Questions regarding battery type and what voltage moving forward

[georgia088]

This is the charger I ordered. Not sure it is the best, but I think it will work. https://www.amazon.com/36-Volt-48-Vo...dDbGljaz10cnVl

[venquessa]

The final + wire to power the BMS, B28 or whatever they call it. That could be a bummer if you missed it. I missed it twice while making up the wiring looms. If that makes you feel bad... I removed the balance leads "I didn't need" from a set of them. I diligently counted multiple times that I had 8 balance leads for 8 cells. Except it's 9 balance leads for 8 cells. Had to find and reinstall a balance lead into the connector. Doh! I had got the point of wiring the battery!

On smart chargers, if it's a "cell aware" charger it's worth a punt. If its just a blunt 2 wire only job... it just depends. I would personally prefer configuration over prescription (forced AUTO).

[venquessa]

This is the charger I ordered. Not sure it is the best, but I think it will work. https://www.amazon.com/36-Volt-48-Vo...dDbGljaz10cnVl

As long as it lets you set "charge current" and "max charge voltage" the cell monitoring and cell protection can be done by the BMS.

[georgia088]

As long as it lets you set "charge current" and "max charge voltage" the cell monitoring and cell protection can be done by the BMS.

Well, probably not the best idea, but I went ahead and installed the pack in the golf cart. Have I mentioned im inpatient! I just wanted to see the cart move, and well, it did. Sound bad that I was rather surprised? I figured I would screw something up, but it’s not over yet…. I pulled the cart about 200 yards around the house. I was afraid to drive it far, before an initial charge? Will discharging the batteries before fully charging them damage them?

Now, I need advice on where to set the parameters within the bms. I’m not going to lie I was shocked as I watched the amp draw on the app in my trip around the house. I definitely pulled over 100 amps for a second or three… I may be pushing the limits of the bms. For this application, what would you suggest I set my parameters to? Cell over voltage/under voltage, at what voltage to balance cells? Temperate? Etc?

He will hopefully get the charger in today so I can get the batteries charged up and give it a real test ride.

[venquessa]

Ah, your post appeared back there, things make a bit more sense now

On the charge specifics, I'll side step that one, there are quite a few folks reviewing it on YouTube though. https://www.youtube.com/results?sear...attery+Charger

For the JK-BMS: Andy's video is the best guide: https://www.youtube.com/watch?v=xTKiOvJ_ejg

I am also currently baby sitting a battery which I hurried into service. It may take a while for it to balance and settle down. It's difficult to do any balancing in the mid charge range, it's best to do it at the top. If they are well out of balance this can lead to a high voltage disconnect. I would suggest if this happens to stop the charge, let the battery rest, run it a bit and recharge until you get a 3.600V cell or a BMS disconenct. Over a few small cycles it will top balance with the BMS and settle down.

The JK settings to assist you are the high voltage disconnect voltage and recovery voltage. As a suggestion, set the disconnect to 3.600V and the recovery way down at 3.300V, this will effectively terminate the charge as soon as a single cell goes rapidly upward. Setting the recovery higher and the BMS will reconnect sooner. If you set it into the "self discharge" region, like setting it to 3.500V it will bounce the pack off the HVC repeatedly every 20 minutes until the pack balances. Not ideal. If you want to take that approach, lower the disconnect a little as it can overshoot by 50mV..

I like the box. I would make a permanent cover. You don't want to drop anything in there

[georgia088]

Ah, your post appeared back there, things make a bit more sense now

On the charge specifics, I'll side step that one, there are quite a few folks reviewing it on YouTube though. https://www.youtube.com/results?sear...attery+Charger

For the JK-BMS: Andy's video is the best guide: https://www.youtube.com/watch?v=xTKiOvJ_ejg

I am also currently baby sitting a battery which I hurried into service. It may take a while for it to balance and settle down. It's difficult to do any balancing in the mid charge range, it's best to do it at the top. If they are well out of balance this can lead to a high voltage disconnect. I would suggest if this happens to stop the charge, let the battery rest, run it a bit and recharge until you get a 3.600V cell or a BMS disconenct. Over a few small cycles it will top balance with the BMS and settle down.

The JK settings to assist you are the high voltage disconnect voltage and recovery voltage. As a suggestion, set the disconnect to 3.600V and the recovery way down at 3.300V, this will effectively terminate the charge as soon as a single cell goes rapidly upward. Setting the recovery higher and the BMS will reconnect sooner. If you set it into the "self discharge" region, like setting it to 3.500V it will bounce the pack off the HVC repeatedly every 20 minutes until the pack balances. Not ideal. If you want to take that approach, lower the disconnect a little as it can overshoot by 50mV..

