Battery Advice Needed For Middle School Competition

Batteries, Chargers, and Battery Management Systems.
User avatar
DrkAngel
10 GW
10 GW
Posts: 4407
Joined: Wed Dec 15, 2010 11:14 am
Location: Upstate-Western-Southern Tier NY. USA

Re: Battery Advice Needed For Middle School Competition

Post by DrkAngel » Mon Nov 06, 2017 8:25 am

Updated ... refined

1. Motor speed can be varied by voltage.
Effectively, a somewhat equivalent of gearing.
1a.Panels in series or parallel.
4 x 12V panels
12V 1 in series 4 parallel (1s4p) 20A 50rpm (no load speeds) for comparison purposes only
24V 2 in series 2 in parallel (2s2p) 10A 100rpm
48V 4 in series 1 in parallel 5A 200rpm

1b. Battery similarly. (180wh)
180Wh / 3.6V Lithium = 50Ah
50Ah / 24 cells @ 2.08Ah
2s12p 7.2V 24Ah 20rpm (no load speeds) for comparison purposes only
3s8p 10.8V 16Ah 30rpm
4s6p 14.4V 12Ah 40rpm
6s4p 21.6V 8Ah 60rpm
8s3p 28.8V 6Ah 80rpm
12s2p 43.2V 4Ah 120rpm
Please note:
Li-ion rated at 180Wh, discharged in 25min can output near 170Wh
SLA Sealed Lead Acid rated at 180Wh, discharged in 25min might output a pitiful 80Wh.


2. Watt-watt Hour meters are fairly accurate and inexpensive. If a throttle is used, maximum safe battery output can be regulated fairly precisely!
180wh x 60/25 min = 432w
Should maintain 400w+ battery output for 25 minutes
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

EBike Toolbox - Bargains! $

Endless Sphere Wiki

BlueBell
10 mW
10 mW
Posts: 27
Joined: Thu Sep 28, 2017 2:52 am

Re: Battery Advice Needed For Middle School Competition

Post by BlueBell » Mon Nov 06, 2017 2:44 pm

Thanks DrkAngel.

I get the voltage/rpm vs amps relationship.
What motor would we purchase to reach that end in our case for our parameters?
When does amperage become an issue?

Controller? Yes we need throttle, spring loaded (dead-man throttle).
Any suggestions?

Interesting about the difference in batteries. So, lipo it is.
Any recommendations?

Watt-watt hour meters: Any model you would recommend?

FYI I have also started a thread in the electric boat section.
Last edited by BlueBell on Tue Nov 07, 2017 2:10 am, edited 1 time in total.

999zip999
100 GW
100 GW
Posts: 8122
Joined: Sun Jan 10, 2010 1:40 pm
Location: Dana Point So. Cal

Re: Battery Advice Needed For Middle School Competition

Post by 999zip999 » Mon Nov 06, 2017 10:18 pm

How about a panko Fisher 3-phase dishwasher motor. At the junk yard or scrapper. There must be a lot of other examples where you can get a three phase motor.
Last edited by 999zip999 on Tue Nov 07, 2017 11:11 am, edited 1 time in total.

User avatar
DrkAngel
10 GW
10 GW
Posts: 4407
Joined: Wed Dec 15, 2010 11:14 am
Location: Upstate-Western-Southern Tier NY. USA

Re: Battery Advice Needed For Middle School Competition

Post by DrkAngel » Tue Nov 07, 2017 12:46 am

"Amps" supplies torque for pushing over large props.
Volts = speed
Amps = torque

Factors to consider:
Desired propeller rpm range?
Direct power, no controller, on solar is slightly more efficient.
Motors are most efficient near 70-80% of no load speed.

250 watt input from panels ≥ 225w (output) motor
400 watt input from batteries ≥ 375w (output) motor
Using voltage to emulate gearing, 750-1000w (output) motor might be desirable?
But I over volt 450w motor for 675w output.

Controllers, typically, have a low voltage limit and high voltage limit.
Unfortunately, I am more familiar with brush motors, so some other expert might have a good suggestion on motor-controller.

Volt Amp Watt meter

Also see -eBike Toolbox Bargains
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

EBike Toolbox - Bargains! $

Endless Sphere Wiki

BlueBell
10 mW
10 mW
Posts: 27
Joined: Thu Sep 28, 2017 2:52 am

Re: Battery Advice Needed For Middle School Competition

Post by BlueBell » Tue Nov 07, 2017 2:14 am

999zip999 wrote:How about a panko Fisher 3-phase dishwasher motor. At the junk yard or scrapper.
Interesting.
Why would you recommend it?
Thank you.

