Proper jump starting

[Ducati1098]

I think I actually do have mine hooked up after the BMS then! Didn't realize the BMS was actually part of this stud. Black wire I'm touching goes to the battery tender. (The brown/orange goop is NOCO battery terminal anti-corrosion spray-on goop)

Yep that is perfectly fine

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[CalvinT]

Connect positive cable to the positive terminal first. Then negative cable to a ground point on the chassis. They say to connect to ground last to avoid sparks near the battery. Not much of a risk with an AGM battery. The old style vented batteries will outgas hydrogen which can make things exciting if it ignites. (Think Hindenberg)

 

[Brian_B]

Connect positive cable to the positive terminal first. Then negative cable to a ground point on the chassis. They say to connect to ground last to avoid sparks near the battery. Not much of a risk with an AGM battery. The old style vented batteries will outgas hydrogen which can make things exciting if it ignites. (Think Hindenberg)

In the Navy, we were always taught to hook up Ground first, then hot.

I don't think it really makes all that much difference for +12V systems, but ships at sea run on ungrounded/floating ground systems (just like cars do), so you want the "ground" connected first to help minimize any accidental arcing -- as opposed to your house, which has a separate Ground and Neutral (I know, DC vs AC there, but the same principle when applied to grounding)

 

[RobWTX]

I need to double check the manual (too lazy right now), but I think it states the BMW will reset after sitting 8+ hours with the doors locked and it goes into a deep sleep mode. Or there is the brake and flashing lights thing you can do, saw a Youtube video on it once.

 

[CalvinT]

In the Navy, we were always taught to hook up Ground first, then hot.

I don't think it really makes all that much difference for +12V systems, but ships at sea run on ungrounded/floating ground systems (just like cars do), so you want the "ground" connected first to help minimize any accidental arcing -- as opposed to your house, which has a separate Ground and Neutral (I know, DC vs AC there, but the same principle when applied to grounding)

It depends on if you're working on a 120VAC or 12VDC automotive. Shipboard wiring has a floating neutral as you said. For 120VAC you want to connect ground first for personel safety, to guard against electrocution and sparks. I measured 90 V from hot to ground and 30 neutral to ground on one of the ships I was on. That floating neutral saved my butt when I accidentally got across a 120 V line.

Not a worry with 12VDC automotive. Then you connect ground last to guard against inadvertent shorts of positive to ground. That's why they tell you to disconnect the ground wire when working on a vehicle.

edit: Think about it. If you disconnect the ground first, you don't have to worry about what your wrench might hit. But if you're disconnecting the postive first, you have to make sure your wrench doesn't bump against anything that's grounded.

 

[Brian_B]

I need to double check the manual (too lazy right now), but I think it states the BMW will reset after sitting 8+ hours with the doors locked and it goes into a deep sleep mode. Or there is the brake and flashing lights thing you can do, saw a Youtube video on it once.

After 8~ish hours the BMS will recalibrate the State of Charge (SOC) -- no action required on the part of the user though.

Deep Sleep is seperate, and will occur if any of a few things happen:
Battery Voltage drops too low
More than 14 (not sure on that number exactly) days of inactivity
Probably a couple of other reasons, but those are the big ones.

The user needs to run the BMS recalibration (the weird combo of pushing buttons and hitting switches) anytime the battery is changed.

The BMS tracks a lot of stuff - how many hours at various loads, how many amps in/out under various conditions, voltage/temperatures when various things occur, etc.

 

[Severum17]

On the battery note, I have a charger that shows voltage and also percent of charge. ts a 12 amp charger/3 amp maintainer. We do some short trips but whenever I hook it up it always shows anywhere from 24% to 45% even after 40 or 50 mile drives. I charge it to high 90s using the ground on the fender. These percentages seem low to me. The other day it went from a full charge to 24% overnight. Is this normal? We had it at the dealer a short time ago for a recall and I had them check the battery and charging system while it was there. All good they said. Is it all good given what I see?

 

[Brian_B]

On the battery note, I have a charger that shows voltage and also percent of charge. ts a 12 amp charger/3 amp maintainer. We do some short trips but whenever I hook it up it always shows anywhere from 24% to 45% even after 40 or 50 mile drives. I charge it to high 90s using the ground on the fender. These percentages seem low to me. The other day it went from a full charge to 24% overnight. Is this normal? We had it at the dealer a short time ago for a recall and I had them check the battery and charging system while it was there. All good they said. Is it all good given what I see?

