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Discussion Starter #1
Hi

How many lead 12v batteries would I need to to propel a 1400kg car to 70mph with a range of 50 miles and what would be the best way to connect them together?

Also what type of charge would I require and to be compatible with PowerPoints available at the side of the road?

Thanks for your help


Regards

Jon

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Don't waste your time with lead. Go with lithium. You should read up a bit in some of the stickies and other posts to get some more information on the rest of your questions. In regards to public charging stations, the standard is J1772. Just look that up.

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Ya, for that big of a car and that range you're probably talking, what, approaching a 15-20 kwh pack? And that's for lithium. For lead it would have to be substantially larger, right?
Rough guesstimate is that a lead pack would add another 50% to the weight of your car.
 

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Hi

How many lead 12v batteries would I need to to propel a 1400kg car to 70mph with a range of 50 miles and what would be the best way to connect them together?

Also what type of charge would I require and to be compatible with PowerPoints available at the side of the road?

Thanks for your help


Regards

Jon

Sent from my F8331 using Tapatalk
50 miles is right on or even beyond the maximum possible for lead acid - you would need over 50% of your vehicle weight as batteries and you are getting to the point of diminishing return

And that is talking about expensive lead deep cycle batteries NOT 12v car batteries

Lead is dead !
 

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Discussion Starter #6
Thanks for your responses guys, really appreciate them

The thing is I'm on a limited budget, and have been given for free 8 high quality 12v telecoms battery's ( I'll post their specifics soon )

So If I can't use lead what am I looking at Lithium wise cheaply? I've found a 2018 lithium battery pack from a Toyota Yaris hybrid for £380 , would that get me 50miles?

Oh and finally what charger kit would I need to be compatible to power lead or lithium to be used at service station etc?

Sorry if this has been covered before, I'm finding it hard to search for the exact Info I need

Cheers

Jon

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There is no way you're going to get even close to the range you want with those batteries. For comparison, Polaris Ranger EV is a bit under 800kg, running on eight 155Ah lead-acid batteries. Manufacturer advertised range is 30 miles (50km), in reality it is about 25miles, and that's while the vehicle can't even go faster than 25mph.

What you want is to put up a few thousand dollars to secure about 20-25kW worth of Nissan Leaf cells, that may get you where you want to be.
 

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Discussion Starter #8
Ok, so my commute to work is 20 miles, so even If I managed to achieve 60mph and charged my car at work to get me home would this be possible or not?

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Ok, so my commute to work is 20 miles, so even If I managed to achieve 60mph and charged my car at work to get me home would this be possible or not?

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With Lead - I would say - no not really - 20 miles on brand new batteries would be possible but six months later you would not make it

Best bet would be either Leaf or Volt or Tesla modules
 

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There's no point in comparing batteries unless you understand how much energy they can hold, and how much you need.

Battery capacity is usually expressed in kilowatt-hours. For each mile you move the car, you need roughly on third of a kilowatt-hour (0.33 kW∙h)... so for 50 miles, you need at least 16 kW∙h. To calculate the approximate energy capacity of a battery if it is not provided, you can multiply the battery voltage by the capacity in amp-hours... if the amp-hour capacity is known.

For instance, eight lead-acid batteries at 12 volts and 100 amp-hours each (a common size) would have a nominal capacity of 10,000 watt-hours, or 10 kW∙h. Unfortunately, that capacity is determined under conditions in which they are discharged slowly; when they are discharged quickly (providing the high power needed by a car), their capacity is greatly reduced, especially in the case of lead-acids.

Non-plug-in hybrids only use the battery to store enough energy to move the car for a few seconds - they have a battery which is usually around one kW∙h. They're generally useless in an EV, unless you want to combine a dozen or more of them.

Plug-in hybrids typically have 8 to 16 kW∙h of battery. The biggest ones can be just enough to provide somewhat useful range in a typical EV, but since the manufacturers of hybrid vehicles typically can't make them go more than 50 miles on the battery charge, a DIY conversion of the same size of car won't make it that far, either. The Chevrolet Volt battery is a popular example; a Volt has an electric range of 53 miles, with a much more advanced motor and other components than a DC DIY conversion would typically use.

The obvious source of a large enough battery for an EV is salvaging one from another EV (such as the Leaf or Tesla already mentioned). The battery (or battery pack, as it is composed of several modules) is as large as over 100 kW∙h in some EVs, and useful EVs start at about 24 kW∙h for smaller cars with moderate range.
 

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Don't forget the aerodynamics at speed. Energy requirements to go 50 miles at 35MPH are significantly different from energy requirements of 50 miles at 70MPH (or 60MPH, not a significant improvement).

