Yeah I get it. Without the Precharge resistor the BMS may take a hammering on startup. And yes just like when you asked me to pull my system down, I know that it is a royal pain to mess around with a perfectly working system to make a test.
Same here.
Right now the 24V unit is not being used for anything. I personally despise 24V.
The inrush trips the BMS over current protection. It could be that the precharge duration is too short, and the caps are not getting fully charged. Or the precharge isn't working at all. Hard to say without evidence.
That is most likely the scenario but I have not seen the evidence to support that as well. Could someone just put a multimeter on the input and see what the voltage rises to?
All potential issues that Signature never addressed or even mentioned in their video. In fact, all they really do is place blame on people who have undersized their battery to their inverter. I understand that's a real problem and something to think about. However, one discover lithium, one SOK, one LL model all started my inverter with no issue where the lifepower failed so that certainly wasn't the issue in my case. That video is little more than a red herring imo.
One observation i was able to make while dealing with this issue was to measure the voltage at turn on. The voltage immediately dropped from 52.9 to the mid thirties and hovered there for about 3 or 4 seconds before the battery would go into alarm mode. This happened every time, no matter what turn on procedure i used.
Very interesting. Seems like precharge worked to get voltage at inverter up to battery voltage but then when turning on, either the precharge did not turn off and current is still going through 10ohm resistor, dropping the voltage or some current limiter or fet is partially turned on and causing a high voltage drop. I’m wondering if you had a clamp meter to measure the current during those 3-4 seconds when the voltage dropped to 3x V.
That's exactly what was proposed by several smart members here. Essentially the pre-charge duration was too long and that caused the voltage drop, which put the inverter into a low voltage state (i set lvco as low as inverter would allow) and the battery going into alarm.
have a scope and everything but I would need a constant current sink of like 1A and if the resistor is 10ohms, I should see a 10V drop for a period before the precharge resistor is turned off. The buzzing sound looks like activation and deactivation which I can’t explain what is happening there.
Just put it across the terminals at the battery or Inverter and set it for a 2 second/Div Sweep and the Voltage to 10V Division. You should see a slow rise up of the voltage and then something will happen that indicates what the problem is. I suspect it will reach maybe 30V and then quickly jump up to 52V when the BMS engages.
Yes, someone with a problem should do this. I don’t have an issue but maybe I would like to see what the clicking is all about.
Pre-charge function is for the battery. To save it from the surge of charging the capacitor in the inverter.The battery BMS is being affected without the pre-charge procedure? I thought it's the inverter that should be protected so pre-charge is needed?
Or I am just being confused after 18+ pages
Can you post the email thread here?
What voltages are you charging them at and what kind of measurements are you getting on the Individual cells?
