Do I need a BMS to charge the batteries?

danelo616

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Dec 25, 2020
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Hello,

I'm new but I've been reading the forum for a few days and I have some doubts.

I've been living offline for more than 10 years and I currently have a 24V system.
I want to switch to 48V and I want to buy 3 packs of 280Ah EVE batteries and mount 4 packs at 48 and then connect them in parallel.


My question is:
Is the BMS necessary ? if the area where I live is not cold there is always between 15º and 30º Celsius.

In total I will have 12 kw/h distributed between 3 80Ah regulators that will give me 4kw for each one.

2nd question:


If I can set the maximum voltage for example 55v of load in all the MPPT regulators what is the BMS for?

And for the discharge I will have an inverter of 5Kw/h that allows me to put the limit of discharge in 51.2V.

Is a BMS still necessary?

3rd Question

Does an active equalizer help me at all?

I have thought of placing a module of 16S for active equalization and that allows me to monitor the cells.

Thanks!
 

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Bob B

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This question has been asked before .... The answer is always ..... get a BMS. There are a lot of $ of batteries .... the BMS is the only device that is able to make protection decision based on individual cell voltages.
 

MisterSandals

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I want to switch to 48V and I want to buy 3 packs of 280Ah EVE batteries and mount 4 packs at 48 and then connect them in parallel.
It sounds like you want to connect your existing 48v battery bank to 3 new 280ah EVE batteries. Connecting batteries that are not identical is usually a recipe for disaster.

Is this what you are thinking of doing? What "48v batteries" are you going to connect in parallel?
 

danelo616

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This question has been asked before .... The answer is always ..... get a BMS. There are a lot of $ of batteries .... the BMS is the only device that is able to make protection decision based on individual cell voltages.
what bms do you recommend to put my batteries in parallel?

I have asked the Daly people and they do not accept to work in parallel.
 

danelo616

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It sounds like you want to connect your existing 48v battery bank to 3 new 280ah EVE batteries. Connecting batteries that are not identical is usually a recipe for disaster.

Is this what you are thinking of doing? What "48v batteries" are you going to connect in parallel?
I currently work at 24v in lead acid I do not plan to use these batteries at all.

what I have in mind is to buy 16 x 3 modules of 280ah and work in parallel the 3 modules.

what happens is that i don't know what bms to use that allows me to put it in parallel.
 

danelo616

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I use the 4s 12v Overkill Solar BMS to parallel my two 280Ah LiFePO4 batteries. Works well, no problem. Connecting in series is more of an issue than parallel.

thanks!


I have 12Kw of solar panel.

I would like to use 3-4 of them for even 6 in the future 10 months from now.

1º if i decide for the overkill can i use this configuration ?

2º The overkill if at any time any is damaged and from 3 I stay in 2 or even in 1 all the solar power would pass through 1 only?

3º How many years can i expect this bms to work on my batteries? 3 - 5 - 10 years?

4º Is there any way to monitor the cells by wifi? because going and connecting the bluetooth is not very comfortable and not always easy.

I've seen that they have a bluetooth connection and can you send that information through the wifi and access it from anywhere?
 
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HRTKD

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thanks!


I have 12Kw of solar panel.

I would like to use 3-4 of them for even 6 in the future 10 months from now.

1º if i decide for the overkill can i use this configuration ?

2º The overkill if at any time any is damaged and from 3 I stay in 2 or even in 1 all the solar power would pass through 1 only?

3º How many years can i expect this bms to work on my batteries? 3 - 5 - 10 years?

4º Is there any way to monitor the cells by wifi? because going and connecting the bluetooth is not very comfortable and not always easy.

I've seen that they have a bluetooth connection and can you send that information through the wifi and access it from anywhere?

Parallel as many as you want. However. I am not connecting the batteries like one would normally see with lead acid batteries. There are no wires directly between the batteries. Instead, each battery connects to set of common bus bars, where all my other connections (loads, solar charge controller, AC-DC converter, etc) are made.

