EV Charging from battery bank and inverter ?

[Paul2129]

Firstly, I think I should really use some of my spare time to get some actual training, maybe a course that might help me understand a subject for which I have interest, but currently little or no knowledge of

I'm aware of the fact that I go about things in the wrong way sometimes, and I spend a lot of time doing things that actually are pointless, but as an experiment, if it can be achieved at a not ridiculous cost, here's what I like to do :

1, get hold of some reasonable priced solar panels and mount them south facing on my garage

2, think I need a charge controller for the above

3, create a nice neat box with a line of ex-car batteries *

4, fit a suitably sized (price to be reasonable) inverter, I guess must be a clean enough wave to work ?

5, plug my electric car in to charge, no full charges, just for fun, and to support a few miles

*think I can source a good quantity of car batteries that are no longer good in a car, and otherwise would be recycled for scrap

so, in not expecting miracles, and not knowing the exact way to work this stuff out, I was guessing maybe 4 to 6 reasonably decent solar PV's, as many batteries as I can get my hands on, a charge controller, and an inverter that can run a solid 6A / 1500watts all day, would this actually work ?

running my car 'partially' on renewables, and recycled car batteries would make me very happy indeed

your thoughts as ever, most appreciated

the guy in the link below has build himself a battery bank out of 18650's, mine would (probably) be car batteries, but in essence, what he's done if roughly what I'm after... with solar panels



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[ProDave]

What is the capacity of your car in kWh?

Have you worked out how much energy you can capture and store?

What percentage of the vehicle capacity is that?

I suspect it will be small

I may be wrong, but I suspect your efforts will be futile.

 

[Sidney]

Car batteries wouldn't last long, you'd need deep cycle leisure batteries.

 

[Paul2129]

thanks for your replies,

for ProDave :

Capacity of car doesn't matter, more what I use per day, how about a couple of kWh's ?

Don't know how much I can capture an store (yet) as much as you can get with 4 to 6 panels and a  couple of dozen 'past their best car batteries ?

vehicle capacity doesn't matter (I have two EV's anyway)

size doesn't matter

you're probably right, most things I do are pointless... so should I give up the idea ?

To Sidney :

you're right, I'm sure, but what if you had a 'lot' of old batteries ? big leisure batteries aren't cheap, and I really like the idea of recycling if poss

thanks guys for your replies, and on your advice, I'll give up another (crazy) idea, as it's looking like it won't happen within my budget. I'm sure that given a ****-pile of decent batteries, a powerful inverter, and a roof full of PV it works perfectly..... but the payback is more than my lifetime !

what a shame

 

[binky]

I am assuing you have EV charge point already, in which case perhaps a small solar system directly feeding the mains supply would be best option if either of your EV vehicles are home during the day? Effectively you already have a large battery in each car. You can also buy solarinverters that are designed to supply EV charge points, but thye aren't cheap. Car batteries are the wrong tech, they are only really desinged to provide a high initial power surge (ie start your car), and don't like being deep discharged.  I would look at off-grid solar / battery charge controllers . I normally fit on-grid systems so I am not very familiar with this side of solar gear.

 

[Paul2129]

thanks guys, I'm barking up the wrong tree then. Even a large quantity of car batteries can't supply a few kWh's ?

thanks for your help, I guess I'll give this one up. There's still a chance of a 'proper' solar project on my place of work, so we'll have to hope for that one instead.

For me, driving an EV makes me feel like I'm doing my bit for the environment, I'd thought that a bank of otherwise recycled batteries (which would have been a lot) would have provided my few kWh's of power, after all, they'd be next to free, so technically there could have been an almost unlimited supply of old batteries. if it won't work, I guess you're right

thanks for all the advice, as usual 

Paul

 

[Doc Hudson]

If the engine isn't running most modern cars will automatically turn the ignition off after 20 or 30mins, so as not to drain the battery below a level sufficient to start the car. (and that is with new good condition batteries). As fundamentally car batteries have one key purpose. Keep enough charge to allow the car to be started. Once it is started the alternator takes over most of the power requirements of keeping all the car electrics running whilst also recharging the partially depleted  battery.  So with no alternator an average car battery cannot actually supply any significant power for a long duration.

Caravan, Boat, Motorhome, leisure batteries are designed to be charged up then keep a decent amount of capacity for a few days to supply basics such as 12v  lights, TV, water pump, maybe fridge  etc.. until a new 230v hook-up can be connected to recharge. So it is your charging and discharge capacities for the required load you need to be calculating.

Assume you do connect up this bank of second-hand batteries to construct your 'power pack', if some are more naff than others then they will start draining power from the 'better quality' batteries so you will be losing capacity within you system. 'IF' it was a semi-feasible concept you would need a bank of good-batteries not second-hand, near end-of-life items. (If you have a torch that needs three 1.5v AA cells, its no good using 2x half decent cells + 1x near dead cell.  Give it a try and compare 3x new, to 2x second hand + 1 near dead, see how lamp life compares).   

Plus are you suggesting your "batteries" are going to be via an inverter to produce mains voltage to then supply your car charger? if yes then this will introduce more losses into the system.  And, even with a standard basic 13A plug car charger, many manufactures quote approx. 6miles per hour charging from a 13A plug. So even if your 'system' did work, the returns are going to even less than this, in which case you are better off just using a standard 13A plug charger and spending your time and money on a few beers and a couple of decent DVD's or Netflix/Amazon Prime subscriptions to watch your favourite programs with friends or loved ones!

Doc H.

 

[Doc Hudson]

Just to add, even if your concept isn't feasible, it was still a sensible question to ask if you don't fully understand some of the nuts and bolts about how electricity works.  Thank you for asking, this may also help others who maybe thinking similar ideas to yours.

Doc H.

 

[Paul2129]

only just noticed this reply Doc, its nice of you to say that, you guys have always been a great help, the time you take to comment on some of my crazy ideas is much appreciate

Paul