Group charger for 3-6 batteries?

General Discussion about electric bicycles.
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phidauex   10 µW

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Group charger for 3-6 batteries?

Post by phidauex » Aug 24 2019 1:40pm

My office recently added a lot of indoor bike parking, which has spawned a big increase in bicycle commuting (great!), and the number of ebikes is going up as well (2 now, and 3 more people are shopping regularly).

Instead of having power strips with tons of individual chargers dangling off them messily, are there any options out there for multi-battery chargers that support multiple voltages? Perhaps ones that would support a rental fleet? If there was a clean practical option we'd spend some real money on it, but it would have to be easy to use and look good in an office.

Thoughts or recommendations?

flat tire   1 MW

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Re: Group charger for 3-6 batteries?

Post by flat tire » Aug 24 2019 2:05pm

The problem is ebikes are like assholes and all have different chargers so the best you can do is provide a bunch of 110 outlets on separate breakers.

john61ct   1 MW

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Re: Group charger for 3-6 batteries?

Post by john61ct » Aug 24 2019 2:33pm

Yes, each owner most likely will need their own different voltage output.

Something like a Grin Satiator would cover a wide range, if you want to provide a subsidy / incentive, about $300 each.

Otherwise just provide mains plugs.

Best if the 120Vac plugs each are on their own 2A circuit,

And if you can, also include some 240V @ 30A or 50A too for future proofing, like drier/oven plugs.

markz   100 GW

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Re: Group charger for 3-6 batteries?

Post by markz » Aug 24 2019 7:00pm

The problem is there is a wide variety of charger connectors.
The store bought ebikes would each have their own "proprietary" connector.
Then there are the DIY'ers that would have XT90 connectors, or XT60, or Anderson Powerpoles, or XLR connector, or 4mm bullet connectors, or 5mm/5.5mm/6mm/8mm bullet connectors, or or or or or or or........................


Then what if someone wants 20A on 120VAC outlet, probably trip the breaker then everyones SOL.

Maybe think about lockers with an outlet inside the locker, that is on its own circuit. Then people can bring their own charger, plug it in and lock it out. Have the lockers on the wall, and the bike rack on that same wall so people dont fall over cords.

https://www.lockers.com/metal-lockers/v ... l-lockers/

Horizontal wall lockers would be better.
https://www.schoollockers.com/lockers/t ... ckers.html

Plastic is better!
Molded Plastic Six Tier Lockers with Clear Doors 12" wide x 15" deep x 72" high
https://www.schoollockers.com/metal-loc ... doors.html
https://www.kingfisherdirect.co.uk/small-plastic-locker

john61ct   1 MW

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Re: Group charger for 3-6 batteries?

Post by john61ct » Aug 24 2019 8:07pm

Connectors issue easily solved

Adopt a Rosetta Stone standard e.g. Anderson PowerPole

and get a bunch of adapters made up

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wturber   1 MW

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Re: Group charger for 3-6 batteries?

Post by wturber » Aug 24 2019 8:51pm

john61ct wrote:
Aug 24 2019 8:07pm
Connectors issue easily solved

Adopt a Rosetta Stone standard e.g. Anderson PowerPole

and get a bunch of adapters made up
So now you only have to concern yourself with four of five different DC voltages ( 36, 48 and 52 as well as maybe 24 and 72) and some way of monitoring charge rate and level for proprietary and home built.

There is a universal standard already, and that is the standard AC outlet. If people want to charge, they should just bring a charger. That's the way I have my bike set up. Charger is integrated and I can just plug into AC and I'm good to go.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

Grantmac   10 kW

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Re: Group charger for 3-6 batteries?

Post by Grantmac » Aug 24 2019 10:25pm

Lockers with AC power and solid enough construction to withstand a battery fire.

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amberwolf   100 GW

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Re: Group charger for 3-6 batteries?

Post by amberwolf » Aug 24 2019 11:05pm

The issue not addressed is that the OP is apparently asking for a single charger to charge multiple batteries at the same time.

This isn't impossible, even with a standard charger, but will only work with batteries that have the same number of cells and are at the same state of charge when hooked up.

And because there's no way to guarantee people hook the right battery up to the right charger, the risk of fire is significant for any non-BMS'd battery, or any with a problem in the BMS.

