Battery drain during flight plan load.

Any DA40 related topics

Moderators: Rick, Lance Murray

Pbwears1
3 Diamonds Member
3 Diamonds Member
Posts: 74
Joined: Mon Nov 23, 2015 2:43 am
First Name: Peter
Aircraft Type: DA40
Aircraft Registration: N329DS
Airports: KBUY
Has thanked: 4 times
Been thanked: 6 times

Re: Battery drain during flight plan load.

Post by Pbwears1 »

Would you elaborate on your BatteryMINDer...make, set-up, etc.

Thanks
User avatar
Rich
5 Diamonds Member
5 Diamonds Member
Posts: 4592
Joined: Mon Aug 30, 2010 12:40 pm
First Name: Rich
Aircraft Type: DA40
Aircraft Registration: N40XE
Airports: S39 Prineville OR
Has thanked: 145 times
Been thanked: 1180 times

Re: Battery drain during flight plan load.

Post by Rich »

Pbwears1 wrote: Tue Mar 14, 2023 2:10 pm Would you elaborate on your BatteryMINDer...make, set-up, etc.

Thanks
BatteryMinder is the brand. They have various models but there is one specifically suited for the Concorde RGM's chemistry. https://www.batteryminders.com/products/

Note it is not specially a GPU.

There is an approved connector to allow quick disconnect. Several threads here on the forum cover the ins and outs of this subject. Here's my connector installation:
BatteryMinder Receptacle.jpg
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
Pbwears1
3 Diamonds Member
3 Diamonds Member
Posts: 74
Joined: Mon Nov 23, 2015 2:43 am
First Name: Peter
Aircraft Type: DA40
Aircraft Registration: N329DS
Airports: KBUY
Has thanked: 4 times
Been thanked: 6 times

Re: Battery drain during flight plan load.

Post by Pbwears1 »

Many thanks, Rich....very helpful
User avatar
Rich
5 Diamonds Member
5 Diamonds Member
Posts: 4592
Joined: Mon Aug 30, 2010 12:40 pm
First Name: Rich
Aircraft Type: DA40
Aircraft Registration: N40XE
Airports: S39 Prineville OR
Has thanked: 145 times
Been thanked: 1180 times

Re: Battery drain during flight plan load.

Post by Rich »

This is old news to many of us, but newer folks perhaps do not know that if you see the alternator current output get abnormally high (> about 35 Amp) the essential bus breaker may trip. This can cause a condition where things otherwise look normal but the battery is slowly being drained. I won't go into specifics here as it's been discussed extensively elsewhere. When this has been observed it's been a consequence of the battery being drained to a low level.

You need to watch for this condition during engine runup as it might not happen during normal after-start and taxi operations. If it happens you do not want to take take off. Correction is made by running the engine at somewhat lower RPMs so the output is lowered and resetting the breaker. This can allow the battery to be sufficiently recharged so the current across that intertie is manageable. Note that you really don't want to be departing - especially IFR or night - until the battery gets fully restored.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
User avatar
BkFlyer
3 Diamonds Member
3 Diamonds Member
Posts: 90
Joined: Thu May 22, 2014 2:47 am
First Name: Adam
Aircraft Type: DA40
Aircraft Registration: N269RB
Airports: KLDJ
Has thanked: 8 times
Been thanked: 25 times

Re: Battery drain during flight plan load.

Post by BkFlyer »

(Edit: I replied before reading Rich’s post which covers this, but leaving for the personal anecdote)

Never do this. It’s dangerous and it irrational.

Dangerous:
Here is my story. I was with a CFI at a remote field during IR training. We loaded flight plan on battery, chatted for a couple minutes and then go on our way. Battery time was probably about 10m. In cruise the alternator puts out a huge current, and the DA40 has no charge controller for the battery, meaning it can draw as much current as it wants… until the breaker pops. Which is what happened. Not great. Luckily this was a brief flight back to the field our A&P was also located. I immediately discussed with him, and he informed me not to do this… it’s what can happen if battery is depleted.

Irrational:
Trading off a very small fuel burn against the health of a $750 battery is not a rational trade off. Ground running for a few minutes, leaned properly, isn’t going to cause any problems. It may help all systems warm up in fact.

If you have a battery minder and preflight with ground power obviously this advice doesn’t apply.
User avatar
Steve
5 Diamonds Member
5 Diamonds Member
Posts: 1953
Joined: Thu Aug 12, 2010 1:23 am
First Name: Steve
Aircraft Type: DA40
Aircraft Registration: N432SC
Airports: 1T7
Has thanked: 81 times
Been thanked: 493 times

Re: Battery drain during flight plan load.

