How much should a converter put out?

That seems high unless it is an old Magnetek.
Could the voltmeter read high? A low internal battery can cause a high reading.

Otherwise you need to post the model number.

I am unsure what voltage your testing or why ... but your negative battery cable is the one that is grounded to your chassis. Make sure you understand the difference between hooking up 6 volt batteries in series vs 12 volt batteries in parallel.

OP here...

OK, was hoping question was generic. I'll find out make and model of converter. (Have to move stuff to get to it)

Not even sure how to calibrate volt meter, but will put in new battery in them.

Have 3 cheap volt meters. To "calibrate" I'll see what reading I get at starting motor. Out of 3 cheapies maybe two will give same reading?

(Will re-post in couple hours with more info)

path1 wrote:
Bought new batteries. Before I install them and I need to confirm which cable is pos and neg.

A wise person would have done that before he removed the OLD batteries. ;)

At this point, the voltage is insignificant without the batteries in place. A very high reading is expected with no batteries in place.

Charge the new batteries fully BEFORE CONNECTING.
Then check the voltage before connecting, after connecting and with the converter active.

P.S. except for being sure it points to 0 when off, you do not calibrate the voltage scales of a multi-meter. And if it's digital, you don't "calibrate" anything.

Digital

Cell

Phone

Camera

Most will be ~13.6 volts.

Mine puts out 13.4v

OP here...

OK have good battery's in volt meters. Readings on volt meters with wives car (independent batttery not assoc with problem I'm working on)

12.70
12.61
12.74

Converter is:

(Reading on decal) Parallax-electronic series 7300, 45 amp model 7345
Input 105-130 vac 60 hz 775 watts
12 vdc fuseblock- max branch circuit fuse size: 20A
(average charge rate: .5 amps)

Another volt meter reading at battery cables was 18.08 (which is higher than first reading)

(Also have call into Parallax. (Not very user friendly so far). Tech help line says, "explain your question in a brief message and tech support will call you back" no more than 2 seconds later "thank you, your call is very important to us" click (phone disconnected). But we'll see if and when they call back.


OK... In the mean time I also took a reading on another RV that has a "Power Dynamtics 9200 series with charge wizard" Reading was 13.61
(Rest of info to small to make out)



So I "think" the question I have is...will I damage batteries charging them with 18 volt when plugged in?

Thank you

Maybe, maybe not. Watch the voltage does not climb above 13.8 over the next couple hours.
Put a replacement PD on your project list.

Path1,

You need to connect the battery and then measure the voltage at the terminals.

With converter output open(no battery) it is common to have a higher than normal operating voltage.

It shouldn't hurt the battery for the short length of time it takes to turn it on and measure the converter output.