Is it OK to replace 40ah scooter batteries with 35ah?

Batteries, Chargers, and Battery Management Systems.
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Is it OK to replace 40ah scooter batteries with 35ah?

Post by Windmaker » Sat Oct 21, 2017 12:40 am

My neighbor has a Pride Victory Sport 4 wheel mobility scooter that needs some new batteries. His original batteries are (2) 12v 40ah (AGM/SLA), but in attempting to shop for him online I see that the prices are much lower for 35ah batteries, and they quite often claim to be replacement for 40ah batteries.

The simple question ....would it cause any significant loss of performance or cause any type of harm if he replaced his 40ah batteries with the 35ah (AGM) units?

Thanks for looking in any case!

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by fechter » Sat Oct 21, 2017 1:01 am

It should be fine. The Ahr ratings for lead acid batteries are not very realistic under normal load conditions anyway. You might get slightly less range, but I don't see any other issues. It's probably more important that they fit physically and the terminals are in the right locations.
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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by redilast » Sat Oct 21, 2017 1:18 am

Internal resistance is more important, because that generally dictates if the cell or battery can handle the same load as the other one. Some lead acid batteries used at heavy loads actually can have 1/2 their Ah capacity, its insane.

If there is a datasheet or something for the batteries try to compare the internal resistance between the 40Ah setup and the 35Ah setup.

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by dogman dan » Sat Oct 21, 2017 5:52 am

As long as the new 35 ah cells are rated for EV use, it will be ok. Slightly less range, but generally a mobility scoot gets to recharge plenty often, and range is not a big issue.

Cheap batteries will be much lighter, thinner lead plates, and not able to recharge as many cycles. Look at weights, if the new batts are more than 5 ah worth lighter, then the lead is not in them. You do NOT want to buy a mower starter battery that weighs half what your old ones did.

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by SlowCo » Sat Oct 21, 2017 6:01 am

If I'm correct you need deep cycle batteries for a mobility scooter. I don't know where you're located or what budget/price range your looking in but these seem reasonably priced:
https://www.amazon.com/Cycle-Battery-So ... deep+cycle

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by Sunder » Sat Oct 21, 2017 6:02 am

Any reason why you wouldn't just buy a 24v 20Ah LiFePo4 battery? Just as safe, if not safer - no gassing, no acid, no chance of fire. You'd probably get just as much range, and it will last 4-10x more cycles for around double the cost. Hurts up front, but by the 2nd year, you'd appreciate not having degraded performance, and by the 3rd year, you'll appreciate not replacing them again.
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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by Windmaker » Sat Oct 21, 2017 10:03 am

fechter wrote:It should be fine. The Ahr ratings for lead acid batteries are not very realistic under normal load conditions anyway. You might get slightly less range, but I don't see any other issues. It's probably more important that they fit physically and the terminals are in the right locations.
Thanks for the comment. Your reply was precisely what I thought the answer(s) would be.

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by Windmaker » Sat Oct 21, 2017 10:05 am

redilast wrote:Internal resistance is more important, because that generally dictates if the cell or battery can handle the same load as the other one. Some lead acid batteries used at heavy loads actually can have 1/2 their Ah capacity, its insane.

If there is a datasheet or something for the batteries try to compare the internal resistance between the 40Ah setup and the 35Ah setup.
Sorry, but there are no data sheets for either the old batteries or the one's for sale, but thanks for your suggestion and the info as well.

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by Windmaker » Sat Oct 21, 2017 10:08 am

dogman dan wrote:As long as the new 35 ah cells are rated for EV use, it will be ok. Slightly less range, but generally a mobility scoot gets to recharge plenty often, and range is not a big issue.

