Charge time

not based on the parameters you've disclosed.

If you know the ACTUAL capacity of this instance of the battery in its current state. And if you know the initial state of charge. And if you know the charge efficiency. And if you know how much charge you're putting in, you can make a gross estimate.

Very roughly 10+ hours with the 1/2 amp charger. More likely 15 hours. The charger should be set to regulated 7.0 volts. PbAc batteries like to be charged from a constant voltage supply. Current limiting for this case is ok.

The formula is Amps X time = AH

tm

no, in addition to the formula, you need to know how good it is and what the temperature is.

Probably, but it's not going to be a simple one.

Charts such as in the article at

can help you figure out (roughly) the state of the battery's charge from the starting voltage. Expect some variation based on the temperature and the exact battery chemistry.

Then, assuming that you're going to be delivering precisely 500 mA into the battery during charge, and given some assumptions about the charge efficiency (the percentage of the charging current which actually goes into electrochemical storage rather than being dissipated as heat) you can guesstimate how long you'll have to charge to bring the battery up to full. Expect quite a bit of variation depending on battery type, health, and temperature, and on the actual output of your charger.

You shouldn't depend on this for actual charging-time setting, as there's a very real possibility that trying to charge in this simple a fashion might overcharge the battery and damage it.

the charge time based on the starting voltage ?

The residual capacity is roughly linear with terminal voltage Vbatt in acc ordance with 1.1 x(Vbatt-5.7) at room temperature, so that used capacity i s simply 1.1 x (6.6 - Vbatt)x 4.5AH. Then assuming charge efficiency of 60 % at 500mA charging current gives time of charge Toc= 1.1 x (6.6-Vbatt)x4 .5/(0.6x0.5) = 16 x (6.6- Vbatt) Hours. Plan on it.

How did you get 500 Ma charge current from the statement, "500 Mah charger"?

The question, as asked, suggests that the OP doesn't understand the question, much less the answer. That's OK, that's how we learn. I question the wisdom of providing a precise solution without the caution that, taken out of context, it might not solve his problem. Typical SLA chargers don't charge at anywhere near constant current. Typical SLA batteries in consumer equipment lose capacity rapidly to sulfation from non-use.

Math and theory notwithstanding, charging a real battery with an unknown charger is not simple.

ne the charge time based on the starting voltage ?

accordance with 1.1 x(Vbatt-5.7) at room temperature, so that used capaci ty is simply 1.1 x (6.6 - Vbatt)x 4.5AH. Then assuming charge efficiency o f 60% at 500mA charging current gives time of charge Toc= 1.1 x (6.6-Vbat t)x4.5/(0.6x0.5)

This is a continuation of a previous thread in which he called out a small Chinese import 500 mA charger, constant current with automatic cutoff.

My answer, although presented as a mathematical formula, translates into "a ll day" in plain English.

The best way to do it is to charge until the voltage is 14.4 V. Keep it that way for an hour to equalize the cells, then go down to 13.7 V for floating. Oh wait, this is 6 V battery, so 7.2 V for an hour, then down to 6.85 floating.

The term constant current can be misleading, its widely used to just mean limited current.

NT

all Chinese import 500 mA charger, constant current with automatic cutoff.

limited current.

It doesn't have to be DC, it is taken to mean DC-average, could even be rec tified sinusoidal r pulsed, makes no difference to the recharge. My guess i s the miniature off-the-line Chinese product is something like a 50kHz flyb ack since it's especially easy to maintain "constant" current with that top ology.

A stronger possibility is a half-bridge inductive ballast stepdown operating in the 30-40Khz regime, this would allow them to tap into the cheap high volume CFL converter supply chain.