Big battery prob

[t8ter]

The Red X is flat ground and starting point. It will flip bms we’re cart is. It actually did better today what little I drove it. Seems like cart definitely doesn’t like a load to be put on it or colder weather. Today was in the 50’s.
This was my late mothers cart that was hardley used. Her and my younger son was very close. So after she passed I’d thought it be good for me and him to fix it up. My oldest is all about Tesla so I thought we’d do a lithium. It’s to the point my youngest hates to even look at it. The cart ran great before this.
Thanks

[Pat911]

Originally Posted by superfan86

According to the manufacturer spec sheet 300 amps for 6s surge is fine and a 150a continuous.

If he is seeing 150a+ over a period long enough to trip the BMS I would suspect issues outside of the battery. Possibly a motor going or he is driving on some constant extreme grades.

I'd be curious how long and under what conditions he is seeing the 140... Agree though, it does sound like BMS is cutting him off.

For comparison, I have a HSKY 48v conversion on the stock PDS 36v AMD motor. With 900lbs in passenger weight driving on mild hills we rarely see amp draw exceed 130a beyond the initial 2-3 second surge from stop. Voltage drops from 53 to as low as 47v on my pack unless I'm approaching empty pack where I'll see 43v from a full acceleration start.

My comment was geared more toward the fact that 140A is a lot of current and a marginal cell will dip at such a high current. This dip could be low enough to trip the BMS's low cell voltage protection.

[Tom47]

Being a 2001 TXT, the motor condition such as bad brushes may affect the amperage draw. F/R lever, controller and connections all need to be checked.

If it ran good with the lead acid batteries, it was because they were not as sensitive to outside influences as lithium is. Lithium has lots of available power that needs to be regulated carefully.

Before we continue to suspect a possibly good battery, check the condition of all components. I'm hoping the problem is not BMS and battery related.

[Volt_Ampere]

Originally Posted by Pat911

My comment was geared more toward the fact that 140A is a lot of current and a marginal cell will dip at such a high current. This dip could be low enough to trip the BMS's low cell voltage protection.

I don't think that 140Amps is a lot for a peak load. It's a lot for a continuous load on flat pavement but not for hard acceleration or hill climbing. My cart pulls 70 amps continuous going 25mph on level pavement.
IMO, any pack that can't sustain 200 amps for at least 15 seconds or more is undersized for a golf cart. Too many of these "drop in" packs are built with cells and BMS that are really not up to the task.

[Pat911]

My point exactly Volt_Ampare.

140A is a lot of current (generally speaking) but it should be ok for a pack that is up to the task and in good operating condition. Throw a bad cell in there and that same 140A will cause problems.

[t8ter]

I came out today to check some other mechanical stuff. The solenoid seems fine. Reads around .10v of battery pack on each side. 1v on each side with bms flipped off. Cart has set last couple days out in the weather. Foggy rainy stuff. Bms flips under minor load with in 20 feet. Motor, battery pack and controller are all dry but it’s heavy condensation out side. So should the moisture be a clue?
Thanks

[t8ter]

Worked on cart more today. Decided to take motor out and clean it. Got excited to see a rusty spot on it. Cleaned it up and reinstalled. Looked good inside except for that spot. Still shuts off in 20 yards. Still wet outside but cart been in carport. Odd thing is I can jack the back up and it will run wide open forever and never flip bms. Set it down and it flips in just a few. Arg

[Pat911]

From this info, it Could also be a loose cell connection.

[t8ter]

I did get it to shut off on jack stand. Not the bms the cart just stopped. Let off pedal and it ran when pedal pressed. I did noticed the blue small wire on solenoid at full throttle was putting out very high voltage. In the upper 50’s.

[t8ter]

Drama builds lol. BB had me do a bms reset late Friday. Now my battery want power back on. Hopefully Ill have some clarity come Monday fr BB.
Still puzzles me why the blue wire on my solenoid puts out higher volts than my pack. Sometimes almost double. Is this normal?
Thanks