Good example of this is Zero motorcycles. ZERO S ZF14.4 (that's almost 15kW, at 400lb total vehicle weight) does 179 miles in the city, and only 90 highway miles at 70MPH. Those numbers are provided by manufacturer, they are probably quite a bit lower in practice, especially with head wind, but proportions should still stand.
 

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Discussion Starter #12
Great information thank you :)

So because of my limited budget would it be cheaper to make my own lithium battery packs? IE using laptop cells etc?

Or is it cheaper and less hassle just to buy a leaf battery or volt battery?

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Great information thank you :)

So because of my limited budget would it be cheaper to make my own lithium battery packs? IE using laptop cells etc?

Or is it cheaper and less hassle just to buy a leaf battery or volt battery?

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Used OEM EV battery packs are plentiful. Wait for a good deal, and you'll save a bundle and get a lot of good parts.

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Discussion Starter #14
Thank you, I'll keep an eagle eye out :)

So how would I connect to a used EV battery? So I have to take it apart?

Also what voltage DC motor would you recommend?

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So how would I connect to a used EV battery? So I have to take it apart?
Since there is no space in an RX-8 large enough and appropriately shaped to take an entire EV battery pack of a useful size, you would need to open up the battery housing, remove the modules, and rearrange the modules (or some of them) to fit some space in the car... and build mounting structures for them, and a box around them, and re-arrange the wiring between them...

This is normal for EV conversions - I've never heard of anyone being able to simply use a complete EV battery pack intact.
 

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Discussion Starter #16
I see, that makes sense, and how would I charge them? Are there charging kits available that are compatible with service station chargers?

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With a 50 mile range where you're bouncing back and forth to work as the defining operational envelope, charging at the house overnight, you're not going to find fast-charge points within your range for any random long-distance trips with the car.

You also are not going to fast charge without the sophistication of temperature management. $ cha-ching. And a fast charger onboard. $ cha-ching.

And, you're going from free "telecom" (which are usually 48V and huuuge (repurposed submarine batteries), so you'll need to validate the donor's claims) lead acid now, to lithium big bucks (a defective, one or two dead cells used module is still selling for an insane $150/kWh on eBay, which is GM & Tesla's rumored cost for *new* packs). $cha-ching. You're now creeping waaay out of your budget by at least a factor of three or four of what it might have cost to do this project on the cheap (can't beat free batteries and a couple or three grand for a DC motor and controller, less if you patiently wait for used to come up)) in order to "do it the right way" instead of the "right way" 20 years ago on forums like this.

My suggestion is that you buy a smashed Nissan Leaf or other cheap used EV and transplant the whole shooting match if you have mechanical talent and are willing to put $7k into a project. It'll cost you less than double the free lead acid cost, and about the same as the lithium battery modules on eBay. You can also go onto Youtube and find lead acid conversions (a high school kid did a Fiero) to see if it's your cup of tea.
 

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my car is a tiny suzuki 800 hatch, i have a 14kwh lithium pack (48 cells 100ah @ 3.2v)
my car weighs about 700kg all included
round trip my car does about 80km (about 50miles)
you want to do the same distance and speed that i do, in a car that weighs twice as much.
with lead acid, this is never going to happen.

i would change to a lighter weight car (most of the conversions on here are light weight, or aerodynamic cars)
get something around a ton or less.


rule of thumb is, the weight of your vehicle in pounds, divided by 10, is how many watt hours it will take to travel 1 mile (not accurate but its ok for guessing) so your car weighs 3000lbs so it will take 300watt hours to travel 1 mile (probably a little more)
to travel 50 miles youll need 15kwh usable battery as an absolute minimum.


with lead acid you can use roughly half of the advertised capacity so you would need a 30kwh lead acid pack (weight about 1625kg)

with lithium you can use roughly 80% of the advertised capacity so you would need a 19kwh pack (weight about 200kg)


if you are from australia where salvaged EVs just dont exist, then going the laptop battery route is going to be cheapest.
getting the pack you want from calb prismatic cells is going to cost about 9k aud, with laptop batteries its going to take a few years and its very fiddly but it will be cheaper.


all of this said, if you are keen then i would have a google search for a car called "forkenswift". its a suzuki swift that was converted to electric for about $1500.
it cant go highway speeds but it would be an excellent learning experience. i would use the telecom batteries to make a prototype and move on from there.


the other alternative is to use the telecom batteries to make your fridge and a few other household appliances "off grid" and charge with solar to get your power bill down
 
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