BlueBell
10 mW
10 mW
Posts: 27
Joined: Thu Sep 28, 2017 2:52 am

Re: Battery Advice Needed For Middle School Competition

Post by BlueBell » Tue Nov 07, 2017 2:28 am

DrkAngel wrote:"Amps" supplies torque for pushing over large props.
Volts = speed
Amps = torque
Yes, that seems correct as I understand it.

Factors to consider:
Desired propeller rpm range?
500 - 1000 RPM
Direct power, no controller, on solar is slightly more efficient.
So we should wire them all in parallel and simply have an on-off switch?
Motors are most efficient near 70-80% of no load speed.
And to control the motor from batteries?

250 watt input from panels ≥ 225w (output) motor
400 watt input from batteries ≥ 375w (output) motor
Using voltage to emulate gearing, 750-1000w (output) motor might be desirable?
But I over volt 450w motor for 675w output.
Okay, so what are you suggesting here in my case?

Controllers, typically, have a low voltage limit and high voltage limit.
Okay, so what does that mean in our application?
Unfortunately, I am more familiar with brush motors, so some other expert might have a good suggestion on motor-controller.

Volt Amp Watt meter

Also see -eBike Toolbox Bargains

User avatar
DrkAngel
10 GW
10 GW
Posts: 4407
Joined: Wed Dec 15, 2010 11:14 am
Location: Upstate-Western-Southern Tier NY. USA

Re: Battery Advice Needed For Middle School Competition

Post by DrkAngel » Tue Nov 07, 2017 9:40 am

Oops, my bad, brushless motors can not connect directly to battery or panels, they do require controller at all times ... said I was a brush motor guy ...

Only found 1 motor controller near optimal, about 500rpm with 30V LVC (48V from panel, or battery, will sag under throttle, 30V allows substantial draw before Low voltage cutoff - safety disconnect.).
$169 500w 36-48V brushless motor-controller

There are lots of brushless motors, but most all are high rpm 1700-3200 etc.
Gear reduction seems only feasible option ... ?
.
Attachments
500w gr.jpg
500w gr.jpg (125.23 KiB) Viewed 137 times
Last edited by DrkAngel on Tue Nov 07, 2017 12:41 pm, edited 2 times in total.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

EBike Toolbox - Bargains! $

Endless Sphere Wiki

999zip999
100 GW
100 GW
Posts: 8122
Joined: Sun Jan 10, 2010 1:40 pm
Location: Dana Point So. Cal

Re: Battery Advice Needed For Middle School Competition

Post by 999zip999 » Tue Nov 07, 2017 11:15 am

I wasn't recommending that Pacific Motor I just mean that there are three phase Motors out there you can get your hands on for cheap.
As dark angel said it's the way it's wound for more torque more speed how many RPMs you want to run at what voltage all that Drk Angels stuff.
I edited my last post but regot to push send last night. What?

BlueBell
10 mW
10 mW
Posts: 27
Joined: Thu Sep 28, 2017 2:52 am

Re: Battery Advice Needed For Middle School Competition

Post by BlueBell » Tue Nov 07, 2017 4:33 pm

DrkAngel,
Wow, a geared motor, look at that, thank you.
So 30V LVC (whatever that means) we'd need 4 - 12V lipo's in series to compensate for sag under load.
It comes with a controller, sweet.
The meter you recommended earlier.
What can we do for a dead-man's-throttle?
Anything else I'm missing?
Thanks

User avatar
DrkAngel
10 GW
10 GW
Posts: 4407
Joined: Wed Dec 15, 2010 11:14 am
Location: Upstate-Western-Southern Tier NY. USA

Re: Battery Advice Needed For Middle School Competition

Post by DrkAngel » Tue Nov 07, 2017 5:13 pm

Any HALL twist or thumb throttle will work. Twist allows more precise control
Any of these Throttles, recommend against cheapest, or buy multiple and compare performance.
With end connector and reasonable length.
Can't think of anything else "needed".
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

EBike Toolbox - Bargains! $

Endless Sphere Wiki

999zip999
100 GW
100 GW
Posts: 8122
Joined: Sun Jan 10, 2010 1:40 pm
Location: Dana Point So. Cal

Re: Battery Advice Needed For Middle School Competition

Post by 999zip999 » Tue Nov 07, 2017 11:29 pm

Dr Angel I read all your and try to hang on. Thanks Bro.

User avatar
DrkAngel
10 GW
10 GW
Posts: 4407
Joined: Wed Dec 15, 2010 11:14 am
Location: Upstate-Western-Southern Tier NY. USA

Re: Battery Advice Needed For Middle School Competition

Post by DrkAngel » Wed Nov 08, 2017 8:51 am

30V LVC (Low Voltage Cutoff) disconnects power if battery, or power source drops below 30V, which is a standard safety for 36V Lithium battery.
With 48V solar panels, 30V will allow throttling maximal draw from panels, reduced voltage offset by substantial amps. Drawing down panel voltage increases panel output somewhat. Larger than needed wire gauge helps too.
Just keep voltage-throttle position above 30V to prevent power interrupt!