Cheap batteries will be much lighter, thinner lead plates, and not able to recharge as many cycles. Look at weights, if the new batts are more than 5 ah worth lighter, then the lead is not in them. You do NOT want to buy a mower starter battery that weighs half what your old ones did.
Got it!.....Lower ah ratings, probably less lead and longevity (and range), and no batteries that aren't rated for EV's......Thanks so much

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by Ykick » Sat Oct 21, 2017 10:10 am

SLA capacity ratings when used for EV purposes should be divided in half. In other words, 40Ah labelled SLA capacity is only about 20Ah in the real world. That's why someone mentioned going to Lithium 20Ah and it would deliver the same range as the original 40Ah SLA.
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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by Windmaker » Sat Oct 21, 2017 10:11 am

SlowCo wrote:If I'm correct you need deep cycle batteries for a mobility scooter. I don't know where you're located or what budget/price range your looking in but these seem reasonably priced:
https://www.amazon.com/Cycle-Battery-So ... deep+cycle
You are correct. They should be deep cycle batteries. I am not buying them however, my neighbor is, so he'll have to decide what he's willing to pay.
Thanks for your link/suggestion as well. I'll be sure to show it to him.

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by Windmaker » Sat Oct 21, 2017 10:19 am

Sunder wrote:Any reason why you wouldn't just buy a 24v 20Ah LiFePo4 battery? Just as safe, if not safer - no gassing, no acid, no chance of fire. You'd probably get just as much range, and it will last 4-10x more cycles for around double the cost. Hurts up front, but by the 2nd year, you'd appreciate not having degraded performance, and by the 3rd year, you'll appreciate not replacing them again.
You know, this is a good point. I happen to have a three-wheeled (fast) mobility scooter myself, and I too will soon need to replace my four 12v 20ah batteries as well. The LifePo4 option is initially much more expensive, as you pointed out, but in the long run it may even be a bit less expensive. I'll certainly raise the option with my neighbor and let him see the costs of these types of batteries and chargers. I'm still a bit on the fence myself, but I'm definitely leaning towards the Lithiums for myself.

Thanks for your suggestion....it's appreciated.

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by Windmaker » Sat Oct 21, 2017 10:42 am

Ykick wrote:SLA capacity ratings when used for EV purposes should be divided in half. In other words, 40Ah labelled SLA capacity is only about 20Ah in the real world. That's why someone mentioned going to Lithium 20Ah and it would deliver the same range as the original 40Ah SLA.
Thanks for the info....

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by Chalo » Sat Oct 21, 2017 2:05 pm

Windmaker wrote:The LifePo4 option is initially much more expensive, as you pointed out, but in the long run it may even be a bit less expensive.
Or maybe a lot less expensive:
https://www.ebay.com/p/691372347

That's 12V x 110Ah for $120. Yes, it needs a BMS, but it would probably last longer than SLA even if you didn't use one, and even if you used an SLA charger for 4S cell groups. If you bothered to use BMS and a proper charger, the per-cycle cost would be hugely lower than any SLA pack.
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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by markz » Sat Oct 21, 2017 8:06 pm

ebay link is gone now, but whatever it was sounds like a steal if they are decent. If you did not snag them, then maybe some Hobbyking LiPo's would do, I just looked and I see 10S (~37V) 4Ah $70usd. NKON has 4.20V 3Ah cans for $2.50, so say 10S3P nets you 42V 9Ah for $75. But then you'd have to tab weld or solder them.

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by amberwolf » Sat Oct 21, 2017 8:13 pm

Something else to note is that a lighter battery pack (LiFePO4 vs SLA) of the same Wh would get you more range simply because you don't have to accelerate as much mass each time you stop and start (or go up a driveway, ramp, etc).

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by markz » Sat Oct 21, 2017 8:34 pm

Weight is def a factor. When I sold the last kit, the little dude was getting 40km when I'd only get 25-28km. I'd guess he is 150lbs at most, then x 2.5 = me!

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How essential is it to get ah rating the same as OEM?

Post by Windmaker » Mon Nov 06, 2017 3:51 pm

I have a 48v (4 x 12v 20 ah) SLA power bank for my three-wheeled electric mobility scooter (Chinese made, no brand). I think I'd like to get a LifePo4 battery at replacement time (which is getting close) and I would like to know if matching the 20 ah ampere of my existing system is essential. I see 10 ah, 12 ah, and 15 ah 48v LifePo4 batteries listed at a considerably lower cost. Would a 48v 15ah LifePo4 work almost as well as the 20 ah, for instance?

Also, I would appreciate some review comments on which brand of LifePo4 battery I should, or should not, purchase. I see a couple of "V-Power" brand 48v 20 ah batteries at auction on Ebay that look like they'll sell for considerably less than the usual retail prices. Would that brand cut the mustard? How about the "SUN" brand?

