Exploring battery boost options (DC Step UP, Fan Switch)

[kuririkura]

Hi All,

Sorry for this stupid question, but anyone here using a DC-DC converter?
Can share the experience?

My current set up:
Controller 48v, 1000 watt (I believe usually the maximum is 63V capacitor)
Battery pack 48v (54.6V at full)

Since the voltage will degraded along with the capacity/load.
I'm thinking of using this DC-DC converter between battery and controller, so my voltage will always be stable at 60V and not depends on battery voltage, so i always have constant top speed and torque
https://www.amazon.com/Voltage-Converter-DROK-Regulator-Transformer/dp/B076TTBKFG

What do you guys think about it?
I know some other have asking same question, but my target voltage gap is not that big, and this item says can achieve up to 97% efficiency (I also will add some fans)

Specs:
DROK 1500W Boost Voltage Converter

Parameters:
Module type: non-isolated step-up module (BOOST)
Input voltage range: DC 10V~60V
Input current: 31~60V input voltage, maximum current 25A
Output voltage: 12~90V continuously adjustable (default 19V)
Output current: 20A MAX, more than 15A please enhance heat dissipation
Constant current range: 0.8~20A (±0.3A)
Temperature: -40~ + 85℃(if the ambient temperature is too high, please enhance heat dissipation)
Operating frequency: 150 KHz
Conversion efficiency: 92% ~ 97%
Protection: input over-current protection, battery low voltage protection, input reverse polarity protection, short circuit protection
Installation: 4 x 3 mm screw holes
Module size(L*W*H): 130 x 52 x 85 mm

 

[amberwolf]

See wturber's thread:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=90369
might be others

 

[kuririkura]

See wturber's thread:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=90369
might be others

Thanks, no wonder I couldn't find it, should be looking for "boost" and not step up.
But after reading the whole thread, seem not a bad idea to use this "booster"
In general I assume as long as the voltage gap not to huge and the batteries able to provide enough amps, the input capacitor still have enough time to charge the output capacitors, so i won't get the "cut off" right?

or do you have any advice on which brand that having much bigger input capacitors bank?

 

[troypi]

HI,

I don't think you'll gain anything using a step up booster in your case. Boosters work at constant energy (almost) meaning that the input energy will be equal to the output energy. So if you input a certain voltage with a certain amperage you will have an output with a higher voltage but less amps.

I have been using a step up booster for a while now but in my case i am using a 24V battery to run a 36V controller, this works fine but I lose amperage in the process.
My input = 24V x 15A = 360W
My output = 360W @36V --> 10A

Also remember that you get speed from voltage and torque with amps so you won't have max speed and torque even if your booster output's 60V all the time.

 

[john61ct]

Plus the actual measured efficiency hardly ever comes close to the rated number published

so the reduction in range, or longevity impact of deeper discharge each run

will be much greater that most would think

 

[billvon]

Sorry for this stupid question, but anyone here using a DC-DC converter?
Can share the experience?

My current set up:
Controller 48v, 1000 watt (I believe usually the maximum is 63V capacitor)
Battery pack 48v (54.6V at full)

Since the voltage will degraded along with the capacity/load.
I'm thinking of using this DC-DC converter between battery and controller, so my voltage will always be stable at 60V and not depends on battery voltage, so i always have constant top speed and torque

In general a bad idea.

What limits torque is primarily battery current, not voltage. And a boost converter requires MORE current from your battery.

Example:

Assume your battery pack max current is 20 amps. Let's say you are running at 1000 watts at 60 volts. Your motor is therefore getting a max of 16.6 amps at wide open throttle. Your battery, meanwhile, sags to 45 volts under the load. The boost is now drawing 24.7 amps from your battery. Your BMS opens the FET to protect the battery and you roll to a stop.

About the only time a boost converter works well is if you have a serious mismatch between motor constant and battery voltage AND your controller cannot do phase advance. In that case it may give you higher speed at the cost of a lot of range (and potential battery shutdowns; see above.) Much better options are:

1) Phase advance controller
2) Higher voltage battery
3) Different wind option for the motor
4) Different wheel size.

 

[john61ct]

So fair to say?

the advantage of voltage boost is a **top speed** increase when high torque is not required

 

[flat tire]

You will LOSE performance doing this.

Get a controller with flux weakening. That will do what you want much better without needing a new battery.

