Ok so ive found a 4kw motor for the build & im looking for suitable batteries to power it. Im no electrician but im trying to find out how many 12v deep cycle 110ah batteries i need to power the motor for approx 90mins per day.

If 1ah = 60am then one battery gives me approx 6000am
a x v = w
so 110x12= 15840watts so 16kw roughly

as the battery is rated in ah does this mean it can sustain 16kw/h?
somehow im doubting that one leisure battery will power the car so where have i ***ed up?

If your battery is 110 amps by 12 volts, then it can supply 1320 Watts (how did you come up with 15840, did you square the 12 for some reason?), so you'll need at least 3 of them to supply enough power for the motor (even then, only just at 100% efficiency; so really you need at least 4).

If the motor is 12v and drawing 333 amps, then to run for 90 minutes you need 500 amp hours, which is 5 batteries. More with inefficiencies considered.

That's over 100kg of battery already, add in the rest of the mass of the car, a driver, and maybe passengers and luggage, and that's a lot of inertia for a little over 5hp to be moving.

ah yes my knackered mouse sometimes double clicks so yes i squared it.
So if i cut the drive time down to 1hour i could just about get away with 3x110ah batteries. @ £80 a pop they aren't cheap. 500 recharges only.

So every 18months i will have to buy new ones. Then again thats cheaper than the equivalent in petrol.

Making one of these?

Is the motor only 12v? thats not much tbh, get one that can take more Voltage and you will get more powerrrrrrrr.

Btw if the battery's are 110ah and the motor will draw 110 amps constant it will run for an hour.

I dont know if this will help at all, but on the older fords that we use for banger racing, we wire 2 12v batteries up in series to feed the starter motors with 24v, which works very well despite them only being designed for 12v, however, when we tried it on some japanese cars we found that it was too much and we blew a lot of starter motors up that way on the nissans, so we now wire 2 12v batteries up in parallell instead, as nissan engines tend to get very tight when overly hot, and a single 12v battery just isnt enough to fire it up again if the engine is baking hot.

what kind of batteries are we talking about here? if were talking lead avoid them since they will only give you the rated capacity if you discharge them at well under 1c (also lead batteries are utter shite in every way possible)

What do you consider an electric car? 4kw is roughly the power of a golf cart
Also be aware that the current a motor draws depends on it's load, not on it's rated power. Without a current limiting motor controller it might easily draw 10x it's rated power, but you can probably guess what will happen then.