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Battery Tender[s]

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aerog

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I'm sure this has been talked about, but I'll be darned if I can find it!

Any comments about Deltran's Battery Tender(s)? I can't drive the MG hardly at all and I hate to have the battery go dead, then charge it, then go dead, etc.

I also have similar problems with the airplane battery. For some reason one vender doesn't recommend the 24v battery tender+ for a certain brand battery. I've yet to figure out why. The problem is the battery needs to be pretty much 100% fresh to pull the prop through. I try to fly a couple times a month, but then I'm only flying an hour or so and the battery just doesn't get "topped off". I saw a Waco UPF7 biplane with a battery tender + mounted to the firewall, the guy only flies a few hours a year and plugs it in otherwise.

So... comments on these suckers before I order a couple?

-sk
 
I have 2 Battery Tender Jrs and they work great. Haven't had any battery problems since getting them. Bought them at the local Pep Boys store for $10 less than advertised online.
 
I used to teach Aircraft Batteries to A&P students. I know Gill does not recommend trickle chargers to be used on their batteries. This is because a trickle charger is a constant current charger that has no control to shut it off automatically when the battery is charged. This can cause the electrolyte to evaporate and kill the battery.

I have never used a battery tender, but I am told that they have sensors that measure battery voltage and charge only when the battery voltage drops below a certain point. Then they shut off automatically when the battery voltage reaches normal voltage. This feature would seem to eliminate Gill's opposition to trickle charger use.

Batteries self-discharge at a rate of about one point of electrolyte specific gravity per day, more if the top of the battery is dirty. If you don't fly often, your battery is going to go dead even if it's in good shape. Clean the battery with a solution of baking soda and water. Don't let the solution get into the cells!!! Rinse with water.

If your battery goes dead from sitting, charge it on a constant current charger (3 amperes for most Gill batteries). Constant current charging is recommended by Gill because it does not have the damaging initial high current that a constant voltage charger has and because a constant voltage charger will never fully charge the battery! This is because the current drops off as the battery becomes charged, and this low current is not enough to knock the sulfide ions off the negative plate back into solution in the electrolyte. But a constant current charger has a timer to shut it off, while a trickle charger does not.

The worst thing you can do for the life of your battery is to get a hand-prop or GPU start! I have seen nice rectangular batteries become spherical from this!

Probably more than you wanted to know, but that's just how old teachers get.
 
Bayless - thanks... I might have to get one for the MG. It and the Corvette don't get driven much.


John - good info, thanks. I'd gathered a good amount of that from Gill's paperwork. My normal charger is automatic with a maintenance/trickle mode - but also can be switched into constant current, which is what I usually use on the a/c battery.

I think part of my problem is that aside from the normal typical self-discharge - I upgraded the radio a couple of years ago. The "new" one has a constant +28v memory backup that runs parallel to the clock circuit. I can't find any information on what the memory backup circuit draws, it can't be much but that seems to be what made the difference (as slight as it is). I might have to resort to sliding that radio out when I'm parked for prolonged periods.
 
I have a Deltran Battery Tender. I can't recommend it highly enough! Well worth the investment in my opinion. Probably the most useful, and used, item of equipment I have. I use it in the summer to keep the snowthrower's battery up to snuff, winter for the cars.
 
I have ~This One~ from Northern Tools.

$20

Charges at .25 AH with a built in control circuit. I use it on lawn tractor battery, race car, etc. Works great.
 
Update:

I got 12v Battery Tender "Plus" ($41.50 from aircraftspruce.com). I didn't think the MG battery was down that much, but I stuck it on the new charger anyway. Took overnight (and then some) before the charger kicked into flashing-green "80% charged" mode, and awhile longer for trickle (well, float I should say) to kick in.

I ended up with a different brand that was recommended elsewhere, and supposedly made for the 24v battery in the Cessna...now I have to fix the busted GPS cable. Stupid (grumble grumble) Garmin (grumble) wiring.
 
Twosheds said:
I know Gill does not recommend trickle chargers to be used on their batteries. This is because a trickle charger is a constant current charger that has no control to shut it off automatically when the battery is charged. This can cause the electrolyte to evaporate and kill the battery.
Click to expand...

Just wanted to follow up on this, John. I read a variety of things on the Gill batteries and happened to come across this in something Teledyne/Gill put out in one of their manuals for the dry charged batteries under maintenance:

<span style="font-style: italic">Teledyne Battery Products recommends that the battery be removed from the plane during such non-use and either <span style="font-weight: bold">kept on trickle charge</span> (13.5V to 13.8V for 12V batteries, or 27V to 27.6V for 24V batteries); recharged every 90 days or recharged prior to flight.</span>

I'm not trying to contradict what you wrote because I've heard (and read, somewhere) the same thing about trickle chargers on their batteries. Maybe they changed their philosophy on charging...

Anyway, Deltran's BT+ and the 24v versions start with what Deltran calls "bulk" charge mode - which, it turns out, is a constant current charge at 2.5 or 5 amps for the 24v version (I don't have the graph for the 24v version to see what it starts at). At about 80% charge it drops into "absorption mode", which really is just a constant-voltage charge. At some point it decides to drop into "float" (storage/maintenance mode) and stays there until the charger's power source is reset, or it senses a certain drop in the battery voltage.

According to Deltran, the voltage they use for the float mode is below the point that gassing occurs - which, in theory, would prevent loss of electrolyte. They claim its better than trickle charging for maintaining lead acid batteries, and its characteristics seem on-par with the description of the trickle charging Gill wants to see.

