Chaos upgrade - 72v 20ah LiMn

[Ypedal]

So if you got 10ah out, I'm wondering if the pack is not of much less capacity than the advertised 20ah. Why not just find out by riding until the BMS cuts off?

Eventually, but not yet. :wink:

I have no way to measure cell voltage manually and have to rely on the BMS, i only have 4 shallow cycles on the packs at 72v, I want to see some consistency for a few cycles before i do a full capacity test.

I have 2 different chargers, a 2 amp and a 4 amp, end of charge using each charger varies + or - 1v so i don't know if this is related to the Ballancing feature of the BMS or if it's caused by the ambient temp or some other satanic doing... .. one pack settles to 41.4v, the other tends to be 41.8 to 42v...

 

[xyster]

So if you got 10ah out, I'm wondering if the pack is not of much less capacity than the advertised 20ah. Why not just find out by riding until the BMS cuts off?

Eventually, but not yet. :wink:

Ok, will wait with bated breath. Until then, I wouldn't assume 74v is half-full or half-empty. According to everything I've read about LiMn, including that graph you posted above, 74v on a 20-cell LiMn pack would be about 80-90% depleted. I know 74v is the end of the line for my 20S LiCo pack without risking over-discharge.

 

[Ypedal]

I've taken a single pack down to 35v at 17ah ( might have been 15.. would need to search back ) ... but i recall 35v and still going strong.

Different cell size and chemistry and manufacture would likely have somewhat/slightly different discharge behavior, your 18650's by All-battery, do you know who manufactures them ?

 

[xyster]

I've taken a single pack down to 35v at 17ah ( might have been 15.. would need to search back ) ... but i recall 35v and still going strong.

That's good. Since you have an energy counting device, perhaps you can post us a discharge chart of these packs when you can. I'm curious since I'm planning a DIY pack of LiMn emoli's.

Different cell size and chemistry and manufacture would likely have somewhat/slightly different discharge behavior, your 18650's by All-battery, do you know who manufactures them ?

They're labeled "Tenergy" -- that's all I know regarding their origin:
http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=1643

 

[MajorMagnuM]

epic boxing

hats off to you sir

 

[Mark_A_W]

Ypedal, I just reread this thread and saw you have a piece of oak shoved up your seatpole..


Good idea. My seatpost just broke. I'm shoving a bit of steel or aussie hardwood up the replacement's fundamental too.

It was not fun...had to walk the damn bike for 4k's.

 

[Doctorbass]

Instead of the Tenergy that have a C rate of only 2C.. why dont you buy the makita LXT 18V 3Ah?

they can be found on ebay for 50-60$ and have 10 cells of 1.5Ah 10C 3.7V
and they dont need any BMS !

that is around 6$ per cell but with 10C... no fire! they are safe too like LiFePO4 !!

I did 1.1kWh pack and will built twice soon.. they never heat.. ! theyr internal resistance is lower. like 30mohm instead of 120 like the li-co or some limn...

http://search.ebay.ca/search/search...=compare&copagenum=1&coentrypage=search&fgtp=


just a suggestion....

Doc

 

[efreak]

nice post


that is in fact where i have been looking he next best thing to lifepo also at toolup.com have the 28v milwaukee s for 80 bock free US shipping


now only the m1s would come back down

efreak

 

[Ypedal]

MajorMag - Thanks ! . the boxes have been taken apart and put back together since this thread began.. now painted black !

Mark - Yes, i filled the seat post tube, the idea is to prevent the dual seat post racks from collapsing the tube as i tightened for all she's worth.. so far so good.

Doc - That's an older post from Xyster, were you around when he was posting ? his tenergy lico cells were driven at low C rate and were working last we heard from him. i wish he's pop in and give us an update.

efreak - seen a few posts on yahoo groups indicating that the M1's in dewalt packs may or may not continue depending on some lawsuits pending.. time will tell i suppose.

----

I finally got my power supply so i can charge with my new Tunder Power charger and ballancer.. very slick !! will post pictures in the morning.

 

[Jonathan]

Ypedal, Just got a chance to run through your Chaos build on your website. What a sweet ride.
That's quite a bit of power for the bike @ 72V / 20Ah.

In the latest picture I saw that you removed your pack at the downtube area. Why? Doesn't it improve handling by moving some of the weight forward?

 

[Ypedal]

I wen from 8ah nimh to 20ah lithium.

When it was nimh, i had 36v on the rear rack.. and 36v on the downtube, made up of 30 x D cells each.


The lithium however, is about the same weight, but larger sized and at the time i built the lexan boxes i did not want to open the packs and split the cells from the dealer built packs.

The handling was far better when it had 8ah of nimh.. but this bike is a road machine as it's currently used so having the weight forward of the axle and as low as i have it makes the bike play nice.. as long as you don't pedal with your toes on the pedals ( heels come very close to the sharp corners of the boxes ) .. :wink: