Solar/AGM Charger-Converter/ Victron Li Charger....All together????

[Randyretired]

3 minutes ago, oldjohnt said:

Until Randy arrives check out this link that will tell you more then you need to know about how best to connect multiple batteries in order to achieve balance so each receives or delivers equal charging and load current. Most aren't aware of the subtle differences and of course its best if EACH battery gets charged the same and delivers the same current into the load. NOTE sure it still works and there are a gazillion wired in parallel in simple straight ladder that work fine, but its good if EACH worked the same WELL DUH..  

 Of course, + to + and - to - and AGM or Lithium or Wet Flooded Lead Acid would still be the same as far as how to connect multiple batteries 

 See if the experts agree or differ from the Smart Gauge approach as how to achieve the best balance, I tend to agree with their approach but that's just me and others may disagree which is to be expected. Of course, subject to how wired and the size,, length,, and resistance of the connecting cables matters and the differences in connection methods may be small or insignificant  BUT THIS IS INFORMATION to take or leave as one pleases even if there's little difference I would prefer that EACH battery in parallel works the same. Thats my story n Ima stickin to it regardless lol . 

http://www.smartgauge.co.uk/batt_con.html

John T

 

Hi John,  The voltage curve on LFP rise very fast when these batteries reach 100% SOC.  When the battery is fully charged the internal voltage will equal the charging voltage (within parameters) and the current will stop.  So if the battery charger holds the voltage steady all batteries will become equal.  That is the way many people top balance the cells before they are arranged to make a battery.  Of course if the batteries have way different SOC then it might take many cycles to even out.  I guess I am saying they need to be close but .05v depends on the SOC and how long bulk charging is set for.

[oldjohnt]

9 minutes ago, Randyretired said:

In my fooling around parallel batteries that are pretty close will balance themselves.  Certainly the first time they are fully charged

AMEN if the cable that connects the two batteries in parallel is low resistance (Big and short) they pretty well have to balance.

John T

[Randyretired]

3 minutes ago, oldjohnt said:

Randy my experience and (old engineers) understanding of Li is similar. My Lith battery BMS will prevent overcharging, disconnect before the SOC becomes excessively low, and prevent low temp charging in case my Smart Lith charger fails to do parts of its job and charging algorithm. Also the resistance of Lith is such that they can accept high charging current in order to achieve 100% SOC faster then Lead Acid. For example, one reason I ordered a smart Lithium DC to DC charger to allow my engines alternator to deliver a certain degree of charging to my Li house batteries (Low resistance) is that if I connected my engines alternator direct to them they could draw excess current and over tax the alternator unless its has protection. 

As always fun sparky chatting with you

John T Too long retired n rusty EE but still enjoy the topic

John, Most but not all lithium batteries are equipped with a BMS like you said and most but not all will limit charging by disconnecting the battery.  LFP will take about whatever current you throw at it but if it is not controlled the battery will overheat.  When batteries are built for fast charging they usually have a means to control the heat.  I don't remember for sure but think Telsa uses liquid to cool some of their batteries.