Battery Tender Question

I've wondered about that myself.

 

I'd unplug it, they are not designed for the current draw of starting a car.

 

Yeah I would unplug it. Assuming the tender is doing its job when it senses the draw from the start it will start charging again.

 

As a test, I have started my BMW with a tender plugged in, and my Ferrari for that matter, no harm. But it is probably better to unplug as recommended above.

 

+1

 

I just called Deltran at their technical service line, and was advised there is absolutely "no problem" with starting the car with their battery tenders connected up. I guess the best advice is call the manufacturer if it is not in the manual.

 

No problem leaving it plugged in but I always unplug it out of habit and just for good measure. Hey, something else to consider...always put that Deltran on a surge protector if you don't want a lightning strike to take out the electronics in your car.

 

It is recommended to unplug and then start the car....infact the 2008 f430 will not start if the battery tender is still plugged in...I tried starting it with the battery tender still attached to the socket under the passenger dash and it was unplugged from the wall electrical outlet...my f430 spider will not start...but once I removed the tender from the car, I was able to start .

 

There is no accurate answer to that question because the circuitry of all battery tenders varies greatly. Some might cause problems with the car's regulator diodes when the car is started, others tenders can be damaged by the alternator when the car is started, and yet others will have no ill effects. Actually, the higher priced tenders are higher priced because they have features, and those 'features' are often the culprits.

What's worse, like eating high cholesterol foods, deleterious effects aren't noted immediately.
100% safest is not to unplug the tender but to disconnect it from the battery.

 

I never thought about a lightning strike. All my outlets in the garage are GFI. Do I still need a surge protector?

 

Triumph Sprint - motorcycle, right? I've done this on my bikes many times, and nary an ill effect - and that's on older Ducatis which have typical Italian, fragile/anemic electrical engineering

 

First the battery is in essence a HUGE capacitor so there will be very little change in voltage. The relatively small wires running from the tender to your battery will be sufficiently resistive compared to the capacitor to create a very low pass filter. The tender won't be able to take the surge so it will short suppressing the surge. PLUS, most of the electronics are isolated because of the ignition switch. Feel free to prove me wrong but there doesn't appear to be a rash or detonated car electronics.

GFI is not a surge suppressor. It cuts the power if the current to neutral doesn't match the current in the hot. That means it is leaking to ground so it cuts power.

Surge suppressors are fast acting diodes that shunt the over voltage situation to ground.

 

John, the only flaw in your thinking is regarding location of the 3 elements (I'm thinking 308 now) ... battery(very front), alternator(very rear), and main stuff (middle or car). All connected by relatively high impedance wires. So an voltage spike won't especially be shunted by the extremely low impedance (your capacitor analogy) battery. And in fact a spike can get amplified by the distance between elements (in resonance). It is too complex to predict with any specificity, which is why I earlier said there is no real answer to the question. A tender is best located very close to the battery and when there are portentially two sources of energy, tender and alternator, best to avoid contention and disconnect the one not in use. Few people disconnect the battery ground before attaching the tender but that too is best.

As one who has fried an alternator by jump starting cars, I have the smoke to verify my findings. And if anyone hasn't read the thread about changing your blinker fluid, I'd highly recommend doing so now before it's too late.

 

Are you using a Ferrari tender? If you are, it's garbage (I have one). Put it in the nice leather case, stick it in the trunk and get a Deltran. The Deltran will afix directly to your battery.

 

No if you house is surge protected, but GFI is not surge protection. Surge protectors are dirt cheap so I think it is just good insurance.

 

A surge protector is around $12-$20. When was the last time you got a tow or service performed on your Ferrari for that? If you are right and I don't need one I threw away $12-$20 bucks. But if you are wrong and your car is damaged from a strike you just blew a big wad. PLUS, I have modern and vintage cars. Do you think the isolation even from the ignition switch is as good in a 1965 Ferrari as it might be in a 2009? If you do, you haven't ever taken apart a vintage car!

Look, I recommend unplugging the tender before starting the car if for no other reason than to avoid driving down the highway wondering what that darn clanking noise is! AND, I recommend plugging all of your household appliances, including your cars on tenders, into surge protectors if for no other reason that to be able to tell you friends that the device is a special regulator for the flux capacitor feeding the hydrogen generator...

 

Amen!

And I changed by blinker fluid already...what an amazing difference...didn't think blinks could be that good!

 

+1

Or, ripping the socket out of the wall.....

I "saved" a Porsche a while back that was taking off with the tender hanging out of the passenger door! [It had been unplugged at the wall]

The absolute best though was the guy who took off in his ~50ft boat with the shore power still attached! - One of the funniest things I've seen!....

Cheers,
Ian
PS - Maybe the Q should be "Any reason *not* to unplug it first?". [None IMHO btw - Older cars probably don't have the electronics, but we know how sensitive, eg, the ELD in the 360 series dashes are - *Look* at it wrong and it breaks, why take a chance?]

 

Absolutely agree about starting. I was talking bout the lightning claim. In that case the alternator isn't a factor, just tender connection point.

 

Dear Ferraristi,

I use the Deltran Battery Tender + in both my Testarossa and my Lamborghini VT Roadster. I use both cars as daily drivers but the "topped-up" battery puts less stress on the alternator. I too, unplug the tender from the "quick-connect" at the battery then start the car. The tender itself is still plugged to wall and just blinks until plugged in again. I use 2 individual units as the multi bank unit comes with a lesser warranty.

I have my tenders attached to surge protectors because I live in FL and lightning is not a small issue here....cheap insurance. Don't buy the cheap surge protectors. You get what you pay for....I use panamax.


Shamile

Freeze....Miami Vice !

 

Panamax are nice. I have one for my home theater.

 

I just installed a new battery & wired up the Deltran battery tender on a 348, my question is it better to turn off the power from the valet knob rather than leave it on? Also I connected the tender to the battery rather than going in from the engine compartment, I did want to have any averse electrical issues effecting the relays.

 

There may be some confusion here about battery tenders and the official "Deltran Battery Tender Plus". In my experience the Deltran Battery Tender Plus is by far the best unit on the market. Best voltage monitoring and most reliable battery maintenance. I use them on everything from a Ford Crew Cab to Ducati motorcycles. In fact one of my motorcycles has 9 year old batteries and I credit the Battery Tender Plus with making this amazing longevity possible. The Stradale has the original battery and is working great. I am a big fan of this product and can recommend it very highly.

Back to the original question I have started everything both ways, with it connected and not connected. No problem either way. Also I occaisionaly disconnect and reconnect just to have the Battery Tender Plus charge it up to max voltage.

One word of caution. I have had several of the small wall unit trickle chargers over charge a battery. I am no longer using any of those units. Even the Deltran Battery Tender wall unit let me down once. Only the Battery Tender Plus for me.