Comments about your Lithium Battery

[DaveTM]

As a side note, the BMS I use can be set so that if the amp draw exceeds any given (chosen) amp draw setting for more than one continuous second, the BMS will shutdown the pack.

Now, this setting doesn't limit the amp draw like a controller setting will do, but the BMS will simply shut down the pack to prevent a pack damage due to "to much" amp draw which will drop cell voltage.

My settings are on the high side as a "last line" of defense so to speak. I'm counting on the controller to keep the amp draw to a given number even though the motor may be asking\requesting for more.

[demarcor]

2006 Club Car Precedent

1) Brand of battery - Big Battery Eagles
2) Ah capacity - 30 each
3) Number of individual packs - 2
4) Pack voltage - 48V
5) Controller upgrade - None
6) Motor upgrade - None, just a speed magnet
7) Series, Sepex or AC drive - Sepex? Serial number starts with PQ.
8.) O.D. Tire size - Not sure, they just clear WITHOUT a lift, low profile rubber with larger than stock rims.
9) Typical driving terrain - Hilly (very hilly) grass and pavement
10) Estimated range on pavement - enough to make you realize you need a more comfortable seat! (20-ish miles, including serious hills and usually with passengers.)
11) Average and Top speeds - Avg 15 full pedal on flat. Top speed 24 full pedal down hill. My Regen does not kick in until that speed.
12) Likes or dislikes - All likes. 10 year warranty. USA company with folks that answer the phone. No drop off in performance at any charge level. Required NO modifications to battery bucket on an '06 with electronics in the middle. Charges fully in 5 hours.
13) Additional comments - Love it. At the time was $1,800 for this option, only a few hundred bucks more than a pack of Trojans. Everyone here told me I had to do the computer bypass... but I never did. 4 months in, no problems at all.

[Tom47]

Thank you for your response, demarcor. These Big Battery Eagles are new to this review and it sounds like they are doing well for you.

You have an IQ cart, sepex motor.

I know other members are always concerned about anything less than 100Ah packs for hilly terrain. It sounds like you are fine with 60Ah. Your performance and usage are great!

[Pat911]

Tom, it’s not the Ah rate that’s concerning for hilly areas but the max currents. Not too long ago most LiFePO4 batteries were limited to 1C discharge rates (1.5C maximum) so a 100Ah battery could supply 100A continuous or 150A peak. 100A continuous and 150A peak is a good rule of thumb for hilly areas and is why 100Ah was recommended for hilly areas.

Things have changed in the last 12 months or so and the newer batteries that are being released have a much higher C rate than the older ones. The BB Eagle that is described above is only 30Ah per battery but each battery can supply 80A continuous or 180A for 6 seconds. Demacor has two batteries so that’s 160A continuous and 360A peak, more than enough for hilly areas. In fact, one battery would probably be enough depending on the length of the hills. Range would be quite short though.

Cheers
Pat.

[Tom47]

Thanks for the insight, Pat.

Those Eagles are a bit pricey but apparently a good multiple pack alternative similar to Allied.

[Tom47]

Originally Posted by Pat911

Tom, it’s not the Ah rate that’s concerning for hilly areas but the max currents. Not too long ago most LiFePO4 batteries were limited to 1C discharge rates (1.5C maximum) so a 100Ah battery could supply 100A continuous or 150A peak. 100A continuous and 150A peak is a good rule of thumb for hilly areas and is why 100Ah was recommended for hilly areas.

Things have changed in the last 12 months or so and the newer batteries that are being released have a much higher C rate than the older ones. The BB Eagle that is described above is only 30Ah per battery but each battery can supply 80A continuous or 180A for 6 seconds. Demacor has two batteries so that’s 160A continuous and 360A peak, more than enough for hilly areas. In fact, one battery would probably be enough depending on the length of the hills. Range would be quite short though.

Cheers
Pat.

I have a question for you, Pat.

What has changed in LFP batteries recently that permits the higher C rating? Is it actually factory testing or a formula based on chemical compounds.

The Eagle above is 2.67C and my gen.1 Eco battery is 2.43C. I think the gen.2 are the same.

[Volt_Ampere]

LFP have always had a pretty high C rating. That's why they were the battery of choice for most EV's like Tesla, Leaf, Volt, etc. My batteries that I use in my RC planes and quads have very high C ratings (like 100) My little quads pull 100 amps peak out of 1.3AH batteries! It drains them in less than 5 minutes of flying.

[DaveTM]

Originally Posted by Pat911

Tom, it’s not the Ah rate that’s concerning for hilly areas but the max currents. Not too long ago most LiFePO4 batteries were limited to 1C discharge rates (1.5C maximum) so a 100Ah battery could supply 100A continuous or 150A peak. 100A continuous and 150A peak is a good rule of thumb for hilly areas and is why 100Ah was recommended for hilly areas.

Things have changed in the last 12 months or so and the newer batteries that are being released have a much higher C rate than the older ones. The BB Eagle that is described above is only 30Ah per battery but each battery can supply 80A continuous or 180A for 6 seconds. Demacor has two batteries so that’s 160A continuous and 360A peak, more than enough for hilly areas. In fact, one battery would probably be enough depending on the length of the hills. Range would be quite short though.

Cheers
Pat.

Interest information. But just a question….if the controller is set to limit the max draw of amps to say 300amps…would the battery provide 300amps for longer than the 6 second/360 peak amp it’s rated for?

[Pat911]

Dave, no. Using the example above, the battery (2 x BB Eagles) can provide 160A all day long, or until it goes flat. It can supply between 160A and 360A for 6 seconds after which the BMS will turn off the output to protect the cells. If the current goes above 360A the BMS will switch off instantly.

Tom, what changed is a little tweak here, a little tweak there, a gain here, a trade off there. As an example, you design for a higher rate, you might end up with a shorter service life, or higher thermal runaway possibility (lower safety) etc. I don’t know exactly what was tweaked, but the periodic table of elements in known. There have been no new discoveries in the last 12 months, nor is there likely to be any in the future, so all the Chemists and Physicists can do is play with what they’ve got. Also, BMS’s got higher current capabilities.

Volt_Ampare, I think you’re mixing LFP with NMC, or NCM. LFP is another abbreviation for LiFePO4. NMC is what most car makers use and it has a VERY high C rating, but is also much more likely to thermally run away if used under adverse conditions. As I said, what you gain in one area, you loose in another (High C, low safety).

Cheers
Pat.

[DaveTM]

Good to know the that a continuous draw of over 160amps would shut down the pack. I’d have to hook up my laptop today and see how long and what circumstances my cart would draw over the 160 magic number, but I doubt such a setup would work for me.

I have to many steep hills that I climb and I’m certain I’m drawing above the 160# for longer than 6 seconds.

Edit: Just looking at the 2 small screen shots of my previous data, in both of those readouts I’m pulling over 160 for longer than 6 seconds.

This thread has been very informative as at some point in the future I’ll be looking to install the next pack and this is something I really have not considered. OTOH, I don’t plan on a new pack for (hopefully) another 4-5 years. So as technology moves forward this limitation may be bumped up.