Brush motors have greater options and availability ... but with somewhat reduced efficiency.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

EBike Toolbox - Bargains! $

Endless Sphere Wiki

BlueBell
10 mW
10 mW
Posts: 27
Joined: Thu Sep 28, 2017 2:52 am

Re: Battery Advice Needed For Middle School Competition

Post by BlueBell » Wed Nov 08, 2017 11:25 am

Thanks again DrkAngel.

Throttle link terrific.

Aren't we using 48V from 4-series lipo's?
So wouldn't the 30LVC be easily avoided?
Same with panels...?

I'm in so far over my head here it's ridiculous!

I think I'll move the battery closer to the motor to keep cable runs as short as possible.
The panels are already as close as possible.
Although they could be turned sideways to shorten the over-all run...

Hmmmmm...

BlueBell
10 mW
10 mW
Posts: 27
Joined: Thu Sep 28, 2017 2:52 am

Re: Battery Advice Needed For Middle School Competition

Post by BlueBell » Fri Nov 10, 2017 1:40 pm

DrkAngel wrote:30V LVC (Low Voltage Cutoff) disconnects power if battery, or power source drops below 30V, which is a standard safety for 36V Lithium battery.
With 48V solar panels, 30V will allow throttling maximal draw from panels, reduced voltage offset by substantial amps. Drawing down panel voltage increases panel output somewhat. Larger than needed wire gauge helps too.
Just keep voltage-throttle position above 30V to prevent power interrupt!

Brush motors have greater options and availability ... but with somewhat reduced efficiency.
Not clear where the 36 volt battery comes in.
Can you clarify?

Thanks again.

User avatar
DrkAngel
10 GW
10 GW
Posts: 4407
Joined: Wed Dec 15, 2010 11:14 am
Location: Upstate-Western-Southern Tier NY. USA

Re: Battery Advice Needed For Middle School Competition

Post by DrkAngel » Fri Nov 10, 2017 7:38 pm

Motor-controller is 36V or 48V compatible.
With 48V battery, 30V LVC will allow extra battery drain for competition (1 time with risk of battery damage ...
With 48V panels, will allow maximal panel current extraction. Turn throttle till voltage sags near 30V for increased watt output. Important, especially in partial sun.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

EBike Toolbox - Bargains! $

Endless Sphere Wiki

999zip999
100 GW
100 GW
Posts: 8122
Joined: Sun Jan 10, 2010 1:40 pm
Location: Dana Point So. Cal

Re: Battery Advice Needed For Middle School Competition

Post by 999zip999 » Fri Nov 10, 2017 9:42 pm

13s × 4.2 = 54.6 v or 14s × 4.2v = 58.8v fully charged.

999zip999
100 GW
100 GW
Posts: 8122
Joined: Sun Jan 10, 2010 1:40 pm
Location: Dana Point So. Cal

Re: Battery Advice Needed For Middle School Competition

Post by 999zip999 » Fri Nov 10, 2017 10:50 pm

DrAngle help me out 13s and how many ah equals 180 wh hr ? How about 14s ? Or what's the math ?
0r better to run 12s or 10s ?

User avatar
DrkAngel
10 GW
10 GW
Posts: 4407
Joined: Wed Dec 15, 2010 11:14 am
Location: Upstate-Western-Southern Tier NY. USA

Re: Battery Advice Needed For Middle School Competition

Post by DrkAngel » Sat Nov 11, 2017 7:27 am

see post above
  • 180Wh ÷ 3.6V cells = 50Ah
  • 12s2p (2080mAh cells) 43.2V 2000 or 2050mAh
  • 13s2p (1923mAh cells) 46.8V
  • 14s2p (1785mAh cells) 50.4V best ... if available
  • 15s2p (1666mAh cells) 54V 1650mAh cells max recommended
  • 16s2p (1562mAh cells)57.6V
  • 180Wh ÷ 3.7V cells = 48.64Ah
  • 12s2p (2026mAh cells) 44.4V
  • 13s2p (1870mAh cells) 48.1V best ... if available
  • 14s2p (1737mAh cells) 51.8V
  • 15s2p (1621mAh cells) 55.5V 1600mAh cells max recommended
  • 16s2p (1529mAh cells) 59.2V
Depends on cell rating-capacity
12s2p with 2000mAh cells? easily available

Stick to good brand name cells!
Panasonic
Samsung
LG
Sanyo
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

EBike Toolbox - Bargains! $

Endless Sphere Wiki

BlueBell
10 mW
10 mW
Posts: 27
Joined: Thu Sep 28, 2017 2:52 am

Re: Battery Advice Needed For Middle School Competition

Post by BlueBell » Sat Nov 11, 2017 10:45 am

By cell rating do you mean the "C" value?

