Thursday, February 21, 2013

Considering 60 Ah Lithium Prismatic Cells

My Old Post - "Considering TS 40 Ah versus Trojan 100 Ah!!" from Friday, June 18, 2010, Looked at comparing the 40 Ah cells, This time I will look at the 60 Ah Cells, for fit, weight, price, and energy comparisons - leading to potential range improvements.

Looking at Batteries in a Flash - we see a listing for the Lead Acid Battery I used so long -
Trojan SCS150 12V 100Ah Group 24 Superior Deep Cycle Battery - including simple specs, and price: $169.95.

This Lead Acid Battery weighs 50 Lbs (23 Kg), shows a 20 Hour run time rate capacity of 100 Ah, and a 5 Hour run time rate capacity of 80 Ah. It shows a Reserve Capacity at 25 Amps of 150 minutes (62.5 Ah), and a Reserve Capacity at 75 Amps of 36 Minutes (45 Ah). Not shown, but since found out, and mentioned in a past post - March 27, 2012 - is that the Batteries 1 hour run time capacity is just 30 Ah. The Actual page - I found it once again - linked online at the 12 Volt Shop, here -> Superior! On page 2 of the document - you can see from the Run Time Chart - that the Trojan SCS150 Run Time is 1 hour at 30 Amps, or 1.5 hours at 25 Amps, 2 hours at 22.5 Amps, and 2.5 hours at 20 amps.

Taking these facts - basically says - at the 1 hour rating - it is for all intents and purposes - a 30 Ah Battery, in spite of it being rated at 100 Ah over a 20 Hour Run Time. We can also discover from this run time chart - that while the Reserve time at 25 Amps of 150 minutes, shows the battery to have an available 62.5 Ah, the chart shows an actual load time at 25 Amps as just 1.5 hours not 2.5 hours or 150 minutes, meaning we can just get 37.5 Ah from the battery under the 25 Amp load.

With all these elements in place - comparing now to the Winston LiFeYPO4 3.2V 60Ah Cell as found on EV Assemble, shows that the single cell weighs 2.3 Kg, or 5.06 Lbs, so that 4 of them in series for a 12V Module - would weigh approximately 20.24 Lbs Plus Connecting plates, or under half the weight of the Trojan SCS150 Battery, at about 40% of it's weight.

While 4 of these cells price out at $316.00 (4 x $79.00) looks more expensive than the Trojans price of $169.95, start by remembering you are getting 60 Ah versus 30 Ah of actual usable energy. this means that the Trojan, by reason of it's lower energy - would need two batteries in parallel to equal the 60 Ah, and cost then $339.90, or $23.90 More, plus weigh now 100 Lbs, or about 5X the Weight of the Winston Lithium  Cells!

Using the Full TS-LFP60AHA Cell Specification Sheet - you can see that it can run for two hours at the load of 30 Amps (Standard Discharge Current = 0.5CA = 60 Ah x 0.5 = 30 Amps), but can also carry a discharge load of up to 3C or 3X 60 Amps = 180 Amps.

It can also be charged at up to 180 Amps, or a nearly full charge from totally empty in about 20 Minutes.
In a 32 Cell assembly, like for My Electricfly - this means that the Nominal 102.4V x 180 Amps Max Charge = up to 18,432 Watts charging - or about 18 kW. Even a 6 kW charger could charge this pack in about 1 hour!

Plus - the cycle life at 80% Depth of Discharge = at least 3000 Times, or 48 Ah x 3,000 = a life discharge of approximately 144,000 Ah! (Per Cell, x 4 per module = 576,000 Ah Lifetime delivery from a 4 Cell, 12V Module!)

Further - a 32 Cell Set of these would cost $2,528.00 - not free, but not so expensive, either. 32 Cells would net out at 73.6 Kg, or 161.92 Lbs, just over the Weight of 3 Trojan SCS150 Batteries as used so far, or about 3/8ths the 400 Lbs weight of a set of them!

For packaging size - another issue of concern - the Lithium 60 Ah Cell is just 200 mm tall at the case, versus 207 mm tall for the Trojan Case. Overall Height of the 60 Ah Cell is 203 mm (+ Bolt head and strap) compared to 248 mm for the Trojan to the top of the (included) Threaded Post. The Long Width of the 60 Ah cell is just 115 mm compared to 171 mm for the Trojan Case. And finally - the 60 Ah Lithium Cells 61 mm thickness x4 for the 12V Module = 244 mm compared to 286 mm for the Length of the Trojan SCS150 Case.

So in summary - the module of 4 of the 60 Ah Lithium Cells are shorter in Height (by 45 mm), slimmer in Width (by 56 mm), and shorter in Length (by 42 mm); Deliver 2X the Energy, at a net cost of $23.90 Less (Than A Pair of the Trojan SCS150 Batteries); and weigh 29.76 Lbs Less than a Single Trojan Battery - or 79.76 Lbs Less than a Similar Energy rated Pair of Trojan SCS150 Batteries!! (And So much less space than a pair of them too!)

A Double Set of the Trojan SCS150 12V Batteries (to Equal the 60 Ah worth of Energy from this Lithium Cell Set) would cost at least $2, 719.2 or $191.20 more than the TS-60 Ah Cells. The Trojan Double Set of SCS150 Batteries would weigh 800 Lbs compared to 161.92 Lbs, so the 60 Ah Lithium Cells also save 638.08 Lbs in Weight! And - they save 238.08 Lbs from the Current Single Trojan Battery Set Weight of 400 Lbs, taking the curb weight down from 2,000 Lbs on Electricfly, to 1761.92 Lbs!

As to Space (Volume) the Double Set of 16 pieces of the Trojan SCS150 Batteries take up 0.1940 Cubic Meters of space, versus 0.0456 Cubic Meters of Space by the 32 Pieces of the 60 Ah Lithium Cells, or 4.2544 X as much Space!! Even the Current Single Set of Trojans consume 0.097 Cubic Meters of space, or 2.1272 Times the space of a set of the 60 Ah cells!

The 60 Ah Cells can easily Fit within the vertical height constraints of the current battery locations.

SCS150 Data Sheet.
Winston LiFeYPO4 3.2V 60Ah Cell at,

The Trojan SCS150 can be had for less at $158.05 on eBay - also a store by Batteries in a Flash,
Or More ($170.40) at CIVIC Solar.

The 60 Ah ThunderSky cells can be had for less ($64.50) at Alliance Renewable Energy;
Or for more from a Private Sale at $85/Cell in Miami, FL; or maybe more  from GWL Power ($86.94).

Based on these added notes - you can see there are variances to consider, along with things like shipping, waiting time for deliver, along with the basics of packaging, and installing - but in any case - the options for Lithium Cells to replace Lead Acid Cells is rapidly depleting the case that Lithium is more expensive than Lead Acid Batteries for an Electric Vehicle Conversion project.

If wee took the best prices from above - for a 96 Volt car like mine - we could see 8 x $158.05 = $1,264.40 (X 2 =  $2,528.8) vs. 32 x $64.50 = $2,064. Even a bigger spread than shown in my prices!

So - Yes - Lithium is more expensive than Lead Acid - but you are getting more power, energy, and life, and less space needed, less weight to carry, and less cost per Watt hour of Energy!

No comments: