kifo Posted September 18 Share Posted September 18 (edited) Good day i would be happy if anyone can point me in the right direction. I am thinking of getting additional lifePo4 batteries but different brand also different BMS can i use a DC Disconnect switch to move from one set of batteries to the other and how do i connect it if possible thank you in advance forgot to mention i have an Axpert 7.5 inverter . Edited September 18 by kifo Quote Link to comment Share on other sites More sharing options...
Greglsh Posted September 19 Share Posted September 19 I may be wrong here, but what I have read is that it would be best to connect each battery to a common busbar(parallel) through a fuse for each battery, then through a "main" fuse to the inverter, you can then control this either using a smart shunt or voltages from the inverter. Just my 2c Quote Link to comment Share on other sites More sharing options...
kifo Posted September 19 Author Share Posted September 19 Remember i am looking to just switch between two different types of lithium battery one is complete wall battery 48v 100ah and other batteries i want to add to my system is 8 12v 100ah where i would put for each inseries and parallel them which owuld make that side 48v 200ah , then i would like to know if i can connect the dc dsiconnect switch to move form set of battery to other thanks. Quote Link to comment Share on other sites More sharing options...
zivva Posted September 21 Share Posted September 21 You can but .... - no problem when you switch OFF one set of batteries - high current flow between sets of batteries if ever you switch one set previously OFF to ON and both set are not exactly at the same voltage when you switch one back ON. Most BMS will consider the high current flow as a short circuit then may turn OFF Any reason you would want to have a disconnect for each set ? Quote Link to comment Share on other sites More sharing options...
kifo Posted September 21 Author Share Posted September 21 May be the correct question is i have one of those 48v wall battery @ 100ah and i am getting 8 12v 100ah i want yo add to my sytem with a 48v hybrid invert rated at 7500w thanks just wondering how to connect all batteries with inverter. Quote Link to comment Share on other sites More sharing options...
zivva Posted September 21 Share Posted September 21 One option among others : Use a busbar with 1 DC switch / MCB / MCCB to disconnect all batteries. Before connecting the batteries, charge them 1 by 1 to a close voltage to avoid large amount of energy transfer when you finally connect them ... Quote Link to comment Share on other sites More sharing options...
kifo Posted September 21 Author Share Posted September 21 Thanks will go with thi sconnection when i am done with project will let you know how it turn out Quote Link to comment Share on other sites More sharing options...
TaliaB Posted September 21 Share Posted September 21 6 hours ago, kifo said: May be the correct question is i have one of those 48v wall battery @ 100ah and i am getting 8 12v 100ah i want yo add to my sytem with a 48v hybrid invert rated at 7500w thanks just wondering how to connect all batteries with inverter. First of all ensure that the 48v wall mount battery is 16 cells and not 15 cell. Then ensure all battery cells are Lifepo4 and not diffrent lithuim chemistries like for eg. NMC. To prepare the 8 x 12v batteries you need to ensure that before connecting them in series they all need to be at the same SOC. To accomplish that connect all 8 in parallel ( 12v 800ah) and charge them to 100% SOC and keep them connected in parallel for 24 hours after charger has been removed. Connect the 8 x 12v batteries according to the diagram below and incorporate 2 x battery balancers to the 2 string battery connection from there parallel the wall mount with thev12v bank. Also the battery balancers for the 2 series strings. kifo 1 Quote Link to comment Share on other sites More sharing options...
kifo Posted September 21 Author Share Posted September 21 do i need a bus bar also to connect everything Quote Link to comment Share on other sites More sharing options...
kifo Posted September 24 Author Share Posted September 24 Ok i am changing configuration will be using four 24v lifepo4 200ah instead what balance should i get for those thanks. Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted September 24 Share Posted September 24 1 hour ago, kifo said: Ok i am changing configuration will be using four 24v lifepo4 200ah instead what balance should i get for those thanks. If I read it correctly you will be using 2 x 24V lifepo4 in series to get 48V and then another 2 in series which you parallel with the 1st 2? Quote Link to comment Share on other sites More sharing options...
kifo Posted September 24 Author Share Posted September 24 Yes exactly so iwould have to 48v which i need to parallel. Quote Link to comment Share on other sites More sharing options...
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