Premade NiMH packs at more reasonable prices?

[knightmb]

Since the NiMH packs seem to have gone up in price, any tried these battery packs as they appear to be at the "traditional" prices I'd seen before.

http://www.poweridestore.com/NiMH-Battery-Packs

 

[Mathurin]

Expensive?
Where would one get better/cheaper NiMH?

 

[Drunkskunk]

13AH, I believe that makes the F cell packs.
That would make it a pretty good deal for a pre-assembled pack.

I've delt with the company for most of my ebike stuff and have been pretty iimpressed with them for both product and response to my emails.

 

[Ypedal]

http://www.sanforce.com.hk/en/

I see the word sanforce printed on the green pack.


This is kinda funny ( dependin on your version of " funny "
.
http://www.sanforce.com.hk/en/Product/ProductDetail.aspx?ProductID=9

Qutoe "You can even use 72V by using 2 packs of 36V battery, which can blow your bike into air"

 

[NickF23]

Qutoe "You can even use 72V by using 2 packs of 36V battery, which can blow your bike into air"

sounds pretty cool to me 8) I notice in the pics their batteries seem to be suspened in mid air in a forest. :lol:


I heard of 1 person who ordered direct from them in china and seemed happy. The 20AH prismatics looks nice too.

 

[scottclarke]

Whilst these prices seem good you have to be carefull.

I have tested NIMH from 8 or so manufacturers, measuring capacity at discharge rates as high as 10C with varying charge rates. Of these some cells would not deliver rated capacity at anything over a .2C discharge rate. The very worst cells delivered less than 60% at anything over 1C. For these very poor cells I sourced another sample and retested - with no difference in performance.

The very best cells would deliver 95+% back at 10C - best of all they would also happily charge to 98+% at rates as high as 1C.

So, given most people do not want/need a 40 mile range or the accompanying 12+KG of battery it seems to me cell choice is very important.

One of my bikes for eg has a battery which weighs 4.8KG - is a 48V 7.4AH pack. It is truly happy delivering 50+ amps and still returning 95+% of charge at that rate - meaning even though it is small in capacity when I peg the throttle it really delivers the amps yet when cruising at 23-24mph it gives excellent range.

By comparison - a battery like others I have tested would really suffer when pushed hard - delivering less than 4AH.

Obviously - this only applies if the motor/controller combo is likely to ever draw over .2C from your pack - which on mine is about 1.48A ~ 71W - hardly likely! OK - a bit OTT that - but even at the 1C rate a lot of cells were terrible - on 7.4AH 48V that 1C is 355W. Clearly a lot of motors draw more than this - pretty much all that exceed 20mph in fact!

So, tbh I really don't trust any figures from battery resellers unless proper tests have been conducted. I have cells here which were claimed to do 10C and be 3500mah - yet in fact they never EVER delivered more than 2200mah!

FWIW the cells I use - for the 48V 7.4AH pack cost me £180 - about $360. I could have spent £90 $180 for the same rated capacity - fortunately I tested them first!

Scott

 

[Liberator]

Scott, ever test the batteryspace.com NiMH packs? For example, http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2538

 

[Ypedal]

I just want to know what cells your 7.4ah pack is made of ? please ?

 

[scottclarke]

Scott, ever test the batteryspace.com NiMH packs? For example, http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2538

Nope - don't think it would be worthwhile though.

quoted from the site -

Standard discharging rate: 13Amp ( Recommended and warrantied)
Highest Discharging rate for continuous running: 40Amp ( high discharging rate will recue battery capacity )
Max. Discharging capability for short time: 60Amp ( Not recommend as working rate )

all tells me - without reading between the lines - these cells deliver less than 13AH at anything over 1C

Also tells me (as expected - due to the cell shape(heating)) anything over 5C is a no-no

The fact they are less than happy at >1C tells me the cells are simply not as good as some others.

Granted - they do give a lot of capacity and in a 48V 40cell pack as long as you are drawing <600W they will shine.

Obviously, for every second you ask for more than 600W you are throwing capacity away - for this reason they would not find there way onto any bike I run!

Scott

 

[Liberator]

Cool. Thanks so much for the info. I'm certainly gonna be drawing some decent wattage as my commute to work has some hills, is over 8 miles round trip, and I'm 6'1" and 220lbs so I'm getting up there with the power. I guess we'll see once I install my Watt's Up meter this weekend but I may just decide to run these SLA's until they die.

It sure sounds like anything outside of SLA's I'd want would cost me another $1000!

 

[scottclarke]

I just want to know what cells your 7.4ah pack is made of ? please ?

exact cells......

http://cgi.ebay.co.uk/Sub-C-3700mAh-high-capacity-NiMH-With-TAB_W0QQitemZ320113901399QQihZ011QQcategoryZ1200QQrdZ1QQcmdZViewItem

the description is muddled. they also sell 4300's now - equally as good. I am using 80 of these 3700 items.

Last year I couldn't recommend these since I didn't really have enough cycles on them. They have long since passed any reasonable benchmark - well in excess of 600 (I stopped recording at 500) and still delivered 90+% on the bench test (at 500 cycles).

I was loathe to dissasemble the pack to extract a cell - hence no data between new and 500!

I've also been playing with some of my lipo. I have gathered together all my PQ2500 cells, stripped em from the packs and tested them individually. I had 13 good ones so wired 12 in series - was comical - bike doing 25mph with a 700g battery pack - not for long obviously!

Scott

 

[Lowell]

That's great to hear you excellent results with those NiMH cells. You should start your own '600 cycle' club. :lol:
I'm almost at 70 cycles on my 2D cells, and I'd be really happy if they hold 90% at 500+ cycles.

 

[safe]

I wish I bought those NiMh batteries a while ago because the Tenergy "D" cells could be had for as little as $5. Now those exact same batteries are up to $6.75. That's a $140 difference for my 80 cell project.

Hmmm... :?

 

[Liberator]

So, modifying the original question of this thread, any decent pre-made NiMH packs out there that people HAVE tested and have experience with and ARE worth the price? While I'm a pretty handy guy, I don't trust myself with a soldering iron.

 

[newbie electric rider]

i have the sanforce ni-cads, 48 volts. the past month has been no problem, under hard riding, throttle fully opened, i get about 30km a charge.with the crystalight 406 btw, i paid an extra 300 cad, for the upgrade.