# Help a Noob! :) (Battery Questions)

Ok, so idealy speaking, i would like to be able to go 50 ~ 55 MPH and go at the very least 20 miles, and preferably 30 miles round trip to be safe. It’s 8 miles to work, and the furthest i would ever really drive is 15~ or so miles.

[B]edit: chargering at work/destinations would be no problem.[/B]

So:
50~55MPH
20~40 miles
acceleration doesn’t matter

I would like to do a 96v or 144v system with 12v batteries if thats at all possible. I would go with SLA - RIGHT? I would like to not have to spend more than 2K on a battery pack. What are my options.

Thank you for helping me out and getting me in the loop. I am having a hard time finding batteries and figureing out what does what so i’ve come here to ask the pros.

thanks for all of your help everyone.

Ok, i’ve had a handful of views but no one has any answers for me.

I have done even more research, but i’m still looking for more answers. My question now is.

[B]What is the voltage of a battery pack directly proportional to? Speed or distance?[/B]

[B]What is the battery packs’ AH (amp hour) rating directly proportional to? Speed Or Distance?[/B]

Any help would be appreciated!

I’m looking at doing a 96v system using T-105 batts for starters and then add batteries here and there possibly getting up to 144v one of these days.

Hi,
The problem I see with that is that controllers and chargers are pretty specific to volts. If you started with a 96 volt system that would be ok until you start adding. Im not sure but I think the controller would handle up to 120 but the charger would have to be upgraded to the specific voltage you are running at.

As I am a noob you might want to wait for verification from someone with more experience.

I’m in the same boat trying to design my first EV as well.
I can tell you that higher voltage is going to affect your acceleration and top speed. Amp hours is how long those batteries will be able to deliver power so that’s your range. Neither of those values alone are really useful though by themselves and you should, overall, try to think of your battery system in watt/hours. Watt = Volts x Amps. So as you raise the volts, you also need less amps to create the same amount of watts.

How many watts do you need for your commute? I have no idea and I’m trying to figure that out myself

I’ve been looking around at other systems and trying average out some of the numbers I’m seeing. It looks like on average you need about 9-10k watts to keep your car moving stedily at 60mph or so. There are of course tons of factors that change how many watts any car will need (aerodynamics, rolling resitence, etc). So doing some simple math if you need to drive 30 miles doing 60mph that’s 30 minutes of driving which would require, lets say 5k watt/hr worth of power. If you have a 144 volt system then you need about 35Amp hours worth of power. This is of course not taking into account any accleration changes, stopping, etc. AND most importanly it’s not taking into account the fact that batteries are rated for a 20 hour discharge, not 30 minutes. I saw a table somewhere for Trojan and it said that with a 1 hr discharge you only got (I think) 57% of capacity and even less for only 30 minutes. In addition you shouldn’t go below 80% depth of discharge, less is better. There are no ratings for 30 minutes but if it was closer to say 50% and you pushed the battiers to 80% DoD you need around 85-90AH. Take into account stop and go traffic and it’s much worse with all that accelerating.

Are these number accurate? Hehe I wouldn’t trust them but it’s all I’ve been able to gather and assume. I’m still waiting for somebody smart to jump on here and give me some good info from experience

Brian

[QUOTE=bblocher;3476]I’m in the same boat trying to design my first EV as well.
I can tell you that higher voltage is going to affect your acceleration and top speed. Amp hours is how long those batteries will be able to deliver power so that’s your range. Neither of those values alone are really useful though by themselves and you should, overall, try to think of your battery system in watt/hours. Watt = Volts x Amps. So as you raise the volts, you also need less amps to create the same amount of watts.

How many watts do you need for your commute? I have no idea and I’m trying to figure that out myself

I’ve been looking around at other systems and trying average out some of the numbers I’m seeing. It looks like on average you need about 9-10k watts to keep your car moving stedily at 60mph or so. There are of course tons of factors that change how many watts any car will need (aerodynamics, rolling resitence, etc). So doing some simple math if you need to drive 30 miles doing 60mph that’s 30 minutes of driving which would require, lets say 5k watt/hr worth of power. If you have a 144 volt system then you need about 35Amp hours worth of power. This is of course not taking into account any accleration changes, stopping, etc. AND most importanly it’s not taking into account the fact that batteries are rated for a 20 hour discharge, not 30 minutes. I saw a table somewhere for Trojan and it said that with a 1 hr discharge you only got (I think) 57% of capacity and even less for only 30 minutes. In addition you shouldn’t go below 80% depth of discharge, less is better. There are no ratings for 30 minutes but if it was closer to say 50% and you pushed the battiers to 80% DoD you need around 85-90AH. Take into account stop and go traffic and it’s much worse with all that accelerating.

Are these number accurate? Hehe I wouldn’t trust them but it’s all I’ve been able to gather and assume. I’m still waiting for somebody smart to jump on here and give me some good info from experience

Brian[/QUOTE]

Brian,

I shouldn’t be on the computer right now because i have other things to do so i’m going stay short. :

I either have no clue what my round trip wattage would be. All i know is that my commute is 8 miles to work and another 8 miles home. the absolute furthest i would have to drive is 15 miles one way and 15 miles home. In this case charging at my destination 15 miles away would NOT be a problem.

