasing Victron Smart Shunt, Victron SCC and now need to decide what BMS to use. It will have to have a reliable low temp sensor since this battery will be exposed to colder temps part of the year.
The technology seems to be evolving so rapidly it is difficult to keep up with. I have seen many just use the Daly. Others {Will) seems to like Overkill while another likes the QUCC.
Would love input from the members here who have experience with at least a couple different BMS models and what BMS they would purchase at this time (knowing solar components evolve/updated all the time}.
I have to make a decision soon as my cells should arrive within a month.

Thanks
 

smoothJoey

mumble...
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Ok so we know you need
4s
low temp cutoff

How much continuous amperage do you need?
Typically we size the bms to handle the full inverter load.
If your pure dc loads are significant we should add those as well.
 

chrisski

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Overkill would have everything you’re asking for with the low temp and high temp cutoffs, but is limited to 120 amp output. 120 amps will run a 1000 watt inverter, except for perhaps some surge ratings. 80 -100 amps equals 1000 watts of power From an AC inverter. I have two of Overkill’s for the larger battery.

I have two Daly BMSs, but those are the small type, 15 amp charge, 30 amp discharge. Although it these have a temp cutoffs and voltage cutoffs, these settings can’t be configured and are way off from what I would like. These are much smaller and quite different than the larger ones most people use.
 

HRTKD

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I have two of the Overkill Solar 4s 120 amp BMS. The low temp cutoff works, but I have warmers on my batteries so the BMS should never have to cutoff the charge. The BMS are working well.

If you go with the Overkill Solar (aka JBD) BMS there are different way to configure it. There is one option to use screw terminals instead of cables. I would have gone with that option had it been available when I bought my two BMS.
 

mikefitz

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I am purchasing Victron Smart Shunt, Victron SCC and now need to decide what BMS to use. It will have to have a reliable low temp sensor since this battery will be exposed to colder temps part of the year.
Fit the optional temperature sensor to the smart shunt or fit the Victron smart battery sense ,

These report to the solar controller allowing the low temperature disable to function.
experience with at least a couple different BMS models and what BMS they would purchase at this time
Daly and JBD ( Overkill). JBD units are my preference.

Now only considering variants from JBD. Being in the UK ,I have found buying from LLT Power and opting for air freight, I receive units within in a week. The link is for the equivalent of the Overkill unit.

home page.


Mike
 

Holoduke

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What about the rec BMS? Is that one not best suited for victron hardware?
 

chrisski

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What about the rec BMS? Is that one not best suited for victron hardware?
I use small 30 amp Daly on a Victron Inverter with a victron 75/15 SCC and For my much larger 560 AH batteries bank I use two overkill’s BMSs 8S 24 Volt 100 amps Which has three Victron SCCs And a Victron Battery Monitor.

I don’t think there’s a recommended BMS except to match to your needs. For me, the first BMS is to a tiny system which Daly is the only manufacturer I found out there. I got the Larger BMS off Will’s website.
 

harpo

Good at many things, master of none
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What about the rec BMS? Is that one not best suited for victron hardware?
Tell me more about the REC BMS. I haven't really seen anyone using this BMS and would like to know more about it.
 

harpo

Good at many things, master of none
Joined
Oct 1, 2019
Messages
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Location
PA, FL
Ok so we know you need
4s
low temp cutoff

How much continuous amperage do you need?
Typically we size the bms to handle the full inverter load.
If your pure dc loads are significant we should add those as well.
To SmoothJoey.........I have a 1500 watt Samlex inverter. We rarely use the inverter anywhere near the maximum wattage. Probably the most power consuming appliance we have is our 1200 watt microwave. Actually, most of the loads do not even go thru the inverter as we designed our minimal electrical needs (lights, small water pump, fan etc.) to run on 12v. The system was originally very small so I designed it basically like the electrical system of an RV. We run very few 120v appliances and even then it is sporadic.

However, I know one has to size the system anticipating the max. load. To answer that question I guess I would have to say 1200 to 1300 watts.
 

harpo

Good at many things, master of none
Joined
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Location
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Fit the optional temperature sensor to the smart shunt or fit the Victron smart battery sense ,

These report to the solar controller allowing the low temperature disable to function.

Daly and JBD ( Overkill). JBD units are my preference.

Now only considering variants from JBD. Being in the UK ,I have found buying from LLT Power and opting for air freight, I receive units within in a week. The link is for the equivalent of the Overkill unit.

home page.


Mike
To Mike.............I believe the Overkill (JBD) has a low temp. sensor. Will tested that function and found it to be consistent.

I guess my question is why I would need or even want the Victron battery Sense or Smart Shunt optional Temp. sensor if my BMS is going to handle this function??? Am I missing something or are you considering redundancy?
 

smoothJoey

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To SmoothJoey.........I have a 1500 watt Samlex inverter. We rarely use the inverter anywhere near the maximum wattage. Probably the most power consuming appliance we have is our 1200 watt microwave. Actually, most of the loads do not even go thru the inverter as we designed our minimal electrical needs (lights, small water pump, fan etc.) to run on 12v. The system was originally very small so I designed it basically like the electrical system of an RV. We run very few 120v appliances and even then it is sporadic.

However, I know one has to size the system anticipating the max. load. To answer that question I guess I would have to say 1200 to 1300 watts.
Its my policy to size the bms for the for maximum continuous rating of the inverter.
1500 ac watts / .85 conversion factor / 12 volts low cutoff = 147.058823529 service amps
You require a bms capable of handling 150 amps continuous.
If your Samlex inverter is the "pst" model there is a workaround.
 

mikefitz

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860
believe the Overkill (JBD) has a low temp. sensor
Worked for me.
My view is that the BMS is the last line of defence and there should be other components to ensure the system operates in a safe region.

Mike
 

Cal

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Its my policy to size the bms for the for maximum continuous rating of the inverter.
1500 ac watts / .85 conversion factor / 12 volts low cutoff = 147.058823529 service amps
You require a bms capable of handling 150 amps continuous.
If your Samlex inverter is the "pst" model there is a workaround.

The microwave also has a power factor of about 0.7.

Max current = 1200 W / (0.85 * 0.7 * 12V) = 168 A

Has the OP powered the microwave with the 1500 W inverter? It might be too small.

Sounds like a 200 A BMS is in order.

No one suggested a Electrodacus BMS?
 

smoothJoey

mumble...
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Yes, my Samlex inverter is a PST.
The workaround is to have the inverter bypass the bms.
This is possible because the inverter is controlled by a via its external switching by an Victron Smart Battery Protect.
You would also need shunt based battery monitor because you bms will no longer have the full picture of current in and out of the battery.

A simpler and cheaper solution is to get a bms that can handle the appropriate amount of current.

I've no experience with this one but it looks like a contender https://www.aliexpress.com/item/1005003327457730.html
 
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