PDA

View Full Version : Hooking Up A Battery Tender



Bill Walsh
07-18-2011, 02:00 PM
My 94 E500 hasn't been driven for about 3 months and I want to charge the battery with a Battery Tender. The Battery Tender directions say to connect the negative clip to the chassis. The owner manual says to disconnect the battery from the electronics. Should I disconnect both battery cables and connect the two Tender clips to their respective battery posts?

Thanks in advance for instructions.

Bill

2phast
07-18-2011, 02:07 PM
For all the years I have used trickle chargers, I have always connected them directly to the battery and left the battery connected to the car. When the trickle charger detects a voltage drop, it kicks on, charges up the battery then shuts off.

gerryvz
07-18-2011, 03:03 PM
What 2Phast says -- I've done this with both motorcycles and cars and you can safely leave the battery connected. Don't get a cheap battery tender -- get one that is voltage-sensing and that can turn itself on and off as necessary. $50 on up is what you will likely pay.

Cheers,
Gerry

Bill Walsh
07-18-2011, 03:26 PM
Thanks for the quick replies. Gerry, I bought a Battery Tender Plus. I think it was $60.00 or so has kicks off when the battery is charged.

spaceman_west
02-18-2016, 05:30 AM
any ideas why TWO battery tenders i just tried to keep giving me the blinking red light indicating that it's not hooked up right?
i'm clamping them on top of the connectors while the battery is still connected.

gerryvz
02-18-2016, 06:34 AM
The Battery Tender is connected to the battery with either a ring connector on each battery terminal (and a male/female plug connector) or using clamps to the battery terminals directly. For my vehicles, I use the ring connectors on the battery posts.

As long as the (+) and (-) clamps/ring connectors are connected to the correct pole of the battery, then the Battery Tender should work when connected. Generally if the Battery Tender is connected and charging, you'll see a steady red light, which may trickle over the course of hours (or even overnight/couple of days if the battery is down) and then turn green when the battery is up to snuff.

With the Battery Tender, a blinking red light means either that the Battery Tender unit is disconnected from the battery, or it has failed (if it is properly connected and still blinking red).

The Battery Tenders tend to fail after just a few years. They are cheap and Chinese-made. I bought three of them a few years back (Battery Tender Jr.), and just had one fail on me about 2 months ago with the blinking red light. I chucked it in the trash. The other two I have attached to my E500 and my motorcycle.

The funny thing is that honestly they didn't see heavy-duty use. Again, this is for the Battery Tender Junior model. I can't speak for the regular Battery Tender and Battery Tender Plus models. I got mine discounted via Amazon for around $20-25 apiece. At that price, it's just a throwaway item when it fails.

However, I won't be buying any more Battery Tender branded items. My next battery manager will be one of the Griot's Garage models, which at least have a lifetime warranty if they fail.

Cheers,
Gerry

gsxr
02-18-2016, 08:27 AM
I use PulseTech Xtreme Charge, which also doubles as a trickle charger / maintainer, and desulfator as well.

Amazon is currently $70 as of Feb-2016:
http://www.amazon.com/Xtreme-Charge-XC100-P-Maintenance-Desulfator/dp/B001JSTM8I/

Additional reading here: http://www.500eboard.com/forums/showthread.php?t=5641

:shocking:

Hakie
02-18-2016, 09:01 AM
The battery tender i have needs a little power left in the battery to work. With a complete empty battery mine will not begin to charge. For a complete empty battery i need an other type charger. Something to keep in mind when a battery tender is not charging.

Guss

sheward
02-18-2016, 09:43 AM
Yes, in the case of a completely drained battery an initial charge with a powerful high amp charger may be necessary to begin the recharging process. I have been told that connecting the dead battery to a fully charged battery for a while accomplishes the same thing. Batteries don't take well to this kind of treatment though and may degrade sooner.

drew

tanger
02-18-2016, 11:29 AM
I've had the Battery Tender Plus for 5 years+, and haven't had any issues. I once used it to bring back an AGM battery from the dead (using the E500 battery in parallel?serial? configuration).

I connect the negative lead to a solid chassis part (and it has to be a pretty good clamp with enough contact area). Also try adjusting the clamps - sometime when it doesn't have enough contact with metal the light will blink.

