# S-10 guys - Battery Pack size



## Joe_L (Sep 17, 2008)

I am moving towards an S-10 conversion after an earlier thread on the roads the EV will be driven on.

My first set of questions is based on a 144 Volt system.

I have found a lot of people use 24 T-145 Trojan Batteries (Evalbum website). I have noticed a lot of the people using this 24 battery system are making a fair trek to work. My drive to work at present is 11 km (7 miles) one way. So 22 km total (14 miles). If I went out to get groceries I would be looking at 40 km total for a day if I decided to not plug it in at all. 

I was wondering if anyone has done an S-10 conversion with 12 T-1275's? Or perhaps 18 T-890's? If so what kind of range are you finding with this conversion? 

Would I be able to get 40 km with 80%DOD on just 12 batteries? Or should I move up to the 18 batteries. For my purposes, I think carrying around the extra 6-12 batteries would only be extra weight on my conversion as I would seldom need any range past 40km without charging and probably 90% of the time be able to charge with only 25 km on the pack that day. But if I am wrong, please correct me.

Also, if my drive to work has a lot of 50 km/hr and a short "highway" of 80 km/hr (less than 1.5 miles) would I be better off just having a 120 Volt system instead of 144 volts?


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## TX_Dj (Jul 25, 2008)

Joe,

I'd bet a 120v system built on 8v batteries would work well for your needs. You can easily cram 4 of them under the hood, and the other 11 under the bed behind the cab.

That would be a good compromise, I think, vs. 12x 12v.

The main advantage you'd gain with 144v vs 120v in your setup is the reduced amperage that would be required from the pack, which helps to reduce losses due to peukert's law because you can draw fewer amps to do the same work with the higher potential.

I will semi-frequently need long range, and I want the longest possible life for my pack (even more important in the TX heat) so I'm designing mine so my longest infrequent trips can be handled within 80% DOD and the rest of my regular trips are between 30-50% DOD.

The less you stress your pack, the more cycles it will last.


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## dimitri (May 16, 2008)

I'd recommend to use 6v or 8v batts if you have room for them because they are capable of higher current and Peukert's effect is lower on these batts thus allowing higher range. Although 120v will have higher amp draw than 144v, ability of 6v and 8v batts to supply higher amps is far more important than benefit of slightly higher voltage, everything else being equal.

Of course if you can do 144v with 6v or 8v batts, that would be best option.


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## TX_Dj (Jul 25, 2008)

Agreed. And with 8v units, you could cram 144v into only 18 modules, whereas my truck will use 6v, requiring 24.

Also keep in mind, the S10 is heavy to start with, and not the most aerodynamic brick on the road (less so if it's a 1st gen), so your Wh/mile will be greater than a more aero car, meaning you need more energy storage to go the same distances, and more power output to get rolling and accelerate/maintain speed.


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## Joe_L (Sep 17, 2008)

Thanks,

I think the 15 Battery 120 Volt system might be the route. Maybe go with the bigger motor so later if I am not happy with the performance of 120 volts I can add the extra 3 batteries?

The S-10 is a brick. From my research I have been doing calculation based on 450 Wh/mile for the S-10. I actually measured my drive today in my G5. From my work building to my driveway was 8.5 km (5.4 miles). The drive is flat with a few minor hills. 

What about a small Saturn? More Aero, probably only 300 Wh/mile, but the roads are rough (lots of pot holes) and that could leave the frame very stressed.


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## ElectriCar (Jun 15, 2008)

I'm nearing putting my '91 on the road with 24 US 2200XC batteries. They're 232AH each and the pack weighs 1500lbs. My commute will include a number of small hills and is about 8 miles each way. 

The answer to mileage is LEAD. 12x12 won't be near the same as 6x24! I'm hoping to drive to adjacent city's on business. This will be 20 or 25 miles one way.


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## TX_Dj (Jul 25, 2008)

More or less, lead weight == range. 

But, don't get tricked into thinking that just because battery X weighs more than battery Y, that it will have better range. Every battery model performs a little different than every other battery model. The real thing to worry about is the peukert exponent and peukert capacity. However, the manufacturers are very likely to never give you this information, and their sales crews are very likely to have no clue what you're asking about.

Pick a few different types of batteries that you like the price and size of, and then get the manufacturers to send you their Ah capacity charts down to *at least* the 1-hour rate, if not down to the 30-minute rate (not likely), and also try and get the "reserve capacity" charts up to at least 125A. These will let you see the peukert's numbers in action.

Just because one battery claims X Ah at the 20-hr rate does not mean that it will have significantly better capacity at high discharge rates, and in fact in some cases, some batteries with lower 20-hour capacities actually perform better at the 1-hour rate.

When calculating your expected range, use the figures for the 1-hour rates to find your actual watt-hour capacity. I.E. if you have a 250 Ah (20-hour rate) battery which has a 125 Ah (1-hour rate) capacity, figure your watt-hour capacity against the 1-hour figure. If that was a 120V system @ 125 Ah (1-hour rate) that'd be 15 kWh capacity (not 30 kWh when the 20-hour rate is figured). If your vehicle consumes 450 Wh/mile, then you can expect about 26 miles range at 80% DOD. (15,000 * .8 / 450 = 26.666)


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## ElectriCar (Jun 15, 2008)

It just occurred to me that due to the P-effect, by adding 10% to the pack voltage/kWh, will that give me MORE than 10% in mileage as I'll be using less amps for a given task thus less P-effect?


