Looking for best bang for the buck in 48v lithium conversion would these work?

[dundeebarnbuggy]

My buggy a real gentle take off on the level pulls 150 amps for a few seconds. Hills is a relative term. Nothing crazy long here but I've seen it pull 250-300 especially if it is cold.

[LithiumMoto]

up to 300amps .. hmm, how did you measure that ? .. you have a digital ammeter hooked up on the dash ?
that seems like a lot. in which case, the lithium battery BMS and cells need to handle it.
I needed that info for building my new BMS.

[ThreeCW]

I plucked this out of a thread I started a few years ago:

I did some current testing on my Cushman using a Fluke 325 Clamp Meter as follows:
- Metering point = 2 AWG battery cable between battery 7 and 8 (see photo)
- Cart Base Weight (with driver) = 1850 lbs
- Cart Loaded Weight = 2800 lbs (loaded with 950 lbs of feed bags - see photo)
- Drive wheels equipped with tire chains (giving traction but added rolling resistance)
- Outside Temperature = 1 C (34 F)
- Cart was previously stored inside garage at 5 C (41 F) … assumed starting battery temperature

DC Amperage Testing Results as follows:
Flat Road (packed snow on plowed gravel road)
- Soft Start = 100 amps at base weight
- Full Acceleration Start = 280 amps at base weight
- Cruising at ~5 mph = 50 amps at base weight / 75 amps at loaded weight
- Cruising at ~10 mph = 100 – 120 amps at base weight / 80 amps at loaded weight

Uphill Road (packed snow on plowed gravel road)
- Soft Start = 120 amps at base weight
- Cruising at ~2 mph = 125 amps at base weight / 150 amps at loaded weight
- Cruising at ~5 mph = 200 amps at base weight / 300 amps at loaded weight
- Flat out (+5 mph) = 250 amps at base weight / 300 amps at loaded weight

Flat Terrain With Snow (6” deep lightly crusted snow on lawn)
- Soft Start = 150 amps at base weight
- Cruising at ~2 mph = 150 - 200 amps at base weight / 180 - 200 amps at loaded weight
- Cruising at ~5 mph = 250 - 400 amps at base weight / 380 - 400 amps at loaded weight

Analysis:
- This amperage testing was done to determine the battery discharge requirements if a lithium battery system was installed in the future.

- The above testing is not my typical operating conditions but does simulate the maximum continuous amperage that could be experienced during extreme operations.

- Given the above results, a lithium battery continuous discharge requirement of 400 amps would be required to stay within the safe operating capacity of the batteries.

- Given my preliminary review of lithium batteries, it might be difficult to “economically” achieve this 400 amp continuous discharge requirement.

Here is the full thread: https://www.buggiesgonewild.com/showthread.php?t=138364

The bottom line is that you should understand the amperage draw of your cart and use that information to select the correct lithium batteries for your application.

[dundeebarnbuggy]

Originally Posted by LithiumMoto

up to 300amps .. hmm, how did you measure that ? .. you have a digital ammeter hooked up on the dash ?
that seems like a lot. in which case, the lithium battery BMS and cells need to handle it.
I needed that info for building my new BMS.

Blue Sea 8248 volt/ammeter that I have checked with a certified Fluke 325.

[LithiumMoto]

ok, great info i needed to make my batteries.
Now, As u would correctly assume, the higher the C rate the higher the cost of the cell.
1C rating is the cheapest and what most all the other lithium cart battery makers are using. After 1C is 3C, then 5C and up..... So, The 5C is what i need to use then. BUT...
are people willing to pay for it ? that is the question. (These would be LiFepo4 cells by the way ) On top of that, the BMS needs to be able to handle 500A... not the easiest thing to obtain. and again, the higher the current ability, the higher the cost of the BMS.
Now, for a 100 or so Ah 48V battery pack, the pricing limit seems to be about $2600...
am i right ? ... and thats for the "RP" battery using 1C cells ( the charger alone costs $200 ). Maybe I should just sell the cells and BMS to DIY'ers..???
If I price the pack at, say, $2800-3000 with 500A capability that cuts out any middlemen dealers . Would that be ok with everybody?
Of course, we're talking about work carts it seems, not the fair weather flat land, paved road cart communities whose main objective is going grocery shopping at tea time and would only need 1/2 that power.....? So, they would only need maybe a 60Ah capacity. the higher C rating means less voltage drop, so, they would still have the power, just not the range.
Also, is the market for lithium batteries saturated already ? What would be a competitive advantage at this point ? ... price only ?

[Volt_Ampere]

If you can limit the current with your controller, you may be able to get by with less current rating on the batteries. I could live with a 300 amp limit on my cart even though I have it set to 400. My cart cruises at about 25 on level ground drawing 70 amps. (Alltrax logging to my Laptop during the run) My BMS does not limit my current - I have a 300 amp fuse that does that. (came with the Alltrax controller) I built my own BMS but If I were to buy one, I would not have it limit my current - just shut down on low cell voltage.

[DaveTM]

Highest AMP draw? Here in SW Pa. we have hills....and mountains. Not as big or often as W. Virginia, but we got some good one's and they are everywhere.

Here's a snapshot of my cart going up a steep, rutted short hill of maybe 35-degree angle

[Volt_Ampere]

That's a steep hill. Expert ski slope.

[bronsonj]

My cart pulls 70 amps maintaining speed on a flat paved road.
I have a 300 amp controller and the max I've seen in my data log was 304 amps.

If you want a BMS to control 300 or more amps then use the BMS to control a solenoid so the BMS sees the charge current but not the load current, only the solenoid sees the load current.

[bronsonj]

Originally Posted by LithiumMoto

Of course, we're talking about work carts it seems, not the fair weather flat land, paved road cart communities whose main objective is going grocery shopping at tea time and would only need 1/2 that power.....? So, they would only need maybe a 60Ah capacity. the higher C rating means less voltage drop, so, they would still have the power, just not the range.

Also, is the market for lithium batteries saturated already ? What would be a competitive advantage at this point ? ... price only ?

I live in Saint Petersburg, FL. It's all paved and flat. I have 94ah pack and I know a couple other people that have lithium and their packs are the same or larger capacity than mine. So don't assume that the city dwellers like me would be good on 60ah, although some certainly would be. Just not all.

If you pre-package your packs with the BMS controlling a HD solenoid so your pack can handle 500 amps continuous then that's a marketing niche that's not been tapped yet (and a competitive advantage).