Battery Voltage

[INA201]

I’ve got a six month old sealed Concorde 35axc battery and am curious about static voltage.  Usually the voltage before start up has been 12.2 volts.  Today I went to update my GPS and the voltage was 11.8.  My return voltage during flight is 13.7 to the battery.  My reason for this concern is that the mechanic who installed the battery hit it with a high amp charger(I’m pretty sure) and some electrolyte May have come out.  Anyone have any thoughts on this or what you guys see prior to flight? Thank you for the help.

[jaylw314]

When you say "static voltage", I assume that means "open-circuit" or "no load" voltage.  Since you said your voltage was 11.8 when you updated the GPS, I assume that means you had a load on the battery with your avionics on.  If you have a volt-meter or multimeter, you could check the voltage at the battery terminals with the master off.

With lead-acid batteries, the open-circuit voltage gives you a pretty good idea of the battery's state-of-charge, where 12.8-13.0 V means it's at 100%

If your voltage is truly 11.8V, your battery would be around 20% charged.

However, that's not your problem if you've lost electrolyte--that doesn't change the voltages, but it does change your full capacity.  The open-circuit voltage is only proportional to the RATIO to full charge, but it doesn't tell you if you're full capacity has decreased.  For that, watching a difference in the voltage at a known amp load gives you an indirect estimate of decreased capacity, but realistically the only way of measuring your capacity is to do a capacity test, where you discharge the battery by a known amp-hour amount, then measure the change in open-circuit voltage afterwards.  Concorde says this has to be done every two(?) years.  While I'm guessing most IA's don't do this, they should be able to do a capacity test.  

Alternatively, if you have anyone who is into RC models as a hobby, they should have a battery charger/discharger that can this can be done with.

[N201MKTurbo]

I would be more concerned with your regulator voltage. An RG battery should be 14.2 volts. 13.6 would be correct for a flooded cell battery. At 13.7 you will not be fully charging your battery.

if you think your mechanic damaged your battery, you should call Concord and talk to them about it. I have found they provide good support.

[N201MKTurbo]

5 minutes ago, jaylw314 said:

When you say "static voltage", I assume that means "open-circuit" or "no load" voltage.  Since you said your voltage was 11.8 when you updated the GPS, I assume that means you had a load on the battery with your avionics on.  If you have a volt-meter or multimeter, you could check the voltage at the battery terminals with the master off.

With lead-acid batteries, the open-circuit voltage gives you a pretty good idea of the battery's state-of-charge, where 12.8-13.0 V means it's at 100%

If your voltage is truly 11.8V, your battery would be around 20% charged.

However, that's not your problem if you've lost electrolyte--that doesn't change the voltages, but it does change your full capacity.  The open-circuit voltage is only proportional to the RATIO to full charge, but it doesn't tell you if you're full capacity has decreased.  For that, watching a difference in the voltage at a known amp load gives you an indirect estimate of decreased capacity, but realistically the only way of measuring your capacity is to do a capacity test, where you discharge the battery by a known amp-hour amount, then measure the change in open-circuit voltage afterwards.  Concorde says this has to be done every two(?) years.  While I'm guessing most IA's don't do this, they should be able to do a capacity test.  

Alternatively, if you have anyone who is into RC models as a hobby, they should have a battery charger/discharger that can this can be done with.

Your chart looks like it is for a standard flooded cell lead acid battery. The charts for a recombinant gas (sealed) battery are a bit different. The voltages are a bit higher.

[carusoam]

Back-up for the logic given above...

Battery Minder chargers are battery specific.

The voltage range from full up to mostly empty isn’t very large...

If your charging system isn’t set-up to charge properly, the battery isn’t getting filled all the way up.

These guys say... a fully charged battery should read 12.5 to 12.9 V after being charged, then allowed to rest 12hours...

http://www.batteryminders.com/why-an-aviation-specific-charger-maintainer/

You can also read up on the desulfonation process their chargers have... another thing that gets in the way of battery performance over time...

Sitting for three or four weeks can also drain a significant amount of charge...

 

Details from Concorde indicating the max charge of their 12v battery is 13.0V.

No fancy graph indicating V vs. %charge though...

http://www.concordebattery.com/otherpdf/5-0171.pdf

They may have some special procedures for testing for damage... like the ordinary capacity test.

