Setting up the regulator

[amiklic1]

I got charge regulator (homemade) I built few months ago, and it's working very fine untill now. I even sold few of them to the people around here, and they too seem to be satisfied.

I have just one problem with that. I set it that it charges the batteries all the time, and when battery voltage raises to 14.4 volts, it turns the shunt load on. (I use 4 H1 car bulbs (55 W each) connected in series/parallel, so it is 24V/220W, and it performs quite well. 12V setups were burned when the alt is spinning high rpm's)

My problem is in the fact that charging voltage (from the alt to the batteries) is allways higher than the actual battery voltage. Alt's Voc (without the batteries, open circuit) can go as high as 40+ volts at moderate winds. It seems that battery (three in parallel, but performing as one because they're the same) allows a few volts higher voltage to come into than it's own actual voltage (state of charge).

From that fact, when my regulator is switched to dump the power to bulbs (dump load), voltage on battery terminals (measured by regulator) is 14.4 volts. But when I disconnect the alt and all the wiring, and than measure the voltage on the battery terminals, I get only 12.5 volts.

It's obvious that I need to allow higher charging voltage if I want to have 13.8 volts in fully charged battery. How high can I go? I have some circuits that are swithing off the charging current at 16.5 Volts. My batteries are lead acid, 80 Ah each (allmost new, 6 months old).

Can I go to 16.5 volts? Regulator is easy to set up to any desired voltage.

[ghurd]

It sounds like you may be confusing the charging voltage with the battery voltage.

It sounds like the charging amps were kind of high too.

When the charging amps are high, the charging voltage is higher than the battery voltage will be when it is disconnected.

A battery is 'full' at 12.65V, but it needs charged up to 13.8V (14.4V) to quickly reach and maintain 12.65V after sitting a while.

With low / moderate charging amps, the difference is less drastic.

With low (small solar) charging amps the difference is still noticable if readings are taken for 5 minutes. Partly from surface charge.

Then there is surface charge. The battery voltage reading will be higher right after charging, then slowly go down to the true state of charge voltage. This is very noticable with a half charged medium sized battery and smaller solar panel. An hour before sundown the battery may read full (surface charge), but the next morning at sunrise the battery reads 75% charged (more accurate).  It is the way the battery works, it didn't leak out overnight.

I believe the regulator is working just like it should.

Don't change the set voltage. Higher will cook the batteries.

G-

[Nando]

Can you post the schematic of your charger ?.

I am sending via direct mail an article about battery charging.

If you disconnect the charger and immediately read the voltage, you may see around 13.8 dropping to the 12 volts area, depending this in several factors, like charging current and the time the current has been charging the battery and the age of the battery besides any load you have attached to the battery, the test should be done without any battery load to make sure that the measurements show the battery actual state of charge.

Nando

[amiklic1]

My system is configured like this:

(It's Flux's file from my diary section)





It happens with my solar panel charging the batteries. If I measure 12.00 Volts before connecting the panel, and than measure 21.09 Voc at panel wires, and than connect the panel to the battery (alone, no loads or other "chargers"), I can se 12.5 V at battery terminals (not exactly this value, but somewhat higher than battery alone V.

The same thing as with the alt.

And yes, I know  regulator is working like it should. I was just wandering can I gain battery state of the charge this way?. But it seems 12.5 is "full batt" state. I allways put some load on the batt (for 10-20 seconds), than disconnect it and than measure the battery voltage after full charge (generator switched to dump load).