E-ODIN - Diskussionsthread

[bob2.0]

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I thought the BMS could shut off an over-voltage/over-charge scenario.
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Yes, why shouldn't it?

Well, there would be transistors (presumably) in the circuit, and those would be current limited.

So, there would be transistors going in on the charge port, and transistors coming out on the battery power terminals. And I would presume they would be cost-down so that the transistors on the charge circuit would not be particularly large?

That's why I though charging was current-limited, so that the current does not exceed the input transistors in the BMS on the charging circuit (so that it can cut them off, if it needs to)?

[bob2.0]

I measured the cable cross-section for the charging port, it is approximately 4 mm². So the charging port ist fit for about 40A.
This aligns with the types of chargers that DAYI previously offered: the standard 10A charger (which is included with the bike), a 25A model, and even a 40A model.
However, as far as I recall, the 40A model was subsequently discontinued.

I am being offered (24h offer) a 20% discount on Aliexpress, so I am pondering getting one of these.

I am still wary of overloading the charger circuit, but if you say 25A was once an optional charger (not withdrawn), then I guess I have to trust that the BMS protection transistors are at least rated (as you say, maybe 40A rated, but pushing them?).

So, 24h to decide on the saving.

There is a specific benefit/need. I have an 80 mile trip I do on this bike regularly, and I stay overnight or linger to charge up, but doing the round trip in one day is not practical with anything less than a 20A charger.

[jeff-jordan]

A charging current of 25 A is no problem. I have installed my 3.3 kW charger in the right-hand side case and use it regularly (twice a week). It charges at up to 40 A.

[bob2.0]

This charger have no Bluetooth, only wifi. I wrote with Google's ki an esp8266 Code that bring the data to our home wifi Network.
Lowest Current are 3A, it goes lower if the battery are almost full.

You are right and my reference to bluetooth earlier was wrong. Sorry. It seems it was just the person showing what their battery was doing, when charging.

[bob2.0]

A charging current of 25 A is no problem. I have installed my 3.3 kW charger in the right-hand side case and use it regularly (twice a week). It charges at up to 40 A.

Thanks for that.

I looked for a 25A but found a new listing for a 20A, 10V-93V charger that was a bit of a no brainer at the price.

Maybe that is a price someone here likes, too. Here is the link if anyone is interested; https://www.aliexpress.com/item/1005005366012024.html

I missed the £9 off voucher (they offer a certain number of vouchers, and you have to use them before anyone else) but got a £4 off, and then I got the 20% cashback (that prompted me to go looking today). So, it was about £65 to me .... assuming it arrives, working.

I was not sure if the option list was the connector on the unit, or on the end of an extension lead. Either way, XC60 works for me, I have spare plugs I can make up any options I want.

My XLR socket I installed as the daily charger port (see link in last page) are usually rated for 15A though the one I bought says 20A. I'll begin with 12A charges and increment slowly, check everything works OK, see if anything warms up too much.

[bob2.0]

This arrived yesterday.

9 days from China ...... far too long .... should have only take 3!

Anyway, now I have to figure how to best use this.

The 'easy plug' I put in is rated for 15~20A so would be maxed at 20A, and the wiring from that plug is not 20A but I can uprate that.

However, I am thinking that perhaps instead I begin installing a new setup. I would value your thoughts and knowledge.

I am thinking of a connection direct to the power terminals on the inverter to a cable and plug that emerges in my top box.

It would not be quite direct but via an 'ideal' active diode, blocking any reverse current out of the battery.

My thinking is that I can then sit this charger in the top box (opened when charging) and it can deliver 20A direct to the battery, not via the BMS.

Should I have any concerns about charging the battery that way? Is the BMS really such an important safety feature in this setup? (Maybe it is)

My motivation to do it this way is that I can then rig up my two 36V packs I have for an e-pedal-bike that I have, for an extra 10 miles or so of range. I just have to plug them in, providing they are less voltage than the main battery, so they will start delivering/sharing current for the motor once the main battery voltage drops below them.

[bob2.0]

Hang on, am I being totally stupid?

Are the charger port terminals already connected directly to the inverter terminals?

So, charging into the inverter terminals is already into the BMS?

[bob2.0]

I've now made up a lead with an 'ideal diode' and run it up to 20A. The charger starts getting warm, even the (substantial) mains power lead.

But the lead I made up seems fine. The ideal diode has a little heat sink. I put heat shrink over it, and then cut out a little window for the heat sink to vent. It was barely detectably warm at 15A, but it was warm (not hot) at 20A.

The whole of the ideal diode board warms up at 20A (I guess did not help wrapping in heat shrink) but just 30~40C. There does not seem to be any hotspots at where I soldered the 4mm^2 cable to it, I think it is the board itself, and the cables draw heat out of it.

I tested the lead on a lead acid battery (as the voltage can be set down to 10V) and tried short circuiting it (on the far side of the diode). It's fine. It seems 'safe' as a way to stop battery voltage getting out but letting voltage in.

Part of my plan is also to use this lead to set up a couple of 36V lithium packs I have, in series. These should add 15Ah or so of extra capacity for an additional ~6kg in my top box.

I'll run longer tests at 15A and 20A later, but it doesn't need charging atm. It seems OK.