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Charging issues with paralell batteries


Oily

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Hi guys,

I've managed to get twin 132wh batteries (almost a 16sp2, but with 2 BMS's) hanging off 1 side of my EUC - well enough that the cover still fits with longer screws, with a 1cm gap all the way round.  I still need to go for a test ride - but standing on it in the house (all wired up & turned on), I think it'll work....

My question though is charging - I've got 2 sets of charging wires coming off the 3 pin port - when I have either battery connected, it works fine & charges normally. But when I have them both connected, as soon as the charger is plugged in (with no kettle lead, so no mains power at all), the charging light comes on to say the battery is fully charged ?

Is this just because there is now twice the wh, or does this mean something more worrying ?

Thanks

Olly
 

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no idea why the light turns on, it shouldn't be the case. you sure the batteries are wired in parallel? what you should be super careful about though is this 1cm gap ! you really, really shouldn't put any mechanical pressure on your battery pack or take any risks of water splashing in and causing a short circuit (you know, it can cause a fire that can't be extinguished until it burns out)

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The discharge is wired with a parallel connector I got online.

The charging just has 2 wires coming off each of the 2 charging posts on the main charge point.

The 1cm gap won't be being left open - I'll do a test ride with it covered in duck tape, but will then fill with either silicone or a new home made fibreglass cover.

Although this is only to tide me over until I have the funds for a 25kmh+ wheel...

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Both were fully charged on Thursday so should still be fine.

Haven't dared try - just incase its the sign of something bad! :)

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does the charger light switch on like this in a normal case, i.e. when one fully charged battery is connected without the charger plugged into mains?

well, if I were you I would try charging with one battery connected, then with the other, and then with both. but then, I can't check your wiring, and I'm not a battery expert, so don't hold me responsible if something blows up .')

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Each battery charges fine when plugged in with the other unplugged.....

I guess it's time to run an extension lead outside, plug them both in & see what happens ! :blink:

I'll save that for tomorrow !

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There are several ways to charge for additional battery pack.

1. Charge separately and not at the same time
pros: only one charger is needed 
cons: have to manually change charge port(as a matter of fact, no need to change, because below); 
charge thr discharge port(of the other pack, no charge protection for that);
need to hide the charge plug of the new pack when riding.

2. Charge separately and not at the same time
Need disconnect the Y-connector of the discharge before charge
pros: only one charger is needed 
cons: have to manually disconnect the discharge connector every time; large charge current(may exceed the standard charge current of the batteries).

3. Charge separately but at the same time
pros: fast charge(as it takes less time)
cons: need two chargers; large charge current(may exceed the standard charge current of the batteries).

4. Charge thr original charge port only
Need the charge wires also connected by a Y-connector permanently.
pros: normal charge(normally a 2A charger is best suited to a 2-paralleled)
cons: there is a very very small chance that parallel connection of two charge port may not working(not working for protection, but still working for charging).

5. Charge thr a DIY(or purchased, if u can find) Y-connector of GX16
Need a Y-connector of GX16, plug into original and new charge port before charge
pros and cons: same as above(point 4). 
Y-GX16.thumb.jpg.e1d85a8173e57bbeea131c4

Btw, the charger's light will be turned on(normally green in most cases) if the output plug is connected to a voltage(say 50V to 67V) without plugging it into the mains. This normal and it is not the indication of charge complete or being charging. 
 

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I couldnt really understand how you have the batteries connected. Maybe you can post a pic?

You should have both charge and discharge wires connected in paralell.

If you connect only discharge wires in paralell then you will be charging one of the batteries through the discharge wires therefore bypassing the BMS with all the risks that involve...

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