Redpacket said:
Daveyboy said:
A few days ago my Sunkko 709A Spot welder packed up. .... I also tried it on my cooker power supply in the house, which is 50A it turns out. but this just blew the Sunkko fuse in the back.
Sounds like there's a serious short in there, maybe the transformer?
Re the Batrium shunt, the point of having the shunt is to know the battery SoC by tracking current in & out.
I've tested the transformer for short. No short. Definitely something up with the PCB. I've seen some continuity between live in and live out when the power switch is on, but foot pedal not engaged and that's not right at all. I don't know whats causing that though.
Yeah, the Shunt will give me SoC. I get that. I just don't need it. I know when the battery is going flat based on voltage under load and current draw. My aim is to oversize the battery by quite a large margin, so as to only use half the capacity anyway.
Hi Hermit, yes, the 20P design allows the powerwall to go into service sooner than waiting until you have enough cells for 80P for example. It will also be easier to fix problems. I intend to leave the battery online when removing a 20 cell pack for replacement / repair. It would be great to not have to shut it all down for maintenance.
I wouldn't be discarding cells that are <4.1V. My cutoff was 0.5V, which worked well as Opus tends not to register them below 0.5V anyway. Some of my best cells were as low as 2V, but recovered well. I stick them all in the charger and those that don't take a charge well, will top out at about 2V then say they are fully charged. I also remove any heaters. Then let the cells sit for a good month and remove any that are below 4.05V after resting. I don't want that level of self discharge in my wall.
I considered using XT60 or XT90 connectors, but finally settled on ring terminals. Easier to install with just a crimper, plus you don't put much strain on the cables when trying to disconnect the pack.
I haven't fused the packs, no. I'm thinking about it. I have cell level fuses, but yes, additional fuses are a good idea as Fullycharged pointed out to me recently.
My offer to lend you spot welder is subject to me fixing the thing first too. I need to finish my packs, and I can't get the welder working. Its going to be either a new (same) PCB, or for around the same money, go with an arduino controller. Offer still stands to borrow my 5x Opus chargers though if you want to speed up testing. I'm not processing any more laptop packs for a few months now.