ElectricMotorcycleForum.com
Tech => Home Brew => Topic started by: craigster on October 18, 2019, 08:34:09 PM
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Hi all,
I had an exciting week - I was able to take my project bike out to a flat rural road and do some road tests, and it didn't break down! woohoo. I have my cycle analyst set up and at the end of my testing (till the bike wouldn't go any further) I had used 2096Wh. I plugged the bike into the wall using a Kill A Watt metering device and 24 hours later when I came out too the fully charged bike it said I had consumed just over 3kWh.... could the charger be eating up that much power? or is there something else going on here?
some more technical information:
- I'm using 2010 Zero S components - 3.7kW battery pack (of course only 80% usable and 10 years old there is some degradation going on, but still functional!)
- 27km of range - I was accelerating up to full throttle, holding that for about 1.5km, stopping and doing the same in reverse. flat ground.
- Averaging 75Wh/km
- charger is a 48V Quiq
Can you help me make sense of the fact the bike took 3kWh when it only used 2?
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I would guess that the extra kW was consumed while in Float. It can also be the age of the cells, being they are at 80% now there should also be a charge efficiency hit.
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Also, the charger's efficiency isn't 100% even if the battery itself is. It has to convert the voltage from the input to the output, and the circuits balance often by doing voltage splitting (wasting little bits).
Those percents add up, and the older a battery is, the less efficient it is.
So I wouldn't be surprised to see a 70% efficiency sometimes.
-Crissa
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I would guess that the extra kW was consumed while in Float. It can also be the age of the cells, being they are at 80% now there should also be a charge efficiency hit.
The bike consumed just over 2kW while new it had 3.7 so that means my batteries are down to about 54% even. Does it make sense though to use a whole extra kW (50% extra)? That seems like soooo much to blame on the charger, degraded battery and circuit balances. But I’m not sure
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I would guess that the extra kW was consumed while in Float. It can also be the age of the cells, being they are at 80% now there should also be a charge efficiency hit.
The bike consumed just over 2kW while new it had 3.7 so that means my batteries are down to about 54% even. Does it make sense though to use a whole extra kW (50% extra)? That seems like soooo much to blame on the charger, degraded battery and circuit balances. But I’m not sure
When my daughter's 2014 Zero S charger was dying, it would only charge the battery pack to 87% before giving up and shutting off. After the charger was replaced, the new one would fully charge the battery pack to 100% and to 117 volts. :) So a funky charger could be your problem. If you are using the original on-board charger, perhaps you should give a different compatible charger a try. It would be a lot cheaper than replacing the batteries. Maybe you could borrow one from a friend just to see if that makes a difference.
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I generally figure 80% for charger efficiency and go from there.
Given the state of your batteries, you are probably charging to
a point, then falling off where the charger picks up again. You also
have wasted energy use on top of the 80% My 2013 FX 5.7 charges
to full, then settles down to around 90%~95% but deletes quickly when
ridden. Given that you have 48 Volt and so ( relatively ) small pack, you
" should " be able to find a replacement that should work well for you.
https://www.ebay.com/itm/48-volt-Nissan-Leaf-Lithium-ion-Mini-Power-Pack-Battery-3-5-kwh-66ah-Storage-G1/123612201639?hash=item1cc7dc82a7:g:~4MAAOSwQZFdk4XL
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Interesting to note thank you. I guess maybe I’ll charge it again and just keep a better eye on the kill a watt and see what’s going on when. I’m not looking for battery replacement but it is neat to know that someone builds that battery and sells them.
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I would suggest re-wiring the cycle analyst so it sits between the DC output of the charger and the battery. That way you are actually seeing the energy put into the pack vs AC energy going into the charger.
Also do you have regen turned off on the bike? It's possible that the cycle analyst dose not see this energy going back into the battery pack.
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That’s an interesting idea I may just try that. The bike doesn’t have regen so nothing there