40T, neodymium magnets, plasti dip cycle test

Batteries, Chargers, and Battery Management Systems.
goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 20 2020 8:51am

tested overnight and once again, house cooled off and battery temp was 73f/23c when it started the 5th charge. im going to try and insulate the battery, its too cold.

Image

Image

Image

Image

im doing a test right now where discharge is 10amps to 3.5v then switches to 7.5amps to 3.0v in one discharge curve to see if I get more mah by discharging at 100% for half the cycle and when it switches to 7.5 im hoping when it cuts off the cell bounces back to 3.22ish?

I took a picture of 7.5amp discharge mah around 3.35v compared to 10 amp test above
Image

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 20 2020 8:58am

I took the 16 gauge wire and splayed it radially on the 3/8 magnet, I need to go get some copper Permatex then do a test
Image

Image

Image

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 20 2020 11:48am

heres the 10amp/7.5amp discharge
Image

the data
Image

combined capacity 3148mah
combined wh 11,149

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 20 2020 11:52am

got the copper antisieze Permatex, swapped out magnets and plasti dipped. the battery is charging then ill do a 10 amp discharge

Image

Image

Image

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 20 2020 1:07pm

heres the 10amp with Permatex magnets and 16 gauge splayed wire
Image

Image

volts after discharge
Image

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 20 2020 1:46pm

heres a question, I can run 10 cycles of the 7.5amp battery or 10 cycles of the 10 amp battery and will be ready tomorrow morning, which battery should I run?
the 10amp reached 107f on discharge and was still 96f when charge started, second discharge again 107f so I stopped it

Image

Image

im doing the 10amp to 3.5v then 7.5amp to 3.0v cycle test. its the test I think im going to life cycle

Image

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 21 2020 6:27am

Image

Image

Image

Image

im doing another 5 cycle test but ive changed the charge from 5amp to 3.95amp

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 21 2020 9:20am

im losing 10mah every cycle so I ran it again changed charge to 3.95amps and paid attention to temperature on the discharge. 10amps the line got scratchy at 3.6v and temp reached 98f at 3.5v, when it switched to 7.5amps temp stayed around 96f til 3.2v then climbed to 103f by 3.0v

Image

Image

I made a change and the discharge temperature reached 92f

Image

not much mah

Image

ive made another change, charge is 3.75 amps

Image

Image

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 21 2020 10:47am

heres the new test numbers, battery temp was 73f/22.7c when discharge started and reached 83f/28c when it switched from 10 amp to 7.5 amp peaked at 94f/35c when it switched to 3.75 amp

Image

Image

total mah is 2865, wh 10.057

Image

3.352v was when the charge started

Image

I think this is kind of simulating a fast ebike ride cycle?

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 21 2020 11:46am

the last test was 10 watt hours. I run 17s4p at 2200 watts on the trike and 2500 watts on the other bike. 68 cells to the pack is
680 wh. I average 20wh/km, that's 34km range.
charged battery would be 17x4.12= 70.04v dead battery 17x3.2=54.4

2500 watts/54.4= 46amps/4p=11.5amps per cell
2500 watts/70.4=35.5amps/4p=8.9 amps per cell

2200 watts/54.4= 40.44 amps/4p= 10.1 amps per cell
2200 watts/70.4= 31.25 amps/4p= 7.8 amps per cell

930 watts/62= 15 amps/4p= 3.75 amps per cell

when I ride if im not going up a hill im going down a hill or stopped at a light

I use 10 amps from stop lights and steep hills.

I don't want a huge battery so if I can fully recharge in 80 minutes that isn't too bad.

ill cycle this setting a couple times and hopefully not lose 10mah/cycle

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 21 2020 12:18pm

im running these settings through 5 cycles
Image

Image

emailed my battery guy for a new 40T but hes completely out, I figured id do the test with a brand new cell. theres a glitch in the chart when it switched from 7.5a to 3.75a on discharge. im just going to let this cycle for a couple days.