I like the box. I would make a permanent cover. You don't want to drop anything in there

Welp, got the charger in and batteries charged. The charger has no user settings other than 36/48v selector and a mode button to selector 5A 10A or 13A. Not sure that I like that although it’s probably best because I the user don’t know what to set the parameters at. I would just be going on advice found on here.

Charged the batteries and let them sit for a day. According to the bms they were all pretty well balanced. So I took it for it’s real run. Ran great. Picked up quite a bit of speed. I clocked it with gps speedometer at 31 mph (probably topped out at 21-22 mph before. Too fast for the braking and handling on this thing! I want be doing that often! It sure does pull a lot of continuous amps though according to the bms data. On flat ground with the pedal to the floor it stays well over 100Ah

This was kind of a bummer. I really hoped the cart was going to be more efficient than that. I could go in to the alltrax controller and throttle down some I guess. But he doesn’t want me to. He likes it. How long will it last??? I guess time will tell. Obviously the bms will handle it. I’m sure it’s tough on the batteries, but he rarely ever rides it down the road. Most of his driving is 100-200 yard trips across the property. If he needs the speed he wants to be able to have it.

I went approximately 5 miles and the bms dropped from about 99% charge to about 81%. Seems like it wouldn’t have dropped that much from what I’ve read. That would calculate to approximately 25 mile range on full charge. I’ve read lfp in carts should get close to double that. This is a small sample size I know. The amperage stat can also be calibrated, but I don’t have a good way to do that.

Another concern, when the pedal is held on the floor, the cart seems to cut in and out of power and becomes a little jerky. What would this be? An rpm limiter?

Thanks!

[georgia088]

The post for this pic got flagged again. Here is the screen shot after the ride.

[SunEagle]

The post for this pic got flagged again. Here is the screen shot after the ride.

There was too many links in venquessa's post. Which is why your post went to moderation.

[georgia088]

Ah, your post appeared back there, things make a bit more sense now

On the charge specifics, I'll side step that one, there are quite a few folks reviewing it on YouTube though.

I am also currently baby sitting a battery which I hurried into service. It may take a while for it to balance and settle down. It's difficult to do any balancing in the mid charge range, it's best to do it at the top. If they are well out of balance this can lead to a high voltage disconnect. I would suggest if this happens to stop the charge, let the battery rest, run it a bit and recharge until you get a 3.600V cell or a BMS disconenct. Over a few small cycles it will top balance with the BMS and settle down.

The JK settings to assist you are the high voltage disconnect voltage and recovery voltage. As a suggestion, set the disconnect to 3.600V and the recovery way down at 3.300V, this will effectively terminate the charge as soon as a single cell goes rapidly upward. Setting the recovery higher and the BMS will reconnect sooner. If you set it into the "self discharge" region, like setting it to 3.500V it will bounce the pack off the HVC repeatedly every 20 minutes until the pack balances. Not ideal. If you want to take that approach, lower the disconnect a little as it can overshoot by 50mV..

I like the box. I would make a permanent cover. You don't want to drop anything in there

Ah, your post appeared back there, things make a bit more sense now

On the charge specifics,

I am also currently baby sitting a battery which I hurried into service. It may take a while for it to balance and settle down. It's difficult to do any balancing in the mid charge range, it's best to do it at the top. If they are well out of balance this can lead to a high voltage disconnect. I would suggest if this happens to stop the charge, let the battery rest, run it a bit and recharge until you get a 3.600V cell or a BMS disconenct. Over a few small cycles it will top balance with the BMS and settle down.

The JK settings to assist you are the high voltage disconnect voltage and recovery voltage. As a suggestion, set the disconnect to 3.600V and the recovery way down at 3.300V, this will effectively terminate the charge as soon as a single cell goes rapidly upward. Setting the recovery higher and the BMS will reconnect sooner. If you set it into the "self discharge" region, like setting it to 3.500V it will bounce the pack off the HVC repeatedly every 20 minutes until the pack balances. Not ideal. If you want to take that approach, lower the disconnect a little as it can overshoot by 50mV..

I like the box. I would make a permanent cover. You don't want to drop anything in there

Welp, got the charger in and batteries charged. The charger has no user settings other than 36/48v selector and a mode button to selector 5A 10A or 13A. Not sure that I like that although it’s probably best because I the user don’t know what to set the parameters at. I would just be going on advice found on here.

Charged the batteries and let them sit for a day. According to the bms they were all pretty well balanced. So I took it for it’s real run. Ran great. Picked up quite a bit of speed. I clocked it with gps speedometer at 31 mph (probably topped out at 21-22 mph before. Too fast for the braking and handling on this thing! I want be doing that often! It sure does pull a lot of continuous amps though according to the bms data. On flat ground with the pedal to the floor it stays well over 100Ah

This was kind of a bummer. I really hoped the cart was going to be more efficient than that. I could go in to the alltrax controller and throttle down some I guess. But he doesn’t want me to. He likes it. How long will it last??? I guess time will tell. Obviously the bms will handle it. I’m sure it’s tough on the batteries, but he rarely ever rides it down the road. Most of his driving is 100-200 yard trips across the property. If he needs the speed he wants to be able to have it.

