Endless Sphere

Since you have two identical batteries, just set them up to swap easily? Better (safer simpler easier) to charge one pack at a time but if you really want to parallel them, do so at the cell/group level 1S so whatever you are using to keep the packs in balance can monitor at that level to prevent an...

Get a charger (or PSU, or DC-DC converter) that allows you to custom-adjust both maximum setpoints, CV and CC current.

If your source is cheap grid power, don't need to be too concerned about efficiency.

Auto-termination is IMO much more important, safety first.

LTO chemistry is an exception, 10min charge NP

But much lower energy density, for a low speed dump truck or big bus maybe

Current **limiting** is not a function of any BMS I know of. Most don't even have current protection, they just give a rating - usually too optimistic - and release the magic smoke if current is allowed to go too high. Charging very fast can greatly reduce pack lifespan, especially in cool weather. ...

at a given voltage, drawing at a lower C-rate results in higher Ah capacity regardless of resistance, heating losses etc A 0.1C rate will show higher capacity than a 0.3C rate. So, swapping out three 30Ah batteries sequentially gives less range than one 90Ah battery See Peukert's Law Unless maybe if...

Apparently the welding circuitry does not limit current drawn, I've read about batteries delivering "too much" power? I was hoping (if that is the case) there might be guidelines for getting to "as much as possible without going over". Or maybe going to big lead units would be be...

So what are the pack specs to get top output power?

Voltage range?

Actual peak vs continuous maximum amps drawn?

What are the specs that might get to be "too much"?

Would a pack tested capable of true 25C continuous be better or worse than one that can only handle 15C?

yes all DC circuits should have a Common Reference, tied in with Negative Returns

Aha I thought you meant electrical isolation, like diodes or circuit protection between groups

rather than physical protection, insulation

But why?

How many watts for how long are needed?

Even a low Ah pack will deliver much more power than you could with a reasonable PSU

and if warm, then fully recharge in 10min or so, without losing too much lifespan.

So two more normal PSU/chargers, two packs, swapped out. . .

If by group you mean (as is standard) cells in parallel only, at the "lowest" level in the layout at 1S voltage, then those (cell) groups connected together to create one series string then No there is no current flow possible between those groups, they do not affect each other even if at ...

Think of each section (sub pack?) involving strips, whether soldered or welded as a rigid monolithic block, no flexing stresses allowed at all. Then the flexible wiring with zero solder involved, connecting between those blocks, their connection ends well supported so the crimped terminations are (o...

You'll get longer range (higher actual Ah capacity) by paralleling for the whole ride.

Better current flow, less voltage sag and longer lifespan too.

I am not talking about strip, at all. I am saying, where you are using the wire I spec'd to accommodate flexing, abstain from touching that wire with any solder. If you are connecting wire to strip, then do so via solid connectors with a wide contact surface area crimped to the wire, perhaps quality...

another http://www.mekacademy.com

No solder terminations, use crimp connections.

Again, no flexing until you get well into the insulated wire body.

LFP is only rarely used for EVs. Much longer lifespan, thus better value by far much safer, thermal runaway (boom, fire) less likely but also lower energy density, thus slower performance and/or lower range. Tesla using it in the China-produced models only. Otherwise the 3.6 - 3.7Vnominal chemistrie...

Fine-stranded tinned wiring, ideally marine grade UL 1426 rated (BC-5W2 usually 105°C)

No movement at terminations obviously, just leave slack in the length portion.

There is a huge difference between "rough" discharging packs for storage and needing precise CC regulation for accurate capacity testing of individual cells. The purpose of using chargers like FMA PL and 4010 is to get the latter control functionality. Apparently at that 2-4V discharge ran...

spinningmagnets wrote: generic sine wave 500W for $80

Wow lots of flexibility there!

Apparently can order 72V input and output 240V 50hz

EV packs for multiple uses, off grid living, get away from inefficient USA appliances.

A more stable imports source would be ideal, not sure if SPIPOWER is the canonical branding

Yes as stated, the only grid connection being your bank charger, makes for a very simple, inexpensive and safe design. No aircon obviously. There is no need for any 3-way switch, just power off your mains charger and there is no input from the grid. The SC will always be active. ______ I also read t...

Some towns/counties have a few Hazmat disposal days per year where they accept most anything

This looks like a good seller?
https://www.ebay.com/itm/313014455885

That's a bit too strong, overstated IMO but yes, this use case is not motivated by too many practical benefits. But getting off the grid completely is IMO a fine goal if you can afford it. I lived that way for decades, but in a place where just connecting to utilities would have cost more than the l...

In my experience asking dealers, they only supply the software and license to paying customers, either buying the hardware or retaining them on an annual service contract. My impression was the goal is to reduce the value of secondhand units in circulation. I don't understand why there aren't freela...