Using a VSR with lithium batteries

PluckaPlucka Posts: 61Registered Users ✭✭
What do I need to know using a VSR with lithium batteries ? Should a Lithium setup be earthed to the chassis - If so how-- Mine aren't. I had the VSR being used when I was on lead acid batteries but wasn't sure I should use it with lithium.

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  • mike95490mike95490 Posts: 7,969Solar Expert ✭✭✭✭
    What are you calling a VSR ?
    Li batteries need both a High Voltage Disconnect and a Low Voltage Disconnect.  Your BMS (Battery Management System) should incorporate these.
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  • BB.BB. Posts: 28,085Super Moderators, Administrators admin
    VSR = Voltage Sensitive Relay?

    Battery bank grounding usually depends on other things (type of AC inverter, if DC power system B or negative grounding, etc.).

    By itself, Li Ion does not really change/affect the general grounding questions/solutions.

    Normally, for a typical power system, negative grounding of the battery bank to cold water pipe, "green wire safety ground common", vehicle chassis (if car, RV, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PluckaPlucka Posts: 61Registered Users ✭✭
    edited July 2 #4
    VSR is a voltage switching relay.
  • BB.BB. Posts: 28,085Super Moderators, Administrators admin
    Do you have a link to the VSR you wish to use?

    Li Ion batteries... Need to know the chemistry and min/max voltage for the cell and battery bank. Chemistry is important... LiFePO4 (lithium iron phosphate) and similar batteries are a bit less energy dense but much less likely to catch fire.

    Physial building of battery packs... The larger cell types can be strapped together to help hold their shape.

    If you have parallel cells--How are you going to series/parallel connect them. Parallel single cells, then series connect them (only one "measurement point for BMS per group of paralleled cells), etc...

    A "good" BMS measures per cell voltage and some can bypass charging current around a full cell to allow the rest of the cells in series to continue charging (Balance charging, or sort of the Lead Acid battery equivalent of equalizing charging).

    If you are using smaller cells, there are cells that have their own battery monitor (cut out if overcharged or over discharged)...

    Li Ion is quite a large range of subjects, and if done wrong can be expensive (killed cells or explosions/fires for some chemistries).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PluckaPlucka Posts: 61Registered Users ✭✭
    Bought lithium battery charger dc to dc  to run off standby battery in engine bay.
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