PINNED - Lithium battery conversion/info

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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 28 May 2022, 20:38

More or less. Its actual settling voltage may vary between identical cells, may vary due to a couple of degrees temp difference, and may be lower on cells with higher self discharge rates. Even though all are still full as far as capacity is concened. The biggest difference is between similar cells from different manufacturers or even batches. So voltage doesent tell you very much and thats why you should only really try to balance when full or almost so, when the voltage has suddenly jumped up to 3.5v or so.
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Re: PINNED - Lithium battery conversion/info

Postby fishinjunky » 09 Jul 2022, 14:34

im going to replace my balance cable connectors from 3 mt30 connectors to a single DB9 connector. while keeping the main charging cables separate using a SB50 connector. Where in the U.S can i find good quality db9 connectors atleast 5amp rating. heres links for male an female db9 solder kits but i want the male db9 with thumb screws an the female db9 with jack screws like in the screenshots i attached. That way i can secure them together. Any thoughts help or links will be greatly appriciated :thumbup:

db9 male kit
https://www.showmecables.com/db9-male-s ... it-plastic

db9 female kit
https://www.showmecables.com/db9-female ... it-plastic
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image_2022-07-09_093100803.png
housing with thumb screws for male db9
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female db9 and housing with jack screws
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Re: PINNED - Lithium battery conversion/info

Postby expresso » 10 Jul 2022, 00:04

https://www.digikey.com/en/products/det ... LF/1001838

5A rating -

https://www.amazon.com/Adapter-Connecto ... s9dHJ1ZQ==

shells - you can practice soldering on these and use just the shells with the 5A rating ones -
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 10 Jul 2022, 10:45

im going to replace my balance cable connectors from 3 mt30 connectors to a single DB9 connector. while keeping the main charging cables separate using a SB50 connector.


If going to the trouble of doing that why not use a single connector for charge and balance as I do?
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Re: PINNED - Lithium battery conversion/info

Postby fishinjunky » 10 Jul 2022, 13:47

Burgerman wrote:
im going to replace my balance cable connectors from 3 mt30 connectors to a single DB9 connector. while keeping the main charging cables separate using a SB50 connector.


If going to the trouble of doing that why not use a single connector for charge and balance as I do?


Your right wouldn't make sense to not do all In one. Much more convenient and neater.

I'll either use the d-sub same as yours or the one shirley_hkg posted the HY2+9P one but the 2 big contacts are only 30amps an the small contacts are 5amps. I sometimes charge at 45amps but not any higher so the connector would need to handle that. We just like the sb50 connectors a lot they give such a good strong connection. Bm which to you think has a longer life span in the same application a sb50 or a d-sub?
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Re: PINNED - Lithium battery conversion/info

Postby shirley_hkg » 10 Jul 2022, 15:49


These are better.
Single large pin rates 40A. You will have 2 for each main cable . @$4.3
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 11 Jul 2022, 08:40

Which last longer? Probably anderson. But they only have 2 contacts. You would need lots! You should fit anderson too.

I have one or two on everything. Drills, aboyt 10 chargers inputs and outputs, vehicles, chairs, my bed, inverters, solar system panels and connections and outputs in my room, lots of things like car polishers, etc. Even on my RC stuff like the goggles I use on FPV planes and quadcopters. And on my patient hoist. That thing always has a partly dead battery. It frequently refuses to lift me even if full as the batts are too high impedance. And it just bleeps. It only does about 3 lifts per charge even if the batt is new..
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Re: PINNED - Lithium battery conversion/info

Postby ex-Gooserider » 12 Jul 2022, 01:32

I agree, but I find that I like the smaller 15/30/45A powerpole connectors better for most things as they aren't as huge as the SB-50's... My chair that is still on lead bricks, I have the main charge / power wires done w/ PP-75 powerpoles in a compact 2X2 block, w/ a matching jumper block to bridge the two 12V batts to make 24V... I then put a pair of wires to a smaller pair of the PP-connectors across the otherwise empty 24V pins, which I use to connect anything I want to run off 24V...

This lets me make lots of jokes about my 'cordless' drill that runs off my chair....

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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 12 Jul 2022, 08:30

This lets me make lots of jokes about my 'cordless' drill that runs off my chair....

ex-Gooserider


Ditto... I too have a cordless drill.Now its corded. It runs better off the chair. Or the van. Or the lawnmower. Or the solar system. Or any of my power supplies or reserve battery. Or wherever I happen to need it. And its always "charged".


Hacksaw, black epoxy, soldering iron. Much cheaper than a new battery. When I say everything has an anderson on it I mean it! :D
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Re: PINNED - Lithium battery conversion/info

Postby fishinjunky » 12 Jul 2022, 13:30

Burgerman wrote:Which last longer? Probably anderson. But they only have 2 contacts. You would need lots! You should fit anderson too.

