Mount BatteryMinder Control Unit Inside Plane?

Sinistar

Sinistar

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A friend recently sold her Citabria :( and sold us her Battery Minder. Yes, the unit specifically for the Concorde battery which we both had in common. But this question should be relevant to almost all tender brands.

#1. I know some owners who place (and even permanently mount) the control unit inside the aircraft. They then bring the AC power cord through a port or window or door.

#2. In past I installed the DC quick disconnect to the battery and pass that out the baggage door and the control unit sits outside the plane.

Is there any reason to favor one over the other?

This is for a Skylane so battery is in back and room for either option.

I'm leaning towards #2 again. Was going to ask AP to put in a small bulkhead quick disconnect for the DC plug so I don't have to pinch it in the baggage door anymore.
 
Sinistar said:
Is there any reason to favor one over the other?
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Have seen it and installed it both ways. I usually recommend just the DC side left on the aircraft as it is a cleaner install. But both ways are doable. For example, one owner wanted just a 110v plug in because he kept forgetting to bring his charger when he moved his aircraft around. Another example, an owner also had a Tanis preheat system installed and wanted a single 110v plug in to power a battery charger and the Tanis.
 
I do #2. Just easier to have the lead sticking out the baggage wall and plug it in when it’s parked.
 
I want my Battery Minder fire or meltdown to occur outside of my airplane. I bought the 25ft (?) DC cord and the minder is attached to the hangar right next to the outlet.
 
455 Bravo Uniform said:
I want my Battery Minder fire or meltdown to occur outside of my airplane. I bought the 25ft (?) DC cord and the minder is attached to the hangar right next to the outlet.
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I hope that 25’ cable is made with a large enough conductor. If not there will be enough voltage drop over it to get an inaccurate reading from the battery back to the tender for accurate control of the charging.
 
MBDiagMan said:
I hope that 25’ cable is made with a large enough conductor. If not there will be enough voltage drop over it to get an inaccurate reading from the battery back to the tender for accurate control of the charging.
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You may be right, but it’s made by them so I thought it’d be fine. I always end up 12.7-12.8 when I’ve checked the battery.
 
For those of you permanently installing a battery minder or charging cable, don’t forget a fuse at the battery connection. That tender wire is a direct connection to the battery and if it chafes or shorts on something over time you have no way to stop it inside the cockpit.
 
My fuse is right at the positive battery terminal for the very reason that Kmacht properly pointed out. Very important this!
 
Doug Reid said:
Does your Skylane have a aux power socket ?
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It likely doesn't connect to the battery if it does. Most of the aux power plugs are on the bus side of the battery contactor. This is important to know because if your battery is completely flat, and you start it with the aux power plug, the alternator may not charge the battery in flight.
 
Thanks for all the responses.

I am really favoring #2, firstly because of @455 Bravo Uniform concern regarding the charging unit having a failure (fire).

I also like #2 because the short DC lead with protective cap makes for a nice way to check battery voltage without removing rear baggage bulkhead panel.

There is enough room in the skylane and any little weight in back usually doesn't hurt. However being able to see it easily at all times (ie. Outside the plane) is another benefit to being outside.

Maybe if having to park outside frequently where it rains (eg. PNW) it might be nice to have it inside.

So, can a AP install a bulkhead pass thru connector for the DC end...like on truck trailer hitches? I got sick of closing the baggage door over the DC cable when we had our previous Gill on the tender. Something like this (visual example only) but more wx proof, etc:

https://www.amazon.com/Pack-Weather...t=&hvlocphy=9052449&hvtargid=pla-902361551015
 
Doug Reid said:
Does your Skylane have a aux power socket ?
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No.
kmacht said:
For those of you permanently installing a battery minder or charging cable, don’t forget a fuse at the battery connection. That tender wire is a direct connection to the battery and if it chafes or shorts on something over time you have no way to stop it inside the cockpit.
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The Battery Minder short DC cable to the battery has a fuse very close to the actual battery terminal.
 
