Cycling a pwII charger

kgsc

I was reading through another thread about batteries as we are about to buy some 8 volts but it high jacked into another question about putting an external timer to cycle the charger. As some may know that won't normally work because the charger uses a sense wire from the pack and the charge plug must be unplugged to cycle. It was also mentioned about putting in another timer to switch the sense wire to fake the timer out into thinking it cycled.

Now my question.. Could you just install another relay in the charger that closed upon putting 110 on the charger to cycle the sense wire? In essence, if the charger gets unplugged, the charger thinks the charge plug was disconnected. It could be a relay with a 110ac coil or one with a dc coil at whatever voltage the charger was.

Thoughts?

BGW

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tteckster

Maybe mount a intermatic digital timer (water heater timer) to the charger case. I think it has an extra relay built in that you could use for the sense wire. Just a thought.

JohnnieB

Use a 120VAC relay.
Connect the coil to the chargers AC power cable before it goes through the control board.
Many of the have 1/4' push on connectors for both hot and neutral, so a couple of two-to-one adapters would work.

Connect either the red wire or the black wire to the control board through the N.O. contacts of the added relay.

Now when AC Power to the charger is interrupted (IE: External timer at the wall outlet), the battery sense circuit is opened until AC Power is applied again.

kgsc

May just have to try this on one of the lake carts... Will have to look for a 110 relay. Was thinking the lower voltage to pick up post transformer..

yurtle

There are several ways to do this. Your way may affect the ferroresonant circuit, as a relay coil is an inductor. A timer that turns off the whole charger will work with a relay on the sensing wire, or a timer with dry contacts on the sensing wires would also work, and could be mounted internally.

JohnnieB

Low voltage side of transformer won't work since the back feed from battery pack will keep relay energized.
The main difference between an AC and DC relay is the permeability of the core.
A DC relay becomes a buzzer when fed AC, but an AC relay works just fine on DC.

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Yurtle is right about the coil being an inductor and altering the balance between the Transformer and Capacitor.

kgsc

Will look for an AC 110 relay. And back feed? I would think there would be some protection in the circuit that from happening so when plugged into the cart there wouldn't be 110 on the AC plug.

JohnnieB

I was thinking you were thinking of a relay connected after the rectifiers, but if you connected an AC relay before the rectifiers, the rectifiers would block the DC back feed from the batteries.
However, the AC voltage of the secondary is going to vary as the pack voltage increases, so you'll have to find a relay that won't drop out or burn up, while just about any off the shelf 120VAC relay will work on the AC line coming into the charger.

kgsc

Understood. I'll get in touch with my hvac guy and see if he has one laying around.

yurtle

With a 120 volt relay, you simply need to power it from the incoming 120 volts, and use an external timer. For an internal timer, there are lots of timers that have "dry" contacts, meaning they are not powered. With that type of timer, you'd simply need to interrupt the sense wire, with no need to disconnect the power from the charger.

Something like this would work:

http://www.hottubwarehouse.com/Inter...FdJj7AodcnAA5w

You'll note the timer motor is 120, yet the contacts are good up to 277, meaning they are dry contacts.

There are plenty of fancier panel mount timers could be mounted internally.