what do you think of those already made batterys?

[yeshelp]

https://rocksolar.ca/products/rocksolar ... 5038333219

they have this serious waranty Warranty: Trustworthy 11-year warranty, showcasing its robust build and reliability.

yes i have another post about lifepo4 but when there are too many questions or avenues or subjects adressed in one post i lose myself, i hope you will understand.

This post does not invalidate the possibility of going diy 16s route but i need to evaluate other options especially since the diy cell might be too much work for me at this moment in my life dependingon how complicated it is .

So there is this rocksolar possibility. that is already made. so probably much quicker. The donnator might prefer this one because it is quicker (he wants to see me roll with them and because they are guaranty to make me roll because i have no xp with 16s build so he wont like the idea diy .

Any way rock solar are 846 usd 1,139.99 cand for the set . a bit more than MK .He might accept to pay more than the gel to get me those already made lifepo4 if i can convince him.....

Before trying to convince him I need to know myself what is best.

how do 2 mkgel 75 AHMK24G-FT compare to two solarrock 100ah lifepo4..

wich one would you choose ? i dont do long distances . I imagine that if i stay between 12 and 88 pourcent (100 - 24 ah) = 76Ah i will be able to do the same distance as a brand new set of get 75AH? right?

what are the pro s and cons of this rocksolar in case the diy idea is rejected by me or the donator?

and what charger not too noisy (better if silence) not to expensive could i propose with that ? (i regularly have 12hours in a row of plug wall time sometimes 16hours

thanks

[Burgerman]

Way too small, will not last. Warranty will not help as its manufacturing defect only. Thats not what will cause you problems. This will:

Maximum Continuous Discharge 100A

Presumably the controller on your chair is 120A per channel? So if used hard say climbing a steep slop while accelerating etc you can potentially reach up to 240A drain. Thats 2.4x as much as these batteies can give... So the BMS that is the thing limiting this current (to protect the too low C rate or too small cells from damage) will chop off power suddenly until the BMS is reset. I have explained this so many times over the years that I can type it while watching this movie...

There are no decent or sensibly priced drop in lead brick replacements. That 100A is really 80 since you need some in reserve or you will drop the voltage under load and the BMS will pull the plug again. That should give you around twice the range of the MKs, but you will never see the long service life that you can get with a proper large pack setup. You only need 8 by the way, not 16. 8x 230Ah ideally. And NO BMS as the chairs control system alredy does all the protection stuff regarding load etc in a proportional controlled way. And wth a large enough pack you cannot use it all in a day so low voltage cut off also isnt an issue.

[shirley_hkg]

They are G27 form factor, 13" long.

[yeshelp]

Presumably the controller on your chair is 120A per channel? So if used hard say climbing a steep slop while accelerating etc you can potentially reach up to 240A drain. Thats 2.4x as much as these batteies can give... So the BMS that is the thing limiting this current (to protect the too low C rate or too small cells from damage) will chop off power suddenly until the BMS is reset. I have explained this so many times over the years that I can type it while watching this movie...

There are no decent or sensibly priced drop in lead brick replacements. That 100A is really 80 since you need some in reserve or you will drop the voltage under load and the BMS will pull the plug again. That should give you around twice the range of the MKs, but you will never see the long service life that you can get with a proper large pack setup. You only need 8 by the way, not 16. 8x 230Ah ideally. And NO BMS as the chairs control system alredy does all the protection stuff regarding load etc in a proportional controlled way. And wth a large enough pack you cannot use it all in a day so low voltage cut off also isnt an issue.

Ho i see. well i dont know about the precise controller channel spec but i do know that putting too much pressure on cell damages them and even though i dont go up hill everyday nor abuse acceleration nor speed but it is nice to have option to go uphill . And then the 27 inch confirms it is not an option for me .

By any chance could anyone propose an already made battery lifepo4 or link that would be decent so that i could propose it to the donator to satisfy everyone as a better alternative than the MK gel75Ah?

I dont understand some words or expression in this sentence so maybe it answers my question i dont know:There are no decent or sensibly priced drop in lead brick replacements

[Burgerman]

There are non that are any use or really worth buying. There are no drop in dummy no skills required batteries that are any good. They are all overpriced, half the capacity you need for double the cost and have BMS built in that is the cause of all the reliability problems. Even safety issues.

There was only 1 that ever looked like it was even worth testing and I forget its name. It was red... And 135Ah. And group 24 so correct size. If you drive a chair with more or less stock grandma style programming it may work for you. I will try to remember the name! But it will not be reliable wont last decades, will give you half the range of a 230Ah setup, less actually if you leave the same amount in reserve for safety and longevity reasons, and so on. But at this point you have to ask yourself why are you fitting lithium?

So why ARE you fitting lithium?

The reason we all do it on here is because DONE PROPERLY it has enourmous benefits. The reason to do it is this:
Done properly it INCREASES reliability and allows those that are control freaks to monitor and see exactly what is going on.
Main reason is that lithium allows MUCH GREATER Ah to be fitted in the same space as the Group 24 battery used to be. And this allows 230Ah. That in itself means:
MUCH longer service life.
Less frequent charging in the order of a week or more. Which in itself means you use up the cycle life 7 to 10 times slower...
Because a big pack has an esy life. Low Amp draw per Ah means you are treating it super gently. This increases longevity too.
Range. When you have 5x the range ALL range anxiety or need to even look at or have a battery guage is gone! YOU cant run it out of power as time doesent let you.
Charge speed. At 40A charge as I normally do, I put back the same amount of energy as a complete set of lead batteries per hour! Or if you prefer you replace 20 miles every hour. And unlike lead you do NOT need to complete the charge. Well you should do that maybe monthly.
Weight of 230Ah is around 2/3rds of the weight the lead once was. So lighter. But not so much lighter that it causes stability issues.

Lead always takes 10 to 16 hours to PROPERLY and fully charge. Because it slows down to a crawl for 8 hours. Even if charged at 40A. Lithium charges at full power for 99% of the charge. So you put back 100 miles in five and a half hours. Instead of 15 to 20 in 16 hours...

A big pack will last 5 or 6 tmes longer because you
a) dischage it daily to a much lesser degree. So you get at least double the cycle life. So maybe 4 to 10 thousand cycles.
b) recharge it weekly or monthly if you dont go far. Just do it as soon as you lose maybe 1 light on your controller so that you never run it low. That way you have maybe 4 to 10k cycles and only use them up weekly... So tens of years. Maybe 30 years.
c) low C rate doscharge. Means longer service life and no unreliable BMS required to protect the cells or cause fires etc.
d) range! The whole point and the reason we do it. Do you want to increase range by maybe almost double? Or 5 times!
e) cost... As mentioned a big pack means much longer service life, and even when it old, in 10 to 30 years time range will still be double that of new lead...
f) control. And knowledge. And the fact that you now KNOW whats going on and why.

So NOT fitting as big a capacity as possible misses out on all the great benefits. Which is the whole point of going lithium in the first place