Recent content by sprint2freedom

https://diysolarforum.com/threads/do-not-discard-a-dead-victron-mppt-100-30-or-its-kind.23289/

I'd second the suggestion for an aluminum heat spreader. To reliably read the internal temperature of the battery, you can epoxy the thermistor inside an (uncrimped) lug and add it to one of the battery terminals. Don't trust tape.. if the thermistor falls off it may read as cold while the...

Hard to see with the leaves there but it's maybe a GFCI?

Filling the center hole with caulk is another method to quiet (but not totally silence) those buzzers, and is a little more effective than tape.

The reason for my comment was prior experience with PLA-printed parts melting/warping in a hot car. Reprinted in ABS and those parts held up fine. YMMV

Looks great but I would not personally be comfortable with the choice of PLA. If a modest amount of heat is generated by a bad connection and/or being in a hot vehicle, those parts could start to warp or even liquify. ABS seems like a better material for this application.

Shouldn't it be possible to at least partially correct the power factor with an appropriately selected capacitor? e.g. https://electrical.theiet.org/media/1687/power-factor-correction-pfc.pdf

You probably want DDP, not DAP

IMHO, throw those alligator clips in the trash. The contacts are the flat, round surfaces on the battery itself. The stud is just there to provide a means of clamping something (e.g. a lug) against the contacts. If you care at all about the quality of a measurement you're taking, you ought to...

This looks like a bad connection to me.. A poor connection is exactly what would cause it drop out like that and then pop right back up to where it was before as the connection improves (through subtle thermal expansion/contraction), especially if you are using a 2-wire setup as opposed to...

I believe you are looking at the specs for LTO, not LFP. The relevant table is here (from Heltec's web site):

The way around this is to use a 4-wire load tester, for example the newest version of the Atorch DL24. Voltage is measured by a dedicated pair of sense wires connected directly to the battery terminals (that carry essentially no current and thus have almost no voltage drop), and current is...

P = I ^2 * R Getting the same power at 12 volts vs 48 volts involves 4 times the amperage, and power lost to resistance heating is a factor of 16 times higher. Everything is going to run much hotter, cables yes but especially terminals. It's difficult to properly implement protection with such...

During my capacity testing, I found that a poor connection at a terminal can cause heat to be produced at the terminal which is then conducted into the cell warming the whole case. Perhaps this is what occurred in the cell that failed and it then overheated the cell. It's not possible to...

Tell us about your charge termination parameters. Did you capacity test these cells prior to putting them into service as a pack?