Recent content by Philtao

The BMS knows the battery configuration so it corrects cell IR for the number of cells in parallel. But in the manual calculation I did earlier I did not and you are right: the individual cell IR is 0.50 mOhm (twice nominal value!). The difference is that the BMS only calculates IR under load...

Thank you all for your input. So after all my cells may not be as bad as I thought :) I'll keep investigating on the cell connection side... if / when the event happens again. I will measure cell voltage at the terminals as well as the terminal temperature. Then I will clean and redo the...

Yes balancing is independent from the BMS protection and energy management functions. But when the event occurred the cell voltage was too low to allow balancing. Just did that with 110 A load. Measured from cell terminal top to cell terminal top using a Blue Sea multimeter (1mV is the limit...

I did that on the first occurrence (a few months ago) and DMM reading were the same as reported by the BMS... but I did not record the measures in my log book :( If it happens again that will be the first thing I do and record data for reference.

Max load is the boiler with 110A load. All cells react the same way. Before load: 8.35 A charge - cell voltage from 3.280V to 3.289V (9 mV range) 3.5 seconds after applying 106 A load: cell voltage from 3.252V to 3.259V (7 mV range) Which approximate the cell IR between 0.245 and 0.262 mOhm...

Good idea... but that is a lot of work getting the battery out from where it is in the boat. Will do it tomorrow. The first 3 years for that battery was in the tropics (> 30°C) with a very basic BMS that did not control the chargers to stop charge at lower SOC . So I guess there must be some...

Thanks for the suggestion. I have plenty of sense wires in stock so I will replace with a new one.

Thanks @sunshine_eggo and @Skypower for your suggestions - that helps me in my thinking... and come to a conclusion. I use the BMS I have designed and sell: the TAO BMS The condition corrected by itself before I cleaned the connections. I cleaned the connections as, at that time, I did not...

Hi, On my boat I have a 600Ah DIY 12V bank with Winston cells installed 6.5 years ago (cells with sequential serial numbers). The cells are well top balanced and yesterday the voltage for one of the cells dropped suddenly by more than 100mV compared to the other cells... then later came back to...

My understanding is that absorption time exists to compensate the fact that most chargers cannot use the voltage + tail current criteria to stop charging. But some BMS can use those criteria to declare the battery full: minimum battery voltage (I use 13.8V) maximum tail current (I use 0.025C)...

I have been thinking about that for a while from a technical point of view (less on the cost and ease of installation) and this is what I came up with based on my readings and experience as EE. For most (all?) "drop-ins", each battery has its own independent BMS that will disconnect the...

Very good point raised by @Steve_S This is the cause of so many questions I receive like "why the charger goes to float before the battery is full?" In addition you must take into account that this voltage drop (loss) is not constant (proportional to the current)... and that makes it a...

I created that table for my own use, so I thought it might be a good idea to let others benefit from it. I am sure there are many more latching relays on the market and I welcome references I can add to this table. Click here for information on a newly released latching relay driver: TAO...

I had a look at the user manual, but it does not give much information on communication with the outside world. I did not find any mention of CAN bus there is a remote control port (ref 10 on page 4), but no details further! there is a BMS port (ref 14 on page 4), then on page 16 they say...

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