mine is a 2007 e4. different suspension , softer then the previous years . mine got a little stiffer . I put taller ( 60 series ) tires that gives more rubber between rim and ground . helped a lot . also dropped air pressure from 32 to 30 also helped a little .
vlad on here added air shocks on his . there is a thread on it .
Once converting to lithium batteries, one concern I had was making sure the batteries donāt fall below a minimum charge level (i.e., 2.5 volts per cell). This is especially true since I keep my GEM at vacation property and it may sit a few weeks between use. My battery cells have BMS (battery management system) boards attached to each cell. Although a very slight load, these BMS boards have the capability of discharging lithium batteries below the recommended minimum voltage.
So I purchased this weekly timer from Amazon for about $10.
The timer is working great. It can handle 15A and my lithium battery charger draws 10 amps. I leave the GEM plugged into the timer and set it for a short charge cycle once a week. Thursday PM charging for a couple hours ensures the batteries stay charged and the GEM is ready to drive before I arrive for the weekend.
It is my understanding the newer GEMs have a storage charging capability that older GEMs do not have. Just leave them plugged in and they will occasionally charge. My aftermarket lithium charger does not have this feature. But for just ten bucks this solution can give GEM car owners with lithium batteries a little piece of mind (assuming your charger draws less than 15 amps).
RWD
the delta q chargers 2005 and newer , have a restart feature every 2 weeks that keeps batteries topped off . iām using the Nissan cells that are lithium manganese instead of lithium iron ( they have a different voltage profile). the factory controller shuts down if a battery pack drops to 60 volts . so with 20 cells , even if you drive it tell it stops , they wont go below 3.0v each . on the high side the charger profile charges them to 90% then shuts down , so protected on the high side .
storing lithium fully charged shortens their lift span and is not recommended . I donāt recharge it every time I use it , only when the pack gets low , there for reducing the time the pack stays at full charge . when traveling, I drain the pack to about 50% charge then turn off the breaker . since lithium has a very low self drain the voltage is almost identical, months latter , to where I left it .
the chemistry you are using is more tolerate to being stored at full charge , but it still does reduce life span .if you could find a way to store it at less then 100 %soc your pack would last longer. there is a good website called battery university that has great info on different lithium chemistries .
what voltage are you charging each cell to ?
Yeah, I do understand storing a battery pack at mid charge is better for the batteries. In order to accomplish that I would have to make some kind of battery monitoring system that would turn on the charger when the pack gets below some defined mid charge level (vs a timer that periodically runs the charger). Plus, the car would not be fully charged and ready to drive when I got to my vacation property.
Iām charging each cell to 3.65 volts. I have a 1972 MGB I converted to LifePO4 batteries more than 5 years ago and I keep it charged around 3.65 volts because I do drive that on a regular basis. Itās been running on the same LifePO4 batteries for 6 years and continues to run strong. Thereās no reason to doubt I should get at least 8 years of battery life on that carās batteries.
The final thought on this is that the lithium charger I have for the GEM is a CC/CV charger. So the final topping off to 3.65 is far less than the 10 amp capability of the charger.
Yeah, a half charge would be better but, if I can get 6-8 years of battery life in my GEM, Iām not going to get overly concerned either.
RWD
Does that timer retain settings if the power is interrupted?
10 years is what Iām hoping for mine but highly doubt I well have the cart for that long . Nissan warrants the batteries to have no less then 80% life span in 5 years or 60,000 miles and projects the packs to have 70% capacity @ 10 years and 100,000 miles. seeing how cheap lithium has become I think a lot more people well be going that way
Yes, it retains the settings and the day/time.
RWD
Another reason Iām not sweating the battery life is that I can lose some battery capability and still have the GEM work for me. Iām figuring I have around 40 miles range. Iāve driven 30 miles on a charge and the cells were still at 3.18 volts each. I canāt imagine driving it and needing 40 miles. Thatās a long way to go between charging for a neighborhood electric vehicle. So, if it drops to a 30 mile range after 8 years and is at an 80% DOD, who cares?
RWD
We have closed this thread as it was getting a little long. A new thread about converting to lithium batteries has been set-up at:-
Please add your comments to the new thread.