Lithium hunting cart overhaul

[langnolen]

I have the same setup and I set my charger to charge to 4.1 and also balance during charge and storage. If you connect the charger with the bms via rj(telephone cord) it will detect when your cell reach whatever voltage you have it set to start balancing and what maximum you have. Mine I have set to start at 3.6 and max cut off at 4.1. It will go above 4.1 on one or two cells while charging but if disconnect it’s actualy at 4.05 4.01 so not really over. The charger is basically taking from high and distributing to the low cell. If you leave it alone and let it go all the way your cells will be whatever you set the tolerance/diff to. Basically all this is a long way of say set your numbers and it’s dummy proof. Of course this means as long as your numbers aren’t too high or too low..like is written all over this forum;).

[fstop]

Originally Posted by MyCousinVinnie

Thanks. I'll check it and report back.

So I received my Chargery 16 BMS today, and am concerned I may have the same issue you had with your first unit (I think...).

I don't have my Leaf modules yet, and haven't assembled the other components, but powering the BMS with an external 20v PSU, and setting it up for 14 cells, you can see by the attached photo that it is not reading 0.0v on all cells - some are as high as .035, sometimes it blips a little higher maybe to .037.

So not sure if a no voltage situation is causing issues, but some report properly at 0.0v - which is concerning.

Accuracy of cell voltage is pretty major.

Any thoughts on this?

Thanks!

[fstop]

Originally Posted by fstop

So I received my Chargery 16 BMS today, and am concerned I may have the same issue you had with your first unit (I think...).

I don't have my Leaf modules yet, and haven't assembled the other components, but powering the BMS with an external 20v PSU, and setting it up for 14 cells, you can see by the attached photo that it is not reading 0.0v on all cells - some are as high as .035, sometimes it blips a little higher maybe to .037.

So not sure if a no voltage situation is causing issues, but some report properly at 0.0v - which is concerning.

Accuracy of cell voltage is pretty major.

Any thoughts on this?

Thanks!

Update: Jason at Chargery says this would be normal as no voltage on any input terminal will produce unstable readings - makes sense.

[MyCousinVinnie]

I'm nearing the end of this project, I hope. I don't have any new pictures, but will try to get some here soon. My problem right now is addressing the possibility of mud, moisture, etc.

Below, I have posted two pictures below that show the areas I am concerned about. Because of the way the supports work on an electric golf cart, there's just about now way to get this area completely closed. You can tell the areas that will remain open from the back and from underneath. The picture without the wooden casing shows where the wooden casing butts up against and the gap is circled. there's no way to get rid of that gap entirely because of the potentiometer.

The batteries are in the middle and passenger side. 8 in the middle and six on the passenger side.

there are also gaps along the supports as indicated.

I'm using a chargery BMS and display. I am not worried about either one getting wet, and I'm locating those in an area that should not get wet or muddy, or if it does, I will just put them in a waterproof container.

My concern is with the BMS wires to the cells, to the relay, and to the current shunt. I'm sure I can rig something to try to close these gaps as much as possible, but I would imagine in a hunting cart, it's just about going to be impossible to keep 100% of the moisture out.

What's going to happen when the end of those BMS wires get exposed?

At this point, I feel like if I can't figure how a way to keep everything out, I am going to have to drop back to 7 cells, and build a much better enclosure. the six cells just barely fit on the passenger side, and the 8 cells just barely fit in the middle. In fact, I am having to move my F&R switch to under the driver to make it fit if I am going to keep this configuration.

I'm wondering if some thin neoprene or flexible HDPE or LDPE wouldn't keep out 99% of what I am worried about.

If you have any suggestions, please let me know. Thanks.

[DaveTM]

My cart is a EZ-GO txt so the frame configuration is a bit different. The below pic is what the box looked like prior to the install.

On my EZ-GO the place of "concern" about water and mud getting in was the "gap" at the rear facing part of the box. What I did was, using screws\big diameter flat washers, I fastened a heavy mill plastic on the top rear of the wooden box, and then with a small piece of wood I fastened the other side to the cart frame at the top.

The first pic below is the entire wooden and metal box and the second pic is my attempt to explain the water shield. Now...I have the two pics shown in a "backwards" alignment. The first one the rear is to the left, the second the rear is to the right.

Now, I didn't plan for, nor believe that I could make the box completely waterproof and as you can see on the top of the metal box, the "dried" remains of a small amount of water. I drilled weep holes in the bottom of the wooden box for any water that got in to allow it to get out. What I was going for was to shield any major water\mud splashes out while at the same time allowing a good air flow around the batteries.

I using this cart thru two hunting seasons in drenching rain, mud guck that makes the cart look like tossing mud was it's entire existence.....I've never had any water infiltration that caused any issues. And BTW...those "chunks" of mud got their from my power washing of the cart just yesterday. The heavy plastic really does the job of keeping out the mud\water that is being thrown off the rear tires.

In looking at your pics I'd be concerned with the gap at the rear of your cart. The small area you show at the front I'd attempt to screw in a small piece of wood to just close the gap. I wouldn't be concerned with any water that may get in there from a splash.

BTW I know the way I did it is not the only way to achieve your objective. But it's what I did. And I don't think you want or need to make the compartment a "waterproof bubble". Remember, the FLA batt's had zero protection and they held up just fine.

I hope this helps.

[MyCousinVinnie]

Thanks. As of right now, I have some wires coming through the holes in the back on the passenger side, but I could easily re-route those over the top of the box. Then, I could mold some neoprene with screws into the motor side of the back of that wooden box. the neoprene would have to be slightly "split" to accommodate the supports but after that, the amount of water/mud in there would be minimal, at most, I would think, far less than would get anywhere near those FLA batteries. Alternatively, if I re-route the wires, bet I could just use some foam to fill up the openings.

the opening on the back on the driver's side doesn't worry me as much. That's the potentiometer side. It slightly protrudes into rear, just like it did when I had the FLA's in there. It seemed to function fine with lots of wear and tear on it, so that side isn't as much of a worry.

Underneath along the supports, again, I think could be remedied with either foam or neoprene or both. Now, I just need to find some neoprene.

At least now, I think I'm going to keep all the batteries. It's a real tight fit in a DS this old. Here's a lesson learned on this build for all you other folks out there - if you want to convert an older DS to lithium, you might be better off staying with 7 modules, or go to the cobalt. I'm going to look at NCPW's build again to see whether he could have put 14 in there easily. I don't think so.

[DaveTM]

I've posted a previous thread about adding another 7 modules to my existing 7 module set. That's gonna happen when I get back from an impending trip my wife and I are taking.

[MyCousinVinnie]

DaveTM,

Do you have another battery that powers your winches and lights or are you running a converter? Also, how important do you think the disc brakes are? My cart is not a speedster. Torque motor.

[MyCousinVinnie]

After looking back over NCPW's build, I'd say that if you are doing an older DS, go with those metal plates he has here.

I think then, you will have plenty of room. I wish I had had access to someone who could build that.

[NCPW]

You do. Contact Gary (PingEye3) through PM. Super guy to talk to and willing to help.

As for your concern with mud/ dirt getting in around the frame rails; I think you'd be fine the way it is but if you're really concerned about it, get some aluminum tape used to seal off HVAC duct work. If can be found at your local hardware store or, of course, Amazon.

Something like this https://www.amazon.com/K-Flex-USA-80...m+hvac&sr=8-16