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stevew avatar image
stevew asked

Victron LiPo Batteries w/ External BMS - Discharge Rate ??

Greetings from Southern California and THANK YOU for all of the expertise shared here.

I‘ve acquired two (not brand new) Victron 160ah LiPo batteries. They appear to be in fine shape - the cells all display the exact same voltage value.

I‘m curious / perplexed about discharge rates. Other LiPo batteries that I’ve researched have output current limited by their BMS - I don’t find such a feature with any of the Victron external BMS options.

Is this over-current-draw protection provided by fuses on the positive side of the batteries ??

I’m aware of the battery protect devices and their ability to power off a load with a ve.bus.bms connection… but these devices are ‘not allowed” between the battery bank and an inverter. It appears that only the multiplex inverter/charger accepts this remote off signal.

And this signal originates from cell imbalance - not from over current draw… ??

I’m also aware of the Orion Smart DC-DC charger and its remote on/off control.

And again - this signal originates from cell imbalance - not from (incoming) current.

Might there be any other chargers, solar chargers, or inverters that integrate with the ve.bus.bms ?? Or even better - directly with the BMS 3-wire circuitry ??

And any BMS features related to current ??

Thanks again,

Steve W


BMS
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2 Answers
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pwfarnell answered ·

You need a mindset change for the Victron Smart batteries regarding current protection. Yes you need fusing to protect against short circuits but not overload. The 160Ah batteries that you have a peak discharge of 320A each, so potentially 640A if you connect them in parallel. In lithium batteries with built in BMS it is the BMS that has the lower current limit not the lithium cells sand the cut off is to prevent the BMS from being overloaded. Look at many suppliers with a range of batteries from 100Ah to 400Ah, all will have a 200A max rating because they all use the same BMS which is silly when you consider things. The victron set up uses the BMS to control charge or discharge sources direct or via battery protect modules so you can tailor these better. In terms of devices, I suggest you read the VE BUS BMS mk2 manual as this has many examples of how to control things like the victron MPPT, inverter etc.

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stevew answered ·

Thank You pwfarnell -

A change of mindset is an accurate description !!

I didn’t realize that that current protection was to protect the BMS - I always thought that it was to protect the cells. And I often wondered why it was so low - especially for higher capacity (AH) batteries. Exactly as you stated.

I’ve been reading plenty of manuals - I’ll be sure to include the VE BUS BMS mk2 in the list.

Along with the batteries acquisition - i got a VE BUS BMS version 1. Any major changes to version 2 ?? Please DISREGARD this question. I found the table / list of differences in the V2 manual.

Thanks again,SW


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