J-Sauce
02-18-2016, 12:07 PM
The battery tender i have needs a little power left in the battery to work. With a complete empty battery mine will not begin to charge. For a complete empty battery i need an other type charger. Something to keep in mind when a battery tender is not charging.

Guss

This^

Do you have an instruction manual for your exact model? Mine behaves as Guss posted, and the feature is explained in the troubleshooting section of the manual.

Hakie
02-18-2016, 02:17 PM
(using the E500 battery in parallel?serial? configuration).


Yes you can use an other battery (parallel) to the empty one. After a while you can hook up the battery tender to both and the tender will fill up both batteries. That could take a while.
If you want to speed up the charging process you might need an other (powerfull) charger.

This is the setup i somethimes use:

47357


Guss

gsxr
02-18-2016, 02:21 PM
If you want to speed up the charging process you might need an other (powerfull) charger.
Correct... but in general, it's best to use a low charge current. Something in the 1 amp to 5 amp range is great. 10-12 amp is about the most I'd want to use, beyond that it charges fast but generates heat, which batteries don't like. I know people don't always have the time to wait several days for a "slow" charge, but if you do have the time, that is the preferred method.

:grouphug:

tomer
02-18-2016, 05:21 PM
Gerry,

How do you route the wires so the trunk can be closed?

I am sure you have a clever method :-)

Thomas..


The Battery Tender is connected to the battery with either a ring connector on each battery terminal (and a male/female plug connector) or using clamps to the battery terminals directly. For my vehicles, I use the ring connectors on the battery posts.

snip

Cheers,
Gerry

gsxr
02-18-2016, 05:26 PM
Gerry,

How do you route the wires so the trunk can be closed?

I am sure you have a clever method :-)
I'm sure Gerry does have a clever method. :D

I just route the wire out the trunk lid and close it. The trunk gasket has enough compliance to allow the wire through without pinching anything. Another option is to leave the trunk lid open, and pull out the white/gray pin switch so the trunk light remains off.

:gwag:

gerryvz
02-18-2016, 05:30 PM
Yes, I just close the trunk lid on the flat cable to the battery tender. Just have to make sure that you don't close the trunk if the cable is on or near the latch in the trunk sill.


Sent from my iPhone using Tapatalk

Glen
02-18-2016, 05:44 PM
I'm sure Gerry does have a clever method. :D

I just route the wire out the trunk lid and close it. The trunk gasket has enough compliance to allow the wire through without pinching anything. Another option is to leave the trunk lid open, and pull out the white/gray pin switch so the trunk light remains off.

:gwag:

I do the latter, leave the trunk open and pull the grey switch :-)

gerryvz
02-18-2016, 06:14 PM
I don't want critters getting into my car through an open trunk, but I realize that some parts of the US don't have critters like we do here in Texas.

:tejas:

gsxr
02-18-2016, 06:21 PM
I don't want critters getting into my car through an open trunk, but I realize that some parts of the US don't have critters like we do here in Texas.
Gerry, you don't... gasp!... leave any of your cars OUTSIDE, do you? Or are critters common inside Tejas garages?

:blink:

gerryvz
02-18-2016, 06:22 PM
Critters are common everywhere. Doesn't matter in your house, garage, yard, etc.


Sent from my iPhone using Tapatalk

nocfn
02-18-2016, 06:48 PM
Nothing like the geiko gecko jumping on your face while you are flat on your back installing an oil pan. Scares the crap Out of me every time[emoji527]

sheward
02-18-2016, 06:56 PM
This is the reason I finally acquired ''the grey switch''.

drew

J-Sauce
02-18-2016, 07:06 PM
Armadillos can wreak serious havoc on wiring harnesses.

Maui
02-18-2016, 07:49 PM
I'm sure Gerry does have a clever method. :D

I just route the wire out the trunk lid and close it. The trunk gasket has enough compliance to allow the wire through without pinching anything. Another option is to leave the trunk lid open, and pull out the white/gray pin switch so the trunk light remains off.

:gwag:

I drive my 500E so little I keep a battery tender on it most of the time. The trunk closes just fine.