Broken charger (ex go marathon)

[Volt_Ampere]

That black box is a relay. THat is how the charger turns itself on and off. If you bypass it, it will probably not shut off and you will overcharge and cook your batteries.

[bbradf44]

Originally Posted by Volt_Ampere

That black box is a relay. THat is how the charger turns itself on and off. If you bypass it, it will probably not shut off and you will overcharge and cook your batteries.

So my relay is probably fried? It doesn't work when i don't bypass it

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[JohnnieB]

Here is a schematic for a TC-III
It is a ferroresonant transformer design and the charging profile is designed into the matched transformer and capacitor, so it will charge the battery pack properly with the relay is bypassed as long as the transformer, capacitor and diodes are good.

Put a DVM on the battery pack and monitor the On-Charge voltage.
Terminate the charge when it reaches 46V or has been on charge for 16 Hours.

You may not be able to find the exact replacements for the ammeter or the control board, but most any ammeter that will fit in the hole and pass up to 25A will work and control boards for later model charges will work.

Note: The relay is probably good, the control board that runs it is most likely bad.

[simple man]

Just a thought here too, check your battery pack voltage. IIRC, 32V is required for the charger to initiate. When you bypass the relay, the charger will come on no matter what. You may have to do this to get the batteries up enough for the charger to come on automatically.

[bbradf44]

This morning i plugged in my cart with the relay bypassed and it was going well. A couple hours later i went to check on it and the charger was very quiet and there was very little voltage going into the batteries from the charger

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[simple man]

What does your battery pack voltage read when off the charger ( a few hours ) and then after it is on the charger ( again for a few hours )? You should have around 44 - 45V reading when the charger is on and just about finished it's cycle.

[bbradf44]

Originally Posted by simple man

What does your battery pack voltage read when off the charger ( a few hours ) and then after it is on the charger ( again for a few hours )? You should have around 44 - 45V reading when the charger is on and just about finished it's cycle.

I don't have a multimeter but my power meter is still on the bottom bar

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[bigstik40]

Just a suggestion here, but if you are really serious about repairing your charger yourself, you should invest in a DVM (Digital Voltmeter). I use a really cheapie Harbor Freight DVM (under $5 & sometimes free) which seems to do the job. Also, Johnnieb has suggested better models (which still don't break the bank @ around $20). Also, this will be a valuable tool for you in the future. IMO, everyone who owns an electric golf cart should have a DVM as a necessary tool for battery checking/maintenance. Hope this helps !! - RAY

[bbradf44]

Originally Posted by bigstik40

Just a suggestion here, but if you are really serious about repairing your charger yourself, you should invest in a DVM (Digital Voltmeter). I use a really cheapie Harbor Freight DVM (under $5 & sometimes free) which seems to do the job. Also, Johnnieb has suggested better models (which still don't break the bank @ around $20). Also, this will be a valuable tool for you in the future. IMO, everyone who owns an electric golf cart should have a DVM as a necessary tool for battery checking/maintenance. Hope this helps !! - RAY

I actually did have one but a couple days ago it broke..

Could i just have a broken fuse? I accidentally used the redneck way of checking voltage and found that one side of the fuse had power while the other didn't

Edit: nvm its not the fuse...

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[Volt_Ampere]

Just because it works when the relay is bypassed doesn't mean the relay is fried. The circuit that actuates it may not be working properly. You need to measure the voltage on the relay coil to see if the circuit is trying to actuate it or now.