One here as well.

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dexion
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Joined: Monday, July 13, 2009 - 05:49
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One here as well.

Howdy,

I ordered a 60ah lfp EVD from rmartin last week (7/9/09) and am awaiting delivery. I have a few questions for those that have one. I want to verify that the batts are balanced but given the multitude of ways/opinions on the subject, I am not sure which way to go. Until the warranty is over I have to use the thundersky charger so my automatic options are limited. So, if someone has any advice on how to do it while keeping the warranty intact. I am assuming a few things here.

1. Batteries that start off balanced will slowly drift apart.
2. The further the drift, the faster they will spread.
3. It is possible to manually balance a battery pack given one has access to all the batts.

Here is my understanding of the problem. My battery pack has 21 batteries. Due to the varying AH capacities/internal battery quality they will not all charge/discharge at exactly the same rate. For instance I may have a battery in the pack that is 62AH and one that is 58AH or one that seems more stubborn to take a charge and is always undercharged. Ok let’s look at the stubborn one as an example. Let’s say for argument it’s just this one battery that is a problem in the whole pack. It is always charged less than the others because it won’t charge as fast. So while the others start out at 3.6V the "bad" one is at 3.3V. While that is in the "safe zone" for these batts (2.5V-4.2V) it is possible that it would drop below 2.5 while the rest of the pack are safe at 2.7 because it started out lower. This problem would never "fix" itself since the next charge would bring it up to 3.3 again and not 3.6. The reverse may also be true. I may have a bat that always is high compared to the others so one bat may go higher than 4.2 while the others are at 3.9 at the end of charge (to settle down around 3.6.) Again this wouldn’t be fixed with a new charge since its higher than the others when one started charging it.

Ok now I have a few questions.
1. Wouldn’t over time the high battery "charge" the rest of the batts in the pack and they would self balance (or vice versa the low batt gets a charge from the rest in the pack.) Sort of like water seeking the lowest point. Now, this doesn’t appear to happen given what I have read. I am not an electrical engineer so I am missing some of the basics on the subject. Just for my edification can someone explain why they don’t self balance (a Google search doesn’t really help all that turns up is balancing charges/bms systems.)

2. It seems to me this isn’t really any sort of magical problem that is difficult to solve manually. If there is a batt with too much charge on it, drain the charge off the battery until it is close enough to the other batts in the cell (say all have a .1V spread.) Then check it every month (or more often if one finds monthly isn’t frequent enough and rinse and repeat.) Or if there’s a stubborn cell get a 4.2V charger for lfp batts and charge it on its own until it’s close to the others. (I realize there may be low and high batts in the pack so both methods may need to be practiced on certain cells.) Am I being overly optimistic in thinking I can manually balance the batteries with these methods and they will stay close for the month? I.e. is it too much of a balancing act (pun) for a person to attempt oneself or too time consuming to be worthwhile?

I don’t have the scoot yet so I can’t tell how (un)lucky I am with the pack yet perhaps it won’t be much of a problem. I would also if someone has a bit of time like some guidance in what range I should be shooting for. I’ve read the specs on the batts and they say 2.5-4.2 but I would like to know what people are comfortable with in terms of swing between the low and high batt in the pack. I am assuming take readings fully charged and then depleted after my longest ride so I can determine if they are all in the safe zone and how far they drifted to then get safe max distance traveled.

Also, I would like some guidance with a single 4.2V lfp charger so I can address the stubborn ones if needed (or a bank charger if it turns out I have several low ones.) And also what would be a good safe method for draining off excess charge from the high ones (i.e. hook a light bulb up to it for a while etc.)

Once the warranty is up, I am thinking of going the bank charger way so each cell is charged on its own. Can anyone suggest a solution that can handle 21 cells. My thought is to get the batts close to full with the thundersky charger and then finish them off with something else that charges each cell on its own. But there may be better ways.
Thanks to everyone in advance for any help you could provide.
dex

dexion
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Last seen: 4 years 4 months ago
Joined: Monday, July 13, 2009 - 05:49
Points: 32
Re: One here as well.

Ok the evd has arrived in good condition. I scooted around the parking lot at work for about 40 minutes today (no plate on it yet.) The only thing I cant get to work is the horn. Ive tried left button, right button, both buttons. I cant seem to find the fuse box or the actual horn. The explosion of the electrical system in the manual shows it near the right turn signal in the front but I dont see it there. Does anyknow know where they are? I will try to take apart the front end tomorrow in an attempt to find the horn I am assuming its not plugged in.

proempiet
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Last seen: 9 years 4 months ago
Joined: Friday, August 8, 2008 - 06:52
Points: 24
Re: One here as well.

The Rmartin should be allmost the same as the Extreme 5000Li please look in that thread there are some nice single charger boards (http://visforvoltage.org/forum/6553-additions-my-xm5000li).

My scooter has now 1400Km's and they start to drift 3,5 till 3,7 Volt. This after I balance the pack completely with an VoltPhreaks (//p10.secure.hostingprod.com/ [at] www.voltphreaks.com/ssl/catalog/product_info.php?cPath=3&products_id=28">https://p10.secure.hostingprod.com/ [at] www.voltphreaks.com/ssl/catalog/product_info.php?cPath=3&products_id=28) charger.

If only the horn works maybe the fuse under the seat has triped or is not switched on!

XM-5000li like scooter (top speed gps 938 Km/h max range (XM-5000Li speedometer) 87,6 )

dexion
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Last seen: 4 years 4 months ago
Joined: Monday, July 13, 2009 - 05:49
Points: 32
Re: One here as well.

Thanks ill read up on those links. The horn is the only thing that doesnt work. Ive looked under the seat theres an access panel but I dont see any fuses once I removed it. I have some time tonight im going to disasemble it until i find the horn and fuse box heh

garygid
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Last seen: 9 years 10 months ago
Joined: Friday, December 19, 2008 - 23:25
Points: 441
Re: One here as well.

On the XM-5000Li, the horn is in the upper front area, right of center, almost under (but slightly in front of) the "fuel" indicator.

Remove the front "V" trim, then the front "cover" (that supports the windscreen and instruments). No need to remove the windscreen from the "cover" or disconnect any wires.

Probably one connection to the horn (or the common to the horn buttons) is not connected well.

You should see the DC-DC converter in the center there, with a 4 or 5 amp fuse in, and about 15 amps in the 12v out line. I think that there are no other fuses in the 12 volt system.

Note headlamp and turn lamp bulbs, and how to access them.

Cheers, Gary
XM-5000Li, wired for cell voltage measuring and logging.

dexion
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Last seen: 4 years 4 months ago
Joined: Monday, July 13, 2009 - 05:49
Points: 32
Re: One here as well.

Yup that did it. I removed the inst cluster and the windscreen (all in one piece) and everything is there. It turned out to be the horn adjustment screw was too tight I losened it up and it works now (since 12 volts were getting to the horn when the buttons were depressed.)

Ah so no fuse box its just the dc to dc converter. Thank you very much.

so far 40 miles on it without a problem (20 on a charge so far is the max ive gone.)

Cells seem ballanced all are within .1v of each other man what a pain to get to the lower ones. Once the warranty is up I am going to put leads on each one up to some sort of concentraiter for easy testing/ballancing.
dex

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