Charging efficiency

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Charging efficiency

Postby RobSmith » Mon Aug 02, 2010 8:25 pm

I am intending to use wind power / PV panels / diesel and possibly other energy sources to charge a number of forklift lead acid batteries.
I am thinking we might use two packs of 24 cells of 2v each and about 1000Ah.
I am not sure how efficient the charging and using of electricity from the batteries is.
If my sources of power produce 12kWh per day I was wondering how much of that would be lost in the charging / inverting process.
If we are to charge an electric car we may be charging batteries to then charge the batteries in the car so we loose out twice.
It seems that PV panels are next to useless when it comes to trying to keep up with the demands of a household and car.
I am trying to figure out what size, hieght and number of wind turbines we would need so any charging losses make quite a big influence on the turbine/s we end up with.


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Location: Hampshire, Basingstoke

Re: Charging efficiency

Postby arsharpe » Tue Aug 03, 2010 7:28 am

Just of the top of my head switching electronics, e.g. switched mode chargers and inverters are about 85% efficient.

I wouldn't have said PVs are useless. They are good in that they are less intrussive on installation and have a high feed in tarriff return

You could save a lot in conversion losses by charging from the generators (PV 7 wind turbine) directly from the DC source. But
...-you may need a spare EV or leave your EV at home during the day.
...-the generators would have be sized to fit the EV or the other way around.
...-you would not get the feed-in-tariff benefit because you are taking the power before the meters that are used to determine your benefits.

I am doing something similar myself and it is all a compromise. My intention is to install PV and hot water panels and configure system to charge my EV and allow my EV to supply power to the house if we get power cuts in future. It just takes a bit to get the sizing and accessible connections right. See attached file for my PV spec wip.
Spec of PV for charging EVs & EV powering house.
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