I have one or two on everything. Drills, aboyt 10 chargers inputs and outputs, vehicles, chairs, my bed, inverters, solar system panels and connections and outputs in my room, lots of things like car polishers, etc. Even on my RC stuff like the goggles I use on FPV planes and quadcopters. And on my patient hoist. That thing always has a partly dead battery. It frequently refuses to lift me even if full as the batts are too high impedance. And it just bleeps. It only does about 3 lifts per charge even if the batt is new..


I'm getting everything converted to anderson sd50 connectors

I've had the same problem with all the battery operated patient lifts I've tried I hated them. I ended up getting a manual one
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Re: PINNED - Lithium battery conversion/info

Postby fishinjunky » 12 Jul 2022, 13:31

ex-Gooserider wrote:I agree, but I find that I like the smaller 15/30/45A powerpole connectors better for most things as they aren't as huge as the SB-50's... My chair that is still on lead bricks, I have the main charge / power wires done w/ PP-75 powerpoles in a compact 2X2 block, w/ a matching jumper block to bridge the two 12V batts to make 24V... I then put a pair of wires to a smaller pair of the PP-connectors across the otherwise empty 24V pins, which I use to connect anything I want to run off 24V...

This lets me make lots of jokes about my 'cordless' drill that runs off my chair....

ex-Gooserider


:thumbup: 5
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Re: PINNED - Lithium battery conversion/info

Postby fishinjunky » 12 Jul 2022, 13:34

Burgerman wrote:
This lets me make lots of jokes about my 'cordless' drill that runs off my chair....

ex-Gooserider


Ditto... I too have a cordless drill.Now its corded. It runs better off the chair. Or the van. Or the lawnmower. Or the solar system. Or any of my power supplies or reserve battery. Or wherever I happen to need it. And its always "charged".


Hacksaw, black epoxy, soldering iron. Much cheaper than a new battery. When I say everything has an anderson on it I mean it! :D


Great idea :thumbup: I just spent half a day trying to find my charger for my cordless drill banghead

The sb50 connectors seem like the best connectors for just about anything.
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Re: PINNED - Lithium battery conversion/info

Postby ex-Gooserider » 19 Jul 2022, 01:33

My feeling is that the SB-50's (and the PP-75's that use the same pins) are nice but HUGE, and overkill for pretty much everything except maybe charging the chair from your car or a BIG power supply....

The smaller PP-15/30/45 connectors are suitable for almost everything else, and are a fraction of the size.... They are also able to handle a lot of power for their size, I have seen them used on many chairs as connectors between the power module and the motors, using the AWG 10 / 45A size pins on the motor wires and the 15A pins for the brakes...

It is sort of like the difference between a US 110V AC plug and the big honking things that you use in most of the 220V countries....\

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Re: PINNED - Lithium battery conversion/info

Postby fishinjunky » 19 Jul 2022, 22:15

This picture is around 5hours after a full charge has finished an the cells have settled I plugged back in to check voltages an I see cell 8 is around 0.011 Volts higher than the others. Is this a problem?
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 19 Jul 2022, 23:54

No. All cells have a slightly different self discharge rate, and that charge voltage is higher than the full voltage (and there isnt one) So they were all held at 3.55 or 3.60V for at least 15 to 30 mins after balance finished? Then all are 100% full.
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Re: PINNED - Lithium battery conversion/info

Postby fishinjunky » 20 Jul 2022, 13:20

Burgerman wrote:No. All cells have a slightly different self discharge rate, and that charge voltage is higher than the full voltage (and there isnt one) So they were all held at 3.55 or 3.60V for at least 15 to 30 mins after balance finished? Then all are 100% full.


Yep, ok thanks BM :thumbup:
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Re: PINNED - Lithium battery conversion/info

Postby fishinjunky » 01 Aug 2022, 13:46

I was checking on IR of the cells while charging at 20amps. I noticed cell #1 is 0.3 IR an the other 7 cells are 0.4 IR. But when not charging all 8 cells show 0.3 IR. Is this something I should be concerned about?

What would you guys consider a high IR in a 200ah cell?
What would you guys consider a low IR in a 200ah cell?
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IR while charging at 20amps
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IR while off charging
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 01 Aug 2022, 14:10

Thhe resistance of a cell is lower than that of its connections, cables, and the chargers ability to measure this. Dont let this worry you.
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Re: PINNED - Lithium battery conversion/info

Postby fishinjunky » 01 Aug 2022, 14:16

Burgerman wrote:Thhe resistance of a cell is lower than that of its connections, cables, and the chargers ability to measure this. Dont let this worry you.


