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NG3 chargers can't current limit on lithium batteries?

60277 Views 144 Replies 21 Participants Last post by  jollmo
We've been using an NG3 charger for the last several years to charge our lead acid pack. We originally had Electric Conversions install an optional low current mode switch on the NG3 so that we could charge on a standard 15 amp outlet while at work.

We're in the process now of upgrading our pack to lithium. Before we purchased the new batteries we had contacted Electric Conversions regarding modifying our NG3 to handle the lithium batteries. They said they would be able to modify the charging profile for our configuration.

Now, after just receiving the charger back from Electric Conversions we noticed that the low power option had been removed from our unit. They failed to mention this little detail to us. I contacted them and all I was told was we can't current limit on lithium batteries and it would take to much time to do. If you can current limit on lead acid why not lithium? If the hardware of the NG3 supports current limiting on lead acid it should be just as capable of current limiting on lithium. I realize that it might require a separate charging profile or something but it can be done.

My plan now is to figure out the profile programming of the NG3 and modify it myself. I have a lot of professional experience in reverse engineering electronic systems and feel that it can be done. I know a lot of people have been down this path before on here and have found some decent information. If anyone has information about the NG3 charger that would help speed up the process it would be appreciated.

Two lessons here, NG3s don't currently have a current limiting capability on lithium and avoid Electric Conversions. After reading some of the other posts on here, I'm not the only one to have problems with this company.
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my question is has anyone got a similar control on thier Zivan as it would be handy to make use of it but i don't know how to ?
The black box has the characteristics of an opto coupler and is controlled by the GEL BMS with a 0-5V signal.
This modification, according to the guy that wrote the BMS software, was made in an attempt to control the charger to pull back the current supplied in the latter stages of the charge.
To be more precise, it does not regulate the current... it regulates the voltage (which will of course affect the current, so the statement is not entirely wrong;))
The voltage can be adjusted 10-20% only.

In my humble opinion this is a hack that has little to no effect, and we've therefore decided to cut the connection to the BMS and refit the multiturn potmeter (details on the potmeter is to be found here: http://www.diyelectriccar.com/forums/showpost.php?p=353628&postcount=2)
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