Would someone explain to me what DoD is (depth of discharge)? What exactly does it mean?

Nick

regee:

a lot of the stuff i’m getting including charger and controller are rated from 96 all the way to 144 and the specific system i want can handle 96 thru 144 v so i’m not toooooo worried.

[QUOTE=PATZKE;3478]
Would someone explain to me what DoD is (depth of discharge)? What exactly does it mean?[/QUOTE]

DoD is just how far you drain the battery and is the inverse I guess of how full it is. So if you start with a 100% full battery and you do 80% DoD then you have 20% of your battery remaining. It sounded complex until I read up on what it meant, then I was like oh…duh

If you only have to go 15 miles round trip you are sitting pretty darn good. I need 75 or so round trip but can at least charge at work. So I need 35-40 range.

Again no expert here (still trying to design my first EV) but you could probably use some 12v 50AHish batteries and be fine.

I recommend going to evalbums.com and trying to find builds close to what you’re thinking of and look at some of their ranges. Don’t trust all the numbers though, get a good sample set because I see some people putting in ranges that are guesses etc as they note the build isn’t done yet

Brian

[QUOTE=bblocher;3485]DoD is just how far you drain the battery and is the inverse I guess of how full it is. So if you start with a 100% full battery and you do 80% DoD then you have 20% of your battery remaining. It sounded complex until I read up on what it meant, then I was like oh…duh

Brian[/QUOTE]

hahah what an active guy you are on the forum. But yeah thats what i figured on the DoD, I just wanted to confirm. But people say not to go below 80% DoD?

Now i have to do more research on my batteries. hahaha i thought i knew more.

Thanks Brian!

I just found this info on an Advanced DC #FB1-4001A, 9.1", double shaft motor.

Horsepower Ratings:

At 96 VDC, 20 HP continuous, 23 HP for one hour, 35 HP for 5 min., 70 HP peak

At 120 VDC, 25.2 HP continuous, 27.5 HP for one hour, 43 HP for five min., 85 HP peak

At 144 VDC, 28.5 HP continuous, 30.4 HP for one hour, 48.8 HP for five min., 100 HP peak

One Hour KW rating:

17.3KW @ 96VDC, 20.8KW @ 120VDC, 22.9 @ 144VDC

The last bit would be the important part for trying to figure out your range…it appears my guess of around 10KW was way off Half of what this motor is claiming to require.

Ugh,
Brian

[QUOTE=bblocher;3489]I just found this info on an Advanced DC #FB1-4001A, 9.1", double shaft motor.

Horsepower Ratings:

At 96 VDC, 20 HP continuous, 23 HP for one hour, 35 HP for 5 min., 70 HP peak

One Hour KW rating:

17.3KW @ 96VDC, 20.8KW @ 120VDC, 22.9 @ 144VDC

The last bit would be the important part for trying to figure out your range…it appears my guess of around 10KW was way off Half of what this motor is claiming to require.

Ugh,
Brian[/QUOTE]

Brian: The motor specs that you found were for a 9.1" motor which from what i’ve seen is for a lot more performance based, sweet cars. For a general street conversion EV car, people are using and say that 8" motors.

Both examples are on a 96VDC system using 5AH ratings:

Ok, so if i did my math right, with 12 8v T-875’s would give me 13.9KW (right?). So does this mean that i would be able to run just under an hour (.8 of an hour)

With 16 6v T-105’s that would give me 23.6KW giving me 1.4 HR of full blast run time.

Things are starting to make sense, I have to find the rating of the motor I want to get.

How can you determine how far one can drive off of 23.6KW of energy?

The math is correct, BUT, the capacity of the battery you are doing is for a 5 hour rating…If you are expecting the battery to be dead in say 1 hour then you need the 1 hour rating of the battery which is less. I believe the trojans were something like 57% of the 20 hr rating for a 1 AH rating which would only be 97 AH on your t-875 example. This is assuming you drove 1 hour non stop and that drained the battery completely.

The BIG question we need to figure out is how many watts we will use on average (cruising speed). I started thinking about the numbers I found on that motor and I’m thinking the 17.3KW is how much it takes if you are pulling the 20HP continuous rating. If we don’t need that much power for cruising we would draw less power. If you do mostly stop and go you would use more than this rating.

So it may be that my original figure of about 10KW for cruising might still be accurate. I got that number from build the guy did in the “Convert It” book and the build at www.kiwiev.com (awesome info in both places).

In regards to the 9" motor, I’ve just seen these mostly used. But you’re right, let me look at some motor specs and compare a few things. They are lighter and cheaper. My only concern is having the power to cruise at 65mph without over heating it and is it more effiecient to work a little motor harder or under work a big motor?

Brian

I got some amazing information that I think will answer your questions, as good as you can without doing some trial runs after you build.

Visit http://www.ev-america.com/ and email them for their free EV information. It covers a range of great information on how to calculate your range.

