SLA battery charging with PWM but which frequency

[mackrackit]

To fully charge a battery it needs to be over charged . ( but not to much ) That is where the 14.2 volts comes from. (2.36 volts per cell ) The battery will only show this voltage when it is on a charger and fully charged. If something is wrong with the battery it may never reach this voltage. ( bad cell ) Or reach this voltage very quickly. ( shorted cell )

[chuck]

Floating voltage should not go higher than 13.80V and only 5% of the maximum current to maintain the 13.80V. You should really only go to 14.2V if you cycle it regular.

When charging a SLA you need to limit the current otherwise if you get the battery to hot the gel will crystallise the gel inside and the battery will not hold the charge. There are quite a few designs out there, I used to build the SLA chargers for the golf buggies the golf trolleys and sell them has a product I only used the L200 2 Amp regulator with a few components, 2 Pots 1 for setting the maximum voltage (open circuit 14.4V) and the other to limit the current along with a couple of LEDS to let the user know the when it was bulk/float charging. Once it was set to carry out a full test and leave it charging sometimes a little adjustment was made to maintain the 13.8V.

I will try and see if I can find it (if I still have it) and upload it,

[showtime]

Hi chuck,

Thank you for charging ideas wihch i know. I want to know some details about mackrackit's booster charger.

Will I see normal charging values like conventional circuits. I'm trying to say step by step that is important for me:
-I assume I have boost circuit which is controlled by PIC or not. It boost's the voltage to 14.2V when PV give me i.e 9V. Therefore I always measure 14.2V without the battery. Because the circuit adjust the output via feedback.
-We sure we connect the battery to the PV, voltage is decreased. for exmple 10-12V. If this is OK

-Will always Our buck-bust circuit adjust itself to 14.2V constant voltage during charging?.

I know I'm your headache but forgive my experience and my bad English.

[mackrackit]

-We sure we connect the battery to the PV, voltage is decreased. for exmple 10-12V. If this is OK

Yes.

-Will always Our buck-bust circuit adjust itself to 14.2V constant voltage during charging?.

A buck- boost circuit would. The LM2588 is for boost, so when the PV voltage becomes higher than 14.2 the LM2588 will basically shut off. The voltage from the PV will go straight through the inductor and diode to the battery ( minus the inductor resistance and diode drop ). This is where the PIC could help. Some way to monitor the voltage at the battery. When the battery is "FULL", shut the whole thing off or switch to a maintaining "FLOAT" voltage. This all depends on what the battery is used for. Backup power - a float charge . Charge the battery to use daily - shutting the charger off until the voltage drops to 13? might be good for you.

[showtime]

I don't know how much i can thank you. I understood everything.
Last night I see MPPT charging technic. I was happier. They are famous style to get maximum efficiency. You are expert.

Best regards.

[mackrackit]

Glad you got it, but I am no expert. Thanks for the compliment though

[iw2fvo]

Dave,

is there any MPPT PV> battery Charger project available ?
Possibly using PIC and PICbasic !
Thanks
Ambrogio