Low voltage under load

[b1reed]

First off I will say that I did search on here and I did find a few threads on this topic but none of them seemed to answer my questions.

I have a 97 club car 48 volt that is far from stock with a brand new set of US batteries in it. With the pack fully charged, if I take it up the road by my shop which is a pretty steep hill I can drop the pack voltage to 36-37 volts. Im pretty sure that's not normal but im not sure considering I have a 500a controller and d&d motor. Ill list the specs on the cart below...


97 club car ds
Imaginative Manufacturing 4x4 lift kit with 2 speed rear end
Alltrax axe 4855 500a controller
D&D motor, not sure what the specs are on it...
US batteries 8VGC XC2, I have about 10 cycles on them
2ga wires throughout the whole cart
hd f&r switch
400a solenoid from scottyb
efx moto 350 tires (maxxis bighorn lookalike) 26-12-12 rear 26-10-12 front


I'm sure I am missing something in that list but that gives everyone an idea of what I'm working with. For those of you not familiar with the 4x4 kit it is a normally open diff in the rear until you lock it and then you can also lock in the front wheels. My issues with voltage drop is without the front driveline engaged and the rear diff open just like a normal cart, so its not caused by excessive drag on the drive line. The motor is a D&D but I have no idea what the specs are on it, I bought it used. the cart will run 18mph in high gear up the hill with the voltage dipping down to the 36-37 volt range. In low gear it will run 11mph up the hill and bring the voltage down to 40-41 volts.

Is there something im overlooking here or is this all normal for the mods that are done to the cart?

Thanks for any help!!
Brandon

[gornoman]

Those numbers look good to me. I suspect they will improve slightly as the pack breaks in.

[b1reed]

Really? that's a bit of a relief... so im not hurting anything running it at that low of voltages? I read on a few posts that you should never take the pack below 45 and some said 42 for shot periods. will it hurt the pack at all?

Is there enough info there for anyone to give me a good guess on how long of a runtime I will see when the batteries get broken in?

[Volt_Ampere]

The voltages you usually see are not under load. It is normal for the voltage to drop significantly under heavy load.

[Great white north]

Irreversible damage can occur if the batts are drawn down below 1.5 volts per cell , ( i would not go below 1.75 volts per cell) do ot attempt those steep hills until battery pack is broken in

[b1reed]

I think my confusion is that some people are talking about standing voltage, and some are talking about voltage while driving the cart. I have never taken the pack below 48.5v as far as a standing voltage is concerned. However, even on flat ground if I floor it the pack will come down to around 40v or so. I haven't ran this thing enough to have a bunch of collected data. its been -10 and -15 with wind chills up to -40 around here and needless to say isn't the best carting weather!

So I guess my question is lets say I take it up a hill and the pack is at 36v for 2 minutes, when I stop the pack recovers just fine to 49v+, for those 2 minutes did I cause harm to my batteries?

[scottyb]

What size batteries did you put in the cart? How many amp hours is their rating?

[simple man]

According to their site, his battery model is 170 amp hour rating (20hr rate).

[TerryH]

Originally Posted by gornoman

Those numbers look good to me. I suspect they will improve slightly as the pack breaks in.

I'm with G on this one. I see mine go that low under hard acceleration and it has from the start. Have not seen any ill effects in 2 plus years of hammering it.

[TerryH]

Originally Posted by b1reed

Really? that's a bit of a relief... so im not hurting anything running it at that low of voltages? I read on a few posts that you should never take the pack below 45 and some said 42 for shot periods. will it hurt the pack at all?

Is there enough info there for anyone to give me a good guess on how long of a runtime I will see when the batteries get broken in?

I don't think those voltages for short periods of time are going to damage anything. As for the run time, that will depend largely on your right foot.