Lithium battery upgrade for mobility scooter

General Discussion about large electric scooters and motorcycles and other things with no pedals.
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Diamondback   10 kW

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Lithium battery upgrade for mobility scooter

Post by Diamondback » Nov 01 2019 8:53pm

Hi all.

It’s been quite some time since I posted anything in the forum. Life kinda got In the way.

My father (79) has a few health issues and few years ago I bought him a scooter. It’s a 3 wheeler. It has 2x12v sla 28ah (supposedly 28ah) batteries in Series for 24v.

The lead is not giving anything like the range it used to. And it’s taking ages to charge. So I’ve ordered a 24v 30ah ping battery and charger combo for it.

That part I’m good with.

I have a quick question about the bms and cooling for it when charging. The pack will be mounted inside a plastic tub under the seat of the scooter without much airflow.

I want to hook up a 24v fan that will automatically turn o. When the charger is plugged in and stop when unplugged.

Does anyone know if I can just tap off the wires going from the charger to the BMS to power the fan ?
Or would this just back feed the fan off the battery when the charger is unplugged?

As this is for an older man, who has health issues, I need it to be fully plug and forget. No switches to remember to turn on or off.

Could I run a diode to stop power back feeding the fan from the battery ?

I’m still waiting for the battery to arrive , after stupid customs sent it back to China. With no reason given.




Jason.
Ignorance can be solved, stupid is forever

dustNbone   10 kW

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Re: Lithium battery upgrade for mobility scooter

Post by dustNbone » Nov 02 2019 12:07am

Generally yes, the BMS will feed power back through the charging connector, some designs actually have them directly connected together.

Depending on the rate of charge, you might not need to worry about cooling at all, I'd say 5 or 6A would be totally OK.

The simplest solution, that would also cover cooling while discharging, would be a thermostat set to turn the fan on at say 100F. Should be fairly easy to come by in 24V, sounds like the kind of thing that might be found on a commercial truck.

Diamondback   10 kW

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Re: Lithium battery upgrade for mobility scooter

Post by Diamondback » Nov 02 2019 12:30am

A thermo switch hadn’t really occurred to me. , but given where we are, summer often sees days much hotter than 30°c so would have to be careful that a temp switch doesn’t drain a parked up battery either.


The charger we have coming is a 4A unit.
And the scooter is only 400W brushless dc.
So not too high powered.

Jason
Ignorance can be solved, stupid is forever

dustNbone   10 kW

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Re: Lithium battery upgrade for mobility scooter

Post by dustNbone » Nov 02 2019 3:58am

Given the size of the battery and the very low amount of current you're asking it to handle I don't think you'll have much to worry about even without active cooling.

Another way to tackle it might be using a 4 pin connector set for the charger, with 2 of the pins on the scooter side going to the fan. You'd bridge the 2 sets in the charger side plug, so the fan would be connected only when the plug was inserted.

Diamondback   10 kW

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Joined: Dec 15 2008 3:52am
Location: Sydney, Australia

Re: Lithium battery upgrade for mobility scooter

Post by Diamondback » Nov 02 2019 4:58am

Thanks.

I like the 4 pin idea.

Edit. Thinking about it, I should be able to achieve this using the current 3 pin xlr charge plug it has now.

The negative side of the fan can run to the battery charger directly (scooter side) and the positive line in the charger side plug can be bridged to the 3rd (currently unused) pin.
Then run the fan positive wire to the 3rd pin scooter side.

Thanks heaps for the idea. I know that given the lower power requirements, both charge and discharge, the fan is probably overkill. But I just want to make absolutely certain that I don’t have any heating issues.

Thanks again.

Here’s a pic of the scooter and it’s owner.
6DEB9F0D-0054-4BBB-9DC5-3D24EA09DD5E.jpeg
6DEB9F0D-0054-4BBB-9DC5-3D24EA09DD5E.jpeg (182.77 KiB) Viewed 202 times
Jason.
Ignorance can be solved, stupid is forever

dustNbone   10 kW

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Re: Lithium battery upgrade for mobility scooter

Post by dustNbone » Nov 02 2019 6:45am

You're right, 3 pins is enough, I should really sleep one of these nights.

The logical next step after improving battery cooling is to make it go much faster.

Diamondback   10 kW

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Re: Lithium battery upgrade for mobility scooter

Post by Diamondback » Nov 02 2019 7:59am

Not with the way he drives already. Lol.

I could hide a “turbo” button somewhere though ;)

Jason.
Ignorance can be solved, stupid is forever

AussieRider   100 W

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Re: Lithium battery upgrade for mobility scooter

Post by AussieRider » Nov 05 2019 3:23am

G'day boys & girls.
First, here's something you might consider.
One of reasons mobility scooters use lead acid batteries is all that weight down low helps stability.
'nother thing you should know. The XLR charge socket uses the third pin ( green wire ) as an inhibit signal so the scooter can't be driven if the charger is plugged in.
You might want to look into "Fusion" LiFe batteries. They're signed as drop in replacement for SLA, are the same size & shape & the BMS can even use an SLA charger though I'd recommend getting a 8A unit.
Good luck!

AussieRider
Evolving E-bike
Retro style mid drive beach cruiser
Mid drive chopper
EVT 168 scooter

Diamondback   10 kW

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Posts: 530
Joined: Dec 15 2008 3:52am
Location: Sydney, Australia

Re: Lithium battery upgrade for mobility scooter

Post by Diamondback » Nov 08 2019 10:47pm

I didn’t know about the drop in option. I’ve already ordered the ping battery. So have to make that work.

This particular scooter only uses the 2 pins on the xlr plug.
It’s a cheap Chinese import. (Cheap is relative when it comes to mobility scooters)

Good point about the weight. Hadn’t considered that.
Might have to add extra to compensate. Last thing I need is for him to tip it over.

I will post a few pics after the battery is finally installed.


Jason.
Ignorance can be solved, stupid is forever

AussieRider   100 W

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Joined: Jul 30 2010 9:03pm
Location: Seaford, Australia

Re: Lithium battery upgrade for mobility scooter

Post by AussieRider » Nov 09 2019 9:18am

Hey DB.
Standard mobility chargers have the third pin ( ie, inhibit ) shorted to positive in the plug. If your XLR charge socket has 3 pins, you could do the same thing & power the fan from the middle pin whenever the charger is connected.
I used 4 Fusion batts in my EVT 168 with limited success. Charges ok from the OEM SLA charger & doubled my range but limited acceleration because the BMS only allows 10a continued with 80a burst for 10 seconds. Not enough with a 1400w motor / 120a controller combo. Take it easy & it's ok but punch it & one of the batts shut down for a minute.
Evolving E-bike
Retro style mid drive beach cruiser
Mid drive chopper
EVT 168 scooter

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