Another charger is called the "Battery Minder" made in NJ. I haven't seen the nitty gritty on it, but it looks to be similar to Deltran's Battery Tender. They added a function that is supposed to de-sulfide the plates. Their advertising sounds vaguely like the black-magic MPG pills and other things advertised in Popular Mechanics, but a few people swear by them.

Finally (whew), I don't think I'm going to stick my Gill on a 24x7 float charger - but I've read a few things from people that have done just that. Several have just treated them like the car guys use the Battery Tender, and have had a very good service life from their battery. Whether the charger was a big help or not remains to be seen, but they certainly haven't had any ill-effect.
 
Thanks for the update, aerog. I can deal with it because I have a lot of experience at being proved wrong!

I was working from memory (always a dangerous thing to do). Maybe Gill revised their manual to reflect newer technology in trickle chargers.

It is definitely hard on a battery to get charged from an aircraft (or car) alternator after a jump start, so, it's better for the battery to be kept charged during periods of inactivity.

By the way, if an aircraft battery is totally flat dead, and you get a hand-prop or GPU start, the aircraft generator or alternator won't charge it even if the generator will run the rest of the electrical system! This is because the battery contactor that closes when you turn the battery master switch on is activated only by battery current.

I'd have to look at a wiring diagram again, but I think it's possible that an alternator won't put out anything if the battery is flat and you get a hand-prop because the alternator field needs battery current through it to start the process of generation. So your engine will run, but you won't have any avionics or lights. This won't happen with a generator; residual magnetism will start the process of generation.

All this is good reason to keep your battery charged up for flight and not depend on the line boy to start your engine because the battery is flat!

As a pilot, you may service your battery as preventive maintenance.
 
I don't think you're wrong, I remember hearing or reading the same things you'd said before. Deltran states clearly not to use their equipment on aircraft batteries, and I think they single out Gill and Concorde. Aircraft spruce states clearly NOT to use Deltran products on Gill and Concorde. I just can't figure out whether there's real harm, or whether they're trying to shed liability. I'm over it, but it was an interesting subject :smile:
 
A little update...mostly aviation oriented:

Apparently "Aviation Consumer" magazine had previously recommended Deltran's Battery Tender products for use on aviation batteries. Mike Busch also recommended them in his "Savvy Aviator" column on avweb. I cannot find any specific information to cite from Aviation Consumer about their recommendations, and Mike only brushes on the technical capabilities (and reasons for using) the chargers he recommended. It's fair to say their (and other's) recommendations for Deltran's products is open to debate.

In any event, I ran across another article from "Aviation Consumer" singing the praises of VDC's aviation-specific "Battery Minder".

I'd previously dismissed VDC's product because the only real support they were providing was a .pdf of an embellished ad from Popular Science... the latest article(s) go into detail about VDC's Battery Minder though - and it seems good. The aviation version of the "minder" adds a battery-mounted temperature probe (they were previously an option on the other chargers, I'm told) that fine tunes the charge characteristics and protects the battery from over-charge - the charge algorithm is set up to work along the specs provided by the battery manufacturers. The product testers found that the float charge changed appropriately for the battery temp - which brings the maintenance charging in line with what the manufacturers want to see.

All VDC's Battery Minder (aviation and consumer) chargers also provide full-time de-sulfation that theoretically increase overall battery life. Whether it really works or is hooey along the lines of the fuel-saving "tornado" remains to be seen, but there is some support for their de-sulfation method.
 
Scott - I put a small battery tender on the Norton's battery when I layed it up for winter & by the end of winter when it was time to ride, the battery was dry & burned up! & the charger was showing 'green' most of the time & only went to 'red' rarely. But, the battery guy told me that even when it shows the battery is fully charged, its putting a little electricity into it which over time will drain a battery!
 
That's true for the battery tender(s), sort of, but what you describe is curious. Once a charge cycle is complete the Battery Tender(s) will show a steady green light and will go into "float" mode. If it fails to maintain in "float" and the voltage drops to a certain level the tender should go back into regular charge mode and show a flashing-green light.

If the battery goes dead or destroys itself somehow (let's say it has a crack in it), then I would assume the tender would simply see that low-voltage state and go into regular charge (flashing green) mode for a period, then show a flashing-red light when the voltage drops below 3-volts.

Then again they say that a steady-green shortly after attaching the charger to a battery indicates a defective battery.

Anyway, supposedly their float charging shouldn't result in boil-off and a dry battery. A good "float" maintenance charger will regulate itself and charge only enough to compensate for internal discharges, which should be low enough that gassing and electrolyte loss is minimal...whereas a trickle charger can destroy a battery, the float mode on the tender shouldn't do that.

On the other hand.... horse-manure happens :wink:
 
I bought a Battery Tender about a year ago for my project car.
The car sits in the shop and only moves to go on the rack. It starts every time and will even charge up from dead when I forget to reconnect it or run it down.
 
I have four like Nial has. One thing to remember, a battery with a "Maintainer" hooked up to it, must be treated the same as if it's in daily use in the car. Meaning the liquid level should be checked periodically and a proper level maintained. Only 1 or 2 continuous amps will depleat the liquid level over a period of time. I plug my maintainers into a timer set to come on for a steady 24 hrs once a week. I check the liquid level once a month and never had a problem. I keep 3 large motor home batteries and the "B" battery on one when not in use. Works for me.
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