The DC extension cord is a interesting solution provided it doesn't fu uo the highly priced tender wonderfulness. Woyld much prefer to mountbthe unit on the hangar wall!

Gonna have to dig a bit deeper on that one.
 
Sinistar said:
So, can a AP install a bulkhead pass thru connector for the DC end
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Yes. It may have to be installed in a certain position/area to keep it as a minor alteration. In the past have used cannon plugs like below to route wires from inside to a point on the exterior. You would just need to modify your DC wires to work with it.
prcpc34d.jpg
 
flyingron said:
It likely doesn't connect to the battery if it does. Most of the aux power plugs are on the bus side of the battery contactor. This is important to know because if your battery is completely flat, and you start it with the aux power plug, the alternator may not charge the battery in flight.
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You might be correct...I know a few owners who modified their aux to charge the battery directly.
 
455 Bravo Uniform said:
You may be right, but it’s made by them so I thought it’d be fine. I always end up 12.7-12.8 when I’ve checked the battery.
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I expect that you are right about the cord being adequate since it was supplied by the manufacturer.

Just so you know though, measuring battery voltage with a meter and getting what you expect is not a valid test of the cable and connectors because it is not under load. You could make a meter voltage measurement with one tiny strand and get a correct voltage reading because it doesn’t have to flow any current. When it is flowing current, then the voltage measurements are meaningful. Such circuits are usually tested with a voltage drop test while under load.
 
I've had a "Battery Tender" brand, used for my motorcycles, develop a failed component and smoke really well.

My shop smelled like smoked capacitor when I got to it the following day.

I'm glad that, at least in the motorcycle world, there's not much option for most except to have it as an external component.
 
Is this a special aviation-specific unit?

My plane had a battery minder installed next to the battery when I bought it. Seemed like a convenient feature (the factory ground power port apparently doesn't charge the battery) but current IA said it had to be removed for him to sign off an annual inspection.
 
School me please. My limited understanding of electricity is switch on or switch off.. Is a battery minder specific to a brand of battery i.e. concord vs Gill. If not, why does my $$$$ aviation specific battery charger have a dip switch specific to my battery brand..and it must be set correctly before charging, or else the battery melts and becomes toxic. Also, my plane doesn’t know what brand of battery is installed cause it can’t read my log book, I asked and it said “no can read”, and I do not have a switch in my plane to tell my alternator what brand of battery has been installed so the battery can be charged correctly. gracias
 
GoDores said:
but current IA said it had to be removed for him to sign off an annual inspection.
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Was there a write up in the aircraft record for installing the battery charger?
 
RandyB said:
School me please. My limited understanding of electricity is switch on or switch off.. Is a battery minder specific to a brand of battery i.e. concord vs Gill. If not, why does my $$$$ aviation specific battery charger have a dip switch specific to my battery brand..and it must be set correctly before charging, or else the battery melts and becomes toxic. Also, my plane doesn’t know what brand of battery is installed cause it can’t read my log book, I asked and it said “no can read”, and I do not have a switch in my plane to tell my alternator what brand of battery has been installed so the battery can be charged correctly. gracias
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I always wondered the same thing.

Two guys I know have the expensive aviation version for their Concorde batts. My 93 year old hangar neighbor with 2 Bo’s has been using the cheap one for each plane, with a simple timer that runs em for 3 hours daily. He learned it from a Bonanza Society newsletter.

Me? I run the cheap one, 3 hrs, 3 times a week. Battery will be 4 years old in July. The last one was 9 years old when I replaced it, but that was the prior 2 owner’s doing (whatever they did), not mine.
 
Bell206 said:
Was there a write up in the aircraft record for installing the battery charger?
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Not that I saw, but I asked the shop if the install could be made legal and the IA said no.
 