Large power-dissipating heatsinked diodes on every output connector can help with the differences in state of charge, but wastes significant power. Also, the majority of current will always be pullled by the lowest state of charge battery.

If the charger is capable of significantly higher current than the battery or it's BMS were designed for, another risk of fire exists.

If a charger is setup for 14s (52v), and someone plugs a 13s (48v) battery to it, it's going to overcharge that battery, unless the pack's BMS cuts off the input. No BMS, no cutoff, cells overcharge. Not so bad with the 13s battery. But plug a 10s (36v) battery in there, and the overcharge could be severe enough to cause a fire.

There are other issues as well.

But basically, without a special charger that can control each output individually (essentially a bunch of separate chargers all within one box), *and* special connectors on every battery that fit only the right voltage for that battery, there's no good safe way to do this. :(

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amberwolf   100 GW

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Re: Group charger for 3-6 batteries?

Post by amberwolf » Aug 24 2019 11:20pm

Now, there are adjustable-voltage single-battery chargers, such as the (expensive, but worth it if you need it's abilities) Cycle Satiator, which can have up to 8 profiles preset in there, and there are a bunch of adapters on the Grin Tech http://ebikes.ca site for that to plug into the most common battery connectors.

However, the right profile must be manually chosen by the person plugging in the battery, before they start charging. It must be the right voltage *and* the right current for that specific battery. Most people won't have any idea which profile to choose, and picking the wrong one could lead to battery damage, and potentially fire, if not now, eventually.


It's probably a lot safer for people to bring their own chargers that are specific to their batteries.


But...the risk of fire due to a failed battery or charger (or a mixup of two similar looking chargers with very different outputs) still exists, with that many batteries charging in one place, it's multiplied by the number of batteries and chargers at a time, and the amount of time they're charging, and the number of times (days) they are all together, etc. The single risk is low...but the more there are the more it's multiplied.

So...I'd recommend some sort of "charging locker" for each charger and battery, that's vented to the outside, and flameproofed so any fire that does happen is contained to the single battery/charger that's involved.

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amberwolf   100 GW

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Re: Group charger for 3-6 batteries?

Post by amberwolf » Aug 24 2019 11:38pm

Now, *IF* everyone that charges there is guaranteed to know details about their battery like charging rate (amps) and final charge voltage (and/or number of series cells / chemistry and appropriate per-cell voltages), then you could use a "common charger" that people could set to their battery when they use it, or a set of common chargers for various voltages and currents.

But just one person that didn't know could blow stuff up (say, hooking a 72v battery to a 36v charger) or cause a fire.

That still doesn't allow the use of a multi-battery charger setup, where one charger charges several of the same voltage battery, unless they are all identical batteries (because of the current (amps) rate).


So... *IF* everyone had the *same* battery, that could tolerate high charging rates, then you could use a single multi-output charger (with power diodes on each output port), like a sealed/fanless Meanwell HLG or ELG / etc series LED PSU set to max current output that one pack could handle, and hten that current would be divided among all the packs hooked up to it.

(the reason for sealed/fanless is so that there's no fan to fail and allow a charger to overheat and fail or catch fire. Also cant' be damaged by having someone spill their drink on them, etc).

john61ct   1 MW

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Re: Group charger for 3-6 batteries?

Post by john61ct » Aug 25 2019 12:39am

I was not saying the original OP idea was workable, just that connectors aren't a significant issue.

I agree too much liability to get too involved.

Simply providing AC power as I outlined, and offering a Grin Satiator as a reward / benefit / incentive, becomes the employee's property, along with an appropriately fire-safe location with lockers,

is I think a good solution, without the company taking on too much responsibility.

RunForTheHills   100 W

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Re: Group charger for 3-6 batteries?

Post by RunForTheHills » Aug 25 2019 10:01am

Maybe something like this would work:

https://www.store-batteries.com/
Image

markz   100 GW

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Re: Group charger for 3-6 batteries?

Post by markz » Aug 25 2019 12:59pm

People that buy an ebike or build their own ebike already have a charger.
Those people can bring their own charger, plug it in to an outlet and lock it up in a plastic locker.
Then there's no one to blame but them.

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Re: Group charger for 3-6 batteries?

Post by john61ct » Aug 25 2019 1:11pm

If I worked for a company that would **give** me a $300 Satiator as an incentive to get an eBike, that would both be motivating, and reflect very well on the employer.

And I would not need to buy one.

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