I just installed a Mighty Mite battery pack in my 2000 Gem e825 (4 seater). My trial run went well, top speed of 26 mph. Charged the battery pack and a few days later the speed was only 19-20mph. Nothing is dragging, voltage at 78, no funny noises. I’m at a loss to explain the reduction in speed. From what I’ve read on this forum, if it is a controller issue, I’ll probably have to send it in to be checked. Any ideas before I take that step? Thanks!
When you charged you pack a couple days ago, did you turn off the car via MainDisconnectSwitch or via app? (beyond shutting down via KeyOFF).
I suspect not. 78v divided by 24 cells is 3.25v per cell. Charge the car again and do your hot lap. A fully charged battery will be more up around 81 to 83v. It won’t stay there for long (the nature of Lifepo4 voltage/SOC curve), but if you first tested right after a hot charge then you need to do that again.
Future storage
KeyOFF and parking the car is good for short term, but the car remains partially active and ready to go. The controller is charged and the DC Converter is active. When not planning to use the car it is better to fully shut down the car- ESPECIALLY if going away for more than a couple weeks/months.
Also review what motor is in this car. When was the last time it was serviced?
Beyond a dragging brake, low air pressure in the tires will slow a car down.
Hi! Thanks for responding! I do turn the battery off after I charge it. In fact, I’m going to extend the button from the BMS to the dash so it’s visible and accessible. I’ve never had the controller serviced. I’m using the Delta Q with lead acid programming as suggested by the battery supplier. I noticed after charging overnight the charger was flashing 2 red lights, indicative of low battery voltage. I assumed the BMS shut the battery off when it was fully charged, sending the low voltage signal to the charger. As far as the motor goes, do you know if there is a trouble shooting guide in this forum somewhere? I’m sure the motor has never been serviced. Thanks again for your help!
Are you positive a brake shoe isnt dragging? What you describe is almost classic of a dragging brake
I’ve never had the controller serviced.
Not normally something that needs to be done unless there is an issue.
The neat thing about the MMite is that you can access the BMS via phone app and see exactly what the battery is doing.
I noticed after charging overnight the charger was flashing 2 red lights, indicative of low battery voltage.
Yes and no. It’s more indicative that it lost track of the battery. If the BMS shut down the charge FETs, then the charger simply faulted with the Red(2). This is normal, but you should check via app.
The BMS will normally reset the charge FETs for the next charge cycle, but if there is another issue it may take the battery offline. (it is doing it’s job).
If the battery is not present when you plug in the charger, it will also fault with a Red(2). Verify that it is charging before you walk away.
As far as the motor goes, do you know if there is a trouble shooting guide in this forum somewhere? I’m sure the motor has never been serviced.
I don’t recall (never looked). Most likely you will find a couple of other discussions where others have offered up what they have done. Some motors are easier than others, depending on what you have installed. Depending on your location, there might be someone that can service it for you if you don’t have the skillset/time/tools to do it yourself.
Also, (depending on what motor you have) there may be something better you could be running in your car.
CAn you fully charge battery and post a screenshot of the voltage page?
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Hi, been away from home for a few days. I checked each wheel, nothing dragging, tires are at 30psi. Test drove again, 19-20 mph, like controller is suddenly set for that speed! Attached is a screen shot of the batteries. They have been turned off, last charged about 4 days ago.
I will charge and post pic…
Are you sure that it’s not? Bumped the turf switch.
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Normal if the bms has control of charging.
I’d say that pack is pretty much charged. There are a handful that appear to be saturated and probably ramping up quick(triggering OVP) and shutting off Chg Fets (which appear to have reset in this pic). There are a couple that are lagging behind but the active balancing will take care of those. (Delta is only 6 hundredths of a volt).
Still slow?
Show us a pic of your motor?
Either that or the Motor temp sensor has tripped. I knocked my bypass loose and was surprised how much it affected the performance. Yep- My temp light was on.
Embarrassed here, bumped the turf switch when I was installing a voltage gauge. In my defense, it was sticky and didn’t look to be in turf mode! Cleaned that up. Just got back from an 8 mile test drive, worked perfectly! That would’ve been way past “push” with my old batteries! Thanks for all the help!
Nice!
I almost never think of that switch, half because it is so obvious, but also that I thought turf was actually set to around 11 to 14 rather than 20mph.
Thanks for coming back with the resolution.
I’ve bumped mine enough times it was the first thing I was thinking happened when seeing battery voltages in reasonable ranges. Speaking of batteries, if those are LFP batteries then a 3.5-3.45V top is fine but if they are Li-Ion then they should/could be taken to 4.0V per cell.
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I love it when you make sexy talk like that…
