Yet another battery thread

[epretot]

No when wired in series the voltage will increase but not the amps

Ok...so if a battery has a BMS and a max charge rate of 50 amps, what happens if 80 amps is coming in?

Asking for a friend.

[richard5933]

Ok...so if a battery has a BMS and a max charge rate of 50 amps, what happens if 80 amps is coming in?

Asking for a friend.

Could be wrong here, but I believe that amps are pulled and volts are pushed. In other words, it makes no difference how many amps are available to the BMS, it will only pull as many as it needs. Volts, however, will continue to push against it and cause all kinds of problems if they are too high.

What exactly are you describing when you say that there are 80 amps available?

[buswarrior]

The other variable that gets glossed over during the selling job...

A "BMS" is not some universal thing.

Just like if we used the term "fuel delivery" for your new car. What's to prevent it from being a 2 barrel carb, and not the electronic direct fuel injection you were assuming...

Try to find the parameters/performance/history/reliability of the "BMS"...

If the brains don't do what they are supposed to, the lithium bits get damaged, and/or dangerous.

Still too much wild west, carnival atmosphere, "trust us"...

happy coaching!
buswarrior

[epretot]

An example would be two solar chargers rated at 40 amps wired in parallel coming from 2 solar arrays.

I'm still researching the Lithium batteries. SOK has a more affordable lithium battery. However, it's max charge is 50 amps.

Hence the question about their capability wired in series.

[epretot]

Perhaps I asked the question wrong.

I think a better question is...

Does the max charge capacity increase when four batteries are wired 2 in series then paralleled together?

Forgive me...still learning the lingo.

[richard5933]

Perhaps I asked the question wrong.

I think a better question is...

Does the max charge capacity increase when four batteries are wired 2 in series then paralleled together?

Forgive me...still learning the lingo.

The max charge capacity of each battery will remain the same no matter how it's connected to the other batteries. Depending on how you connect them (series vs. parallel, etc) you will be raising and lowering voltage and amperage according to the equation watts = amps x volts, and the watts will be the constant for a battery equation.

The difference will be in the efficiencies of the various methods of connecting and/or the efficiencies of the type of charger being used.

[sledhead]

my current set up

4 x 12 v starts and 6 x 6v GC for house and I can combine them all if needed for starts if needed  but when it is time to replace I thing I will go to the 8 x 6 v GC and use for everything on 1 system like  JC

dave

[luvrbus]

I don't get the LikePo4 charging and draws yet ,James told me the Lifeline you cannot charge with more amps than the LifePo4 is rated for .like jumping a 100 amp with a 200 amp alternator.I think you could work around that though by letting the alternator regulator controlling the voltage and amps needed but I may be wrong since Zach has a 100 amp alternator for his LifePo4s.Everything posted here is about solar and the LifePo4 charging and you need away to charge when the sun doesn't shine for weeks I would think a lot to learn for me,no solar on the van so they are going to charged by the alternator (140 amps)still don't have any idea how I can get the volts needed to charge the LifePo4 to full charge with the stock alternator,I have the same problem with my AGM batteries in the RV but it has a inverter so I plug it in the van doesn't have the inverter charger it has a piece of crap 4 stage charger   

[Jim Blackwood]

What's this BMS business?

[luvrbus]

What's this BMS business?

Battery Management System to keep the LifePo4 safe in their operating range,it will disconnect the charging source if it detects low,high voltage or high or low temperatures or supposed to anyways     

[buswarrior]

What's this BMS business?

Or, Battery Monitoring System, which is NOT the same, but unscrupulous peeps will just throw the acronym and take your ca$h...

There are other prophets out there suggesting there is no need for a BMS to charge your lithium...

I sure do miss the engineers that used to hang here with us...

happy coaching!
buswarrior

[luvrbus]

Or, Battery Monitoring System, which is NOT the same, but unscrupulous peeps will just throw the acronym and take your ca$h...

There are other prophets out there suggesting there is no need for a BMS to charge your lithium...

I sure do miss the engineers that used to hang here with us...

happy coaching!
buswarrior

Lol but some of those guys could get in outer space too, like the electrical  engineer that installed halogen lights in the ceiling and almost caught the bus on fire   

[freds]

Ok...so if a battery has a BMS and a max charge rate of 50 amps, what happens if 80 amps is coming in?

Asking for a friend.

Ah it is a bit confusing in this case the BMS would limit the maximum charge rate to 40 amps. The two solar controllers that you speak of have a maximum charge rate of 40 amps. Generally they are configurable for the output voltage so 40 amps at 12V it would be 12 X 40 = 480 , 24 X 40 = 960 or 48 X 40 = 1920 watts.

A 40 amp BMS is fairly wimpy you really want 100 amps or higher. With 40 amp BMS you would more and likely have to have multiple batteries in a series/parallel configuration to drive an inverter with enough power to run a microwave.

You generally want your house batteries to be higher than 12V, however that also generally dictates multiple batteries in series.

Most solar panels output between 36-72 volts, while you can get 12v solar panels they IMO are waste of money and time.

Solar charge controllers are generally first targeted by the output voltages 12/24/36/48 and by maximum solar panel input voltage; followed by the output amperage.

The maximum solar panel voltage is for when you string solar panels together in series, not something I recommend for bus nuts. As a partially shaded panel reduces the total output of all the panels in the string. Recently watched a video of relocated solar panels that saw drop in output from the shadow from an antenna guide wire in a series string.


Go to amazon and search for "victron solar charge controllers".

Note when sizing your solar panels you really can't have too many! (More power!!!). You want the biggest high power panel(s) that you can fit!!!


Here's a view looking back along the top of my bus:



Also note there is an energy tax for each stage in the system as charge controllers, batteries and inverters.

Note: a 400watt power will only produce that amount when all the ducks are in a row.

[luvrbus]

 I see people in Quartzsite washing and cleaning the solar panels on the roof that must be why Freds, never even thought they were that touchy 

[windtrader]

A BMS function is totally different from a charge controller function. All the BMS does is make sure the batteries are balanced and in operating range and cuts off draw if below the set low voltage limit.


The charge controller is the circuit that manages the flow of power flowing into the battery and ensures the battery is not overcharged.


Generally, the solar charge controller is a separate device, designed and engineered into the charging side of the system. Well built lithium battery pack include a BMS inside the battery pack to ensure long life of the battery pack as the cells are balanced and the battery is kept from being drawn down too low or when too cold if outfitted with a temperature sensor.


More rare is combined solar controller and BMS functions into single device. The Electrodacus SBMS0 is such a device and what is in my system. Can not comment on pros/cons but it works very well for me in MY system and a lot cheaper.


As to DIY costs, 25% of retail is way too high. You can DIY today for around $125/kW, not $1,000/kW retail.