[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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



Interesting comments. I have a 94 Chevy S10 electric truck that I put a Nissan Leaf pack in (with Nissan BMS) in 2016. I drive and charge it in summer and winter, put about 20k miles on it so far with no issues or real loss of range.

The key I think for Lithium is slow charge: For a 60ah pack I charge it at about a 6ah rate. That seems to keep the pack happy and limits degradation. I also limit discharge to 30ah or so which is plenty for my driving.

Chris

On 2/10/2023 8:39 AM, john wrote:
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



_______________________________________________
Elec-trak mailing list
Elec-trak cosmos phy tufts edu
https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak