PINNED - Lithium battery conversion/info

[Burgerman]

That purple line looks like a bad connection somewhere in the pack?

[Burgerman]

RELiON:

Compared to lead acid batteries, lithium batteries offer significant advantages, including improved discharge efficiency, longer life span and the ability to deep cycle while maintaining performance. While they often arrive with a higher price tag, minimal maintenance and infrequent replacement makes lithium a worthwhile investment and smart long-term solution.

However, most American consumers – electronic enthusiasts aside – are only familiar with a limited range of lithium solutions. The most common versions are built from cobalt oxide, manganese oxide and nickel oxide formulations.

Although lithium iron phosphate (LiFePO4) batteries aren’t new, they’re just now picking up traction in U.S. commercial markets. Here’s a quick breakdown on what distinguishes LiFePO4 from the other lithium battery solutions:
Safety And Stability

LiFePO4 batteries are best known for their strong safety profile, the result of extremely stable chemistry. When subjected to hazardous events, such as collision or short-circuiting, they won’t explode or catch fire, significantly reducing any chance of harm.

If you’re selecting a lithium battery and anticipate use in hazardous or unstable environments, LiFePO4 is likely your best choice.
Performance

LiFePO4 batteries perform well in several areas, especially life span. Service life usually clocks in at five to six years, and cycle life normally exceeds other lithium formulations by 300 or 400%. However, there’s a tradeoff. Energy density is typically lower than certain counterparts, such as cobalt and nickel oxide, meaning you’ll lose some capacity for the price you pay – initially, at least. A slower rate of capacity loss compared to other formulations might offset the tradeoff to some degree. After a year, a LiFePO4 cell typically has approximately the same energy density as a LiCoO2 lithium ion cell.

Battery charging time is also considerably reduced, another convenient performance perk.

If you’re looking for a battery to stand the test of time and charge quickly, LiFePO4 is the answer. However, remember that you might be trading density for longevity: If you need more raw power for a large application, other lithium technologies may serve you better.
Environmental Impact

LiFePO4 batteries are non-toxic, non-contaminating and contain no rare earth metals, making them an environmentally conscious choice. Lead acid and nickel oxide lithium batteries, by comparison, carry significant environmental risk (especially lead acid, as internal chemicals degrade structure over team and eventually cause leakage).

If you’re not sure what will happen to your batteries after you’ve exhausted them and want to guarantee minimal impact to the environment, choose LiFePO4 over other formulations.
Space Efficiency

Also worth mentioning is LiFePO4’s space-efficient characteristics. At one-third the weight of most lead-acid batteries and almost half the weight of the popular manganese oxide, LiFePO4 provides an effective way to make use of application space and reduce overall weight.

Trying to get as much battery power as possible while keeping weight down? LiFePO4 is the way to go.

If you’re looking for a lithium battery that trades rapid energy delivery for safety, stability, long-term performance and low environmental risk, consider powering your application with LiFePO4.

[shirley_hkg]

Cylindrical cells seem more reliable .
SONY 26650 @3000mAH .

[Burgerman]

Thats exactly what I see with lifepo4 though.

With the PL8 you need to set it for 4 decimals to see the differences on the graph, or it averages the data.

VIEW > PREFERENCES > CELL DISPLAY > SHOW 4 DECIMAL PLACES

[shirley_hkg]

Dunno it can do that .

[Burgerman]

Your graphs wont look as pretty, but it shows more detail, no data averaging. It shows you why a long CV matters for balance after you stop charging for eg. It also shown you just how crap BMS are if you monitor a pack being charged. Looks like a range of mountains!

I only set to 4 decimal places and no rounding, when figuring out how long CV or what is the best termination current. Ideally you want long enough to be sure all cells end up properly balanced and charged. But as short as you can get away with as they dont like being held high for a long time. And different packs vary a fair bit. Then change it back.

Do you like the PL8? I think its an invaluable tool for anyone playing with batteries. There isnt another comparable at the moment.

[shirley_hkg]

Have to admit that I charge with PL8.

Nevertheless , I haven't rule out BMS ,
as they are now user adjustable , bluetooth connected and 200mA balance @£50 . May be tempted to get one on a small pack , to see if I'm up to installing it.

[steves1977uk]

The balance current needs to be at least 1A (1000mAh) on a large pack otherwise you'll be waiting until Doomsday!

Steve

[Burgerman]

He is talking about a small pack, and wiring the chair directly to the battery so bypassing all that power cutting safety bullshit. And only using it to charge the battery. And I suspect at 8x 3.550V per cell, rather than at 3.65V. That means he will only be bouncing the cells up to about 3.6 repeatedly...

For what its worth,the BMS in my mower has just screwed up the battery again. as its only cutting for 5 mins instead of 1 hour and then it just stops dead in the middle of the lawn and refuses to go back on charge automatically. Because the BMS cut all power. Last time it did that the pack was miles out of balance. Since it didnt have time to balance the cells before it went out again. (2x a day). Horrid things. Mower keeps stopping due to 1 very low cell. The other 4 are 95% full. Charger cuts off automatically after a couple of hours at CV so it doesent wreck the full ones. So never ever balances with its stupid 50mA balance circuit. 5Ah pack. BMS are stupid.

The PL8 can balance it WITHOUT bouncing cells up and down, and it can do so for as long as it takes to balance properly. Which isnt long as 1A proportional controlled balance current is 20x faster than 50mA ON/OFF for hours on end. And it will continue till it IS balanced, and until its actually charged. But that means bringing it in the house and plugging it in! But by now the pack is already ruined.

[shirley_hkg]

Back from long weekend and drained to 24.6V . . . . lowest ever.

Put back 253.352Ah .

[Burgerman]

I like your yellow cell best.

[shirley_hkg]

Someone asked about BMS . I'd only recommend programmable ones . It's because we don't want it over shoot 3.6V that most BMS couldn't do .

For eg. the MaYi bms can set over-volt cutoff at 3.6V or lower . It still bounces all around the balance period , but it can't hurt any cell.

Balance current is max @ 200mA .
It's only 1/5 of that of PL8 though , you can still get away with it if your cells were low in self-discharge .

Bluetooth connected too. Selling @£50

Don't know if it has English version program . Here is a hits …

https://endless-sphere.com/forums/viewt ... 14&t=88676

[Burgerman]

Damn that thing looks simple....
Where does the smoke usually come out?

Funniest comment!

Ignoring the charging part, where the PL8 is far nicer to the pack, completely proportional, 5 times faster and much more accurate. And doesent hold all the other cells high for many hours while it tries to balance the high one.

Do you realise that once you fine tune its multitude of protection settings so that it doesent interfere with driving the chair safely without cutting out. I.e; the correct settings for your chair, then its main purpose in life (cell protection in use), will actually do absolutely nothing? Making it pointless.

And many on that forum, connect their ebikes directly to the battery and not via the BMS as it reduces the issues/fires/mosfet failures and resistace losses and BMS issues they suffer over there! And so only use its charging option. That said it may be useful on my auto mower as I cant control what it does (or use the PL8) as its all autominous and robotic. But of course no PC option via bluetooth? So maybe no use for that job. The built in BMS has already cost me 2 batteries in 3 years! How I love those things. No smartphone here.

[hobie1dog]

John: you put a link in on page 28 to this site for us to read/ learn from

http://scriptasylum.com/rc_speed/lipo.html

It doesn't work for me. Got another link?

[hobie1dog]

Just finished reading all 3494 posts over 117 pages.

Thanks to John for sharing your extensive knowledge with everyone, you have the patience of the biblical/mythical Job. No one hates a BMS as much as you do.
Expresso, you set a record with 11 questions in a single post.

I'm still dumber than a sledload of manure when it comes to all this, but better than before.

[Burgerman]

John: you put a link in on page 28 to this site for us to read/ learn from

http://scriptasylum.com/rc_speed/lipo.html

It doesn't work for me. Got another link?

I dont. Sometimes good sites vanish.

[foghornleghorn]

John: you put a link in on page 28 to this site for us to read/ learn from

http://scriptasylum.com/rc_speed/lipo.html

It doesn't work for me. Got another link?

I dont. Sometimes good sites vanish.

This is another link to the page https://web.archive.org/web/20180116140 ... /lipo.html

When a website disappears there will often be a saved version on https://archive.org/web/

[baker99]

I'm probably going to sound dumb as usual and haven't read every post in this thread (117 pages is a little much), but could I just dump these in my Frontier X5 to replace the current MK GEL (M24 SLD G FT 12V63AH C/5 12V74Ah C/20) batteries without swapping charger etc. ? https://www.lithiumion-batteries.com/pr ... attery.php

I'd rather do it the proper BM way, buy seperate cells and connect together etc. but I don't have anymore around who can do it for me, I also don't have the cash right now anyway but want to know in case I ever have enough spare.

[Burgerman]

Over and over!
Just read post 1 viewtopic.php?f=2&t=1813

I'm probably going to sound dumb as usual and haven't read every post in this thread (117 pages is a little much),

viewtopic.php?f=2&t=1813 You need to read post 1 only. And follow links etc.

but could I just dump these in my Frontier X5 to replace the current MK GEL (M24 SLD G FT 12V63AH C/5 12V74Ah C/20) batteries without swapping charger etc. ? https://www.lithiumion-batteries.com/pr ... attery.php

Yes you could. Will it "function"? It might or might not since its max continuous rating isnt really high enough. Nandol fitted a set of those. He broke down all over the place when the internal BMS decided it didnt much like curb climbing or any kind of high currents for more than 1 second. The BMS usually pulled the plug and stopped his chair, needing you to turn the controller back on regularly. But eventually the mosfets failed and he had to be rescued. I warned him of this over and over but he did it anyway. They had to eventually pull off the battery tops, disable the BMS protection in everything but charging. Which left the cells in the same state as if no BMS was fitted.

And then it worked. But limited range as the batteries are no bigger than the ones they replaced. So defeating the point of going lithium. Why remove 74Ah and replace with 75Ah? Remember that nandol eventually ordered a 180Ah pack, mine are 120Ah, the salsa will be getting a 180Ah, expresso has a 90Ah pack used with a 30 or 40 or 60Ah additional addon. Snaker has 160 or 180Ah I think, and shirley has over 200Ah. The entyre point of fitting lithium is that it allws a large Ah increase if planned well. With huge range, performance, and longevity benefits. By limiting it to the same small 75Ah as the lead, you work the cells harder, which shortens life, and you lose one of the other lithium benefits. So you end up paying out a fortune for batteries that will not be reliable, will only offer minor range increase, and may not last. So its unwise. Especially if done carefully with chinese cells you can get double that Ah for the same or less money!

I'd rather do it the proper BM way, buy seperate cells and connect together etc. but I don't have anymore around who can do it for me, I also don't have the cash right now anyway but want to know in case I ever have enough spare.

That makes no sense. Its already cheaper to do it properly! Those lead brick replacements are offering just 75Ah for 2000 dollars!!! I have a bridge to sell you.

[baker99]

Thanks BM, I figured it would be too easy for them to just work, it would be nice like you've said in other threats if wheelchair manufacturers would start using these instead of regular batteries, I'll have to wait a bit longer, one day I'll make friends with someone who has the right knowledge to build yours from the tutorial, at the moment there's no chance sadly. I really need a company to start customizing chairs with everything on this site, somehow I doubt there'd be enough money in it for someone to open a wheelchair custom shop, would be good though, go faster stripes would be cool too

[Burgerman]

When those lead brick grp24 replacements reach 100Ah, it begins to be worthwhile. As long as you disconnect the BMS, and only use it for charging with a dumb charger. But beware, charging using the BMS is also problematic in some cases and why you will see a shorter life. Not you, the battery!

Also that is not to say those batteries wont work in a fashion. If you or the chair isnt programmed like mine, and you dont climb curbs, etc than they may never trip out. If the battery stays in balance with the BMS then you may be lucky and get reliability. And you will get a small range gain. But its certainly not cheap as you are only getting 70Ah for 2000 dollars. It MAY work to a degree if you are lucky. But you will miss out on most of the advantages.

[baker99]

Yep definitely doesn't seem worth it, the current batteries do the job for now, although I think the dx2 controller has a short, need to get it serviced soon as I use a microswitch plugged in the joystick unit to turn it on and off, now when I connect it it randomly makes the chair turn off, no buttons work and a blank screen until I unplug it, I've tried two different microswitches so pretty sure it's the joystick controller that's the issue, chair also randomly stops working and needs a quick off/on to start again while out with switch not connected, it doesn't completely die and the screen stays on but it's a pain.

[Burgerman]

Fire some switch cleaner at the connector.

Check its not programmed to enter sleep or suspend.

[baker99]

I'll give that a go, BM

[FJC10]

Hi,

I need some help.

I have mounted the battery but I have a problem with the connection bridge for both batteries. The copper wire is very rigid and thick so I can't put the batteries together.




Any ideas?

[Burgerman]

Make it longer. Like 2 foot longer so it can be a flat loop.

[FJC10]

Make it longer. Like 2 foot longer so it can be a flat loop.

Can I use a longer cable? I thought the shorter the better.

Can I use silicone cable? AWG 10 or AWG 8, maybe? They are more flexible than copper cables....

Can you pass me settings for the charger? My battery is 9P-8S.

[Burgerman]

Shorter is better but it needs to be adequate to allow you to fit it! Silicone is more flexible but its insulation is quite fragile. That looks like ott cable size. 10sqmm is easie to flex. Or connect to a top and a bottom cell so it isnt opposed...

What is Ah?

[FJC10]

That looks like ott cable size. 10sqmm is easie to flex.

Cable information:
Cable: Copper
Cross section: 16mm2
Diameter: 8.3mm
Outer coating: PVC (Water and oil resistant)
Max constant amps rating: 110amps
20cm (8") lengh

I forced him a little and I think he'd fit in my chair:

Or connect to a top and a bottom cell so it isnt opposed...

Can I connect it like this?



I think it would be better. And I could make the cable shorter...

What is Ah?

12ah x 9 = 108ah

[Burgerman]

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