 

[kuririkura]

Also remember that you get speed from voltage and torque with amps so you won't have max speed and torque even if your booster output's 60V all the time.

so the reduction in range, or longevity impact of deeper discharge each run

will be much greater that most would think

About the only time a boost converter works well is if you have a serious mismatch between motor constant and battery voltage AND your controller cannot do phase advance. In that case it may give you higher speed at the cost of a lot of range (and potential battery shutdowns; see above.) Much better options are:

Hi All,
Thanks for the inputs
Sorry I forget to mention

1. My targets is to have top speed whenever I need it, especially when i need to take the "bus line" the bus here is capped at 45kph so if i can get 50kph then I should be "safe"

2. I don't really care about range or battery amps, since my configuration is 13s10p 3C (which can have max 75A peak and range more than enough)
While my target is only 1200 watt @60v @20A output

3. My motor are limited by RPM/volt so the higher the volt the more top speed i can have. It didn't care even if I have lots of current (amps) available, it wont give me more speed. (I've checked it using current meter, at 'stable' top speed it only drag around 10-12A even when the throttle start it can sucks up to 40A)
And the vice versa, when the volt get lower I lose my top speed (back to my requirement number 1, i need to have constant volt)
I have tried it by giving additional 4v and 8v battery pack (1s and 2s) it boost my speed a lot more
(Can reach 52kph with the 4v on gps)


And seems this booster option is more efficient than changing my motor, and my wheel already at max size considering my bike frame

Changing my battery configuration will also not suitable to my needs, even i have enough voltage at full charge, but i wont have "top speed" all the time

 

[billvon]

1. My targets is to have top speed whenever I need it, especially when i need to take the "bus line" the bus here is capped at 45kph so if i can get 50kph then I should be "safe"

2. I don't really care about range or battery amps, since my configuration is 13s10p 3C (which can have max 75A peak and range more than enough)
While my target is only 1200 watt @60v @20A output

3. My motor are limited by RPM/volt so the higher the volt the more top speed i can have. It didn't care even if I have lots of current (amps) available, it wont give me more speed.
And the vice versa, when the volt get lower I lose my top speed (back to my requirement number 1, i need to have constant volt)
I have tried it by giving additional 4v and 8v battery pack (1s and 2s) it boost my speed a lot more

And seems this booster option is more efficient than changing my motor, and my wheel already at max size considering my bike frame

OK. So why not use a controller with phase advance/field weakening? Phaserunner is good to 50A battery current (96A phase current) and will do phase advance.

(You're not likely to get to 50kph with 60V 15A by the way. That boost is only good to 15A without "enhance heat dissipation.")

 

[kuririkura]

OK. So why not use a controller with phase advance/field weakening? Phaserunner is good to 50A battery current (96A phase current) and will do phase advance.

(You're not likely to get to 50kph with 60V 15A by the way. That boost is only good to 15A without "enhance heat dissipation.")

I just check the phaserunner (seems this a controller with built in step up?)
I think it can solve my requirement, but it's too expensive for me. Compare 20-30$ with 295$ solution

I know it only able to reach 15A only (or 20A if input more fan) but seems i'm able to reach my stable top speed with 12A so it still adequate for now (the 60v 20A i mention is only when torque needed at start)
PS: I'm still searching whether there's still more step up with higher amp

 

[john61ct]

Long as you know by going for higher voltage, you're throwing some amps away.

Never heard of $20 controller OMG

 

[billvon]

Never heard of $20 controller

His boost converter is $33.

 

[kuririkura]

Long as you know by going for higher voltage, you're throwing some amps away.

Never heard of $20 controller OMG

His boost converter is $33.

My local seller has it, around 25 USD
He has the 1200 watt version around 20 USD

I just use the amazon as reference since it is in english

DC-DC Boost Converter Step Up Power Supply Modul 1500W 30A via @bukalapak https://www.bukalapak.com/p/elektronik/elektronik-lainnya/13yv7e9-jual-dc-dc-boost-converter-step-up-power-supply-modul-1500w-30a?utm_source=apps

 

[kuririkura]

By the way I'm exploring other options...

Will the diagram below works?
So when I'm in the need of voltage, i just press the 2nd or 3rd button
1st button is normal mode,
0 button is off
2nd button is +4.2V
3rd button is +8.4V

Sorry if this just a stoopid idea

@amberwolf, if i'm not mistaken you looking for some solution to be able press button when needed right?

 

[amberwolf]

Never heard of $20 controller OMG

There's a lot of cheap stuff out there; the catch is the sellers don't really know anything about it, and what you get may not look lke (or have the same specs as) the ad page, since they may just get batches of this and that whenever they restock. Its' been a while since the thread started, so the price went up, but there's a $14.99 Sunwin Controller thread around here somewhere.

But that's not relevant to this thread.

 

[amberwolf]

@amberwolf, if i'm not mistaken you looking for some solution to be able press button when needed right?

Sorry, no idea what you're talking about. :?

The post you got the above from is just this:

See wturber's thread:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=90369
might be others

where I answered your question with a reference to the thread I knew where this type of thing had been done before.