24V Lead Acid Battery Charger Control Module PCB Recommendations

I should've realized I'd leave out details since the post was composed quickly.

The charger consists of a ferro-resonant transformer (third xfmr winding wound over the xfmr secondary and 2uF AC capacitor), and a full wave rectifier (2 diodes).

A relay handles the begin/stop-off control (xfmr primary energize/off), and the charger has no high current components (other than the diodes).

I don't see what takes care of the 24V voltage regulation.

The Lester control board has a small sealed pc-mount pot and 7 ICs, but no power handling components.. only about a dozen resistors/capacitors/diodes, and 2 TO-92 transistors.

The power for the circuit appears to be supplied by the to-be-charged battery voltage.. so it seems that the circuit won't pull in the relay when connected to a very low or dead battery.

The relay has a manual button to close the contacts, which is how the charging cycle is initialized by the user (button is actuated thru front panel).. this is the only start button (no on-off switch).

The output leads are just two 16 gage conductors.

-- Cheers, WB .............

The battery does that, think of the charger as a current source.

So it drops out the relay when charge is complete? There's enough logic to make a comparator (741) and timer stuff with logic to take battery through to full charge. Wheel chair battery charging is cyclic, take battery up to a voltage, if you are using old flooded cells then start a timer when voltage reaches a certain point for a controlled over-charge.

Unsuitable for modern SLA or VRLA batteries due to that timed overcharge.

Maybe you're better off replacing the charger, unless you can reduce the current for the top-off part of the charge cycle?

Grant.

Thanks for your comments, Grant. A friend brought me this charger that he intended to use for maintaining/trickle charging a 24V forklift battery (approx 1500 lbs battery).

The forklift sits idle for extended periods, and then is needed to be used just as a lift.. not using the traction motor for moving heavy loads around. The trouble with this particular charger is that it shuts off and doesn't restart without manually being restarted.

Since the control circuit is about 25 years old now, I thought it would be best to replace the controller, to avoid other issues which could arise from the aged components.

I've seen circuits with a few components and a zener diode that can control a relay for a charging circuit capable of maintaining lead acid batteries, but I was more interested in just buying a control circuit to install into the charger, if someone could recommend a module.

-- Cheers, WB .............

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Get a regular 24 hour mechanical clock timer and use it to power a relay whose contact is in parallel with the push-on start contact on the power supply. Set the timer for the minimum possible on time, usually 15 minutes per day. That will start the power supply once each day and that should kep the batteries charged just fine. Simple solutions for simple problems!!!

that ferroresonant transformer does the voltage regulation- no joke either. That's what the really weird core or shunts and extra winding with the capacitor are for.

The solution of using a daily, short duration timer cycle would likely be a very good maintenance solution for many common batteries.

The forklift battery in this instance is more than a half-cubic yard in size, weighing about a half-ton, and somewhere in the neighborhood of about

The history of the battery is unknown, but has been able to meet the demand of occassional lifting, but has recently been subjected to some neglect by the owner. As I mentioned previously, the forklift is used only occassionally as a lift, not for moving heavy loads around with the traction drive.

If the charge can't be automatically/routinely refreshed, it may just become a scrap battery, which would then need to be replaced with a bank/stack of automotive or marine batteries, as one possible fairly economical solution.

The heavy duty charger is indoors, and moving the charger to the forklift is complicated/troublesome, which is why the owner has been neglectful at keeping the battery charged on a regular schedule. Once the battery has been charged, a small automatic charger might be able to prevent further decline of the battery's health from sitting idle without proper attention.

-- Cheers, WB .............

Get a regular 24 hour mechanical clock timer and use it to power a relay whose contact is in parallel with the push-on start contact on the power supply. Set the timer for the minimum possible on time, usually 15 minutes per day. That will start the power supply once each day and that should kep the batteries charged just fine. Simple solutions for simple problems!!!

Good luck with that. I've seen people try it, and all they did was ruin a bank of truck batteries.