Any idea what this battery is going to weigh?

User avatar
DrkAngel
10 GW
10 GW
Posts: 4407
Joined: Wed Dec 15, 2010 11:14 am
Location: Upstate-Western-Southern Tier NY. USA

Re: Battery Advice Needed For Middle School Competition

Post by DrkAngel » Sat Nov 11, 2017 11:33 am

BlueBell wrote:By cell rating do you mean the "C" value?
Rated as 3.6V or 3.7V = average discharge voltage over full discharge cycle.
BlueBell wrote:Any idea what this battery is going to weigh?
24 18650 cells = 2-2.5lbs.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

EBike Toolbox - Bargains! $

Endless Sphere Wiki

BlueBell
10 mW
10 mW
Posts: 27
Joined: Thu Sep 28, 2017 2:52 am

Re: Battery Advice Needed For Middle School Competition

Post by BlueBell » Sat Nov 11, 2017 11:44 am

2 -2.5 pounds, nice!!
Helps make up for the 17 pound motor!

What can we use to charge the battery from the four panels?
On race day, we're not allowed any shore charging ( from 120v A/C ),
only what the panels will give us.
It ( along with the panels ) can be removed for the 25 minute, battery only heat.

User avatar
DrkAngel
10 GW
10 GW
Posts: 4407
Joined: Wed Dec 15, 2010 11:14 am
Location: Upstate-Western-Southern Tier NY. USA

Re: Battery Advice Needed For Middle School Competition

Post by DrkAngel » Sat Nov 11, 2017 12:43 pm

BlueBell wrote:2 -2.5 pounds, nice!!
Helps make up for the 17 pound motor!

What can we use to charge the battery from the four panels?
On race day, we're not allowed any shore charging ( from 120v A/C ),
only what the panels will give us.
It ( along with the panels ) can be removed for the 25 minute, battery only heat.
1. Charge w/AC before race day. Quality Lithium does not bleed energy.
12s Lithium - 12 x 4.2V = 50.4V
Hold checking for something! Looked for DC\\DC step-down converter but couldn't find one, yet. 2. If you monitor voltage, you can manually top off voltage directly from panels, if output is above 50.4V ... do not charge above 51.6V!!! Wattage from panels might be excessive for safe-proper charging?
Panel voltage will sag to near battery voltage when attached

Affordable quality 2000mAh cells look scarcer than I thought.
Bargain on Sona cells!
In 20 cell bricks, 2s10p
24 cells need 2 minimum, recommend 3, for 2 builds + spares. Better price on 5 or 10.

Charging 6s tools
1/2 in 2 stages
iMax B6 for charging - testing

Homemade battery packs Index page
Balance cable
Last edited by DrkAngel on Sat Nov 11, 2017 1:08 pm, edited 1 time in total.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

EBike Toolbox - Bargains! $

Endless Sphere Wiki

999zip999
100 GW
100 GW
Posts: 8122
Joined: Sun Jan 10, 2010 1:40 pm
Location: Dana Point So. Cal

Re: Battery Advice Needed For Middle School Competition

Post by 999zip999 » Sat Nov 11, 2017 12:48 pm

How about a samsung 35g ( I'm guesing) at 3500 mah and 20amp cell or so 12s 1p style. Now I have to investigate the biggest baddest 18650 cell. I get back to you. 180 watt hours is the hard part.

User avatar
DrkAngel
10 GW
10 GW
Posts: 4407
Joined: Wed Dec 15, 2010 11:14 am
Location: Upstate-Western-Southern Tier NY. USA

Re: Battery Advice Needed For Middle School Competition

Post by DrkAngel » Sat Nov 11, 2017 1:16 pm

14 x 3.6V x 3.500Ah = 176.4Ah
50.4V 3.5Ah
Nearly perfect!

Should work nicely, maybe better, with 48V motor-controller.

2 x 1750mAh cells would sag much less and provide noticeably better efficiency.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

EBike Toolbox - Bargains! $

Endless Sphere Wiki

BlueBell
10 mW
10 mW
Posts: 27
Joined: Thu Sep 28, 2017 2:52 am

Re: Battery Advice Needed For Middle School Competition

Post by BlueBell » Sat Nov 11, 2017 2:15 pm

This is fantastic guys, thank you.

I should have mentioned earlier, we have a $1000 budget for the project...
Batteries can get pricey...

Post Reply

Who is online

Users browsing this forum: aschigrunder, Rube and 8 guests