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Batteries?

What are the best batteries for an electric motorcycle, and for a car too. Or can someone explain how to read the batteries specs (like amps, watts,volts) for the best suited for your ev project?

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Ruy Liu7 years ago
I think LiFePO4 battery is the best type for this, What about a try? we can supply you as an experienced LiFePO4 battery supplier, we made many for EV, HEV, LiFePO4 has longest cycle life, no harm materials to environments, powerful, smaller size with bigger capacity. I'd like to talk with you by emails on more details. Ruy ruy@gebattery.com.cn MSN: ruymax61@hotmail.com General Electronics Battery Co.,Ltd
PKM8 years ago
What are the best batteries for an electric motorcycle, and for a car too.

Opinion is divided. It depends whether your top priority is cost, longevity, weight etc.

Or can someone explain how to read the batteries specs (like amps, watts,volts) for the best suited for your ev project?'

Oy... I'll have a go. Volts are self-explanatory (if you don't know how volts work, I suggest reading up more before attempting an EV project). The vast majority of commercial batteries are 12V or occasionally 6V. People tend to run batteries in series because (I think) higher-voltage motors are marginally more efficient.

The actual current rating of batteries (ie CA or CCA) shouldn't be relevant, if you are drawing that much current for any length of time your batteries won't last long, but you may be thinking of the related Amp-hours capacity, which you can multiply by the voltage to get watt-hours and then divide that by your estimated watt-hours per mile (for a typical DC homebuilt EV you can expect 200 to 300 watt hours per mile) to find your range in miles.

The power of your motor in watts determines the horsepower of your EV, simply put one thousand watts is about one and a third horsepower, but electric motors are rated for continuous not short-term power, so you don't need as many rated KW from your motor as you would need horsepower in a car.

To find the best batteries for your EV- decide on your priorities as listed above (cost, longevity, weight), then decide on a pack voltage, motor and controller combination. Then- if money is no object, buy lithium. If you want decent performance, weight and range but don't have a spare half a million, NiMH are a good tradeoff (available from scrapped Priuses (Prii?)) but difficult to get hold of because Chevron still own the patents and refuse to produce them in significant quantities. If you are on a budget, buy deep-cycle sealed lead acid batteries, and consider putting aside a little of the budget to get your suspension strengthened- a large EV lead-acid pack can weigh over half a ton (the EV-1 pack weighs 1,175 pounds).
bennelson PKM8 years ago
A big part of why higher voltage systems are used is that they draw lower current from the batteries.

Batteries range and life is greatly extended by drawing a smaller current from them.

Volts x Amps = Watts (or work). If you raise the voltage, you drop the amperage to do the same amount of work, such as drive up a hill.
PKM bennelson8 years ago
A big part of why higher voltage systems are used is that they draw lower current from the batteries.

Really?

Say you have six 12V batteries. In series, that would be 72V, so a 500W motor would draw 500/72 = about 7 amps from all the batteries.

In parallel, it would be 12V so the motor itself would be drawing 500/12 = about 42 amps, but that current is divided between the six batteries meaning each one provides the same roughly 7 amps each.

If you are drawing the same amount of power then the current draw and therefore power drain on each individual battery is the same whether they are in series or parallel, provided there are the same number of batteries in each configuration.

I figured that if the motor part of the circuit is running higher voltages, then the current in it is less so you have less resistive losses (power loss = I2R), and as I said I believe high-voltage motors are more efficient in general than low-voltage ones, but that part is more of a guess.

Of course, if you meant that having more batteries means lower current draw on each one then I totally agree.
bennelson PKM8 years ago
MORE batteries in series does lower current on each individual battery. A number of batteries in series OR parallel will pretty much pull the the same current. But in the series configuration you will have MUCH greater speed! Also, you can use thinner wiring through the rest of the system, because of the lower current. (Assuming you don't want to run one cable for each battery to the charger, the controller, the motor, the contactor, etc.)
Plasmana8 years ago
A lead-acid battery. I think...
westfw8 years ago
"best battery" is strongly dependent on whether "money is no object" or not...