After many pages read.... I didn’t find any charger output voltages...?

PP thoughts only, not a mechanic.

Best regards,

-a-

[jaylw314]

6 hours ago, N201MKTurbo said:

Your chart looks like it is for a standard flooded cell lead acid battery. The charts for a recombinant gas (sealed) battery are a bit different. The voltages are a bit higher.

Good point, an AGM would be about 0.6V higher, so 11.8V would actually be pretty much 0% charge

[ArtVandelay]

To be clear, the voltage you are reading if by using engine monitor or other panel device is not the resting voltage of the battery which everyone is referring to : you are now drawing power and the voltage is the buss voltage, depending on connections especially the master solenoid or radio solenoid might be somewhat less than battery voltage. Actually measure voltage on the battery, you could have a bad connection or a bad solenoid.

 Edit: the buss voltage should be within ~0.1v of the battery terminal.

[INA201]

Thanks guys!  Does my voltage regulator need to be raised to 14.2?  It sounds like I should be showing at least 12.2 and probably higher especially after a flight or when fully charged.  I haven’t had any issues starting or whatnot just noticing the voltage on the JPI 900 was 12.2 most days and 11.8 when I turned on the master to changed the GPS cards out. 

[carusoam]

A few ideas I picked up from MS over the years...

1) Concorde for Batteries...

2) BatteryMinder for chargers...

3) Zeftronics For VRs

4) To avoid missing some important detail.... Always good to work with your mechanic on this...

5) The last detail is the alternator... MS has some good experience on these as well....

 

Not being a mechanic, I’m unable to make a valid recommendation....  but, going  to the Zeftronics website can be educational....

https://www.zeftronics.com/product-category/alternator-controllers/?filter_over-voltage-protection=16-0v-0-4v&filter_voltage-regulation=14-2v-0-4v

The charge setting seems to mention 14.2 + 0.4V often...

The over volt protection seems to be 16V

My Zeftronics experience came from 12V, 50A, M20C.... the old sticks and stones and springs VR melted solder out of the generator.... the R fell off the VR...  

The Concorde and BM are used with my O...

Best regards,

-a-

 

[Andy95W]

10 hours ago, INA201 said:

Thanks guys!  Does my voltage regulator need to be raised to 14.2?  It sounds like I should be showing at least 12.2 and probably higher especially after a flight or when fully charged.  I haven’t had any issues starting or whatnot just noticing the voltage on the JPI 900 was 12.2 most days and 11.8 when I turned on the master to changed the GPS cards out. 

This is from the Concorde manual for its RG batteries:

[RLCarter]

Had to charge my battery yesturday, charger was on most of the day and when I checked the voltage at the end of the day it was 14.21vdc across the terminals. 

[N201MKTurbo]

19 hours ago, INA201 said:

Thanks guys!  Does my voltage regulator need to be raised to 14.2?  It sounds like I should be showing at least 12.2 and probably higher especially after a flight or when fully charged.  I haven’t had any issues starting or whatnot just noticing the voltage on the JPI 900 was 12.2 most days and 11.8 when I turned on the master to changed the GPS cards out. 

Was it colder than usual? 

[INA201]

17 minutes ago, N201MKTurbo said:

Was it colder than usual? 

I’d say 37 from what I recall. 

[N201MKTurbo]

Here is the maintenance manual for the battery.

http://www.concordebattery.com/otherpdf/5-0171.pdf

It says you can charge it at 280 amps without harm. (8 X C1) where C1=35 amps.

[PT20J]

There's an old saying: A man with one watch knows what time it is. A man with two watches is never sure. 

In my plane I got the following voltage measurements (engine stopped, master and avionics ON):

Aspen PFD: 23.6V

EDM 700: 24.9V

Mooney voltmeter: 25V (best guess - not enough graduations to read accurately)

Fluke DVM at main bus: 24.35V

Fluke DVM at battery terminals: 24.4V

The DVM is, of course, the most accurate.

So, be careful where and how you measure your voltage.

[jaylw314]

24 minutes ago, PT20J said:

There's an old saying: A man with one watch knows what time it is. A man with two watches is never sure. 

That's a good one!