Frame Ground - How could it be?

GaryW · 07-04-2009, 02:54 PM

I am installing a 48v to 12v converter and the instructions say that I should make sure that there is no voltage between B+ to the frame or b- and the frame. I have both.
I get 29V showing on my meter.
I have disconnected all accessory wires to the batteries and removed the main positive and negative cable. There is nothing connected to the battery pack and I still read 29v from the postive battery post b+ and the frame.
These batteries are all new T875s less than one month old. Cables are new.
This makes no sense to me at all.
Any thoughts would be most appreciated.

pizzamaker · 07-04-2009, 03:00 PM

them sparkys know! but not many here this weekend, scottyb will be along in a bit

DOOmsman · 07-04-2009, 03:03 PM

DOOmsman · 07-04-2009, 03:05 PM

Had to joke a little but Pizza man is right the sparky guys on here know their stuff.

scottyb · 07-04-2009, 04:11 PM

Dooms's picture is right! You are getting surface grounding. With a voltmeter see if you can get voltage readings off of the battery tops and one post....are the batteries wet on top? This surface charge will follow the water down to the frame. Check to see if batts are over full &/or over charging......

remove all batts and clean and dry frames and batteries and re-install.....

GaryW · 07-04-2009, 07:16 PM

You're absolutely right. I can get voltage from the post and the battery top, but they don't appear wet. Tomorrow morning I will take all the batteries out and dry everything. Great suggestion, ScottyB. Thank you.

Happy 4th!!

tonyton · 07-04-2009, 07:39 PM

Quote:

Originally Posted by scottyb

Dooms's picture is right! You are getting surface grounding. With a voltmeter see if you can get voltage readings off of the battery tops and one post....are the batteries wet on top? This surface charge will follow the water down to the frame. Check to see if batts are over full &/or over charging......

remove all batts and clean and dry frames and batteries and re-install.....

Who would have ever thought that?.....WOW.!

GaryW · 07-12-2009, 07:36 AM

Well I finally got back to the project. After cleaning and drying the batteries and frame, I put the batteries back in with the same problem.

Yesterday, I took just one of the batteries out. Cleaned it again and dried it with a towel and waited overnight for more drying time. This morning, I can read about 4V from the positive to several different places on top of the battery. This is sitting on the garage floor so the cart is completely out of the equation.

These are 1 month old Trojan T-875 batteries. All 6 are new. I am waiting to hear back from Trojan tech support.

I appreciate the help in steering me in the right direction. I'll post the response from Trojan. I've heard that these are the best batteries to get. We'll see.

Thanks!

GaryW · 07-17-2009, 07:40 AM

Trojan Response:

It is highly probable that your batteries need to be cleaned really well and neutralize it as well. Please read our user's guide to help you with this. If you have electrolyte on the case of the battery, it will be enough to carry a charge (voltage), but not current.

-------

They were right and they really are the best battery. Neutalizing (with baking soda) was the part I was missing. They were clean but the electrolyte was there.....Lesson learned.

miferrel · 07-17-2009, 07:48 AM

Leave it to scottyb to teach us something. Thanks Scotty.

07-04-2009, 02:54 PM	#1
GaryW Not Yet Wild Join Date: Feb 2007 Location: Canton, GA Posts: 7	Frame Ground - How could it be? I am installing a 48v to 12v converter and the instructions say that I should make sure that there is no voltage between B+ to the frame or b- and the frame. I have both. I get 29V showing on my meter. I have disconnected all accessory wires to the batteries and removed the main positive and negative cable. There is nothing connected to the battery pack and I still read 29v from the postive battery post b+ and the frame. These batteries are all new T875s less than one month old. Cables are new. This makes no sense to me at all. Any thoughts would be most appreciated.

07-04-2009, 03:00 PM	#2
pizzamaker ****tard supreme Join Date: Jun 2008 Location: waldo,wisconsin Posts: 5,401	Re: Frame Ground - How could it be? them sparkys know! but not many here this weekend, scottyb will be along in a bit

07-04-2009, 03:03 PM	#3
DOOmsman Gone Wild Join Date: Jul 2008 Location: Reddick IL Posts: 11,220	Re: Frame Ground - How could it be?

07-04-2009, 03:05 PM	#4
DOOmsman Gone Wild Join Date: Jul 2008 Location: Reddick IL Posts: 11,220	Re: Frame Ground - How could it be? Had to joke a little but Pizza man is right the sparky guys on here know their stuff.

07-04-2009, 04:11 PM	#5
scottyb Happy Carting Join Date: Dec 2007 Location: Southern California Posts: 73,419	Re: Frame Ground - How could it be? Dooms's picture is right! You are getting surface grounding. With a voltmeter see if you can get voltage readings off of the battery tops and one post....are the batteries wet on top? This surface charge will follow the water down to the frame. Check to see if batts are over full &/or over charging...... remove all batts and clean and dry frames and batteries and re-install.....

Today
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07-04-2009, 07:16 PM	#6
GaryW Not Yet Wild Join Date: Feb 2007 Location: Canton, GA Posts: 7	Re: Frame Ground - How could it be? You're absolutely right. I can get voltage from the post and the battery top, but they don't appear wet. Tomorrow morning I will take all the batteries out and dry everything. Great suggestion, ScottyB. Thank you. Happy 4th!!

07-12-2009, 07:36 AM	#8
GaryW Not Yet Wild Join Date: Feb 2007 Location: Canton, GA Posts: 7	Re: Frame Ground - How could it be? Well I finally got back to the project. After cleaning and drying the batteries and frame, I put the batteries back in with the same problem. Yesterday, I took just one of the batteries out. Cleaned it again and dried it with a towel and waited overnight for more drying time. This morning, I can read about 4V from the positive to several different places on top of the battery. This is sitting on the garage floor so the cart is completely out of the equation. These are 1 month old Trojan T-875 batteries. All 6 are new. I am waiting to hear back from Trojan tech support. I appreciate the help in steering me in the right direction. I'll post the response from Trojan. I've heard that these are the best batteries to get. We'll see. Thanks!

07-17-2009, 07:40 AM	#9
GaryW Not Yet Wild Join Date: Feb 2007 Location: Canton, GA Posts: 7	Re: Frame Ground - How could it be? Trojan Response: It is highly probable that your batteries need to be cleaned really well and neutralize it as well. Please read our user's guide to help you with this. If you have electrolyte on the case of the battery, it will be enough to carry a charge (voltage), but not current. ------- They were right and they really are the best battery. Neutalizing (with baking soda) was the part I was missing. They were clean but the electrolyte was there.....Lesson learned.

07-17-2009, 07:48 AM	#10
miferrel Gone Crazy Join Date: Jun 2008 Location: Mississippi Posts: 2,183	Re: Frame Ground - How could it be? Leave it to scottyb to teach us something. Thanks Scotty.

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