500 amp shunt questions for 36volt ezgo txt with lead acids

[TBcart]

I just installed the LNEX 500 amp battery monitor shunt with color screen. Everything looks amazing and seeing real time info is great. My one question is I have six 6 volt powertron p2000 batteries that are 3 years old and the only info I can find online is they are 210ah.
I fully charged the batteries and set the capacity to 100% charge I put 210ah in on the battery monitor setting and we drove the cart about 15 miles last night. When we got home it said I had 150ah left and 74% of battery remaining but my old battery fuel meter with 10 green dots was at the 4th dot and the cart felt like it was really about 40% of battery remaining. Do you all think since my batteries are three years old they don't really have 210ah capacity anymore and I should maybe move that setting to more like 150ah on the monitor. How would one tell what the batteries are capable of?

I mainly purchased this momitor to see what lithium battery I will need in the future with my amp draw from hills to carrying 4 people since I have a 500 amp controller. So far with two people I'm at 250ish amps on take off, 85 amps full pedal down on flat terrain, and 130amps climbing a long uphill grade.

[Capt. Lenny]

I doubt your 3 year old batteries have 210ah remaining. The only true way to test your current capacity is to use a capacity tester. You can get a cheap Chinese one on AliExpress for around $30 or on Amazon for around $45. I think they're pretty accurate I just used one on my lithium setup. Will Prowse on DIY solar has a good video on one. pretty simple.

[Pat911]

What capt. Lenny said, but I’d like to add that your batteries are not 210Ah when used in high current applications like a cart. You will only get 210Ah when brand new, and more importantly, when drawing only10.5A. It’s the C/20 rate. You need to check your battery specs for a higher discharge rate and it will be considerably lower, probably only around 140Ah.

A very good rule of thumb is that you only need around 1/3 the capacity when moving to lithium. So, 70Ah lithium will give you a similar range to brand new 210Ah Lead Acid.

Lithium capacity will not drop anywhere near as rapidly as lead acid either. Expect your capacity to remain at the as new level for many, many years. Lead Acid capacity drops off very quickly, being noticeable as soon as 2 or 3 years.

[TBcart]

Originally Posted by Pat911

What capt. Lenny said, but I’d like to add that your batteries are not 210Ah when used in high current applications like a cart. You will only get 210Ah when brand new, and more importantly, when drawing only10.5A. It’s the C/20 rate. You need to check your battery specs for a higher discharge rate and it will be considerably lower, probably only around 140Ah.

A very good rule of thumb is that you only need around 1/3 the capacity when moving to lithium. So, 70Ah lithium will give you a similar range to brand new 210Ah Lead Acid.

Lithium capacity will not drop anywhere near as rapidly as lead acid either. Expect your capacity to remain at the as new level for many, many years. Lead Acid capacity drops off very quickly, being noticeable as soon as 2 or 3 years.

Powertron P2000 Battery
Model GBAP2000
Manufacturer POWERTRON
BCI Group GC2
Battery Type
Battery Application
Voltage 6
Length 10 3/8
Width 7 1/8
Height 10 5/8
Weight 58
5 HR Rate AH 175
10 HR Rate AH |
20 HR Rate AH |210
100 HR Rate AH |
Capacity 25 amps 383
Capacity 56 amps
Capacity 75 amps 105
CCA
CA

This is from their website I'm not sure what the high discharge rate would be for the AH?

[TBcart]

Originally Posted by Capt. Lenny

I doubt your 3 year old batteries have 210ah remaining. The only true way to test your current capacity is to use a capacity tester. You can get a cheap Chinese one on AliExpress for around $30 or on Amazon for around $45. I think they're pretty accurate I just used one on my lithium setup. Will Prowse on DIY solar has a good video on one. pretty simple.

Thank you I will look into videos from Will

[Pat911]

Originally Posted by TBcart

Powertron P2000 Battery
Model GBAP2000
Manufacturer POWERTRON
BCI Group GC2
Battery Type
Battery Application
Voltage 6
Length 10 3/8
Width 7 1/8
Height 10 5/8
Weight 58
5 HR Rate AH 175
10 HR Rate AH |
20 HR Rate AH |210
100 HR Rate AH |
Capacity 25 amps 383
Capacity 56 amps
Capacity 75 amps 105
CCA
CA

This is from their website I'm not sure what the high discharge rate would be for the AH?

Looks like the Reserve Capacity is 105 minutes at 75 amps, which would be a typical current draw in a cart. 105 minutes is 1.75 hours. 1.75 times 75 amps is 131Ah, even less than my estimate.

Now, you can use 100% of lithiums capacity whereas you can only really use 50% of lead acids capacity if you want any longevity out of them. So 131Ah is really only 65Ah useable.

65Ah is what you need to equal the range of your existing batteries, almost exactly 1/3 as suggested.

[TBcart]

Originally Posted by Pat911

Looks like the Reserve Capacity is 105 minutes at 75 amps, which would be a typical current draw in a cart. 105 minutes is 1.75 hours. 1.75 times 75 amps is 131Ah, even less than my estimate.

Now, you can use 100% of lithiums capacity whereas you can only really use 50% of lead acids capacity if you want any longevity out of them. So 131Ah is really only 65Ah useable.

65Ah is what you need to equal the range of your existing batteries, almost exactly 1/3 as suggested.

What would you program the shunt monitor with 65AH?

Also I have read that you should only go to 50% of the batteries capacity, how bad will that damage the battery if I was to go lower.

[Pat911]

Start with 65 and see how you go. Correlate with the voltage as that’s the best indicator of state of charge with lead acid.

Continuously going below 50% will shorten the life considerably. Thats lead acid only, not an issue with lithium.

[TBcart]

Originally Posted by Pat911

Start with 65 and see how you go. Correlate with the voltage as that’s the best indicator of state of charge with lead acid.

Continuously going below 50% will shorten the life considerably. Thats lead acid only, not an issue with lithium.

Thanks for your help I'm gonna change the monitor now to 65AH.

[Pat911]

That 65 will be 0% to 100%, so you can go down to 0%.

Check this table for voltage

IMG_6569.jpeg