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Re: (ET) Lithium battery deal

The old charger is too dumb to use for lithium - They need a voltage shutoff, to shut down before getting into overcharge.  It's also not good to trickle charge them, so once current gets low, shut off also.  A BMS is necessary for safety, think of it as a fancy circuit breaker - not a charge controller.  The BMS is there to disconnect the batteries in the event of over current, under / over temp, under & over voltage.
Ambient temperature range for use and storage should be considered.  Different types of lithium batteries have different ranges.
Roughly, Lead acid batteries used at the current draw of typical ET use, only give about half their rated AH.  because the AH is usually measured at a 20Hr rate of discharge.  That is, what ever current would discharge the battery in 20 Hrs.   Lithium batteries have a MUCH flatter curve, so you can get something like 90% of the energy even at high rates.   So roughly 100AH of Lithium is about equal to 200AH of LA.  2000 cycles is common life rating. Shallower cycles would extend that.  I'm using surplus Lithium-ion batteries from a BMW i3.  They are rated for 150A continuous, 300 A for 10 seconds, 75AH.  I have 2 sets paralleled, so 150AH total.  If you remember how your ET ran with a brand new set of LA batteries, fully charged, for the first maybe 15 minutes, that's how mine runs, all the way down to my cutoff at about 90% discharged. 

Dave



On 11/28/2023 12:30 PM, Dean Stuckmann via Elec-trak wrote:

Hi,
I’ve used my ETs since 1980 and have always used good old lead acid with 
the on board chargers. I know nothing about this battery tech and hope you folks can answer 
some questions.

- Performance wise, since 4 sounds like the max, how would they stack up 
to (6) lead acid 235AH GC125s?
- Would there be issues with the on board charger or batteries because of the BMS? 
I’m not actually sure what the BMS does to tell the truth.
- I’m a bit confused with the size specs. The description states 13" x 6.5" x 9” while the dimensions in the spec sheet 
shows 21” x 12” x 17”. Bottom line is do 4 fit in the battery box or not?

Thank you all!

Regards,

Dean Stuckmann
5432 County Road U
Newton, WI 53063-9624

920-901-2288






On Nov 28, 2023, at 11:03 AM, Max Hall <maxmatic gmail com> wrote:

FWIW I have made two purchases from this outfit (2, then 4, mustang mach e 
modules) and it was a good deal and they did a quick and excellent job and 
the batts are awesome.

ALSO there’s a guy selling an Ionique pack on eBay… I have two 
identical ones and the quality is amazing. No internal BMS, but the economics might work

Go, ETs!

-Max

Sent from my iPhone


On Nov 28, 2023, at 11:49 AM, John Jeno <jjjeno hotmail com> wrote:

Spec sheet states a max of 4 in parallel.
What limits it to 4?
(I guess I'll keep two dead Pb t-150's as ballast.)
________________________________
From: Chris Zach via Elec-trak <elec-trak cosmos phy tufts edu>
Sent: Tuesday, November 28, 2023 4:58 AM
To: elec-trak cosmos phy tufts edu <elec-trak cosmos phy tufts edu>
Subject: Re: (ET) Lithium battery deal

That is not a bad idea. Won't last as long as NiCDs, but the voltage
setpoints live up closely with the big stupid charger and the operating
parameters of the E20.

Maybe I could put a few of these in the E15. Will check it out.

C


On 11/27/2023 10:31 PM, David Tiefenbrunn wrote:
I saw this tonight, 38.4V 60AH / 2.3KWhr Lifepo4 battery sale - Already
built, internal BMS.   Surplus never used overstock.   Might be worth
taking a look at, if you are needing batteries.  The spec sheet is on
the page.  2 or 3 of these paralleled would work well in an ET.

https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbatteryhookup.com%2Fproducts%2Fnew-38-4v-67ah-2-57kwh-lifepo4-battery-with-bms-36v&data=05%7C01%7C%7C579919c647cf4c29c7f108dbf011b198%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C638367731067737895%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=ZhLiWlTujtzGhRxu5AofNSmv%2FYVvJi%2BbeZAWgMP1uEA%3D&reserved=0<https://batteryhookup.com/products/new-38-4v-67ah-2-57kwh-lifepo4-battery-with-bms-36v>

I converted mine to Lion a couple years ago, using these would be a lot
simpler.


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