Image

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 22 2020 10:36am

I didn't like the numbers, im new to this, so the problem is probably me, something im doing.

Image

Image

Image

Image

Image

I changed cut off to 0.20a

Image

Image

Image

Image

I looked up the 40t charge specs

Image

changed cut off to 0.16a

Image

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 22 2020 11:02am

hopefully this means I get proper charge saturation and the numbers become consistent

Image

Image

getting better

Image

checked battery temp at end of charge, 70f/21c. datasheet puts low temp at 23c so I put blanket back on box. temps changed when I changed the c/o settings. I want to keep the battery between 25c and 35c, see what happens

Image

during discharge at end of 7.5a to 3.75a switch temp peaked at 98f/36.6c and steadily dropped to 92f/33c at end of discharge. charge started at 88f/31c. once charge reaches 4.12v@3.75a temp is 85f/29c and end of charge temp is 71f/21.6c. I could try turning up room temp but I don't want to run too hot on discharge. leave it and see

Image

Image

Image
Last edited by goatman on May 22 2020 6:23pm, edited 1 time in total.

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 22 2020 5:49pm

on the 7.5amp battery I had the copper electrode magnets but I switched to to splayed wire and copper Permatex, im going to test to see if theres any difference in the result

Image

I like the magnet with copper electrode
Image

heres the effects of temperature on neodymium magnets

https://www.stanfordmagnets.com/ndfeb-m ... tings.html


big difference in result, doing some tests to figure it out, this is the last numbers with electrode

Image

this is the splayed Permatex magnet, battery was on cool side when started

Image

im going to cycle the Permatex on this new setting with adjusted charge c/o to 0.13a

Image

then ill pull the Permatex and try the electrode magnet again to see what the problem is

took 2 hours just to charge

Image

changed the charge to 3.75/0.16 do another cycle then swap magnets and retest

Image

The Vancouver sky hasn't been this clear for years

Image

Image

Image

getting late, im going to cycle these settings overnight then swap magnets in the morning. takes 1.5hrs to charge at these settings

Image

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 23 2020 1:28am

I have a question about charging.
I was surprised a 5amp charge/0.13a c/o took 2hrs, 3.75amp charge/0.16a c/o was about 85 minutes.

it makes me think a 3 amp charge with 0.175a cut off might be faster? would the saturation be as good?

User avatar
fourbanger   100 W

100 W
Posts: 214
Joined: Jul 17 2014 10:09pm
Location: Vancouver B.C. Canada

Re: 40T, neodymium magnets, plasti dip cycle test

Post by fourbanger » May 23 2020 3:24am

Bookmarked for further reading.

Alls I knows is magnets aint so magnetic once theyses gets hot. What's to say of conductivity, I have no idea, except that as a rule of thumb resistance increases proportional to heat in a given conductor. Right?

Thanks to SM for the link from
viewtopic.php?f=14&t=60517

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 23 2020 7:48am

fourbanger wrote:
May 23 2020 3:24am
Bookmarked for further reading.

Alls I knows is magnets aint so magnetic once theyses gets hot. What's to say of conductivity, I have no idea, except that as a rule of thumb resistance increases proportional to heat in a given conductor. Right?

Thanks to SM for the link from
viewtopic.php?f=14&t=60517
I had this posted above but it was kind of hidden
https://www.stanfordmagnets.com/ndfeb-m ... tings.html

that is why im playing with the magnets, find a good method of using the magnet and then cycle test it, end of test, remove magnet and see how much strength is left.
Last edited by goatman on May 23 2020 8:00am, edited 1 time in total.

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 23 2020 7:56am

went to bed and looks like when the battery switched from 7.5a to 3.75a the cycle stopped? I wonder what did that. when I moved my finger across the laptop pad to "wake up" the lap top the tester started and I got this chart with the cycle test resuming.

