08-10-2020, 10:31 AM | #21 | |
Gone Wild
Join Date: Sep 2012
Location: Charlotte, NC
Posts: 9,329
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Re: Best lithium setup for Navitas 600/5kw?
Quote:
That is likely more related to the loss in weight of Lead vs Lithium than the voltage itself, DC carts behave the same when you remove the weight as it increases the HP/Weight ration. Does anyone in your neighborhood have the same controller/motor combo running on a 50v+ Lithium setup to compare? |
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08-12-2020, 07:34 AM | #22 | |
Gone Wild
Join Date: Oct 2019
Posts: 646
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Re: Best lithium setup for Navitas 600/5kw?
Quote:
He and I have the same cart / drive system (he has 22" tires, mine are 22.5", and he has a Curtis Cab on one of his - otherwise same gears, motor, controller etc...), but I have only a 52v battery - my speeds are correspondingly less at only 38mph on flat ground. This indicates that there is a major difference in performance potential with this motor / controller between a 72v input -vs- a 52v input. You've mentioned that input voltage should not make much difference on an AC motor / controller - and I wouldn't disagree with any principals behind it or doubt your reasoning, but the reality - for whatever reason, and, again, probably best asked of Navitas - is that adding 20v to the input voltage makes a major difference in top speed. I would assume acceleration potential would also increase, but that may not be the case. I think acceleration rate is limited in the controller (by parameters not available in the "dealer" app), and may already be "maxing out" with the 52v setups on flat ground. Uphill acceleration and speed-keeping would likely be superior on the 72v as the 52v cart would likely begin to be current / voltage starved on an incline, and not be limited by the FW, but by electrical deficiency. This is conjecture on my part, however. |
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08-12-2020, 07:51 AM | #23 |
Gone Wild
Join Date: Sep 2012
Location: Charlotte, NC
Posts: 9,329
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Re: Best lithium setup for Navitas 600/5kw?
If You have a 52v pack with inadequate capacity to provide the current needed, then either increasing the capacity of the exist 52v pack or using a pack of the same capacity but higher voltage would increase the speed.
The point I keep trying to get across is the speed increase is not related to the voltage as in DC systems, but it could be because your existing pack just cannot deliver the current needed for the load demand. |
08-12-2020, 08:15 AM | #24 | |
Gone Wild
Join Date: Oct 2019
Posts: 646
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Re: Best lithium setup for Navitas 600/5kw?
Quote:
It would be interesting to see current drawn from the battery data from Doug on his 72v setup. I can say on mine, it has no problem delivering ~230 amps during acceleration. It will draw more than this on hills, and for a longer time as you go up that incline. I'll say I haven't pushed experimenting with this because I'm not wanting to stress my equipment for no reason, but the point is that it can supply at least 250 amps for 5+ seconds based on my brief experiments, w/out issue or BMS shutoff. WOT current draw is right at about 145A. So apparently the motor / controller has more current available from the battery system but is not utilizing it for some reason. That reason may be what Navitas could tell you - I'm not claiming to know. |
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08-12-2020, 05:55 PM | #25 |
Gone Wild
Join Date: Sep 2012
Location: Charlotte, NC
Posts: 9,329
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Re: Best lithium setup for Navitas 600/5kw?
fstop, I am not doubting you have seen faster or experienced yourself faster cart speeds with the 72v setups, I guess I have a more focused interest in understanding the factors involved for that increase
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08-12-2020, 07:29 PM | #26 | |
Gone Wild
Join Date: Oct 2019
Posts: 646
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Re: Best lithium setup for Navitas 600/5kw?
Quote:
I suspect there could be logic in the controller that is limiting it in some way, maybe because of liability (a lot less users with 72v, but could still demonstrate the power of the system w/out so much liability exposure?). Or maybe it has to do with component durability within the controller, and 72v system could operate with less current through the controller and they'd have a lower failure rate / longer product life? Both total guesses. |
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08-21-2020, 10:33 AM | #27 |
Gone Wild
Join Date: Mar 2013
Location: Santa Cruz, Californnistan
Posts: 326
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Re: Best lithium setup for Navitas 600/5kw?
All great questions. If no one has answers by the next time I chat with Navitas I'll inquire. I need to call them on some issues anyway. Overall they have great support and are very willing to answer questions.
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08-21-2020, 12:53 PM | #28 | |
Gone Wild
Join Date: Sep 2012
Location: Charlotte, NC
Posts: 9,329
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Re: Best lithium setup for Navitas 600/5kw?
The actual question if You want to ask them is:
Quote:
If You can post their answer or any comments they have it would be nice to understand the capabilities of the Navitas AC Controller. I see from other threads that Navitas is adding a lot more configuration parameters to deal with different lithium battery packs and BMS limitations. |
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08-21-2020, 01:06 PM | #29 |
Not Yet Wild
Join Date: Sep 2019
Posts: 7
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Re: Best lithium setup for Navitas 600/5kw?
Directy from Navitas tech when asked about the benefits of going to 72V:
Good rule of thumb… (Voltage = Speed) – (Amps = Torque) In the end, I will problably not do a 72V 18S battery setup but go for a more standard 48V setup as I am fine with 30mph top speed. (Navitas says 35 mph is to expect with 48V). Torque is more important to me. |
08-21-2020, 01:36 PM | #30 |
Just Gone
Join Date: Sep 2015
Location: North Carolina
Posts: 3,549
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Re: Best lithium setup for Navitas 600/5kw?
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