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Re: How essential is it to get ah rating the same as OEM?

Post by Windmaker » Mon Nov 06, 2017 9:52 pm

I owe this forum an apology..... :oops:

I just realized that I asked basically the same questions in a previous post that I asked in this post. The truth of the matter is that I'm 73 years old and the short term memory has gone to hell in a handbasket, so I had completely forgotten about the previous post. Please forgive my failing memory and I'll be sure to check previous posts the next time I have a question to make sure I haven't already submitted it earlier.

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by Dauntless » Mon Nov 06, 2017 11:19 pm

markz wrote:ebay link is gone now, but whatever it was sounds like a steal if they are decent. If you did not snag them, then maybe some Hobbyking LiPo's would do, I just looked and I see 10S (~37V) 4Ah $70usd. NKON has 4.20V 3Ah cans for $2.50, so say 10S3P nets you 42V 9Ah for $75. But then you'd have to tab weld or solder them.
There's more. https://www.ebay.com/i/351864366128?rt=nc

I wonder why these cost less. https://www.ebay.com/itm/NEW-Box-of-80- ... 1987482937

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by Windmaker » Tue Nov 07, 2017 10:52 am

Dauntless wrote:
markz wrote:ebay link is gone now, but whatever it was sounds like a steal if they are decent. If you did not snag them, then maybe some Hobbyking LiPo's would do, I just looked and I see 10S (~37V) 4Ah $70usd. NKON has 4.20V 3Ah cans for $2.50, so say 10S3P nets you 42V 9Ah for $75. But then you'd have to tab weld or solder them.
There's more. https://www.ebay.com/i/351864366128?rt=nc

I wonder why these cost less. https://www.ebay.com/itm/NEW-Box-of-80- ... 1987482937

Just remember you have a bit of a challenge putting it together.
Thanks for the suggestions....

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by 999zip999 » Tue Nov 07, 2017 3:55 pm

Make a battery out of leaf modules. Professionally made in steel case you just got to recreate some wires inside and still use the metal cases maybe four of them. I think they are 2s 2p and you just cut a couple wires and reroute them and you'll be able to have a 35 amp hour 14 volt battery. I think ? There are articles on Leaf modules and people doing them here on E.S.
Wonder want is the controllers range hvc and lvc. As sla 48volt is 54.4v and what 47volt or sagging sla 45volt ? Or does it have lvc ?
Or some other used option ? Do ditch the lead if money possible.

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by Windmaker » Tue Nov 07, 2017 4:55 pm

999zip999 wrote:Make a battery out of leaf modules. Professionally made in steel case you just got to recreate some wires inside and still use the metal cases maybe four of them. I think they are 2s 2p and you just cut a couple wires and reroute them and you'll be able to have a 35 amp hour 14 volt battery. I think ? There are articles on Leaf modules and people doing them here on E.S.
Wonder want is the controllers range hvc and lvc. As sla 48volt is 54.4v and what 47volt or sagging sla 45volt ? Or does it have lvc ?
Or some other used option ? Do ditch the lead if money possible.
Thanks for the recommendation, but your instructions are way over my head.

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by mark5 » Tue Nov 07, 2017 5:20 pm

He meant using part of a stack of these:

Leaf Cells in a Scooter by Benjamin Nelson
http://300mpg.org/2016/06/02/leaf-cells-in-a-scooter/

Installing Nissan Leaf Batteries in an Electric Scooter by Benjamin Nelson (length: 18m44s)
https://www.youtube.com/watch?v=pO08NL_J5vA


Nissan Leaf Lithium Module Conversion from 2S2P to 4S1P by qwqehwekrhlfjghdklfj (length: 27m54s)
https://www.youtube.com/watch?v=kAznO_p_rEY

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Re: Is it OK to replace 40ah scooter batteries with 35ah?

Post by Sunder » Tue Nov 07, 2017 6:29 pm

I think you might be thinking of the wrong type of scooter. Try one of these:

Image

Same concept though :P

I had considered a Leaf cell upgrade for my Vectrix - too hard and expensive to get Leaf cells in Australia. They're all over the shop in US though.
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