I have a smart lithium battery and 100/30 mppt, 500 wott pannle and dc to dc charger. My. Mppt also gose off bulk charge and moves to asbestos / float before my battery even reaches 50% is there reason why?
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Your MPPT is getting up to the absorption voltage of 14.2V. As your battery is not getting to 100% I expect that you have a high resistance connection between your battery and the MPPT due to the cables being too long or too thin or having a loose connection or you are using the cheap no name thermal breakers that do not work well. Use a multimeter on volts setting when you are charging to check the voltage at each location. Poor connection could be in positive or negative.
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The SOC on the Fogstar BMS is not the best.
It ignores currents under 1.5amps so I’m my case with only a 130w panel there is often a charge going in that just doesn’t register. Similarly my system has a quiescent current of 0.56amps which never registers. That’s 13.5Ah a day it never sees. As I have a smart shunt fitted I ignore the BMS and rely on the shunt
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Thanks guys that really helpful give me somewhere to go and look and have an investigation
Sorry for slow reply but of update I’ve got the one and done fuses type in photo and got the multimeter out the MPPT side is showing a higher voltage than the battery side still can’t work out why after and checking al my cables
When charging what voltages do you get on the MPPT terminals and battery terminals. Set your voltmeter to a lower range, say 0-2V and put the + lead on the MPPT + battery terminal and the other lead on the battery + terminal to see the voltage drop along the + wiring. Then move the + lead from the MPPT to the fuse terminal on the MPPT side, then the fuse terminal on the battery side. This is the volt drop on the + lead and can tell you where the volt drop is occurring. Do the same for the - lead but this time voltmeter + lead goes to battery - terminal and the other lead goes to the MPPT - battery terminal. Basic trouble shooting technique. It can be as simple as some insulation caught in a terminal reducing the contact area. Also, what cable size do you have and length between the MPPT and the battery.