Fully charged but Amps is lowered when it accelerates

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techmind
Posts: 43
Joined: Thu Apr 04, 2013 6:14 pm

Fully charged but Amps is lowered when it accelerates

Postby techmind » Wed Dec 04, 2013 11:21 am

Hi,

This problem started one day with -5 C and same day i feelt the car was slower, got less hk than normal, but it did not 'chipper' amps that day.

Today the car was Fully charged but the Amps 'chipper' when i accelerates or drive up hill.

Current cuts down from about 220 Amps to about 140 amps and back again to 220 Amps

I think it's a bad cell, los wire somewhere or a defect in the bms

I placed a pricipal BMS to curtis schematic here i anyone can use it:

http://techmind.dk/citroen-c1-evie-elbil/erfaringer/elbiler-hugger-nar-den-skal-traekke/

Do any of you experienced this error?

Do any of you have some used space Tundersky cells for sale?
I need to find some way to extract data from the serial connector from the BMS also.


thanks, ;) michael

Grumpy-b
Posts: 991
Joined: Sat Dec 01, 2007 12:06 pm

Re: Fully charged but Amps is lowered when it accelerates

Postby Grumpy-b » Wed Dec 04, 2013 5:11 pm

That is what happens with a failed cell.
They really dont like cold weather. Especially charging at sub zero. In use take it gently for a few KMs after which the cells will have heated up. Charge immediately after using when the cells are warm. Dont wait to charge overnight, it will just get colder.
You will need to change this cell (or cells) as soon as possible.
Dont just unplug the BMS, see my previous posts about this. You will damage the BMS, dont think that turning off the 12v supply will work, it wont. Its not worth the chance of damaging the BMS. With the BMS unplugged you can follow the cell voltages around the pins of the plug, to isolate which cell is faulty, or just put a meter on the cells at the front and if they are OK then unfortunately the cell is in the rear. Dont just split the a battery pack, as if a cell is swolen once you undo the screws holding the straps, the pack will burst apart and it can do damage. To you!! So strap it and gently release.
SOftware for BMS has not been officially released by ECC because they are concerned with users changing parameters and rendering the car unusable.
I have previously offered to get a version written (I have an agreement with the original software supplier and ECC) that would allow down loads and clearing of the memory, but alas no takers.
Since yours probably hasnt had the BMS cleared in the last 6 months it wont be actually hold any data relating to the recent event. Once full it stops holding new data.
The cells are no longer generally available, as the format has changed slightly. I can supply new cells from stock but carriage may be a problem. PM me if you are interested.
WHat country are you located in?

Grumpy-b

mattcarr
Posts: 389
Joined: Sat May 12, 2007 2:27 pm
Location: Hampshire

Re: Fully charged but Amps is lowered when it accelerates

Postby mattcarr » Wed Dec 18, 2013 1:41 pm

Hi Michael,

This happens when the BMS tells the controller to reduce the power. When a cell goes below 2.5 volts it limited the power the controller can take, and when the cells goes back above 2.5 volts it lets the controller take full power. This happens lots of times and it can feel like the car is surging as the power levels change.

In the cold weather, the cells can get very cold if they are not used very often. I find in the winter that the whole battery pack seems weaker than in the summer.

How many KM's habe you covered in your car. I have now done 18000 miles in mine.

Regards

Matt

techmind
Posts: 43
Joined: Thu Apr 04, 2013 6:14 pm

Re: Fully charged but Amps is lowered when it accelerates

Postby techmind » Wed Dec 18, 2013 2:04 pm

hey, my car has run 8500 km, so it is a little to early to replace cells i think.

Yes i feels as someone holds the car back, also i discovered that the voltage go as low as 62 volt at this 'surging' feeling you describe.

;) michael

Grumpy-b
Posts: 991
Joined: Sat Dec 01, 2007 12:06 pm

Re: Fully charged but Amps is lowered when it accelerates

Postby Grumpy-b » Wed Dec 18, 2013 2:35 pm

If down to 62v and not too low a % charge (say 30 or 40%) then you have poor cells.
I have replaced cells in quite a few where they have covered less than 6000miles. Cold will hasten on their demise.

Grumpy-b

mattcarr
Posts: 389
Joined: Sat May 12, 2007 2:27 pm
Location: Hampshire

Re: Fully charged but Amps is lowered when it accelerates

Postby mattcarr » Wed Dec 18, 2013 3:50 pm

I have to agree with Grumpy-b 62 volts does seem very low to me. In the summer time in nice warm weather my car voltage will be around the 75 volts under heavly loads - and in the winter this will drop to about 70 volts. If I do not use the car regularly, and the battery pack sit for days getting very cold, then the voltage can drop to about 66 under heavy load.

techmind
Posts: 43
Joined: Thu Apr 04, 2013 6:14 pm

Re: Fully charged but Amps is lowered when it accelerates

Postby techmind » Fri Dec 19, 2014 1:51 pm

Just a update, on cell was dead, and i removed the original bms, placed another BMS solution from ev-power in Australia, and modified the zivan charger. It has worked for several months now. Here is more about the BMS conversion process http://techmind.dk/citroen-c1-evie-elbil/tag/bms/

;) michael

Grumpy-b
Posts: 991
Joined: Sat Dec 01, 2007 12:06 pm

Re: Fully charged but Amps is lowered when it accelerates

Postby Grumpy-b » Fri Dec 19, 2014 1:55 pm

I have purchased the remaining stock of the BMS used by ECC, directly from the makers, after I bought the last of the ECC stock of parts, (Everything they had)
So I can supply a new board if anyone has a problem with one. I have also done a few repairs, it just depends upon what caused the fault. Most damage is caused by people not turning the BMS off/ disconnecting by the DIP switches, before doing work on the battery pack.

Grumpy-b

techmind
Posts: 43
Joined: Thu Apr 04, 2013 6:14 pm

Re: Fully charged but Amps is lowered when it accelerates

Postby techmind » Fri Dec 19, 2014 7:28 pm

It was the original BMS causing the problem in my car.. And it was not even faulty..


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