Do xtreme chargers really need to be on a timer?

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JasonTaylor
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Do xtreme chargers really need to be on a timer?

According to the x-250 manual:

4. Charge the unit for 6-8 hours. NEVER charge your scooter for
over 8 hours!
6. For safety purposes, DO NOT charge for over 8 hours.

The charger for the x250 turns green but starts out flashing red and green. So it appears to have 3 modes: red, green, and alternatinig red and green. What do each of the color combos mean?

Is the step 4. and 6. from a lawyer regarding a rare explosion when the charger died? In other words, can I leave it plugged in 24/7?

Jason

jthmi
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Re: Do xtreme chargers really need to be on a timer?

Jason,

The three modes typically mean: red(needs a charge), green (good to go) and flashing (approacing good to go). As for leaving it on 24/7, you run the risk of cooking your batteries causing swelling and premature failure. We see it all the time when units come in for repair and they state they leave it on the charger from Sunday to Friday because the customer only uses it on the weekends. So it's to your benefit to put ANY SLA bike on a countdown non-recurring timer. You're also wasting a bit of fuel, so why not.

JTH/Amp Brothers Electric Cycles/MI

JasonTaylor
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Re: Do xtreme chargers really need to be on a timer?

"So it's to your benefit to put ANY SLA bike on a countdown non-recurring timer. You're also wasting a bit of fuel, so why not." Well it takes money and effort and time to put something on a special timer. I think a timer goes for $10. Takes up space in house. Is your laptop charger on a timer? Does it explode? My guess is that you work for xtreme and that the old units would overcharge. That would explain the discrepancy with the manual regarding the lights. In that case, I can leave it on all the time, since I don't have a bad charger.

Thanks for the post. Very useful info.

Jason

Jason Taylor. Fresh rant each day @ http://twitter.com/jasontaylor7

antiscab
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Re: Do xtreme chargers really need to be on a timer?

Well it takes money and effort and time to put something on a special timer. I think a timer goes for $10. Takes up space in house. Is your laptop charger on a timer? Does it explode?

Hi Jason,

The effect is called thermal runaway.

There is a secondary reaction in all lead acid based batteries that splits the water in the electrolyte into hydrogen and oxygen (theres actually a couple of redox reactions to make it happen, but thats beyond what I'm wanting to describe here).

The reaction is modelled fairly effectively by arrhenius, basically the current the secondary reaction absorbs increases with temperature.

The more current that gets absorbed the hotter the battery gets, mainly because the internal catalyst is trying to convert all that hydrogen and oxygen back into water.

if the amount of current the secondary reaction consumes becomes more than the charge current cut-off in the chargers final stage, the charger will ever shut down.

The end result is swollen batteries.

This is a problem for *all* lead acid charging setups.

Nrnnst modelled another affect, where the voltage at which a significant quantity of the reactants involved in the secondary reaction overcome the activation energy "barrier" increases with the concentration of the reactants.
In this case, the higher your batteries' state of charge, the lower the voltage at which you will run into gassing problems.

Matt

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
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MikeB
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Re: Do xtreme chargers really need to be on a timer?

Jason, the reason your laptop doesn't have a timer is because it's got a very smart chip embedded in the charging circuit that cuts off power entirely once the battery is fully charged. Xtreme didn't put in such a smart chip, probably to save a few bucks. After all, their main claim to fame is very cheap products, not very smart ones.

I'll second the above recommendation, get a timer! I don't work for xtreme and have nothing to sell here, but I've read plenty of stories of bad chargers and bad reactions with overcharged batteries.

In fact, I'll go one further, spend a little more and get the Kill-A-Watt Graphic Timer:
http://www.thinkgeek.com/gadgets/travelpower/c3cc/

This gives you the ability to define a 7-day charging schedule, but more importantly it lets you track the energy consumption as you go. This is a good double-check on your charger circuity, since it can tell you at a glance how much power you used per charge. You can tell what your overall economy is, and a sudden change in energy usage is a good indicator of a failing part. More importantly, you can tell if an overnight charge used 0.01kWh when you were expecting it to use 1.2kWh, indicating that the charge process simply didn't happen and you're likely to be stranded on the road.

My electric vehicle: CuMoCo C130 scooter.

JasonTaylor
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Re: Do xtreme chargers really need to be on a timer?

"Jason, the reason your laptop doesn't have a timer is because it's got a very smart chip embedded in the charging circuit that cuts off power entirely once the battery is fully charged. Xtreme didn't put in such a smart chip, probably to save a few bucks. "
I think there is married circuitry in both the Li-ion and laptop itself. The SLA batts don't have any circuitry. I don't think this aspect of SLAs is specific to Xtreme.

Looks like I was off by a factor of 5 on the cost. I think I have both a kilowatt meter and a timer but am extremely lazy so I am not sure I will be programming them just yet. (See next post for deets why.) Thanks again MikeB jthmi and antiscab for the info and suggestions. Especially antiscab for making me wonder if exploding SLAs are like the Fukoshima H explosions.
Jason

Jason Taylor. Fresh rant each day @ http://twitter.com/jasontaylor7

elecscooter
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Re: Do xtreme chargers really need to be on a timer?

In addition to the regular storage maintenance you do with a regular bicycle there are a few things you should do for the Electric Scooters.
Check all the wiring for damage, repairing and replacing as needed. Check all the connections and clean and straighten as needed. Check the motor for any signs of overheating or other problems. Check the connection from the motor to the drive line for alignment, contact, drag issues, or other problems.
Check each battery or cell for voltage and any signs of physical issues. Check the connections to ensure they are tight, signs of corrosion or hot connections. Address issues as appropriate. Traditionally, the battery pack and connections are the problem areas for e-assist bikes. Connections include the fuse and fuse holder, ammeter shunt, and other instrumentation connections.

LeftieBiker
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Re: Do xtreme chargers really need to be on a timer?

I don't know if we have the same model charger: mine is a 60 volt, 5 amp unit that's fairly small. I wouldn't leave mine on for days, but the final, 'float charge' mode seems to be desirable for a few hours to equalize voltages in my lead-acid battery pack. I often leave it on for 8-10 or 12 hours.

Heh. I just looked up the model, and we definitely don't have the same charger, scooter type, etc. ;-) A small unit like yours should be put on a timer if you can't disconnect it yourself, but I'd be concerned about 'drainback' through the charger. Even mine will do that if left connected to the scooter. The best thing is to physically disconnect it from the scooter after the appropriate time.

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