GoDores said:
Not that I saw,
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This is the key point, no write up. Wonder if the previous owner was a PoA member? By any chance was the a shop/IA also a repair station? For reference, you can technically install anything in an aircraft legally. Just need to follow the rules and have someone willing to sign it off. However some entities cant venture beyond certain limits like a CRS. But have installed a number of "non-aviation" items in aircraft with no issues to include battery chargers.
 
I bought a cheap battery minder from a motorcycle store. I took the battery end and secured it to the posts on my battery. I then lead the leads out to where I could connect them the power supply. I maintained the battery in my Cherokee for seven years that way. For the Mooney I did the same thing, though the battery end is sitting in front in the engine bay. I secured it with a zip tie. I've had the same battery int he Mooney 5 years now.
 
RandyB said:
School me please.
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455 Bravo Uniform said:
I always wondered the same thing.
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When learning how to use my fancy battery bench charger years ago was told aircraft batteries had tighter voltage specs and in some cases different internal items than non-aircraft batteries due to TSO requirements. Those differences equated to having to set up my charger differently based on each specific battery OEM manuals. The main difference on the charging side as I recall was on the duration and voltage of the charge depending on battery charge state. Its my understanding the aircraft battery minders are set to those specific OEM charge requirements that I had to do manually. Vehicle battery chargers tend to have much wider charge settings when compared to my calibrated bench charger. Whether that justifies an increase in cost for "aircraft " chargers over a non-aircraft charger couldn't tell you.

FYI: most battery internal damage is done at the initial charge or during extended charging events. If your aircraft's electrical system is top-notch (clean connections, no parasitic drains, etc.) and your battery is in a good condition you probably wouldn't have a problem with a non-aircraft charger. However, if there are issues with the electrical system, especially with parasitic drains, then there's a real possibility the non-aircraft charger will output voltages at durations the exceed the battery OEM specs due to their internal settings. Its those exceedances that add up over time and degrade the battery at a faster rate.
 
I am liking the idea of the charging unit mounted on the hangar wall. I can see the indicators easily without having to go into the plane. If the 16ga extension cord doesn't interfere with their patented, secret, voodoo charging magic then it works out nice. I did check last time, the 18ft extension is not enough or a bit too tight to reach all the way back to the baggage compartment so the 25ft DC extension will be needed.

On Skylanes (and probably all single engine Cessna's) there is a jump start port on the pilot side engine cowl. It looks like on later models there is enough room to place the batter minder charging port there as well. But on our old timer P model the access cover is just large enough for the jump plug need to place in back by the battery, unless it could be placed just inside the oil door. But having that little 12 vdc wire that goes right to battery even remotely exposed in there is a bit creepy, even with the little dust cap which could easily be forgotten.

Either way, If the charger thingy decides to go supernova hopefully it will let out all of its smoke, sparks and fire into the hangar....sparing the plane....for about 6 minutes until the entire hangar burns down (kidding of course).
 
Bell206 said:
This is the key point, no write up. Wonder if the previous owner was a PoA member? By any chance was the a shop/IA also a repair station? For reference, you can technically install anything in an aircraft legally. Just need to follow the rules and have someone willing to sign it off. However some entities cant venture beyond certain limits like a CRS. But have installed a number of "non-aviation" items in aircraft with no issues to include battery chargers.
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Don't know about the previous owner, but the shop does have a repair station certificate. It's possible that "it can't be made legal" meant "it would take more time, money, and/or hassle than we think it's worth". For my purposes I decided I'd rather just leave the battery minder in the hangar, so I didn't pursue it any further.
 
GoDores said:
It's possible that "it can't be made legal" meant "it would take more time, money, and/or hassle than we think it's worth".
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For reference, a CRS needs to have written procedures or other references to perform and sign off work performed under a CRS workorder. However, some APIAs also prefer to stay well within the limits of Part 43 when it comes to alterations so it was probably one or the other that brought on "can't make it legal." Depending on how the charger was mounted or if you want to have it back in the aircraft perhaps have a local AP make you a bracket where you can remove the charger for each annual or possibly address it as "loose equipment."
 
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