Please review my buy list for lithium build

[somfas]

Thanks!!

[OttyFields]

Originally Posted by DaveTM

For the HV (High Voltage) and LV (Low Voltage) cutoff's I purchased these relays from Mouser electronics: https://www.mouser.com/ProductDetail...rrencycode=USD At $5.68 each....way less costly than the big contactor that ZEVA sells.

As for the "hook up" of the relays....take a look at this setup (my setup) and if you have questions please ask.

I really like the "just in case" male to male wire. Smart thinking....

[DaveTM]

Originally Posted by OttyFields

I really like the "just in case" male to male wire. Smart thinking....

Thanks! Actually, the first time I took it out for a test spin I had to use that. My settings were not where they should have been and when the voltage dropped below my setting (as I was driving up a very steep woods hill) the LV did it's job and cut power.

However, at that time I did not have a "sleep" switch installed to reset the ZEVA. Nor did I have a screwdriver small enough to hit the ZEVA reset button.

Other than that....on occasion.....a brilliant idea actually comes along!!

[somfas]

Hey DaveTM, I went to purchase the relays and see that they are 48v. Would that application matter on my 72v cart?

Also, I assume you still think the "CAN Bus" Charger type chargers are the best? I don't have a preference besides thats what Ian recommended and you have offered up the info on where to buy them.

Thanks for all the help. I just ordered the items from Ian. So as soon as I get the charger, I will be ready to start inching forward with this conversion.

TIA

[DaveTM]

Originally Posted by somfas

Hey DaveTM, I went to purchase the relays and see that they are 48v. Would that application matter on my 72v cart?

Also, I assume you still think the "CAN Bus" Charger type chargers are the best? I don't have a preference besides thats what Ian recommended and you have offered up the info on where to buy them.

Thanks for all the help. I just ordered the items from Ian. So as soon as I get the charger, I will be ready to start inching forward with this conversion.

TIA

I think you have to have a 72-V relay for your system. I did a search on Mouser Electronics but I can't seem to find relays that would handle 72-V. That doesn't mean they are there.....it just means I can find 'em.

Is the "CAN Bus" chargers the best? All I can tell you is mine has been working fine since my install.

[Ribfeast]

Better off with contactors than relays, usually rated for more current. You'll want it to be able to break the connection in case of an issue, preferably with a magnet inside to blow out the spark. DC is savage on contactors, usually a pre-start resistor is a good idea, wired across the contacts.

I used Formply (basically weather resistant plywood) for my battery box build, as per:
http://www.buggiesgonewild.com/membe...e-lithium.html

I'd assume the Leaf cells would be similar to the CALB cells I used.
I'd highly recommend the Zeva screen to see what is going on. Not sure how this would work with dual BMS, unless the BMS both talk over CAN and combine things.

I went with a 500A shunt for current measurement, works well. Most I have seen is around 300A from the setup.

[Sergio]

Is not really a matter of better or worst, each application is different.

The relay method (much less expensive) is to interrupt the key switch circuit and not intended to interrupt the battery current.

The gigavac implementation has its advantages and drawbacks, to me keeping that contactor powered ON 24/7 as Zeva shows would not even be an option.

You can mitigate some of that by installing a "sleep switch", but the side effect on an Alltrax Controller is the loss of throttle calibration values when the gigavac is OFF.

In this particular application due to the higher voltage I think that a single gigavac contactor acting as both LV and HV would be best.

Since I think You have an Alltrax controller I would use it to prevent both LV and HV events so it would be an extraordinary event for the Zeva to trigger either condition.

Setting the Alltrax "Under Voltage" slight higher than the minimum pack voltage would prevent a Zeva LV event and automatically create a "limp mode" if your pack becomes really discharged.

PingEye3 has some really nice drawings for the gigavac setup with a "sleep mode" switch that you can use to power down the gigavac.

[somfas]

Thank you so much Sergio. I can't express how appreciated that info is. I am good mechanically and have good confidence with building most things. But these electric golf carts stump me and all the electrical components are completely foreign to me. I'm definitely paying attention to the answers I am getting. Will look into the gigavac deal now.

[Ribfeast]

You would want some sort of protection in case a single cell goes under voltage too (via the Zeva). I have this on my kart, the Zeva will open the main contactor if it drops too low. I have a small override switch on the side of the cart in case of this scenario so I can limp it back to the charger.
I have a second cheapie eBay contactor that cuts off the charger in the event an individual cell hits overvoltage.
But yes there is a small parasitic load from the main contactor always being energized, but less than an amp.

[Sergio]

I agree You definitely need LV protection at the cell level, but the single gigavac setup does that.

The Zeva needing to trigger LV should be an extraordinary event and not a desirable mode of operation.

The new Alltrax controllers will keep lowering the current automatically to keep the pack voltage above the minimum set similar to a limp mode if the pack can only deliver a reduced current.