Charging Problem

Jamie B4 · #1 13-02-2012

Wonder if you can help - seem to have an issue charging lipos.

Got a power pal charger from cml that i use to charge vampire saddle lipos from dms.

When racing and being scruteered my lipos are very low with regards to the 8.40v limit.

Been watching both and the charger seems to be dropping the ampage while not being at 8.40v, is this faulty or a setting on the charger

Is it the charger or lipos cos want to sort this out once and for all, have sent the charger back once to cml for a noisey fan but they did not rectify that.

Please help

adon30 · #2 14-02-2012

By 'low' what voltage are you actually seeing? And are you charging to full capacity? I have a different charger from you and you can change the capacity stop point.
Are you charging from mains or 12v source?

If your not sure about the charger, find someone who's cells are charging to a higher voltage and see if yours will do the same on their charger.

One final question, how old (much use) are the cells?

Jamie B4 · #3 14-02-2012

Charging from battery and mains.

When I say low voltage I mean 8.28/8.30 rather than 8.40v. When I put them on another charger they still need to be topped up. Lipos are about 6 months old and used for all events

Sure its nothing drastic but would like to make sure before new season starts

Not sure how these lipos are charged and balanced

Jamie B4 · #4 14-02-2012

Also charging at 5amps and lipos are 5400mAh but charger can not go any higher

sosidge · #5 14-02-2012

You should also check the cell voltages with a seperate voltage tester, it's possible that the charger is reading the voltages incorrectly, if it is then it will probably need replacing.

Otherwise it sounds like the LiPo is well out of balance and that the charger is starting the balance process very early - ie one cell is at 3.7V but the other cell is only at 3.6V and will need a LOT of balancing to sort out.

I had this with a pack that had been over-discharged, after a few attempts at a charge and discharge I just could not get the voltages to balance and the pack was only fit for recycling.

You can try leaving the charger attached but it may take a LONG time for the cells to balance at 0.1A. Perhaps never. Or you can try a balanced discharge to 3V per cell, and then try charging again. If that still doesn't work, the pack may well be dead.

tyreman · #6 14-02-2012

Jamie

Check what the cell voltage is set to on the charger, as on mine i can change the pack volts in 0.1 incriments.
As most of the current chargers are all the same just rebranded.

RogerM · #7 14-02-2012

Check the balance board ... I have had a similar issue with the same charger in the past and found it was caused by issues with reading the cell voltages. Remaking all the connections in the balance circuit sorted the issue out.

I'm hoping to change to the new Orion charger soon but have to say that the Power Pal has been a good unit thus far.

Jamie B4 · #8 14-02-2012

Cheers Bri

Will check tonight, am tending to think its the charger as its the same on all of my lipos not just one pack

Thanks for advice will try a few of the things mentioned

J

Jamie B4 · #9 14-02-2012

Thanks Roger - will try and do that - do the charger/balance boards suffer from dry joints on the solder if so may just need resoldering

RogerM · #10 14-02-2012

Quote:

Originally Posted by Jamie B4

Thanks Roger - will try and do that - do the charger/balance boards suffer from dry joints on the solder if so may just need resoldering

I believe mine was due to wires breaking inside the insulation from where they had been folded up when packing the charger away. I replaced all the wires with silicone insulated cable rather than the supplied PVC insulated one and not had a problem since.

MatJohnson · #11 14-02-2012

I've got a balance board somewhere you can have a go with to try that if you want

_sleigh_ · #12 14-02-2012

I've had the same problem on my charger in the past and it was the link wire between my saddles. I found that the charger would display 8.40v on the main display and lower voltages on the individual cell display (right arrow while charging).

Charging without balancing would just result in a charge failure due to something like 'Error Cell Voltage'.

imull · #13 14-02-2012

Where are you seeing the 8.28/8.3V? On the scruteneers voltmeter? The cells will drop off as soon as they are charged. Are the cells showing 8.4V on your charger display when it terminates?

If you don't balance charge do you get the same result? Have you tried measuring the cell voltage with a voltmeter during charging and compared the reading with that on the charger? It may be that the charger is reading too high and terminating the charge early.

Sorry for all of the questions, just trying to see where the problem may lie

adon30 · #14 14-02-2012

Quote:

Originally Posted by RogerM

I believe mine was due to wires breaking inside the insulation from where they had been folded up when packing the charger away. I replaced all the wires with silicone insulated cable rather than the supplied PVC insulated one and not had a problem since.

I had a broken balance wire the other week, same as Rog, it was inside the wire itself and in several places. This was the one that went to the central/ link point. However I have a Hyperion EOS. Initially it still charged fine but seemed to take ages then errored. This was due to having problems balancing and reading the voltages.
Then after the wire finally went it tells me that it can not perform a balance charge due to not being able to read the voltages at all.

That reminds me...... I need to fix the balance cable.
If you have a spare cable I would suggest trying that out (or making one up).

_sleigh_ · #15 14-02-2012

Quote:

Originally Posted by imull

Where are you seeing the 8.28/8.3V? On the scruteneers voltmeter? The cells will drop off as soon as they are charged.

I won't expect them to drop that much, if at all. Even when balance charging the previous night, I've only seen a 0.05v reduction on the scrunteneers DVM and that's without any additional charging.

Jamie B4 · #16 15-02-2012

Thanks for all your advice and help am going to have a look tonight but i have changed my leads to the lipos so they are brand new, think i will try as suggested balancing and charging without and then try the balance board

How would I be able to eliminate the balance board?

Again many thanks to all

J

Cardnim · #17 15-02-2012

Quote:

Originally Posted by Jamie B4

Thanks for all your advice and help am going to have a look tonight but i have changed my leads to the lipos so they are brand new, think i will try as suggested balancing and charging without and then try the balance board

How would I be able to eliminate the balance board?

Again many thanks to all

J

+1 to balance board probably being faulty.

Eliminate it from your charging by simply doing each battery seperately.
i.e. set your charger for a ONE CELL (3.7v) charge.
Do each battery, then you will have theoritically a 7.4v fully charged saddle pack.

If you put it back on the charger this time as a TWO CELL (7.4v) charge, with the balance board. Then if it comes back and says they are at 8.3 or anything less than 8.4 you can probably be sure something is up with the balance board.

Jamie B4 · #18 15-02-2012

Quote: I've had the same problem on my charger in the past and it was the link wire between my saddles. I found that the charger would display 8.40v on the main display and lower voltages on the individual cell display (right arrow while charging).

Charging without balancing would just result in a charge failure due to something like 'Error Cell Voltage'.

Phil this is exactly the same problem as i have, while the charger is balancing the voltage is low, I then put it on fast charge and its comes up with "Batt Vol Err, Cell Connect", i then try it again and its fine so seems to be tempermental, have tried 2 charger cables but not sure if the balance board is ok. Can you buy a new board or cable. or does the charger need to be looked at. Any advice would be great.

RogerM · #19 16-02-2012

It's almost certainly the balance wiring / balance board at fault.

Happy to look at it with you on Sunday if your at Kidderminster, we can exchange balance boards and leads as we have the same charger .... that should identify your issue mate.

Let me know if you want to (so I can make sure I arrive with 2 charged packs so there is no panic in the morning).