# Advice on EV conversion from 120 to 144v?



## piotrsko (Dec 9, 2007)

Need more data on component specs. zilla s/b ok, charger could be adjustable, gauges need some series resistance, google is your friend.


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## Paul9 (Oct 2, 2015)

Hi,

You are sort of doing what I have already done but mine is still a work in progress.

I originally built mine with 8 x 12v lead acids nominally 96v dc and when they "expired" instead of replacing with 30 x 3.2v lithiums I installed 32 x 3.2v nominally 102v dc. I had space for 2 more cells so I bought 2 more and installed them giving me 108v dc nominal. I replaced nothing else and the only problem I have had was that the 96v controller went into thermal shutdown just once on an extremely hot day (40 degrees C) on a long trip. Apart from the heat sinks I had on the controller, I added 12v fans to the heatsinks after that incident.

I am now thinking about adding another two cells to get things up to around 114v to 115v. The big problem is that, the higher my voltage, the more problems I may have with components overheating.

My BMS will have to be reprogrammed to ensure it does not stop the charging process at too low a voltage. I have two chargers installed which both charge at up to 130v dc even though they are 96v chargers. I am planning to replace my controller with a 120v controller as the pack will be at approx 120v after the charging process is complete and therefore my 96v controller may overheat if 120v is going into it. I have not and do not anticipate having to replace the dc-dc converter.

Cheers
Paul


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## evnz (Jul 24, 2010)

hi Paul
I have done that but at a greater jump
170 full charged to 340 full charged the controler can handle that but the motor can't so i set the controller to only give the motor 170v and it steps it down.
replaced the heater core dc-dc and relays
owen


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## Gigawatts (Aug 8, 2013)

evnz said:


> hi Paul
> I have done that but at a greater jump
> 170 full charged to 340 full charged the controler can handle that but the motor can't so i set the controller to only give the motor 170v and it steps it down.
> replaced the heater core dc-dc and relays
> owen


Why raise the voltage? Is it because you want more power, higher top speed, more efficiency(mileage), or just trying to raise battery capacity? 

evnz, 
In your case, why double the voltage? If you are using a Warp9 or similar motor, then 170v was already the max for that motor. Was it feeling sluggish with voltage drop or as the battery depleted? As the battery depleted did you not like max rpms dropping?


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