Think I have a charger problem

[JohnnieB]

Originally Posted by kernal

I disconnected the wires from the charge receptacle to the battery pack. Checking between the positive and negative leads with a DMM I get open (no resistance) until meter is set at the 20M scale at which time meter reads about 1.5 with substantial fluctuations. I don't know what that means.
( I have reached the limit of my skill with a DMM )

Your reading is in the ballpark. That is the DC resistance of the wire's insulation and the insulator in the charge receptacle.

The insulation on those wires have deteriorated a little and/or the charge receptacle might be a little dirty, but the current flow between those two wires is only about 63 micro-amps (0.000063A) and we're looking for about 10A or more.

IF possible, try a different charger on your cart and/or your charger on a different cat.
That will tell us if the problem is in the cart or charger.

[yurtle]

I didn't open mine up. I just looked at the end of the plug. I may crack it open to see if the plug has the contact, but no wire running to it.

[yurtle]

I opened the DPI plug and it only has two wires. It does have the aux contact, but it's not connected to anything. It has DPI stamped into it, so they may have hired the same junior engineer.

[JohnnieB]

Originally Posted by JohnnieB

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I suspect the same junior engineer (or engineering student intern) that came up with the Reed switch snafu, probably came up with the questionable idea of using half of a Kelvin sensing circuit (4T sensing) in a charger. (The new kid on the block has to do something to get noticed )

Here is an overview of Kelvin sensing for those that don't know what it is: http://en.wikipedia.org/wiki/Four-terminal_sensing

Works great for measuring milli-ohms and things like that, but I don't think a golf cart battery charger is a suitable application of the concept.

Originally Posted by yurtle

I opened the DPI plug and it only has two wires. It does have the aux contact, but it's not connected to anything. It has DPI stamped into it, so they may have hired the same junior engineer.

The kid did get around.

Actually, using Kelvin sensing in a battery charging circuit isn't a bad idea and a lot of high amp power supply applications and some of them do use it on one wire only, but this is the only application I can think of where it is only used on half of one wire.

It would be best to run two sense wires all the way to the main battery pack terminals, but with a portable charger, they would have to run through a connector also and be just as susceptible to all the same maladies as the wires carrying the charging current.

[kernal]

Originally Posted by JohnnieB

Your reading is in the ballpark. That is the DC resistance of the wire's insulation and the insulator in the charge receptacle.

The insulation on those wires have deteriorated a little and/or the charge receptacle might be a little dirty, but the current flow between those two wires is only about 63 micro-amps (0.000063A) and we're looking for about 10A or more.

IF possible, try a different charger on your cart and/or your charger on a different cat.
That will tell us if the problem is in the cart or charger.

Took my cart to my neighbors and using his charger on his power I get the same results.

To summarize: When charging the batteries, voltage never rises above 42.7 even after 10 hours. Charge amps start at about 18 but are only down to 15 after 10 hours. Didn't ever let it go long enough to see if charger times out at 16 hours. The cart operates normally otherwise with no degradation in flat out speed or abnormal slowing on inclines. Batteries ( T-105s ) were purchased on July 09 and all came from the same pallet. I picked them out myself. They have been meticulously maintained and never discharged below 60% remaining. They have never sat in a state of partial charge for longer than a day. They have LOTS of cycles on them, however. I estimate in the neighborhood of 1200. As stated in my first post this phenomenon happened in one day. One day all is well, the next the charger won't shut off automatically. My conclusion is the batteries are worn out. It isn't just one dragging the others down either. They are giving up as a group. A team effort apparently. The silver lining in this is the cart has been prepped for 48v and I was waiting for something like this to trigger the conversion. ( maybe the batteries were aware? )
As the OP, I consider this thread closed even though no definitive answer has been determined. Thanks to all for your consideration thoughtful responses.

[yurtle]

One bad batt?

Check each battery.