Battery Charger Using Timer

Normally we keep the chargeing current as low as 1A for 24x7.

Inorder to find charging time you have to give the charging current or AH capacity of battery to find charging current.I hope 90AH is yours so in my idea 90/20=4.5A is the maximum current you can use to charge the battery it takes 20 hours to charge it.More design consideration is to be taken like internal battery resistance,conductor gauge etc. If you are not discharging the battery then daily it gets charged upto the same potential as charging.when the battery is full the charging current is zero. I hope the timer is not useful here.

I think you need not to make it complicated.

Normal chargers and batteries are sufficiently safe to be kept on 24/7.

I suuget to keep your system simple to minimise problems.

Have a nice day!

I hope your battery charger has facility to Boost Charge as well as Trlckle Charge .

If you have the battery in fully charged condition (cell voltage 2.0 v and specific Gravity of electrolite is 1200) then It has to be kept under Trickle charge.

The condition to be Checked is that the trickle current shall be set at 90ma ( Thumb rule 1 ma/AH)

It shall also be kept in mind that the cell voltage shall not exceed more than 2.15V

As it was commented in comment 2, once the trickle current is set to 90ma, it will slowly reduce to zero when the battery is charged to the set voltage and will pick up again when discharged for internal reactions. < Therefore regular Battery charge and a regular monitoring and maintenance Schedule is enough. The boost will become necessary only when the local power supply is failed for a long time ,say 8- 10 hours. On resumption of supply, the boost charge shall be carried out for 1 or 2 hours and then put it back to trickle charge.>

Does your battery charger do not have trickle charge, 1 hour per day will not be enough to charge a 90 amps battery. You can put on trickle charge mode, so that the battery is active always.

What is the ambient temperature which you are using.

All batteries are rated for 20 deg C. you should go for 13.2 or 13.8V Battery charger for an ambient of 25 and 30 deg C.

Is there any proof that the ripples contained in the full wave rectified voltage useful for the battery to reduce sulphation build up ?

All batteries are considered as Infinite capacity-capacitors. There are no ripples when on charge, whether 1/2 wave, full wave, 6/12 pulse rectifiers.

http://www.cirkits.com/spc3/

have a look you can convert this to turn on the charger when the battery gets to a set point and turn off when done use a relay to drive it off and on simply and easy