Voltage control on Summit II?

[simicrintz]

I have a situation where I need to keep the voltage on my Lester II charger at 50.4VDC max. Info from Bill at Lester states that I will go to 72V while charging, which won't work for me (why do they call is a 36/48V charger if it goes to 72V?). Bill also mentioned that it is not an adjustable charger. Model is a 30600 if that helps.

I am not smart enough to know how to limit this; anyone here able to point me in the right direction?

Thank you!!

[Sergio]

I think the Summit has a profile for a LiFePO4 lithium chemistry which is 50.4v for 12 cells (4.2vpc).

The Chevy Volt has a maximum of 4.15vpc x 12 cells or 49.8v for the pack.

If they don't have a better solution, You may be able to use a diode inline with the positive wire in order to drop the charger voltage about 0.6v.

[simicrintz]

Thank you, Sergio! The battery supplier is comfortable with the charger going to 50.4V (I have had many conversations with him) which is obviously higher than the 49.8V, so I hope he is right!

The charger does have a lithium option, so if that limits out at 50.4V it sounds like I should be okay. I need to download Lester's app and hook the charger to the batteries (I am waiting for the BMS and cables still; hope to have today) and then choose the lithium option. Is it your understanding that by choosing the lithium option I will trigger the 50.4V max?

The BMS that I will be using will shut the charger off at 50.4 V, but I'd like to have a backup that limits the charger, just in case the BMS hiccups!

[Sergio]

The Lester ChargerConnect app should show you the voltage parameters that will be used when you configure the battery profile to Lithium.

[simicrintz]

Thank you again, Sergio. Since I do not have my cables to hook the batteries in parallel yet I have been waiting to get the app and hook up the batteries to poke around in there.

[Fairtax4me]

You’ll probably have to do some digging around in the Cloud profile list to find the right one you need. The descriptions have the chemistry, VPC, and Some other parameters, but the only thing shown on the list is the profile number.
Did you explain to Bill that you needed a profile for A Lithium battery at 50.4v cutoff? Seems like maybe they thought you were running at FLA battery.

Just for what’s it’s worth, many FLA batteries benefit from charging at around 2.7v per cell, which usually puts the total on charge pack voltage (48v pack) around 64.8v. Some higher capacity batteries can use higher voltage than that while charging in order to properly balance/equalize voltages between cells. The 72v rating also give the S2 capability to charge a 56v FLA pack at around 2.5v per cell.

[simicrintz]

Originally Posted by Fairtax4me

Did you explain to Bill that you needed a profile for A Lithium battery at 50.4v cutoff? Seems like maybe they thought you were running at FLA battery

Yeah-he's on to me :( First time I spoke to him he said the charger will not work on Cobalt batteries, so I waited a while (hoping that he would forget me!).
I spoke to the battery supplier and he came up with a work around and the ability to shut the charger off at 50.4V, but liked the idea of a back up. Bill just flat said they charge to 72V and could not be changed.... He may be using a play from his CYA book to stay clean.

[Sergio]

Is "Bill" a support engineer from Lester or a phone support guy?

The 42v Lead Acid profiles are close to what you want but not all Summit II hardware works with those voltages.

Lester on their manual say to call them if you need a Lithium profile so they can see if the hardware itself can support the voltage.

I would not mention the actual cell chemistry as its only purpose is to determine the charging voltage and if folks are not familiar with the chemical composition they may just say it does not work instead of admitting they don't know what that means.

All they need to know is that you need a profile that charges to 50v without an equalization option.

Curious about the work around they proposed.

What is the backup option?

[simicrintz]

Thank you again for the reply, Sergio.

Here is the signature that I got from Bill at Lester:
Bill Soulliere-Technical Support Manager

He does some of their videos on their site so I think he is legit. I will give them a call and see if I can get the info that you suggest (and thank you again for that!).

The battery supplier has put a control on the BMS that will shut the charger down at 50.4V but would really like to see some redundancy, just in case. I like that idea and if I can get Lester to provide assistance on how to control the max voltage I would feel very comfortable about the system.