Batter Tender battery connection?

[Topblissgt]

Well it is true, it just doesn't cause obvious issues.

Issues like what? Been doing since 2015. No issues here

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[I Bleed Ford Blue]

I don't see how the BMS could be affected since the only time the battery tender is hooked up and charging is when the car is not running or charging. The idea is to keep the battery topped off during prolonged periods of storage, not keep the BMS module happy. As I stated before, I've been doing it this way since 2017 and my car is fine, no issues.

 

[Topblissgt]

I don't see how the BMS could be affected since the only time the battery tender is hooked up and charging is when the car is not running or charging. The idea is to keep the battery topped off during prolonged periods of storage, not keep the BMS module happy. As I stated before, I've been doing it this way since 2017 and my car is fine, no issues.

Exactly. Ive been doing it since 2015 on my F150 and now on my 18 Mustang GT with absolutly NO ill side effects. Its just people overthinkinh stuff. The car is not running when the charger is on it and when you fire it up, the BMS starts monitoring the charge, so its no problem at all

 

[HoosierDaddy]

I am not taking a stand on negative hook up BUT if the purpose of BMS is to maximize battery life and since battery life is impacted by LOTS of factors, there is no way to conclude battery life of any specific battery was not reduced (i.e. had no issues) if BMS was bypassed.

Seems no brainer to connect negative to body if you know about BMS when connecting. Whether worth moving connection after becoming aware of BMS is worth it is another issue. Maybe the opportunity cost or chance of making a mistake doing the move isn't worth some unknown minutes/hours/days of extra battery life. Statistically, the odds of bypassing BMS while maintaining actually reducing the number of batteries an individual owner ends up buying has got to be very low. So, unless bypassing BMS means your battery dies right before you sell the car instead of right after you sell the car it makes no financial difference (to you).

 

[boB]

Hmmm. When I was using a maintainer with the quick-connect plug, I attached the pigtail to the strut tower nut and the positive nut closest to the battery on the fuse block. Now I use a Griot's 2/10/20 amp charger/maintainer that only has big alligator clamps. That first positive nut is recessed too far for the clamp to attach, so I've been using the middle one, and it seems to work just fine. Keeping in mind that the max setting on the Griot's unit is 20 amps (I usually set mine on 10), am I really risking blowing a fuse?

*If* something shorted out it is still highly unlikely a 20 amp charger would have any effect on a 275 amp fuse.

 

[Skye]

It's best to remove the negative cable from the battery, before starting any of this. Dropping a tool at the wrong moment can short something out, causing damage to you or the car. When connecting back up, the car is going to make all kinds of weird noises, several times, as it performs self-checks.

Edit, start.

"Perform a BMS reset when done." This step can be used as part of a t-shooting process, or, when installing a new battery. Otherwise, it is not needed. You do not have to reset BMS when installing a tender.

Edit, end.

https://www.mustang6g.com/forums/threads/bms-reset-no-tools-required.151602/

Yesterday, I attached my Ford Performance battery tender for the first time, to check it out. Using alligator clamps and leaving the hood up might be alright for the weekend, but it wasn't going to work long-term. I began eyeing the fuse block, another pigtail I had with the kit and these threads.

Thank You for the insight and the inspiration. Below are two options I'm playing with. Maybe these ideas and others might help you.

Cowl: the advantage of the cowl is I can tuck it under the hood and take it out as needed. To a passerby, it's almost invisible. The disadvantage is the hood closes snug and its a water area. The cable I fabricated is sealed with heat shrink, but still.

Front: the advantage of the front is all the wiring under the hood stays away from water, sharp edges or rubbing. But the plug poking out isn't very esthetically pleasing. I considered the grill, but it's a heat area and snug fit, for best airflow. If I Sharpie out the orange it will probably be less obvious.

For now, the front headlight area.

The advantages to either solution are not having to pop the hood, being able to hock up in moments and having a visual on the tender at any time.

 

[Skye]

To compliment this thread, product information and user manual on the Ford Performance CTEK unit.

 

[TorresDoe8]

Can someone advise, am I able to use the the positive battery post still if I already have something else connected to it (diode dynamics tribar abd demon eye color lights)?

 

[Jccams]

Everything I have read says not to connect the battery tender directly to the battery, it causes issues with the BMS. Also better to ground on the strut tower than the battery itself.

 

[Skye]

Can someone advise, am I able to use the the positive battery post still if I already have something else connected to it (diode dynamics tribar abd demon eye color lights)?

For the (+) you could, but it begins getting unwieldy, in both aesthetics and maintaining a solid connection.

For the (-) I'd say no, principally because this can interfere with BMS*.

For the tender, I'd attach the (+) to the under hood fuse panel and the (-) to the strut tower. Doing so keeps things out of the way, while supporting BMS.

Using the Ford-supplied connectors, I modified and extended one end, running it out of the front of the car; this allowed me to hock up without opening the hood, while leaving the tender outside for observation.

Three years on, nothing has loosened, become disconnected or caused a problem.

* On the factory (-) battery cable is a Hall Effect sensor. The Body Control Module (BCM) uses the sensor to monitor battery charges and discharges. By connecting a battery tender directly to the (-) lead of the battery, the BCM can't "see" that, and might interpret the charging action from the tender to be the discharging of the battery.

A secondary purpose of the sensor is to monitor the battery's State of Charge, a test the BCM performs after shutdown, often overnight.

People can and do directly attach leads directly to the battery without apparent issue. It's my belief at least an equal number connect this way and do have problems.

YMMV.

 

[McSkillet]

Issues like what? Been doing since 2015. No issues here

I know this is 4 years old, but I was looking to see what others have done to install a semi-permanent battery tender and came across this thread.
Even before seeing your comments I was in agreement with you. Then I watched this video and learned why grounding to the chassis is important.
Ford BMS Battery Monitoring System: How it Works and How to Properly Charge Your Battery!

 

[wingnutt]

lol…all these experts, and nobody talks about the 8 hour self-resetting BMS

alligator clamps here for the last 6 years and 75k miles…one battery change

ymmv, do not leave in direct sunlight and shake well before using

 

[WD Pro]

lol…all these experts, and nobody talks about the 8 hour self-resetting BMS

Who Leaves a tender on for less than 8 hours anyway ?

I’m absolutely with you, I just gave up quoting it and resorted to mild sarcasm … lol

I’m also still on my original battery but please don’t listen to me, I can’t even connect my tender properly …

Taken last month :

I only pulled the cover to clean the drain and check the battery terminals hadn’t disintegrated.

WD

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