Post by Steve »

The Battery Minder for Concorde batteries is rated at 4 Amps max charge current (it is, after all, a trickle charger/desulfator not a GPU), so if your aircraft draws more than 4 Amps to run the avionics, you will still be draining the battery to some degree. I actually do the reverse - if I need to run the avionics in the hangar (database update, troubleshooting an avionics issue, etc.), I disconnect the Battery Minder and run off the battery only. Of course, I don't have a G1000, and can individually turn off the boxes I don't need on (radios, transponder, DME, and AP).

The other thing I am, perhaps superstitiously, concerned about is connecting the Avionics bus to power that has any RF on it. The Battery Minder uses HF pulses to desulfate, and although modern Avionics are designed to mostly reject power supply noise, I don't like to tempt fate...
User avatar
Rich
5 Diamonds Member
5 Diamonds Member
Posts: 4592
Joined: Mon Aug 30, 2010 12:40 pm
First Name: Rich
Aircraft Type: DA40
Aircraft Registration: N40XE
Airports: S39 Prineville OR
Has thanked: 145 times
Been thanked: 1180 times

Re: Battery drain during flight plan load.

Post by Rich »

With respect to "destroying" the battery by running it down (somewhat):

I installed a Concorde RG24-15M in 2009.

2010: Problems with the original SlickStart caused hard starting for awhile. Replaced the SS unit. No instances of popping the ess. bus breaker occurred.
2012: Severe starting problems with the plane. Several occurrences of popping the ess. bus breaker. The problem was finally chased down to a problem with the output lead from the SlickStart to the left mag. Replaced wire, problem solved.
2017: Replaced that 8-year-old Concorde "just because" with the same model. No problems were observed with it. I still have this battery and occasionally put it on the BatteryMinder to see what it thinks about it - seems normal. I keep meaning to having it load-tested (again, "just because") but haven't gotten around to arranging it. This abused battery was not on a BatteryMinder from 2010-2015, as it was tied down outside during that period.

Of course, the original Gill and the 2 subsequent Concordes have all been subject to the occasional hot start extra cranking and once in awhile I've done some pre-start avionics fiddling. The ess. bus problem has not recurred since 2012 and had never happened prior to that period.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
User avatar
dmloftus
4 Diamonds Member
4 Diamonds Member
Posts: 459
Joined: Thu May 07, 2020 3:38 pm
First Name: David
Aircraft Type: DA40
Aircraft Registration: N868US
Airports: KLZU
Has thanked: 211 times
Been thanked: 238 times

Re: Battery drain during flight plan load.

Post by dmloftus »

A better approach than the battery minder is a GPU capable of supplying >10amps, like this one rated for 20A:

https://www.aircraftspruce.com/catalog/ ... ckkey=6344

I have a 4A battery minder for slow charging/floating/desulfating. For running avionics on the ground, I built my own 10A GPU with a lightly used $30 Omron S8VS-24024 power supply off EBay like this one:

https://www.ebay.com/itm/385389119408?e ... R86ug5XeYQ

and a $43 Cessna plug:

https://www.aircraftspruce.com/catalog/ ... kkey=11008

For less than $75, you can run the avionics all day
User avatar
Rich
5 Diamonds Member
5 Diamonds Member
Posts: 4592
Joined: Mon Aug 30, 2010 12:40 pm
First Name: Rich
Aircraft Type: DA40
Aircraft Registration: N40XE
Airports: S39 Prineville OR
Has thanked: 145 times
Been thanked: 1180 times

Re: Battery drain during flight plan load.

Post by Rich »

In my case the regular cycle of updating the NavData for the GNS units doesn't actually require turning the units on at all. The data resides on the cards so just updating the cards and putting them in the appropriate slot completes it. In reality I do then turn the avionics on for the minute or so needed to confirm the cards are successfully readable. If going flying immediately this happens naturally anyway.

Whether the battery will be significantly affected by a "few minutes" of pre-start draw is going to depend on the state of the battery to begin with. Has it been sitting for days/weeks allowing slow discharge? Was the plane running at true idle (<900 RPM) for an extended time before shutdown on the flight before? Did it undergo some maintenance where it had extended low-RPM operation or multiple start cycles before your flight? Is it old? When was the last time it was load-tested? I do occasional quasi load tests on mine (turn on master and avionics, see what the voltage is after 30 minutes) to work around the difficulty in getting a true load test performed.

If your pre-start load is 10 amps, running for less than, say 6 minutes (aka 1/10 hr) would require less than 1 amp-hour (of the 13-ish available). Keep in mind that Diamond only documents a healthy battery will keep the devices on the essential bus operational for 30 minutes.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
Post Reply