Yes, if one battery goes offline, the remaining batteries take on the the load/charge.

I'm expecting to get 10 years out of my battery bank. I suspect that before that timeframe, the technology will have evolved enough to tempt me to upgraded.

No WiFi monitoring of the BMS. I do have a Victron BMV-712 that provides an overall status of the system. However, that is bluetooth also. If I don't want to connect bluetooth, I simply look at the BMV-712's display panel on the wall.
 

danelo616

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Parallel as many as you want. However. I am not connecting the batteries like one would normally see with lead acid batteries. There are no wires directly between the batteries. Instead, each battery connects to set of common bus bars, where all my other connections (loads, solar charge controller, AC-DC converter, etc) are made.

Yes, if one battery goes offline, the remaining batteries take on the the load/charge.

I'm expecting to get 10 years out of my battery bank. I suspect that before that timeframe, the technology will have evolved enough to tempt me to upgraded.

No WiFi monitoring of the BMS. I do have a Victron BMV-712 that provides an overall status of the system. However, that is bluetooth also. If I don't want to connect bluetooth, I simply look at the BMV-712's display panel on the wall.
Of course, I understand that it would still work because it is in parallel but it would swallow 12 kw of solar panel or it would know how to manage it to protect itself or it would damage the BMS?

as I understand the BMS could with 5Kw of solar panel at 48v = 100Ah x 48v
 

HRTKD

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The 280Ah LiFePO4 batteries are good with a .5C charge rate. That's 140 amps. If your charge controller is rated for less than that, you'll be fine.

My 560Ah LiFePO4 battery bank is over designed. I could get by with just one of the 280Ah batteries, but I chose to go with two for longevity (long periods of discharge, not short period of high discharge). If I knew one of my batteries was down I would throttle back my usage.
 

danelo616

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Do you know what would happen with the MppT charge controller if the solar overkill BMS cuts the battery output current for any reason?

I have 3 outback FM 80 and if you disconnect the battery while there is sun it dies... I have already had one at the beginning that I disconnected to clean the battery terminals and goodbye FM80.
 

HRTKD

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I have 3 outback FM 80 and if you disconnect the battery while there is sun it dies... I have already had one at the beginning that I disconnected to clean the battery terminals and goodbye FM80.

Disconnecting the battery (pulling the cable off of it) and disabling the charge circuit (due to a full battery) are to very different things.
 

danelo616

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What about low battery cut-off? It can happen even if you put the inverter to cut-off voltage and wake up in the morning and the MPPT tries to charge and can not because the batteries are disconnected by low battery cut-off.


I still say nonsense because I don't know how this bms works and what I can really do with it and how reliable it is.
Disconnecting the battery (pulling the cable off of it) and disabling the charge circuit (due to a full battery) are to very different things.
 

HRTKD

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What about low battery cut-off? It can happen even if you put the inverter to cut-off voltage and wake up in the morning and the MPPT tries to charge and can not because the batteries are disconnected by low battery cut-off.


I still say nonsense because I don't know how this bms works and what I can really do with it and how reliable it is.

Low Voltage Disconnect is certainly going to cut the solar charge controller out of the circuit. However, if the LVD happens, how likely is it that your solar charge controller is actively trying to charge the battery? If the BMS turned off the discharge circuit in the middle of the night, the solar charge controller won't even be on when the sun comes up.

There is a thread on the forum, started by Will Prowse, in which he posted that he couldn't kill his solar charge controllers. See if you can find it.
 

HRTKD

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There is a thread on the forum, started by Will Prowse, in which he posted that he couldn't kill his solar charge controllers. See if you can find it.

Here is the thread. It's hard to search for because Will misspelled "destroy".

 

danelo616

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Here is the thread. It's hard to search for because Will misspelled "destroy".

thank you very much
 
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