Charging
I used to think of a battery as a storage device which you pump power into to retrieve later.
This is reasonably true, but not correct. This is how we use them, but not how they are.
A battery is a live chemical reaction.
A battery has two states, charging and discharging.
Each of these can be rated to decide how much power this chemical reaction can absorb or produce.
This rating is known as C.
A 24V10AH battery with a 1C discharge rating can provide 24V at 10 amps (240W) for 1 hour. Cheap LiFePO4 batteries can provide around 2C, ie 24V at 20 amps for half an hour. The cells we use have a safe continuous discharge of 13C. This means you can use the 240W of power you have in one 13th of an hour or less than 5 minutes. This means you can provide 13 times 240W or 3.12KW for just under 5 minutes.
So, anyway, we were supposed to be talking about charging, and that is a nice back-drop.
The cells have a 5C charge rate. This means we can charge a 24V10AH battery in 12 minutes safely (60/5C = 12) with no deterioration of the 3000 cycles these cells will produce.
In reality we have a 40 amp charger which recharges to 95% in 15 minutes.
Why only 95% ?
The last 5% is a trickle balance charge which always takes a few more minutes. It is a small current to balance each cell. Critical to battery life. It gets faster as the battery matures and the cells learn to live together.
The 40 amp charger is a very expensive commercial charger which I will be placing strategically throughout the country for free recharges in Cafe’s and Bars. I will start with Christchurch.
Today Christchurch, tomorrow the world………..
The other thing I would say is that all our smart chargers can be paralleled. We provide the cords too. What this means is if you have a 5amp charger which can recharge a 10AH battery in 2 hours, you can plug 2 chargers in (10 amp now) and recharge in one hour. 4 chargers equals half hour and so on. Cool. Bring on the Motorbikes, cars, boats, trains and planes.
It would be remiss of me not to mention PI/PO efficiency calculation when we are talking about charging.
PI=Power in
PO= Piss off or Power Out
LiFePO4 has a fantastic PI/PO ratio of almost 1. One is impossible perpetual motion, although youtube thinks anything is possible. If you are ever bored and want to laugh search youtube for perpetual motion, priceless.