Low cost eZee battery chargers

[flecc]

If anyone wants one of the li-ion chargers used by eZee and wants to avoid the current £95, one ebay seller has 10 of that type apparently complete with the correct XLR connector for the battery. They are priced at £42.99 plus £6.99 P & P via Parcelforce:

Li-ion chargers on ebay

Check the connector with the seller though, since they say the illustration is of the lead acid variant. The XLR connectors are available from Maplin if that had to be changed.
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[torrent99]

If anyone wants one of the li-ion chargers used by eZee and wants to avoid the current £95, one ebay seller has 10 of that type apparently complete with the correct XLR connector for the battery. They are priced at £42.99 plus £6.99 P & P via Parcelforce:

Li-ion chargers on ebay

Check the connector with the seller though, since they say the illustration is of the lead acid variant. The XLR connectors are available from Maplin if that had to be changed.
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The seller is a bit confused about the spec though:
First he says: High Power 36 Volt 3 amp Li-ion Battery Charger
Then: Output: ( 36 VCD, 42.2 V -- 2.5 / 1.5A

And apparently input is in the MHz!

Good deal though.

BTW what makes these different from a constant voltage Lead Acid charger?
I thought that so long as you supply the correct voltage, the BMS does all the clever stuff?


I notice he also has AMG type lead acid batteries i.e. the type intended for EV use.

 

[flecc]

Yes, the BMS does the management of the li-ion charge, though the charger needs to sense the full charge cutoff and change it's charge and indicator LED state accordingly. Maybe SLAs read differently from the charger's point of view.
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[rog_london]

Yes, the BMS does the management of the li-ion charge, though the charger needs to sense the full charge cutoff and change it's charge and indicator LED state accordingly. Maybe SLAs read differently from the charger's point of view.
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They certainly do. A Li-Ion charger for a 37V battery just puts out about 42V and usually current limits to whatever its rating is. The battery's BMS does everything else within that limit.

In order to indicate 'full' a Li-Ion charger just needs to sense the sudden sharp drop in charging current when the BMS detects that the battery has had enough. I haven't done any specific checks but I suspect that a much reduced charging current may flow for a while after that to allow for cell equalisation, etc,

If you plug a Wisper Li-Ion charger in to the mains and switch it on with no battery connected, you get a green light right away. It doesn't know whether a battery is connected or not, and just sees that no current flows, therefore the battery is full as far as it can tell.

SLAs have no built-in management system. You can charge those with a constant-voltage charger which also current limits to prevent itself being overloaded by a flat battery. The usual voltage to achieve a full charge without over-charging an SLA is around 13.5-14 volts per 12 volt battery.

As the battery reaches full charge its terminal voltage rises and the charging current automatically drops to a few milliamps, so it's self-controlling, and leaving the battery connected for a while after this point is reached does a good job of equalizing the cells.

It's an interesting coincidence that the constant-voltage charging requirement for a 36V SLA is also about 42V (3 x 14V) so quite likely the SLA version of the charger mentioned is very little different to the Li-Ion version, except possibly in the circuit for detecting a full charge, since an SLA's charging current tails off over time.

There are more sophisticated ways to charge SLAs - if anyone is interested, I'd be happy to elaborate in 'The Charging Post'!

Rog.

 

[mikescave]

To by or not to buy

I started this somewhat circular thread so am very grateful to Flecc for finding this remarkably cheap source of chargers - and yes the conectors seem the same; they're effectively only two pin anyway.

But being both cautious and desperate I bought a new charger from Cyclepoint - costing £125! ex postage.
However, in view of all the comment here is it worth investing in a 'spare' at the Ebay price quoted? Realistically, how long should a charger last?

Regards to all

Mike

 

[flecc]

I think it's worth going without another one as normally these HP chargers last longer than the bikes Mike. There was just the one batch of HP chargers which developed zener diode faults, but that was the only incidence I've known of with these.

