Charger won't cut off

[coosa]

I've found some other threads about this problem by searching, but nothing quite like this. I'm running a 2008 PDS cart with T-105s in a 36 volt cart. I've been using 2 different chargers on it, the Powerwise that came with the cart, and a Lestronic II that I was using with my old resistor cart. Both worked fine up until a couple weeks ago, when the Lestronic would not shut off. I left it on for over 24 hours and it charged the cart fine, but never shut off. I figured it was a problem with the charger and switched back to the other.

The Powerwise has always been slow to cut off, but it is just a 20 amp charger. It charged the cart and cut off fine the next time I tried it, but yesterday it wouldn't cut off. I had only ran the cart about a mile, but it charged 10 hours and was still humming. Pack voltage was 46.2 and the batteries were bubbling, but it would not shut off. I finally turned it off myself.

This morning, the pack voltage was 38.8, and all batteries were within .2 volts of each other. I ran it a half mile and checked the pack voltage and it was down to 38.1. I put it on the charger and its still running an hour later. Pack voltage was 45.7 after being on for just a few minutes.

I broke the batteries in according to Scottie's instructions, and they seem to be getting even stronger. The cart is fast and has great torque; both have improved since putting the batteries in this cart back in April.

It seems unlikely that both chargers would go bad at once, so I'm thinking it has to be the batteries or something else in the cart itself. Anyone have any ideas of what to test? Thanks!

[yurtle]

You might want to clean the radsoks in the buggy charger port. Some chargers use a separate sensing wire to control charging initiation and completion. A dirty connection could cause higher resistance, making the charger think it hasn't reached 44 - 46 volts.

[coosa]

Originally Posted by yurtle

You might want to clean the radsoks in the buggy charger port. Some chargers use a separate sensing wire to control charging initiation and completion. A dirty connection could cause higher resistance, making the charger think it hasn't reached 44 - 46 volts.

Thanks! I'll go try right now.

[JohnnieB]

Give the Auxiliary contact in the charger plug and the outside of the negative radsok in the cart's charge receptacle special attention.

Unless both chargers have control boards with the an identical symptom (not shutting off when the pack voltage reaches about 45V), the excessive resistance is between the battery sense contact and the control board.

[coosa]

Bingo! Thanks guys! I cleaned everything good and plugged it back up - charger would not come back on. I ran it around my half-mile circle and then put it back on charge. It should cut itself off within an hour, and if it will, I will declare victory.

[coosa]

I might have celebrated too soon. It still had not cut off after an hour, and I had to leave for the day so I unplugged it. Didn't want to boil my batteries any further. Pack voltage was 46.1. I unplugged it and then plugged it back in and it came right back on, so I'm thinking it just hadn't had time to fully charge. I'll try again in the morning.

What should the pack voltage be when it cuts off?

Is there a certain level that it should not go beyond and I should just unplug it whether its turned off or not?

I know its not good for the pack to put a partial charge on it, but it also can't be good to overcharge.

Thanks for the help!

[coosa]

Plugged it back up for over an hour when I got home and it never would cut off.

Pack voltage stayed at 46.2 for over 30 minutes; that seemed to be as much as it can take, but the charger kept going. I have a nice PDS cart and only have a resistor cart mind, so not sure what to try next.

Maybe I didn't clean it right. I used a piece of medium sandpaper to polish everything a little, then sprayed it with an electronic cleaner, then cleaned it all out with q-tips. Both the plug and receptacle look clean. Is there a better cleaning method? Do I need to take apart the box that houses the receptacle and clean everything on the inside?

JohnnieB said:
>>>Give the Auxiliary contact in the charger plug and the outside of the negative radsok in the cart's charge receptacle special attention. <<<

JohnnieB, I don't follow on the 'outside of the negative radsok'. I thought the radsok contacts were in the female receptacle on the cart, and contact would be with the inside of them. When you say outside, I don't get it. Sorry to have to ask such a stupid question.

I also don't fully understand about the auxiliary contact. I thought the only purpose of that extra wire was to keep the cart from being moved while the cart was charging. Apparently, this is incorrect? I'm further confused by the fact that the Lestronic charger only has 2 wires going to the receptacle and doesn't even have an auxiliary contact, yet it has turned off when the cart was charged before.

Thanks for any help.

[yurtle]

Not all chargers use this aux contact. The charging power is connected to the radsoks as you described. However, the aux contact connects to the outside of the radsok in the buggy, and goes to the control circuit board inside of the charger.

The reed switch is what keeps the cart from running if the charger is connected. There is a magnet inside the charger plug that opens and prevents control voltage from allowing the cart to run.

If two chargers are exhibiting the same behavior, and if your Lester doesn't use a separate sensing wire, I don't think that's your problem. I'm stumped.

[JohnnieB]

The charge plug/receptacle area is a busy place since there is (or can be) three separate electrical circuits associated with it, so it is easy to get confused about who does what to whom.

1. The charging loop. This is the only one of the three that actually passes through the interface, the other two stay on either the cart side or the charger side.
The charging loop consists of the transformer secondary(ies), the diodes, ammeter (if it exists), fuse (if it exists), the chargers DC output cable, the male/female radsoks, the 8Ga wire between the radsocks and the main Positive and Negative terminals of the battery pack, the high current cables that connect the batteries in a series string and the batteries.

2. The reed switch is part of the cart's solenoid activation circuit and is not associated with charging the batteries in any way shape or form.
The Reed switch picks up the B+ it feeds to the rest of the solenoid activation circuit from the backside of the Positive female radsok. See Attachment #1.

3. The battery sense circuit. Other than turning charger ON and OFF, this circuit is not part of the charging loop that actually charges the batteries. The battery pack voltage is sensed by all automatic chargers. however where it is sensed at varies with the make and model of charger and the make and model of cart.
For chargers that have a three wire DC output cable terminated in the Powrwise-D plug that is commonly used to charge EZGO carts, the battery pack voltage is sensed via an Auxiliary located in the plug. (Item 36 in Attachment #2 and Attachment #3 shows where it is physically located looking at the front of the plug.)

When the charger's plug is plugged into the cart's receptacle, the auxiliary contact in the plug touches the outside of the Negative female radsok in the receptacle. Excessive resistance (IE: dirty contact) at the point of contact will cause the charger's control board to sense a erroneously low voltage and the charger will blindly continue to charge, vainly attempting to raise the On-Charge voltage to the fixed cutoff voltage, which is typically about 45V for a 36V charger.

Some chargers have a two wire DC ouptut cable and the battery sense circuits look at the Negative conductor within the charger. (See attachments 4 and 5 showing the same charger with both two and three wire output cables respectively.)

If the charger has a two wire output cable and is not shutting off when the pack voltage reaches the predetermined cutoff voltage (IE: about 45V), there is excessive resistance between the battery sensing point and the control board whether the charge uses a tow or three wire output cable, or the control board is bad.

The way to trouble shoot this symptom, is to measure the voltage at the control board (small Red and Black wires typically). If the voltage at the control board is lower than what the battery pack voltage is, then there is excessive resistance between the control board and wherever the charge is sensing the pack voltage.

[coosa]

Many thanks, guys! JohnnieB, you are far better than any book!

I'll try to figure it out this afternoon, and will let you know what happens.