Help! New Swytch Max kit that loses most of its power after 15km on a normal ride

[Ghost1951]

For now, my wife is able to do her 20km run with a 1/5 PAS but I would be curious to know why I get fluctuating voltage from the MAX battery and if that could be an issue (or if I'm not the one doing something wrong when measuring it).

If your battery has a capacity of 180 watt hours, that works out at 12.4 watt hours per mile.

Riding my Argos folder in its mid setting, supplying power up to 11.5 mph, in up and down terrain uses 12.2 watt hours per mile. If I ride it with assistance to 15.4 miles an hour I use 16.4 watt hours per mile.

The weather is colder now than it was when you formed an opinion of how far it should go. Lower capacity in colder weather is to be expected and is absolutely normal. I would stop worrying.

However - if you MUST investigate further, there is a tread on this forum in which Cisco Man explores the purpose of the pins. That thread suggests that the pins you investigated are the charging port pins and so does their behaviour in your video. They are isolated from the battery by BMS circuitry and do not show the true battery voltage - which as you say, would never vary like the multi meter shows in your video.

Cisco man explains how to switch on the outer two pins which he says are the battery output ones. He also issues a warning about messing about with the battery and makes clear that you do so at your own risk.

Here -

Swytch Pro/Max yellow battery connector secrets revealed?

Disclaimer - you mess around with these battery packs at your own risk - what follows are my own observations that may or may not be fact! On the yellow connector on the battery: - the two centre connections (O and D shaped) are charging input only. There is circuitry before the actual battery...

www.pedelecs.co.uk

 

[Az.]

If I were you I would rather explore how to get better and bigger battery.

 

[matthewslack]

Anything electrical, 'use a fuse'!

If you include a low value fuse in your 2 to 5 connection, the fuse will blow before any more serious trouble.

 

[Nealh]

36v/5ah is small for a battery 20 miles range may be possible but would require flat terrain, low powerPAS setting of approx max 2a and plenty of rider input over 15.5mph.
Weather would need to be benign with little or no wind and ambient temperature in double figures.
A cycle fit rider should be able to manage 7- 10kwh per mile so can theoretically manage 18-20 miles.

Pretty much all stated ranges for X bike this or that is with minmal power and good rider input , problem is if they used a rider to calculate range they wouldn't be your average casual cyclist.

My smallest battery is 6ah/44v so 264wh , I have managed 32 miles without hitting lvc. One needs to be quite enthusiastic and be frugal with the power.

 

[saneagle]

iirc all pins are used: discharge is across 1-6 in your picture (not 2-5), and its activated only when 2-5 is shorted. That said, do not short anything without verifying the above as I'm writing from memory.

You measure the voltage on the charge port, not the discharge one, since they are connected directly to the battery. Your video isn't clear, but it doesn't look like you used both the charge connector pins, which are the middle two. You should measure immediately after charging to show the condition of the battery. You don't need to short any pins. There is no danger.

The outer pairs of pins work as a switch to switch on the output when connected to the battery holder. They're not needed for charging nor measuring on the charge port.

 

[jamesporritt]

Pretty much all stated ranges for X bike this or that is with minmal power and good rider input , problem is if they used a rider to calculate range they wouldn't be your average casual cyclist.

They don't say it's on planet Earth or where on planet Earth.

https://en.wikipedia.org/wiki/Tibetan_Plateau

 

[Ghost1951]

You measure the voltage on the charge port, not the discharge one, since they are connected directly to the battery. Your video isn't clear, but it doesn't look like you used both the charge connector pins, which are the middle two. You should measure immediately after charging to show the condition of the battery. You don't need to short any pins. There is no danger.

The outer pairs of pins work as a switch to switch on the output when connected to the battery holder. They're not needed for charging nor measuring on the charge port.

Why don't you read the voltage on the discharge / output port when it is turned on? I have always done that, and it is also the way that any voltage measurement on the LCD measures the voltage.

 

[saneagle]

Why don't you read the voltage on the discharge / output port when it is turned on? I have always done that, and it is also the way that any voltage measurement on the LCD measures the voltage.

Because it's not turned on until you connect the battery to its holder, and when it's connected to the holder, you can't get your probes onto the terminals.