Some other makes haven't been anywhere near as good though.
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[tony18m2001]

cheap NiMH charger plus Cycle Analyst computer

Slightly off topic - move to different thread if you think fit.
I have been using by old Li-ion charger for a year or so to charge a NimH battery on my Ezee Cadence with occasional full top ups from a separate power supply. I was recently doing a web search and found a Canadian company The Renaissance Bicycle Company ( www.ebikes.ca Homepage of the revolution )
who sell very cheap chargers:
Elegance CG362Ni-EL 2A NiCd/NiMH charger
It comes with the correct plug for the Ezee battery and the thermistor spec is correct. It has universal mains i/p and comes with a US plug which I cut off to fit a normal English 13A. It does pulse charging and measures the battery voltage correctly when charging. Trickle charges after peak voltage/temperature detect. Best thing is the price - only 45 USD. They also sell a power monitoring box called the Cycle Analyst - this is just the sort of thing I wanted to design for my Cadence but had never found the time to do, so I bought one - 140 USD. They only charged 25 USD for the p&p for both - the charger is in a light weight plastic case which helps keep shipping costs down. The service from the company was excellent - thoroughly recommend them.
I am fitting the Cycle Analyst this Easter and taking photos if anyone might be interested - involves connecting a high power shunt in series with the battery negative lead, so turning the bike upside down and much burrowing by the side of the chainwheel is involved.
Tony

 

[flecc]

Thanks for that Tony. We know ebikes.ca well and the CycleAnalyst, it was formerly marketed as the DrainBrain, and a number of members use them as well as A to B magazine in their e-bike testing. Useful but expensive, though there is a cheaper alternative called the WattsUp, not as good though.

That charger is an excellent price, lets hope it holds past through the current exchange rates mess. A lot better than the official £125 one at present, so a great tip.

(Word of warning for others, although the Li-ion charger can be safely used on the NiMh battery for a part charge, never try to use an NiMh charger on a Li-ion battery since it has much higher voltages. In most cases they'd refuse to work anyway, but better safe than sorry).
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[tony18m2001]

Power meters and Ezee Over-Voltage

Thanks Flecc for the link to the WattsUp meter - its certainly cheaper than the CycleAnalyst, but doesnt have the odometer input and handlebar mount.
On the subject of NimH batteries and the Ezee - do you know how to adjust the over-voltage trip on the Ezee controller? - I find that I have to remember to disconnect my new charger an hour or more before I use the bike else the volts are too high - have to ride with the lights on for some time before I can get the motor to go. Are the NimH and Li-ion motor controllers set differently?

Tony

 

[flecc]

I don't know how to adjust that Tony, or even if adjustment is possible. They are the same for both battery types, the controller not altered when the Li-ion battery was introduced. The cutoff is normally at 44 volts, plus or minus about half a volt.

I'm surprised that yours operates that cutoff if it's a standard 30 cell battery since they don't usually charge quite that high, unless you are trying to use the battery when hot off the charge with a charger that's going a bit too far before cutting out.
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[tony18m2001]

NiMH charging voltage

I don't know how to adjust that Tony, or even if adjustment is possible. They are the same for both battery types, the controller not altered when the Li-ion battery was introduced. The cutoff is normally at 44 volts, plus or minus about half a volt.

I'm surprised that yours operates that cutoff if it's a standard 30 cell battery since they don't usually charge quite that high, unless you are trying to use the battery when hot off the charge with a charger that's going a bit too far before cutting out.
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Well - the battery was once yours, Flecc, so you might know if it had been modified
Peak voltage at cut-off on my new charger is 45.5V with drop off to around 43.5 when the temperature stabilises. This is around the same voltage as I got with previous charging regimes. So I guess my Ezee Cadence controller max volts is set on the 44-0.5 volts side. If anyone else is looking at this thread who might have any inside info on hacking the controller to change this voltage - please reply or PM. Could also be useful if one wanted to add a couple of cells for a small boost.
Tony

 

[flecc]

No, it wasn't modified.

Your charger is behaving exactly as it should and as mine does, so I can't imagine it's going very high above the Cadence setting. The lights will only discharge the battery at a a tiny rate but if you rig a discharger with some high wattage resistors you could correct the discrepancy. I made one for my radical extra-celled battery so I could use it in my Q bike which also has a 43.5 volt cutoff.

I just rigged 10 ceramic resistors that I already had onto a paxolin strip in parallel, the values were 220 Ohms 7 Watt, with an XLR connector to plug into the charger point on the battery. It gets a bit hot since the values aren't ideal, but it drops the voltage a bit in just a minute or two, and for you it would probably work enough in seconds since you'll only be dropping a fraction of a volt.

These were the ones I had, code L220R
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