ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
GFCI's pops in large numbers
by dsk - 10/21/21 02:03 AM
Need some info on Japanese outlets, 200V 15A
by andey - 10/20/21 08:05 AM
Wire sizing
by watersparkfalls - 10/19/21 07:27 AM
nec 110.3 (B)
by watersparkfalls - 10/19/21 07:09 AM
A 5-20(20a) receptacle is legal on a 15a circuit?
by libellis - 10/10/21 12:46 PM
New in the Gallery:
240/208 to a house
240/208 to a house
by wa2ise, October 9
Now you know.
Now you know.
by Tom_Horne, September 7
Who's Online Now
0 members (), 8 guests, and 17 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 2 1 2
#164670 06/08/07 05:06 PM
Joined: Jan 2005
Posts: 61
J
jkochan Offline OP
Member
I need to install two meters , volts and amps on the outside of a Genset enclosure so that the security guards can, on their rounds, monitor the condition of the batteries and the chargers' status. I know putting another volt meter in parallel with the existing charger meter won’t be a problem, but if I make parallel connections to the existing amp meter will that change the amp reading of both meters? I must be getting old… I used to be able to remember the simple stuff.

Joined: Sep 2001
Posts: 806
N
Member
Put the new ammeter in SERIES with the existing one...

Joined: Jan 2005
Posts: 61
J
jkochan Offline OP
Member
I gues that's the question, since the original ammeter is already in series in the circuit, desn't putting another ammeter in parallel put it in series in the circuit or will the current divide between the two meters? Will putting the ammeter in series with the first meter change the reading?

Joined: Sep 2001
Posts: 806
N
Member
Putting a second ammeter in parallel will result in incorrect readings on both meters. Assuming the 2 meters are identical, each would read half the actual current.

The resistance of an ammeter is generally very low, so placing it in series with a circuit should not cahnge the circuit current by any meaningful amount.

Joined: Jan 2005
Posts: 61
J
jkochan Offline OP
Member
Ah... that's what I was trying to remember! I'll take some readings before and after to double check. Many thanks for the kickstart.

Joined: Nov 2005
Posts: 826
J
Member
I would just caution that you make sure that you are dealing with an actual ammeter and not a mV meter reading across a shunt, with the meter face calibrated in amps. If it is a direct reading ammeter, a second one in series will likely reduce your charging voltage slightly. Make sure you have the right VPC at the battery terminals before you button things up.
Joe

Joined: Jul 2004
Posts: 783
L
Member
Originally Posted by JoeTestingEngr
Make sure you have the right VPC at the battery terminals before you button things up.


VPC? Volts per cell?

LarryC #164716 06/09/07 09:46 AM
Joined: Nov 2005
Posts: 826
J
Member
Thanks for the clarification Larry. That is exactly what I meant. Since battery cell voltage is one thing that we try to keep within a few hundredths of a volt of an optimum, it is one case where inserting an ammeter could have an undesirable effect. If the voltage control sensing is downstream of the ammeter, you probably wouldn't see a difference. Also, without knowing the circuit, I would be alert for my new wiring acting like radio antennas, sending noise back into my control circuit. I'm not saying that any of these will be a problem for you, just that they could be.
Joe

Joined: Jan 2005
Posts: 61
J
jkochan Offline OP
Member
The meter I'm using is from a charger that was removed from the genset after that charger had failed. The meter face is marked DC AMPS (no Mfg name or or part number) and the schematic shows it in the charging current path. The system is 24 volts, Six cells/jar, 2 jars. What should my equalize and float voltages be? I was estimating 28v volts equalize, and 26v float. Oh for the record, the new charger is a Charles Industrial Group C-Charger, Mod # 93-AA2410. The manual has no schematic and no TP voltages. It just has a chart with the idiot light positions. The previous charger had Test Points I could tie to to verify the charger meters'accuracy and the remote meters.

Joined: Nov 2005
Posts: 826
J
Member
You didn't specify the battery chemistry but the voltages sound a little low to me. Aim for the middle of the range on your battery data sheet since the cells will vary. I found an "AA2410" ferroresonant but not the 93...
Joe

Page 1 of 2 1 2

Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
togol
togol
NW In. USA
Posts: 421
Joined: September 2005
Top Posters(30 Days)
dsk 6
Popular Topics(Views)
284,715 Are you busy
217,341 Re: Forum
203,693 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5