[whoever]

It has been two hours and it hasn't make a dent on my Kindle. Wondering if it even worth hooking up to the car

BTW, I think the Kindle battery is 1.5Ah, BMW is 850Ah and the charger is 5w and 250mAh peak

[tr_ms3]

no.

I used to put one in the dash of my truck while at the track. Realized it didn't do anything, so I stopped.

[whoever]

How's this?

[WilliamS]

They do a decent job to maintain a battery when the car is in storage. As for recharging Im going to lean hard on a big no.

[Efthreeoh]

I use one to keep my zero-turn mower battery topped up. Left it on all winter and she fired right up this spring.

[jzchen]

W=IV

I=W/V

You can do the math if you like....

If it's 5w, and your battery is 12V, (actually if you measure it with a voltmeter you'll actually find it's higher,) you'll get .4 amps. I don't think that'll do anything for your car battery.

1.5 amp Schumacher from Walmart for $20 and a long extension cord....

[whoever]

Thanks for the info. How does it compare to Battery Tender? Just want to make sure it has all the "intelligence" and won't over charge the battery.

My car is parked on someone else's drive way, so connecting a power cord is kind of intrusive. I left the car with 12.3v and today is the first day with half sunshine, rain later during the week ... Not very optimistic I have to admit.

I'll give it a try. If doesn't work, maybe I'll just plug it in twice a week for a few hours.

Originally Posted by jzchen

W=IV

I=W/V

You can do the math if you like....

If it's 5w, and your battery is 12V, (actually if you measure it with a voltmeter you'll actually find it's higher,) you'll get .4 amps. I don't think that'll do anything for your car battery.

1.5 amp Schumacher from Walmart for $20 and a long extension cord....

[jzchen]

Originally Posted by whoever

Thanks for the info. How does it compare to Battery Tender? Just want to make sure it has all the "intelligence" and won't over charge the battery.

My car is parked on someone else's drive way, so connecting a power cord is kind of intrusive. I left the car with 12.3v and today is the first day with half sunshine, rain later during the week ... Not very optimistic I have to admit.

I'll give it a try. If doesn't work, maybe I'll just plug it in twice a week for a few hours.

I bought the BMW Battery Tender, made by Deltran I think. It came DOA. You are instructed to install it on the jump start terminals in the engine compartment, but it just plain didn't work. I have the maintainer that I mention on 6 different cars in my household at different times. When I disconnect any one, I am very confident it will start and have had no issues...

The thing is that you said it is limited to 245mA, which I am not sure how that plays into things. If it is true, then that would be even less than the 400mA that the equation works out to....

[Efthreeoh]

A company called Granite Digital sells the one I have. Google saveabattery.com and you'll find it. They have a unit sized to keep an auto battery. The Granite unit is smarter than the Deltran Battery Tender. I've used both.

[jzchen]

Originally Posted by Efthreeoh

A company called Granite Digital sells the one I have. Google saveabattery.com and you'll find it. They have a unit sized to keep an auto battery. The Granite unit is smarter than the Deltran Battery Tender. I've used both.

My BMW branded Deltran didn't even work.... The one from Walmart works just fine on the jump start points. (Glad at least someones' worked!!! ) Called Deltran up and realized it would be a waste of effort/money to get it fixed under their warranty. Went to Walmart and bought another. (I have six of those now...)

[Efthreeoh]

Originally Posted by jzchen

My BMW branded Deltran didn't even work.... The one from Walmart works just fine on the jump start points. (Glad at least someones' worked!!! ) Called Deltran up and realized it would be a waste of effort/money to get it fixed under their warranty. Went to Walmart and bought another. (I have six of those now...)

I first started using a Deltran Battery Tender way back in 1995 to keep my motorcycle battery over the winter. Deltran used to make their units in Florida, but some time ago switched manufacturing to China. My old USA-made Tender died in 2007 or 2008. So I bought a few more Deltrans from Amazon; all of the Chinese-built units died within two years. After that fiasco, I went looking for a solar-powered unit and found the Granite Digital unit. I've since bought two other 120V-powered Granite models besides the solar model. I use both units year-round now keeping my motorcycle topped up and my New Holland diesel tractor charged. I like the Granite Digital units because they have such a varied model selection to choose from and can come with volt meters built in and give better status of the battery condition other than just a red or green light. They also have a nice load conditioning feature for really dead batteries.

[jzchen]

Originally Posted by Efthreeoh

I first started using a Deltran Battery Tender way back in 1995 to keep my motorcycle battery over the winter. Deltran used to make their units in Florida, but some time ago switched manufacturing to China. My old USA-made Tender died in 2007 or 2008. So I bought a few more Deltrans from Amazon; all of the Chinese-built units died within two years. After that fiasco, I went looking for a solar-powered unit and found the Granite Digital unit. I've since bought two other 120V-powered Granite models besides the solar model. I use both units year-round now keeping my motorcycle topped up and my New Holland diesel tractor charged. I like the Granite Digital units because they have such a varied model selection to choose from and can come with volt meters built in and give better status of the battery condition other than just a red or green light. They also have a nice load conditioning feature for really dead batteries.

Had my first issue with one of the chargers this last Fri. Unplugged one to start a car and it was dead. Reconnected the charger and after a little while the light turned "green" stating the battery was good when in fact it was dead. Used my charger to charge it a little while and it started up. I guess they are good for keeping a battery charged, but if it dies, (this outlet tends to go out once in a while,) they are not as good at bringing batteries back up to charge.

[whoever]

Originally Posted by jzchen

Had my first issue with one of the chargers this last Fri. Unplugged one to start a car and it was dead. Reconnected the charger and after a little while the light turned "green" stating the battery was good when in fact it was dead. Used my charger to charge it a little while and it started up. I guess they are good for keeping a battery charged, but if it dies, (this outlet tends to go out once in a while,) they are not as good at bringing batteries back up to charge.

Most of the small chargers claim to charge small but maintain large battery only. And many says do not work on dead batteries.

But charger should not have a reverse draw on battery when outlet goes out, right?

[jzchen]

Originally Posted by whoever

Most of the small chargers claim to charge small but maintain large battery only. And many says do not work on dead batteries.

But charger should not have a reverse draw on battery when outlet goes out, right?

I don't think it will drain a battery. This particular car has an aftermarket Python alarm system on it. I had armed the system. It also has a little hand dial clock that runs all the time. I have the batteries connected to the car so that certain electronics will still have power... I may have been a little confusing. I have a separate 12 amp charger that I used to charge it. The 1.5 amp ones are specifically called maintainers.

I agree, I think they work fine as long as the battery has sufficient charge already, and not dead, although some as Efthreeoh mentions have a function for bringing back almost dead ones. (I honestly don't think you can bring back a real dead one, having studied this chemical reaction in some science classes... You need a "seed" of non-oxidized lead to be able to reduce some back, or something like that... It's been a long time since I've studied it...)

[whoever]

Today is a good sunshine day on east coast. I estimated that the panel can charge an iPhone 4S in about 3-4 hours.

Does anyone know how to do the math? How is charging iPhone vs BMW? Assuming there's sun half of the time, is this enough to maintain the battery? Of course, there imply the question, how much does a parked E60 consume?