Hi friends,
I just bought an RV with a 150 Ah LiFePo4 service battery, with integrated BMS; I would expand the system, installing an inverter and a couple of 330 Ah Smart LiFePo4 with external Lynx BMS; is it possible to connect, in parallel, the existing battery behind the Lynx ? Is a brand new battery from SuperB and it´s a pity to waste it!
Please support me.
tnx.
Hi Alex,
so, at this point:
how can I insert in the system shown in the attache diagram, a 150Ah battey with integrated BMS (the battery is a SuperB Epsilon):
thanks a lot.
You've correctly made all connections on the first hand draw diagram.
On this second one, just connect the SuperB 150Ah battery to the (+) and (-) bus bars.
But again, no connection between any BMS to Cerbo.
Meaning that on the second diagram, disconnect the Cerbo's VE.Can from the Lynx BMS VE.Can. And neither SuperB BMS... don't connect it to the Cerbo.
Configure the BMSes, if you can do that, and just leave them to handle by themselves what they need to do.
And set into the MultiPlus, for example 56V (3.5*16) and 70A current limit. You will play later with current, based on your needs and how system evolves.
Theoretically it should work but I would not recommend to mix different brands of batteries with different BMS'.
I would recommend to sell the existing 150Ah battery or use it for another project.
Why? Can you please give me more infos?
I think that the legend that the batteries from the same company, same rate are 100% identical is a fake! Is enough 1 gram of Lithium more that the batteries are different.
Help.
Why do you ask if you already know it better?
You asked for recommendations and I wrote that I (!) would not recommend it.
You can still do what ever you think is the best for your system.
Hi @listortolui
You need to think a little outside of the box. It will work on certain conditions.
You have there two BMSes, each with its battery. Each BMS will try to do its job, for its battery.
But the batteries will almost never be in the same state and request the same charging and discharging conditions, because they have different capacities.
So idea is to NOT CONNECT neither BMS to the Cerbo (or similar in your system) and just configure your inverter / charger to supply the correct voltage and max current you are feeling comfortable with and let the BMSes to do their job.
I know, the urge to connect a BMS or both to the system is great, in order to see what's happening, but you can't connect any BMS to the system, because the BMS will impose its needs to the system, needs which sometimes will contradict the other BMS needs.
Once you set the correct voltage and current, the Kirchhoff's laws will always apply.
For example, set the voltage to the lower voltage that any of those two batteries are requested.
As per current, set a current that all devices are comfortable with, Multiplus and two batteries, because the batteries' BMS will manage internally the current and anyhow, the batteries can handle a lot more than the Multiplus can supply.
Of course, the batteries should be of same topology, meaning the same number of cells per string, in other words, the same voltage. You can't combine a 15S with a 16S.
Have fun,
Alex
