Re: (ET) Retofit a moderm Electric riding mower Battery pack to fit an ET

[john <johnreinhard rochester rr com>]

Hi Dave,

Your 'runs like that for about 80% of the full charge' statement aligns 
with information I read just 2 days ago in a White paper from Battle 
Born Battery company comparing cold weather performance of  their 
Lithium Batteries to lead acid.

I realize they sorta cherry picked some of their numbers (they explain 
their rationale), but still interesting - and valuable information.

Battle Born also state that their built in BMS PREVENTS charging at 
temps below freezing.

That batteryhookup.com website showed some interesting used SPIM08HP 36V 
48AH modules for $200 each (less expensive than similar capacity new 
solution from Battle Born) .

I would like to find the discharge / life cycle graphs for those 
batteryhookup.com modules.

Thank you for timely post !

John


On 2/10/23 00:37, David Tiefenbrunn wrote:
> My situation - I can store the tractor in my garage or basement. Both 
> are temperature controlled. Basement is about 70-75 year round.  
> Garage gets into the 80s in summer, rarely below 70s in winter.  I'm 
> in CT.  For snow, I use my Dynahoe, because it has a heated cab, and 
> it's not great to let it sit all winter either. The snow thrower also 
> doesn't like a stone driveway much.  I imagine it would work great 
> with the lithium batteries.
>
> I would not ever run lithium batteries, especially the size needed for 
> an ET without a BMS.   The BMS monitors temp, current, voltage [under, 
> over, and difference] of each cell, state of charge, and cuts out if 
> anything goes out of range.   I charge before I plan on running the 
> machine, and if I run it down below 50%, just put enough back in to 
> get to around 50%.   I have fans that run at temps above 85 degrees, 
> mostly just for if I run it outside on a hot & sunny summer day.  The 
> load an ET puts on the batteries I have is nothing for them, one set 
> can supply 150 Amps continuous, 600A for 10 seconds.  I am running 2 
> sets in parallel, for more run time, and shallower cycling.   About 
> 140 AH capacity.  With Lithium, you can use almost all of the 
> capacity, unlike LA, which varies widely on the load current.   LA AH 
> ratings are for a 20Hr rate, which is a lot less than an ET draw at.  
> Lion are also a lot more efficient as far as the power lost in the 
> charge / discharge cycle.
>
> For the batteries and BMS, I spent around what it would cost for a set 
> of high end LA batteries.  But these should outlast them by quite a 
> bit.  No messing with refilling water.  No more acid mist eating the 
> steel, and my floors when the LA get older, and the mist collects and 
> drips out the drains.
>
> The batteries, I bought from Batteryhookup.com.  They get surplus / 
> used, and test them before listing them, so you know how they perform..
>
> Remember how you ET runs for the first 15 minutes or so with a brand 
> new set of fully charged LA batteries just off the charger? With the 
> 10 series Lion cells, it runs like that for about 80% of the full 
> charge, and only barely starts to slow a little near the end.  I have 
> the BMS set to cutoff with a good margin before the bottom, to extend 
> life, and also, as a "get back to the charger" warning, so I can get a 
> couple minutes more run if I loose track of time / charge.
>
> If extreme temperatures are a problem, LTO would be the best option - 
> but they are a lot more $.
>
> Dave