A Different Battery Question

On Wednesday, October 16, 2019 at 5:57:18 PM UTC-7, Dan Marotta wrote:
Yes, that's good advice.Â* I was hoping to not have to remove the rear
console where the switches are located to do the troubleshooting.

Oh well, soaring season is coming to an end and wave season is not yet
in full swing.Â* I guess I'll need something to do in the interim.

On 10/16/2019 12:09 PM, wrote:
How about divide and conquer?

Get the system in the condition you saw with more volts at the battery than the clearnav. (Maybe disconnect the batt and make sure the clearnav powers down just to make sure you have what you think you have.)

Split the path in half by measuring the voltage drop between the battery + terminal and the clearnav +power in. Then the batt- to clearnav power-..


Choose which part of the path has most of the voltage drop and pick an accessable point in the middle. Measure the two halves.

Then repeat with smaller and smaller parts of the path until you have found it.



--
Dan, 5J

Losing over 2V is much more than can be explained by a high resistance connection (it would have to be multiple ohms). I think you have a bad ground connection for some reason, and the battery is finding a ground path thru another instrument. Measure the resistance to your a/c ground bus to the negative battery terminal. Do the same for the positive connection to the 12V bus.

Tom

Really good advice, Tom.Â* I'll do that.

On 10/17/2019 6:26 PM, 2G wrote:
On Wednesday, October 16, 2019 at 5:57:18 PM UTC-7, Dan Marotta wrote:
Yes, that's good advice.Â* I was hoping to not have to remove the rear
console where the switches are located to do the troubleshooting.

Oh well, soaring season is coming to an end and wave season is not yet
in full swing.Â* I guess I'll need something to do in the interim.

On 10/16/2019 12:09 PM, wrote:
How about divide and conquer?

Get the system in the condition you saw with more volts at the battery than the clearnav. (Maybe disconnect the batt and make sure the clearnav powers down just to make sure you have what you think you have.)

Split the path in half by measuring the voltage drop between the battery + terminal and the clearnav +power in. Then the batt- to clearnav power-.


Choose which part of the path has most of the voltage drop and pick an accessable point in the middle. Measure the two halves.

Then repeat with smaller and smaller parts of the path until you have found it.


--
Dan, 5J
Losing over 2V is much more than can be explained by a high resistance connection (it would have to be multiple ohms). I think you have a bad ground connection for some reason, and the battery is finding a ground path thru another instrument. Measure the resistance to your a/c ground bus to the negative battery terminal. Do the same for the positive connection to the 12V bus.

Tom

--
Dan, 5J

On Thursday, October 17, 2019 at 5:59:58 PM UTC-7, Dan Marotta wrote:
Really good advice, Tom.Â* I'll do that.

On 10/17/2019 6:26 PM, 2G wrote:
On Wednesday, October 16, 2019 at 5:57:18 PM UTC-7, Dan Marotta wrote:
Yes, that's good advice.Â* I was hoping to not have to remove the rear
console where the switches are located to do the troubleshooting.

Oh well, soaring season is coming to an end and wave season is not yet
in full swing.Â* I guess I'll need something to do in the interim.

On 10/16/2019 12:09 PM, wrote:
How about divide and conquer?

Get the system in the condition you saw with more volts at the battery than the clearnav. (Maybe disconnect the batt and make sure the clearnav powers down just to make sure you have what you think you have.)

Split the path in half by measuring the voltage drop between the battery + terminal and the clearnav +power in. Then the batt- to clearnav power-.


Choose which part of the path has most of the voltage drop and pick an accessable point in the middle. Measure the two halves.

Then repeat with smaller and smaller parts of the path until you have found it.


--
Dan, 5J
Losing over 2V is much more than can be explained by a high resistance connection (it would have to be multiple ohms). I think you have a bad ground connection for some reason, and the battery is finding a ground path thru another instrument. Measure the resistance to your a/c ground bus to the negative battery terminal. Do the same for the positive connection to the 12V bus.

Tom

--
Dan, 5J

It would also be helpful if got a smarter charger than the one you have. I use the Hitec X2 Pro:
https://hitecrcd.com/products/charge...harger/product
It will inform you how many AHr it put into the battery, which is a critical cross-check. It can also do a discharge test.

We charged LFP battery installed in glider using charger plug that feeds the battery via glider electrical system. We discovered that there was automatic breaker hidden in glider electrical system (DG DEI) that stole little bit of voltage. This caused charger to not charge battery to full. It seems that you cannot have automatic breakers between charger and battery.

At 08:44 18 October 2019, krasw wrote:
We charged LFP battery installed in glider using charger plug that feeds
th=
e battery via glider electrical system. We discovered that there was
automa=
tic breaker hidden in glider electrical system (DG DEI) that stole little
b=
it of voltage. This caused charger to not charge battery to full. It
seems
=
that you cannot have automatic breakers between charger and battery.

Whenever you put any device is series, expect to lose something. For
example with a series diode expect to lose about 0.5volt.

For this reason many radio manufacturers use a back-biased diode across the
supply and a series fuse. In this way no current passes through the diode
unless you cross-polarity the radio, in case it will be a short to blow the
fuse.

On Friday, October 18, 2019 at 3:44:20 AM UTC-5, krasw wrote:
We charged LFP battery installed in glider using charger plug that feeds the battery via glider electrical system. We discovered that there was automatic breaker hidden in glider electrical system (DG DEI) that stole little bit of voltage. This caused charger to not charge battery to full. It seems that you cannot have automatic breakers between charger and battery.

KRASW - The voltage loss/drop across a breaker depends on the amp rating of the breaker. The smaller the rating the larger the drop.

For example, a small value 1A Tyco W32 breaker drops ~0.6Vdc. A 1A Klixon 7277 breaker can drop ~1Vdc! I always use a 5A or larger breaker. A clear case of "bigger is better".

See slides #95 for the full story at http://aviation.derosaweb.net/presen..._Made_Easy.pdf.