Brian

[QUOTE=bblocher;3515]I got some amazing information that I think will answer your questions, as good as you can without doing some trial runs after you build.

Visit http://www.ev-america.com/ and email them for their free EV information. It covers a range of great information on how to calculate your range.

Brian[/QUOTE]

Thank you Brian.

I just sent him an email. looking forward to a reply.

Brian,

Here’s a battery from Universal Batt for 177\$ a peice

Its a 12v @ 75 AH (? dunno the hour rating)…

Are they really 75 AH though …

http://www.batterywholesale.com/battery-store/proddetail.html?prodID=2700

[QUOTE=PATZKE;3582]Brian,

Here’s a battery from Universal Batt for 177\$ a peice

Its a 12v @ 75 AH (? dunno the hour rating)…

Are they really 75 AH though …

http://www.batterywholesale.com/battery-store/proddetail.html?prodID=2700[/QUOTE]

Did you get your info form EV America?

I haven’t commited to batteries yet but I think I’m getting my from Costco for a few reasons. They are 115AH batteries (around 70lbs) and only \$70 a piece. They are deep cycle and I’ve seen some good reviews (although not EV related). My biggest thing this is a very cheap way to figure out the range of my EV with this amperage and if I need to make some adjustments I’m not out much. The math says they will be enough, but just in case

Brian

haven’t commited to batteries yet but I think I’m getting my from Costco for a few reasons. They are 115AH batteries (around 70lbs) and only \$70 a piece.

What batteries are they? I’ll join Costco just to get them. I’ve been looking at tempest batteries. 12V@115AH would be good, especially @ \$70 a piece.

Noisome

[QUOTE=noisome;3659]What batteries are they? I’ll join Costco just to get them. I’ve been looking at tempest batteries. 12V@115AH would be good, especially @ \$70 a piece.

Noisome[/QUOTE]

They are Kirkland brand which I’ve read is actually made by Johnson Controls who makes batteries for a lot companies like the Die Hards for Sears, Duralast, Interstate, Optima…some others I’m sure.

Walmart also has 115AH batteries and they are even cheaper, about \$60 but I prefer dealing with Costco

Brian

[QUOTE=bblocher;3660]They are Kirkland brand which I’ve read is actually made by Johnson Controls who makes batteries for a lot companies like the Die Hards for Sears, Duralast, Interstate, Optima…some others I’m sure.

Walmart also has 115AH batteries and they are even cheaper, about \$60 but I prefer dealing with Costco

Brian[/QUOTE]

Was at Costco with my dad rotating the tires and wanted to look at batteries, but I forgot.

I will go back soon to look at some… If I do not go costco, which I may, I’m very fond of these:

http://store.solar-electric.com/cr225am6vode.html

Those are some beasts for a great price… Kinda heavy though…

[QUOTE=PATZKE;3665]Was at Costco with my dad rotating the tires and wanted to look at batteries, but I forgot.

I will go back soon to look at some… If I do not go costco, which I may, I’m very fond of these:

http://store.solar-electric.com/cr225am6vode.html

Those are some beasts for a great price… Kinda heavy though…:D[/QUOTE]

Those aren’t bad at all. The weight each is decent, and the price is good (except anything you buy online would kill you in shipping I think which is why I’m just looking around locally). I tried to check shipping on that site and it won’t let me. It says the item has a shipping restriction but I don’t see anything about freight shipping

I’d like to go with 6v and more batteries but my little S2000 won’t hold much so I think I’m stuck with 12v (shooting for 144v on my system).

Brian

[QUOTE=bblocher;3671]Those aren’t bad at all. The weight each is decent, and the price is good (except anything you buy online would kill you in shipping I think which is why I’m just looking around locally). I tried to check shipping on that site and it won’t let me. It says the item has a shipping restriction but I don’t see anything about freight shipping

I’d like to go with 6v and more batteries but my little S2000 won’t hold much so I think I’m stuck with 12v (shooting for 144v on my system).

Brian[/QUOTE]

Brian:

Yeah, shipping would be a killer - intact they don’t even ship! They’re not legally allowed to or something wild like that. I emailed them to see if they had a sweet price on 16+ but they got nothing (unless i want 24). I would have to pick them up, which isn’t a big problem seeing they are 2 hours away.

If I go 6 volt i will stay at 96 or 108V.

if i go 12v i’m in the 144v boat with you.

STILL heart broken…

[QUOTE=PATZKE;3695]Brian:

Yeah, shipping would be a killer - intact they don’t even ship! They’re not legally allowed to or something wild like that. I emailed them to see if they had a sweet price on 16+ but they got nothing (unless i want 24). I would have to pick them up, which isn’t a big problem seeing they are 2 hours away.

If I go 6 volt i will stay at 96 or 108V.

if i go 12v i’m in the 144v boat with you.

STILL heart broken… :P[/QUOTE]

I’m so focus on 12v I did forget to mention that costco also carries 6v 220AH batteries for like \$75. The only problem is I usually only see 6 or so in stock at a time

If you’re like me and have 3 costcos within an hour drive it might work out

Brian