Deligreen / QNBBM, Interesting Formula

From Deligreen / QNBBM

Good maker right? I see their BMSs, and balancers very widely mentioned in build threads.

Specs are reasonably conservative, don't need to pay for 200A version if current will only reach 50A?

Decent build quality, don't fail in use any more than others?

Are there other specific brands you consider better? as in reliable, more robust? Voltage setpoint adjustability in protective functions would be great. . .

Links to Ali vendor listings would be appreciated.

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In the Deligreen description page they post a "Tip" formula

Motor Watts peak power ÷ (pack Voltage *2) = max motor Amps

Seems accurate or is doubling an overestimate? How is it useful?

Does it mean the controller outputs double its input voltage?

Or just building in some margin factor for the ampacity of the BMS selected?

Not sure. It's possibly a typo anyway, as (packvoltage * 2) halves, not doubles the calculated current.

It might be trying to work out maximum typical phase current (rather than battery current). The ratio is often 2:1 with phase current being limited to 2x battery current.

I think they are trying to say that peak phase current (motor amps) is roughly double peak battery current (Peak power inputs / pack voltage). Many here on the forum set their phase current limit to battery current limit ratio at 2.5:1 . They are typically trying to compensate for an under-powered system to achieve more acceleration, but that high a ratio leads to overly sensitive throttles and motor heat problems. I run pretty extreme power, as high as 31kw peak input, and I've been happier with phase/battery limit ratios at 1.5:1 or lower for an easier to control high powered ebike as well as help make the system more dependable.

Excellent, thanks.

How about feedback on that maker as far as BMSs go?

Suggestions for better?

john61ct said:

From Deligreen / QNBBM

Good maker right? I see their BMSs, and balancers very widely mentioned in build threads.

Click to expand...

Neither "deligreen" nor "QNBBM" come up in a search except for this thread and a couple of posts in other threads. Definitely not what I would call "widely mentioned". :? At least not on Endless Sphere.

Perhaps there is some other name for them used in the posts you've found, that you don't list?

I mean when people link to the unit they buy, that is the maker that comes up a fair proportion of the time.

Just trying to get a start scratching the surface narrowing the choices down to a reasonable number.

There are dozens if not hundreds of Ali vendors it seems often selling gear from the same list of makers.

Not saying that latter list is a small one either.

This Deligreen 80a 14s just exploded while charging
i heard a boom and went out to my porch to find the battery on fire
After putting out the fire i found out all the cells were ok
the explosion and fire started from this bms

lucky it happened in the evening the same it could happen while the family is sleeping

Many here will recommend never charge a battery unattended.