Image

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 23 2020 12:47pm

this is going to be a trouble shooting post ****Edit why did these pictures get big all of all sudden?****

i could see the glitchs happening but just wanted to get some results before I shutdown and restarted the program
finished 3 cycles on the Permatex

Image

Image

pulled the plasti dip and Permatex magnets and swapped the magnets

Image

Image

started the 4-1 charge and the numbers stopped showing on the sidebar but test is still running, ill take a pic of tester screen when charge is done. then shutdown and restart computer.

the blue line on right side of chart is where I swapped out the magnets, it only took 2 minutes but that's why volts went to zero.
Image

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 23 2020 3:26pm

I figure out the problems, you cant just swap out batteries. now I click disconnect com port, turn off tester change battery then turn tester on and click to reconnect com port.

the Permatex seems to be an issue also, I retested the 10amp battery and got same results as before
Image

so I pulled those Permatex magnets and will try with electrode magnets and compare results.

Image

Image

Image

Image

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 23 2020 7:05pm

this is copper electrode with 3.75a/0.16 charge to 4.12v

Image

Image

Image

tweaked the settings to see if it will charge faster

Image

about 40 minutes into charge when it switches to c/o amps, 2640mah

Image

fully charged in 64 minutes :thumb:

Image

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 23 2020 8:37pm

heres the graph and settings, results. battery temp peaked at 93f end of 7.5amp discharge

Image

Image


this I tweaked a little to 4.15v, 70 minute charge. temp peaked at 94f end of 7.5a discharge c/o should be 3.4v to keep temp at 93f

Image

Image

I gave a 10 minute break between discharge and charge to lower the starting charge temp from 88f to 80f

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 24 2020 12:32am

I tried a setting for the 7amp battery where I was having problems. I did it on the 10 amp cell. ill switch batteries and run a slightly tweaked setting of this.

Image

Image

John in CR   100 GW

100 GW
Posts: 15218
Joined: May 20 2008 12:58am
Location: Paradise

Re: 40T, neodymium magnets, plasti dip cycle test

Post by John in CR » May 24 2020 1:01am

How will all those little magnets affect the inductance of your pack? As I understand inductance of a battery pack should be minimized to the extent possible, eg keep the loop of wire containing the battery from the controller + and - terminals as small as practical.

goatman   100 MW

100 MW
Posts: 2883
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 40T, neodymium magnets, plasti dip cycle test

Post by goatman » May 24 2020 9:51am

John in CR wrote:
May 24 2020 1:01am
How will all those little magnets affect the inductance of your pack? As I understand inductance of a battery pack should be minimized to the extent possible, eg keep the loop of wire containing the battery from the controller + and - terminals as small as practical.
that's a good question, now I need to go google what youre talking about :D

if i see packs with plates of copper or nickel for high amp packs, I wonder if that would be the same effect or tesla packs. I think ill go google it.

heres the 7 amp battery, I think the Permatex is a nogo but maybe less is better? Ill do a little testing today. to compare.

I also need a new 40T to start the test with.

Image

Image

doing a 5 amp charge and you can see the line gets scratchy at about 4.4 amps and 3.2amps. this is the first 5amp ive tried but ive seen the 3.2a scratch on other tests. im just thinking you might not want to charge at 3.3 to 3.0 amps. the charge took 52 minutes and 3107mah. im going to do a discharge at 3amps and see if battery temp gets higher than 88f. test started at 75f
Image

I think I found a problem with the software, doing the test at 3amp discharge battery temps are steady 76f but the screen isn't recording mah this pic is 11 minutes in the test. temp peaked at 79f/ so 4.2 to 3.2v gave 3154mah

Image

I cant even stop the test, I close the program and tester is still going :lol: i know i can program the tester to cycle test without the pc software so when i start the cycle test ill do batches of 50 cycles then do 1 cycle test on the software to post in the thread with the results.

Post Reply