Battery care questions

[okrobie]

I'm really not sure what EMTB stands for but Google sent me here and y'all are talking about the things I care about. So here I am.

I ride a TaoTao electric scooter with a 500Watt motor and 48VDC 18Ah batteries. Currently I'm using SLA batteries and my first question is about how I got the plates so sulphurized in such a short period of time. After only 2 months the internal resistance was 17.5 Ohms? and my battery tester said replace battery. I have a knowledgeable friend who tells me that I may have over charged them. My charger puts out 60VDC into the 48V cell bank. Or I may have driven at maximum speed too much (25 MPH) Anyway thats water over the dam. I can't do much about it now. This time I plan to get Lithium batteries and I don't want to wreck them too. I understand that Lithium batteries come with their own charger so I can't screw that up too much.

OK on my new batteries, I'm sure I will need 48V, but how many Ampere Hours do I need? There are major price differences according to how many AH I decide to get. Please help me figure out what I will need. Thanks, Jim

 

[Beekeeper]

Divide Watts by Volts to give Amps
500W divided by 48v is 10 Amps
So if you bought a 10 amp hour battery pack it would in theory last you 1 hour at maximum power.
A 20 amp hour battery pack would last you 2 hours at maximum power.

 

[wepn]

This time I plan to get Lithium batteries and I don't want to wreck them too

Best way not to wreck them is to keep them charged at 50% when not in use & charge to 80% before you ride. Only charge to 100% if you need the range. Otherwise, depending which battery, most likely the BMS will balance the cells at close to 100% so charge fully once a month or so but don't fully charge & let it stay fully charged.

You'll probably need something like this. Search for 48V, 1kWh battery pack for bike or scooter.

Battery Pack 36V / 48V for UNI Moke

 

[Beatn1K]

Storing your battery @ 50% sounds quite low, & is at odds with most any advice I have been able to unearth...
I have long since believed 80-90% was appropriate , although I have revised this down for my own batteries, preferring to keep it at @70%.
I believe it is important for longevity and efficiency.
What do people who care about this issue believe is the right level of charge at which to leave your lithium batteries in stasis so as not to experience self discharge and maintain minimal chemical degradation...?

 

[wepn]

Storing your battery @ 50% sounds quite low, & is at odds with most any advice I have been able to unearth...

From the Specialized manual:

 

[Beatn1K]

at least 30-39% isnt very specific...and that may be all that is needed...?
I understand all the batteries are essentially comprised of the same cells from one maufacturer and 'packaged' with a brand name thereafter...? Because mine is a Shimano system but I have rather assumed it's the same for the technology across the board...?
The point seems to be that too much charge is as bad as too litle from what I can understand..?

I realise alot of folk think it pedantic but in fact, its so easy to do IMO, as long as you know where to stop...!!

 

[wepn]

30-39% isnt very specific

Only store the battery at an ambient temperature etween -20ºC and +35ºC

They don't do specifics lol

I realise alot of folk think it pedantic but in fact, its so easy to do IMO

Exactly right. Think of 50% literally as happy medium where cells are happiest. Very easy to do OTOH no big deal if you charge to 100% and leave it for a month until the rain stops - just be prepared for increased cell degradation & lower calendar life expectancy.

 

[slippery pete]

Op is talking about lead acid batteries.

Sulphurisation of lead acid happens with deep discharge and rapid charging from deep discharge.

They're a shit technology for transport batteries. They'll be deep cycle batteries (leisure batteries) but they're still vulnerable to overly rapid charging. 60v charging into 48v nominal batteries without current control is a disaster waiting to happen.

For SLA avoid deep discharge. Charge with current limiting (slow). With a battery conditioner, some desulphurisation is achievable.

Correct charge state for long term storage of lead acid is 100% charged.

 

[Kaelidoz]

@okrobie This place is all about Electric MounTain Bike but I'm glad you still found some help.

Endless Sphere - Index page has a pretty neat section for electric scooters, you might find it useful!

 

[Beatn1K]

Nah....I think he's saying he wants to move to lithium ion batteries, having roasted his lead acid efforts, and asks after care advice...!

 

[okrobie]

You folks should really have a spelled out version of your acronym. I couldn't find it anywhere on this site. Thanks very much.But upon reflection, I should have recognized the MTB part because I used to be into MTB riding about 20 years ago. They have some great trails around the Brooksville and Gainesville here in Florida. I've also ridden Tsali up in NC. Now that is some challenging riding. I'm too old now. (77 my avitar is about 5 years old) That's why I'm migrating to E-cycles. I've been to Endless-Sphere but you guys (and gals?) had better battery advice than I got over there. I've got my eyes on a basket case where a guy is selling a junk frame with the kind of motor that you guys call "mid" in the bottom bracket He is selling it for less than $100 so I had better jump on it. It has no battery and no controller but those mid motors are pretty pricey. I haven't decided what kind of frame to put it into. I'm guessing that you guys are mostly using full suspension? But for the moment, I'm leaning more toward a beach cruiser with coaster brakes. (KISS) I got a nice Motobecane cruiser last week at a yard sale for $15. I'm eager to hear what kind of frames you guys favor. Thanks, Jim (I guess I'm a wee bit off topic) but I can start a new thread if you want. (But lets try to wrap it up before anyone notices. ) Regards, Jim

 

[okrobie]

Hey, I'm missing a post here somewhere. It either disappeared or I wrote it and didn't post it. I wanted to thank Kaelidoz and Beatni1k for their posts. Beatn1k, you put into one sentence what I was trying to say in my opener ramblings. Thanks.

 

[FlimFlam]

They don't do specifics lol


Exactly right. Think of 50% literally as happy medium where cells are happiest. Very easy to do OTOH no big deal if you charge to 100% and leave it for a month until the rain stops - just be prepared for increased cell degradation & lower calendar life expectancy.

Wow - thanks for this. Now I am scared, I have been storing my 500Wh battery indoors at 100% for a few weeks now due to storm front after storm front, flooding, utilities outages etc... Does anyone have any data in regards of degradation over time? Graph or something?

I have only had the bike 4 months and always ride the battery till empty (5% / 6% left in battery usually) then I always fully charge the battery when I get home but then it may sit for a week (this time it is going to be 3 weeks between rides). I am probably being overly concerned but if i can get it right from now on I know they will last longer.

Thanks in advance!

 

[Kaelidoz]

@FlimFlam Don't sweat it man they were made to be used like that. BUT if you have the possibility to charge it before it drops so low, and/or only charge it up to 70-80% if you don't need a full charge then that'd be good for your battery.

If you need/want to drain all the battery in one long ride then by all means keep doing it and enjoy your bike, that's the most important.