State of Charge depends on a lot of things. Voltage is a part of it. So it temperature and age. Battery chemistry/type. So is a resting period - part of the reason that the BMS doesn’t calibrate its own SOC number until several hours of inactivity.

so I dunno how much stock I would put in that number you are seeing.

the basic metric is the Bronco usually seeks to maintain a 12.5V ~resting~ voltage — that’s 80% SOC. I think deep sleep triggers at around 12.15V or something. Anything between those two is perfectly normal.

 

[crenca]

On the battery note, I have a charger that shows voltage and also percent of charge. ts a 12 amp charger/3 amp maintainer. We do some short trips but whenever I hook it up it always shows anywhere from 24% to 45% even after 40 or 50 mile drives. I charge it to high 90s using the ground on the fender. These percentages seem low to me. The other day it went from a full charge to 24% overnight. Is this normal? We had it at the dealer a short time ago for a recall and I had them check the battery and charging system while it was there. All good they said. Is it all good given what I see?

No, I would not say that is normal - assuming these percentages are actual SOC that the Bronco's BMS system is seeing, and not an erroneous (for whatever reason) SOC percentage your charger/maintainer is reporting. Forscan would reveal what the BMS believes the SOC is.

I use cheap charger/maintainers from Harbor Freight and they report SOC within a few % points as the Broncos BMS does...

 

[Brian_B]

No, I would not say that is normal - assuming these percentages are actual SOC that the Bronco's BMS system is seeing, and not an erroneous (for whatever reason) SOC percentage your charger/maintainer is reporting. Forscan would reveal what the BMS believes the SOC is.

I use cheap charger/maintainers from Harbor Freight and they report SOC within a few % points as the Broncos BMS does...

When they won't hold a charge like that the battery is just dead. That's how I've seen most AGM battery die..

Either they won't recharge at all, and the charger faults out (or won't even start to charge - only seen this a couple of times on a dead dead dead battery)... or they seem to charge up and the battery won't hold it.

 

[popo_patty]

Fun fact: I’ve jumped many many batteries on many cars including my own Bronco 2x. I always go direct to both terminals. Never an issue.

One day while I was at work, my wife needed a jump. She and a neighbor friend hooked up the jumper cables. She had been taught to hook the negative cable to ground inside the fender from her dad.

Well she did that on her Toyota and accidentally hooked up to a bracket for some module instead…. Fried it. $1400 fix.

Just go to the terminals.

 

[gbub]

I usually ground on the block out of habit with old style lead acid batteries and cars. That should not fry any modules hopefully.

 

[Nibroc99]

I need to double check the manual (too lazy right now), but I think it states the BMW will reset after sitting 8+ hours with the doors locked and it goes into a deep sleep mode. Or there is the brake and flashing lights thing you can do, saw a Youtube video on it once.

I happened to see that on a Facebook post the other day and saved the pic they took!
In case the pic gets deleted and this website's photo archive goes defunct some day in 20 years, it reads:
"RESETTING THE BATTERY SENSOR
When you install a new battery, reset the battery sensor by doing the following:
1. Switch the ignition on, and leave the engine off.
Note: Complete steps 2 and 3 within 10 seconds.
2. Flash the high beam headlamps five times, ending with the high beams off.
3. Press and release the brake pedal three times.
The battery warning lamp flashes three times to confirm that the reset is successful."

 

[Brian_B]

I happened to see that on a Facebook post the other day and saved the pic they took!
In case the pic gets deleted and this website's photo archive goes defunct some day in 20 years, it reads:
"RESETTING THE BATTERY SENSOR
When you install a new battery, reset the battery sensor by doing the following:
1. Switch the ignition on, and leave the engine off.
Note: Complete steps 2 and 3 within 10 seconds.
2. Flash the high beam headlamps five times, ending with the high beams off.
3. Press and release the brake pedal three times.
The battery warning lamp flashes three times to confirm that the reset is successful."

Last time I tried flashing something my neighbor called the cops

 

[DaddyO]

OK guys, either I read the posts too fast and missed it or ya;; are so far above me electrically (which you are) I don't understand all that fancy talk. What is a BMS? Someone finally defined SOC so Im good there. Thanks

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