I went approximately 5 miles and the bms dropped from about 99% charge to about 81%. Seems like it wouldn’t have dropped that much from what I’ve read. That would calculate to approximately 25 mile range on full charge. I’ve read lfp in carts should get close to double that. This is a small sample size I know. The amperage stat can also be calibrated, but I don’t have a good way to do that.

Another concern, when the pedal is held on the floor, the cart seems to cut in and out of power and becomes a little jerky. What would this be? An rpm limiter?

Thanks!

[venquessa]

I would take the BMS state of charge with a pinch of salt. Mine was 25Ah off at the bottom of charge. When I charged them it got to 80Ah and jumped to 100Ah. I figure it might get better over time.

The golf cart itself could have a current limiter or an rpm limiter.

On making it go a little slower, you could modify the pedal. Add a firm rubber block at the end of it's travel, so to get full throttle you have to really press it hard.

[georgia088]

I would take the BMS state of charge with a pinch of salt. Mine was 25Ah off at the bottom of charge. When I charged them it got to 80Ah and jumped to 100Ah. I figure it might get better over time.

The golf cart itself could have a current limiter or an rpm limiter.

On making it go a little slower, you could modify the pedal. Add a firm rubber block at the end of it's travel, so to get full throttle you have to really press it hard.

I made some adjustments inside the alltrax speed controller software. I dropped the "top speed" setting down to 70%. It also has a "turbo setting" that can be selected or deselected. I deselected it. I gave it a whirl and the bms would cut off after about 30 seconds at WOT. This didn't make any sense to me, but it did it three different times. I decided to reselect the "turbo" and increase the "top speed" back to 90%. I drove around about 6-7 miles with no issues at all. It still seemed to run about the same speed as before. The studdering at top speed was still there, but maybe not as bad? What do you think would cause the bms to cut off when I lowered the "top speed down to 70% and deselected the "turbo" feature?

Thanks!

[georgia088]

This is what the alltrax manual says "turbo" does:

TURBO (ON-OFF)

Provides higher seed when not in current limit and throttle is at 100%

[georgia088]

I would take the BMS state of charge with a pinch of salt. Mine was 25Ah off at the bottom of charge. When I charged them it got to 80Ah and jumped to 100Ah. I figure it might get better over time.

The golf cart itself could have a current limiter or an rpm limiter.

On making it go a little slower, you could modify the pedal. Add a firm rubber block at the end of it's travel, so to get full throttle you have to really press it hard.

I am back at the pcb design for my dual source solar panel control board. As I have never worked with surface mount components, I am not exactly sure what is the best way to handle the grounding of them. I typically and in this case plan to use a ground plane on the bottom of the pcb. For through hole parts, this is simple. However, I need to be able to get grounds to the top of the pcb. What is the best way to handle this? Should I use the ground plane on the bottom and just place a via right at the point of the ground pad of the surface mount component? This would bring the ground up to the top and only have a short distance of travel on top of the board? Or, is there a better way to handle this?

Thanks!

[venquessa]

Plated through hole vias. For example a DC barrel jack, surface mount, if the ground plain is bottom only, then I would bring a track out and then stitch it 3 or 4 times.

For higher amps than 1 or 2, you will need to do some research. A technique you see quite often is to use the top of the board as a positive plain and the bottom a negative plain. When you need to pass, say negative up to the top for a power mosfet use a square area of plain on both sides and stitch it with a grid of vias.

Do not be afraid to use physical cables to span the PCB for current paths if the traces might not be enough. You can also place a mask over traces to mark them to "NOT" be covered in solder mask. If you do that, then you can flow a lot of solder onto the track to help it carry higher currents.

Most of the ground plain and stitching details surround noise suppression, both incoming and outgoing. That only really comes into play when you have anything requiring signal integrity, like digital comms or high frequency analogue control signals. For basic power management noise probably won't be a concern.

Additionally Via's can be used under power components to create a thermal mass with lots of copper to "wick" away the heat. In small cases this can even save you from needing a heatsink.

[venquessa]

As a general, often ignored, rule ... do NOT forget your ground return paths. For every component you route also check how the ground current flows back from it. Try to keep those as short as possible. If you, for example, create a penisula on a ground plane, then all of the ground connected on it will have to pass their current via that narrow pennisula. In some cases the ground plain can end up like a maze for the return currents. That will create issues including cross board ground variance.