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## Qer (May 7, 2008)

ElectriCar said:


> It just occurred to me that due to the P-effect, by adding 10% to the pack voltage/kWh, will that give me MORE than 10% in mileage as I'll be using less amps for a given task thus less P-effect?


Yep. The less amps you draw from the battery the more Ah will you get, but the effect will be more noticeable at extreme currents (which we're talking about in EV's) than at low currents. It's doesn't matter if you increase the capacity with higher voltage or more Ah, both will lower the discharge rate and thus the P-effect.


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## Joe_L (Sep 17, 2008)

Thanks,

I have the US battery AH PDF saved on my hard drive. So down to the 1 hour is the best for battery design? It makes sense as before using the 20AH rating seemed to require dividing by 2 - 2.2 (reading the new wiki) instead of the 1 hour rating times 0.8 for actual miles. 

I am really in the debate of vehicle. S-10, Saturn or 93-95 Camaro. The latter would just be something different, and the base Camaro of those years comes with the 3.4L engine, so the same as bolting to a 2.8L S-10, just placing 18 batteries would be tough plus keeping under the GVWR. I was thinking going with a 156 Volt system and using 13 - 12 volts batteries. It is logical, more lead more range. It is like having a 50 Litre tank or 100 Litre tank. I even made a spread sheet based on the NuWiki equations and weight of the car doesn't cause near the issues as drag when it comes to fuel economy at higher speeds. So extra weight is really a function of what a vehicle can handle.

I am big on researching and taking my time. I want to do a conversion like this using cash only. So I will take my time on the donor car and building it right. I have also found someone about 400 km south of me who built an electric Jeep. I want to visit him, just to get a feel for what I am getting into. It is easy to post and talk, but seeing a final product might excite this EV bug even more.



TX_Dj said:


> More or less, lead weight == range.
> 
> Pick a few different types of batteries that you like the price and size of, and then get the manufacturers to send you their Ah capacity charts down to *at least* the 1-hour rate, if not down to the 30-minute rate (not likely), and also try and get the "reserve capacity" charts up to at least 125A. These will let you see the peukert's numbers in action.
> 
> ...


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## BBrown (Jun 8, 2008)

I'm far from expert, and have mastered few of the formulas, memorized even fewer!
I can share that my actual miles on the road experience after about 300 EV miles with a battery pack of 24 US125 six-volt batteries, Curtis controller and Advanced adc-4001a motor:
My daily routine 20 miles is easy - seemingly plenty to spare.
30 miles is a stretch in my terrain - very hilly, mountainous.
That gets me home pulling pack voltage to 90 or 100 volts slowly coming up the driveway.

evalbum.com/2004

Pounds lead equal range. BUT pounds lead also = lots of weight to lug up the hills.
I'm far from disappointed, but will be overjoyed if/when a better technology becomes affordable.
Bob


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## DIYguy (Sep 18, 2008)

I would be interested to know if anyone has done a 160 volt pack with 8 v floddies in a small pick-up. The higher voltage should reduce the peukerts and with the reduced weight and greater power potential (when u need it for hills), might be an interesting comparison to 24 x 6 volts. When I say "comparison" I mean "drive-ability" not flat out distance only. 

Thoughts?


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## dimitri (May 16, 2008)

160 V nominal means at full charge you will have over 170 V for few minutes, which maybe an overkill for typical 144 V controller. I would not risk my controller, unless I have one rated for this voltage.


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## ElectriCar (Jun 15, 2008)

DIYguy said:


> I would be interested to know if anyone has done a 160 volt pack with 8 v floddies in a small pick-up. The higher voltage should reduce the peukerts and with the reduced weight and greater power potential (when u need it for hills), might be an interesting comparison to 24 x 6 volts. When I say "comparison" I mean "drive-ability" not flat out distance only.
> 
> Thoughts?


You're going to have a harder time finding a controller. I was told with a 156V pack and the Curtis 1231 I would have to let the voltage settle a bit before I could drive after charging.


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## DIYguy (Sep 18, 2008)

Hey Guys.....

Yes, I was *not* planning on using a144V controller. 

Here's the thing..... doing a small truck, and wanting decent range, say 40+ miles and also wanting decent acceleration and ability to cruise at hiway speeds, I'm trying to decide on battery type vs voltage. (Ya, we would all like LiFePo's or some new lighter technology For me, it will likely be the second set .. not the first). Most ppl doing small trucks that want range, opt for 20 or 24 X 6 Volt floodies. Ya, the range is decent but they find out pretty quick that the ability to dump current out of 6 volt flooded cells isn't so great. Regardless of the controller, the batteries just don't discharge quick enough to generate the hp. So, if you consider higher voltage, this becomes better.. .except you make a very heavy load, heavier. So, now you look to 8 volt floodies and a compromise. 

Now, AGM's will dump power fast enough to cure the acceleration problem, but won't give you the range. One could actually run AGM's at a "lower" voltage than flooded and get similar acceleration. Hypothetically, and discounting final payload for a moment, what voltage would be required with AGM's to equal say, 156Volts with flooded? If I could answer this, I would consider running two strings of AGM's in parallel... particularly if the answer was 120 volts or lower. Yes, the cost would be pretty high for the batteries, but perhaps I could get the range I want with two strings of 10 AGM's at 120 volts with less on-board weight (20 vs 24 or 26 batteries total) and better perfomance when I want it.

I realize the tempations with better acceleration are always there. But I don't want to exploit it... but I also don't want to have to pull over on a long hill or avoid a hiway for 5 km of my commute either.

Thoughts would be appreciated. 

Gary


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