# Battery Charging - Electrical Model

A common technique used in battery charging algorithms is Constant Current / Constant Voltage. That is to say, initially a battery is charged by applying a constant current (which I believe is what is commonly called 'fast-charge'), up to a sensed condition, and then Constant Voltage is applied (which I believe is what is commonly called 'trickle-charging').

I envision this working (at least logically) as having (1) a Constant Current Source circuit set to the fast charge current and (2) a Voltage Regulator set to the fully charged target voltage, and switching the positive terminal of the battery between these two circuits.

What is a useful electrical model (e.g. for simulation) for a discharged rechargable battery? If it matters, I'm most interested in Lithium cell chemistry (Lithium Polymer to be more specific).

UPDATE

In order to get some more concrete feedback on this question (maybe this should be a separate question?), what does a circuit that practically / realizably implements CC/CV charging actually look like? From there, if you were to want to simulate this circuit, in SPICE or CircuitLab.com or whatever, how would you actually model the battery in that circuit?

• It is like a desktop current/voltage limit supply where it applies the maximum of the setting up to the limit, so you start seeing too strong a short for the CV limit to kick in, the CC limit stops you. The voltage finally builds up and you are limited by CV and it slowly trickles the rest of the way. This seems to be what you know, the only serious feedback I have is that this is going to be very different per battery, they mostly all have a specific mode they are looking for. The temperature change sensing for some batteries freaks me out. I know it is safe, and why, but still... – Kortuk Jan 16 '13 at 20:40
• Are we talking SPICE here or a mathematical formula? (or both?) – Oli Glaser Jan 16 '13 at 23:03