Thanks BM, Your know me the worry wart :lol:

But I like to ask an learn instead of just making my own inexperienced assumptions :thumbup:
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Re: PINNED - Lithium battery conversion/info

Postby wheelerx » 10 Sep 2022, 00:08

good evening all. Before I can go much further on my project, I need to decide what batteries I'm going to use. I would very much like to jump to lifepo4 (or other recommendation) and a smaller size. I have a friend who is capable of building a battery, but he wouldn't be too excited about doing it considering it could literally fry me. Therefore off-the-shelf would be highly preferable. This will be a full-size chair, but I'd don't travel great distances. Any recommendations appreciated and let me know if you have any questions. thank you!
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 10 Sep 2022, 01:14

Question.
If you dont go far, why LiFePO4 when the cost is greater (but not that much greater if you DIY and fit a decent sized pack. But a lot greater for less reliability and possible additional issues with a drop in lead brick replacement?

There are many reasons that a large capacity lithium pack is better even if you dont go far. And that means DIY unfortunately.
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Re: PINNED - Lithium battery conversion/info

Postby shirley_hkg » 10 Sep 2022, 11:58

wheelerx wrote: I would very much like to jump to lifepo4 (or other recommendation) and a smaller size. I have a friend !

A 40--50Ah add-on will also be a very good pick. It will triple your range , and extend lifespan of your gel battery too.
https://www.wheelchairdriver.com/board/ ... 52#p186852

OR

https://www.wheelchairdriver.com/board/ ... 2&start=60
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Re: PINNED - Lithium battery conversion/info

Postby Furio » 10 Sep 2022, 17:14

Hi,

A set of lifepo cells arrived. Not a familiar brand, 230ah.Is anyone using this make of cells?

@BM Please give a preset for charging individually and as a set.Thanks.
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 10 Sep 2022, 17:19

Can you show a link to the supplier?
EVE are well known.
So I can see prices and dimentions etc. Thanks.
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 10 Sep 2022, 17:30

https://www.wheelchairdriver.com/preset ... iFePO4.zip use the 200Ah one. For all.

And this for 1 cell.
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Re: PINNED - Lithium battery conversion/info

Postby wheelerx » 10 Sep 2022, 17:45

I don't typically go far, but I do need the ability to go far occasionally I suppose. Vacations, amusement parks, etc.

Thoughts on https://www.amperetime.com/products/amp ... o4-battery?
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 10 Sep 2022, 19:51

My thoughts are that the BMS will be problematic under heavy loads. Esp when the battery is more discharged. And since its just 50Ah (and unless you want to end up stranded or ruining the pack rapidly) you should be aiming to use around 40 of that. And so you will get the same range as a set of lead bricks, with the extra expense and less reliability (built in BMS firestarter) for no gain. So why?

The whole point of fitting lithium is because when done correctly, you can get 200 to 230Ah (See furios new cells in the posts above) in the same place as the lead bricks. That means that you almost never load the pack heavily because it big. Heavy loads on a small battery or high daily discharge levels are what kills batteries. So it lasts donkeys years longer if its big! It also means that you CAN either charge weekly or less if you dont use it much, so dont use up all its cycle life with repeated daily charging. This may add another 3x extra serice life to it because its big! It also means you can get up to 5x the range of lead on the odd days you may need to. Up to 80 miles. Or charge once a week. Or some combination.

And because you are not murduring the battery every day, it will last at least a decade. I have batteries that old that still hold the same capacity as they did a decade ago! I expect them to continue! BECAUSE adequate Ah was fitted. Fitting the same as lead, or even LESS than the lead you have now means you lose all the advantages lithium offers. Longevity, range, doesent matter if you forget tocharge for a few days. So pretty much pointless.

This is why I asked you WHY you want to go lithium. If its to gain all the advantages, then only doing a proper DIY setup will give you that. If its to say you have lithium, with little of the benefits, then thats OK. Use a drop in replacement and cross your fingers that it keeps working, and doesent keep cutting out and leaving you stranded every time it detects a low cell, bad balance, high load, etc.
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Re: PINNED - Lithium battery conversion/info

Postby wheelerx » 11 Sep 2022, 02:07

interesting and very informative. The main reason I want to go lithium is to get lower seat height. width and length can be standardish but I'd like a shorter package. Off-the-shelf 100ah+ is looking impractical from a cost perspective. Not to mention probably impossible to find one to fit my dimensions. I'll look into the furios cells and see if I can find somebody interested in building one. Thanks again
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Re: PINNED - Lithium battery conversion/info

Postby Burgerman » 11 Sep 2022, 09:27

"Sombody"... Be very careful!
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Re: PINNED - Lithium battery conversion/info

Postby Furio » 11 Sep 2022, 10:27

Hi BM,

The supplier is from India and he doesn't supply the cells abroad. The cells cost US $132 each. I am attaching the specs.
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