Batt Charger?
 

Can anyone recommend an amperage I'd need to keep my batteries charged up when not driven? Such as a tender/charger

I picked up a 1A and it's way too small, so I figure maybe a 10A would be enough? :confused:

Why isn't 1A enough?

Been on there for three weeks and hasn't gotten one battery up yet.

Maybe the battery has to be disconnected? :confused:

I've liked the Guest brand units available from the usual marine stores (West, etc.). I use a 3A for winter storage--4-5 months--and have had no problems; I leave the battery connected and simply clip on the charger leads . That said, I've had no problems *without* a charger for a month or two, ever, and that goes back to the 1960's. The only times I've had trouble getting and keeping batteries charged are when the battery's bad or there's a drain that shouldn't be there (checkable with an ammeter). BTW, I've never had a battery go truly flat, for whatever reason, without finding that it didn't do well afterwards and needed to be replaced.

Mercedes sold a kit at one time, a cigarette type jack that mounted in the trunk liner and a jack with a transformer that plugged into the wall. A couple of amps should be plenty unless you have a bad battery. West Marine has a 2 amp battery maintainer, it comes with three cables, clips, lugs (wire to your battery), and lighter jack (wont work unless ignition is on) $49.99. You can unplug the charger portion and leave the cable attached to the battery.

5 Amps would be about right for a big honkin' diesel battery. 1 Amp would probably maintain, but would not be enough to recharge a battery that was down a bit.

Here's one with built in overcharge protection.

http://www.a-aengineering.com/

Hit Man, I've got a couple of these smart charges made by Yuasa. Have been pleased with them and they get slightly higher ratings than the Battery Tender products. They won't charge a completely dead battery, FWIW.

http://www.yuasabatteries.com/chargers.asp

http://www.yuasabatteries.com/images...ts/1201501.jpg

1 amp is perfectly fine for maintenance charging. The best is to get a standard
10amp charger PLUS a 1amp to balance things out. I use an Ampere Damper
which simply drops the 10 amp charging system down to .5 amp and 1 amp
(switchable). This allows me to handle the big jobs, eg when I leave the lights
on, fast charge (the 10amp charger has 50amp boost) as well as the safer
trickle / maintenance charge.

Neither the car's charging system, nor the 1amp chargers were designed to
restore depleted charge of the battery. To do that, you should use charger
which is 10% of the total amperage of the battery. Usually 10amp charger
will do the trick most of the time w/o fear of overheating or overcharging.

Mercedes Benz makes a solar charger, P.N. W900 589 02 63 00. They were made available to dealers about two years ago to trickle charge stock vehicles. I don't know if they're available for sale to the public though.

Be very careful about what kind of charger you put on a battery when the battery is attached to the car. Some cheap ones have a lot of ripple (some don't even have "full wave" rectifiers). This can harm the electronics in a modern car, especially if you are trying to charge a dead and/or bad battery. This is because the dead/bad battery won't smooth out the waveform from the charger very well.

Thanks. This is the best explanation I have run across about how to choose a battery charger. When I went to buy one, I was totally baffled by all of the choices.

I have found a Chicago charger at HF for $25-30.00. I think I'll pick one up this weekend. it's rated as 2/10/50, which means it has a boost charge of 50 amps, a regular charge of 10 amps, and a trickle charge of 2 amps. Is this correct?

I have one of these...
 

and it works quite well for keeping my 300E charged in the winter when stored in the garage.

Solar charger
 

1.5 or 5 Watt

Youch! the Mercedes branded solar charger is well over 100 dollars.
(AND the little sunlight rays don't know they're being converted into Electrons
by a cheap Chinese photovoltaic array.)

I picked up one from Sears years ago and it has performed well.

It has 3 switches for different auto & marine requirements :

6 / 12 V

2 / 10 / 60 A

Manual / Automatic Deep Cycle / Automatic Regular

I set it at 12V, 2A, and Automatic Regular to top up the car battery during winter months. Plug it in at night and it's done next morning.