SLA to Lipo conversion. Help needed please!

[CertifiedMike]

Sooooo. I have this old Razor Scooter thing that has sealed lead acid batteries that are fried.
Since lipo's seem a reasonable option to explore, here I am exploring.
Current batteries are 2 DZM 12-6 batteries wired to 24 volts.

https://mefast.com/MKBattery/MKcross-over/HangYue.html

I am stuggling to understand how a pair of batteries like this are operating in the 1-3c range based on the size of the motor and the large man weighing it all down.
I feel like I am missing a big step here.
If I have this right, I need 7s to meet approximate voltages.
I believe this speed control will operate between 24 and 36 volts based on the battery ranges and what I can find on internet but there are NO numbers on it to nail down factuals.
I am concernered about over volt protection also.
So 7s and 12000mah also? I am in over my head trying to understand the differences in a lead acids ability to provide power safely at a lower cell voltage vs lipos and theirs.
The motor on it is a brushed MY1018. 2750rpm Rated current is 14a and its 250 watt output.

There has GOT to be a Castle brushless upgrade for this thing! Extended hard tail with twiisted spoke wheels and a long girder front end?!?!?!

How do I figure this out so the batteries will not die and leave me stranded, nor will I blow them up underpowering?

There is a good amount of room in the battery compartmnt but I haven't worked out an easy access to the battery tray yet.
I'm hoping for as few as batteries used as possible while keeping costs down. A pair of maxamp 7s $485 batteries is out of the question here. (it might have been a different company*)


Nominal battery ratings of current battery

20hour rate ( 0.6A to 10.50V ) 12Ah
	10hour rate ( 1.2A to 10.50V ) 12Ah
	5hour rate ( 2.04A to 10.20V ) 10.2Ah
	1C ( 12A to 9.60V ) 5.4Ah
	3C ( 36A to 9.60V ) 4.32Ah

 

[Jerold]

Short story is 6S is "probably" the right voltage. This would give you an absolute input voltage range of 18V-25.2V. Realistically you shouldn't get close to 18V if you like your batteries.

A fully charged 12V SLA is about ~13-V or 24V system would be 26V max. It's ~11V (or 22V) minimum.

If you ran 6S and kept it between ~22V and ~25+V, it's probably fine. That gives you a LiPo Cell range on 6S of 3.6-4.2V.

With all that said, this is only looking at the voltage. If there is any sort of regenerative braking or over/under voltage cut offs it may not work at all or be a total fire hazard. I dunno?

You can make your own low voltage sensor with a LiPo alarm if you need to.
https://a.co/d/03phFuz1

Keep in mind that the SLA you have above is a 12,000 mah battery that will cost you $61 shipped to your door. It's low risk and requires no modifcation or extra work. Using LiPos wills save some weight (about 1/2), but to get the same capacity in LiPo is going to be at least 2x the price and you have make it work.

 

[CertifiedMike]

I agree with the price issue. I want to have some fun with it but clearly I'm not trying to race it. (unless I find that Castle system. Lol!)
There is a simple mechanical drum brake and a one way chain/sproket hub so no regen system I think.
I run some large 3s in my Granite right now. maybe I'll step them up to 12000's. If they don't work out on the bike, the Granite will FLY for at least an hour/pack! Lmao!
As far as weight goes, I could prob diet for a week and loose what weight difference is saved, lol!
I was thinking more about having the amps to keep it fun up until the low voltage alarms beep ( I have some but I'll get more!)
Is the lead acid or the lipo going to be more prone to sag?
This brushed motor is a giant and is a good heat generator from what I read.
I'm not totally opposed to going with the SLA battery but I don't have a good local supplier for them.
I feel like I am rolling the dice with my money to get a quality SLA battery with an unknown supplier.

 

[tntpoof]

unless you add your own low voltage buzzer on the balance tab I dont think the scouters will work. If you filled out your profile completely I could help you find a retailer near you.I have 6 different ones within 10 mile radius of my location.. a lipo will give you the voltages you are after..
these are by me
Batterys +
studz hardware
battery company(all makes of batterys)
autozone

 

[CertifiedMike]

I have Lipo alarms like we use for rc, I didn't mean in the scooter's esc.
I hadn't considered autozone honestly. A quick search shows me that the specs i'm interested in aren't online.
Maybe I'll have to stop in to a store.
These batteries are pretty small @ 6 x 3 3/4 x 3 3/4" might be more along the lines of a lawn tractor battery than a bike but if they fit and make it go... lol.
The size is what made me think that the lipos would be a reasonable subsitute. I would not be attempting this in my 1:1. Lol!

 

[Jerold]

Sure swap the connectors and try it out then.

There are brushless scooter motors/ESCs out there and they are pretty in expensive compared to some of the high stuff we use.

The voltage droop on the LiPos vs the SLA is unknown. It depends on the quality/condition of the batteries and the load. Larger mAH batteries should (in theory) have less droop. You can always run multiple batteries in parallel/series configuration. That's 2 or more sets of batteries in parallel, wired together in series. It gives you more juice (amps).

 

[CertifiedMike]

I think I will do that actually. I'll hav# to order some more batteries to get the mah up over 12000. (my 3s are 9000 mah now.
I dunno. I guess just trying to get my head around the smallness of the batteries I will be using compared to the performance on paper made me feel like I was missing something.
Its just a goof project thats time has come. Finish it or toss it!

 

[Jerold]

Seems like others have done this too.

https://endless-sphere.com/sphere/t...milar,,and you'll get a 24v 10ah lipo battery.

I would be very careful with the open blade connectors.

 

[Greywolf74]

Id run it on 6S and get the highest mAh rating you can. The only caveat is that you will have to use a low voltage alarm on the lipos when you are using it.

 

[CertifiedMike]

The plan is to order up a few more lipos. I'm planning to double up on 3s packs that will still go in the Granite but as high Mah as possible.
I need headset bearings so its on hold until the "fire" button gets pressed and fun gets shipped.

 

[CertifiedMike]

https://inv.nadeko.net/watch?v=S8ov87b6FrI&listen=false

Possibly a different solution???

This guy is my HERO!!!

 

[Greywolf74]

Thats great!

 

[CertifiedMike]

The guys shoes look like they are about to catch fire! Lol!
He looks like he is LOVING that scoot!