Batteries charging to only 12.5 volts

[Mark S]

My batteries are charging up to only 12.5 volts. I’ve tried putting the Progressive Dynamics charger/converter in boost mode but it did not make a difference. The led on the charger is as the book says. The AC input is going through my Progressive Industries surge protector so I know I am getting good power in.
All connections on the charger and the batteries are tight. I confirmed with a voltmeter and hydrometer that I am getting 12.5 volts at the batteries.
I know some had an issue with a loose ground and not charging but I am charging up to 12.5 volts.
Can you think of any reason, other than the charger going bad, why I would get reduced voltage?

Thanks.

[Stingray75]

How old are the batteries? What size? 12v or a pair of 6v?

[Mark S]

Originally Posted by Stingray75

How old are the batteries? What size? 12v or a pair of 6v?

Four 3 year old Duracell 6 volt golf car batteries. I just spoke to Slowpoke about this and I will isolate and check each battery in the morning.

[JimD]

I had to replace my 1 year old converter because it quit going into boost mode. I contacted the manufacturer and they sent me a free replacement after I did some testing.

I have attached the troubleshooting section from my converter. Look at the last box where it says the voltage output must be 13 volts without a battery disconnected.

[Rustynuts]

Here is another converter troubleshooting sheet with test procedures. I was going to mention you might have a bad battery but looks like SloPoke has that covered.

[SloPoke]

Originally Posted by Rustynuts

Here is another converter troubleshooting sheet with test procedures. I was going to mention you might have a bad battery but looks like SloPoke has that covered.

My conversation with Mark was focused on separating and isolating each of his 6V cells. By isolating one 6v-6v pair of batteries from the other, by disabling the +/- connections of one of the pairs. Then, if we see a rise in the battery voltage/charge voltage at the batteries - we dive deeper on the individual cells pulled from service...

If we see no change, after we do the same on the other pair. If both of the battery banks have the same issue... then we look at Converter. More voltage measurements are needed....

[Rustynuts]

That’s what I figured when he said he talked to you. That troubleshooting guide shows to test the converter output, so that’s easy to test. That is the guide that let me know I had no ground to the converter which gave me a no charge issue.

[Jeffur]

What makes you think you can get a battery float charge greater than 12.5 out of 4 - 6V batteries in a series / parallel combination? Also depends on internal state of each battery. An indication of questionable battery is rapid boiling in one and not the others. Greyed coloured water, actual plate cell flakes visible in the cell water, heat in one battery and not the others - or in all the batteries.

[Mark S]

Originally Posted by Jeffur

What makes you think you can get a battery float charge greater than 12.5 out of 4 - 6V batteries in a series / parallel combination? Also depends on internal state of each battery. An indication of questionable battery is rapid boiling in one and not the others. Greyed coloured water, actual plate cell flakes visible in the cell water, heat in one battery and not the others - or in all the batteries.

I was referring to while it was on the charger. I have always gotten readings in the 13 range on the inverter readout.

[Mark S]

So I isolated and checked my house batteries today. Left side showed 6.19 and 6.17 each and in series 12.4 V. Right side 6.26 and 6.22 and in series 12.5 V.
Before I did this the inverter showed 12.5.
After I reattached and left for a couple hours inverter reads 13.5 plugged in. I’m guessing there was a loose connection and hopefully problem solved. Tomorrow I will check all the connections in the battery compartment.
Thanks to all for the helpful advice and especially SloPoke for calling and walking me through the diagnostic process.

[javamon]

Thanks for the update Mark. The posted PDFs are very informative. Excellent thread!

[TaftCoach]

Thank you for the update. Checking all connections is something I need to do on a more regular basis.