Battery question

[B_Mo]

I recently took a stock 36v to 48v with FSIP high torque motor, Alltrax 500 400amp solenoid and brand new T875s. I Used my new Lester II charger To charge the batteries. I took a couple of test drives 10 min total and then parked it. I didn’t plug it back in after the test drives because I thought you are supposed to take them down to 75% before charging them. 2 days later (today) I am about to go ride with a friend and I plugged the Lester in just to see where the batteries were and they were at 48% (according to the charger). I have no accessories hooked up and I thought everything was wired correctly because it runs great. Am I wrong in thinking that batteries should hold a good charge while not in use? Before the comments com, I already have the battery meter from Scotty B, but haven’t been able to get it put in yet. Could the Lester be giving me bad info? I just checked it again (10 min later) and it’s at 95%

[DaveTM]

What does your Multimeter say? How many volts does the pack read?

[B_Mo]

Originally Posted by DaveTM

What does your Multimeter say? How many volts does the pack read?

Don’t have one. I do smell something strange coming from the battery area while charging. Could that just be new wires getting broken in?

[JohnnieB]

Originally Posted by B_Mo

I recently took a stock 36v to 48v with FSIP high torque motor, Alltrax 500 400amp solenoid and brand new T875s. I Used my new Lester II charger To charge the batteries. I took a couple of test drives 10 min total and then parked it. I didn’t plug it back in after the test drives because I thought you are supposed to take them down to 75% before charging them. 2 days later (today) I am about to go ride with a friend and I plugged the Lester in just to see where the batteries were and they were at 48% (according to the charger). I have no accessories hooked up and I thought everything was wired correctly because it runs great. Am I wrong in thinking that batteries should hold a good charge while not in use? Before the comments com, I already have the battery meter from Scotty B, but haven’t been able to get it put in yet. Could the Lester be giving me bad info? I just checked it again (10 min later) and it’s at 95%

The 75% Soc is a limit rather than a goal. In other words, don't take them below 75% SoC until they are broken in.

Charge after each use, or at least every night if the cart has been used during the day, just like you do after they are broken in.

In general term, lead-acid, wet-cell, deep-cycle batteries self-discharge at about 1% SoC per day. Some make/models faster, some slower and faster when warmer and slower when cooler.

The controller has a bunch of filter capacitors that are kept charged to near battery pack voltage to reduce the amount of arcing on the solenoid's contacts as they bounce during closure. For safety, the capacitors have a bleeder network that discharges them so people don't get zapped when they pick up a disconnected controller at touch the wrong place. So controllers draw a few milliamps all the time it is connected to the battery pack and a the Run/Tow switch is in Run if it is a sepex controller.

All the charger and DVM or battery meter have to go on is battery pack voltage and the only time that battery pack voltage can be used to estimate SOC is when they have been at rest for about 12 hours after being charged or about an hour after being used. Otherwise they are transitioning from the On-Charge voltage or the Under-Load voltage.

The difference between 50% SoC and 90% SoC is about 2.0V while the difference between On-Charge and Under-Load voltage can be up to about 20.0V, so a bar graph type battery meter doesn't stand much of a chance of accurately estimating SoC unless the cart is stationary and has been so for a while.

The charger calculates SoC based on the On-Charge voltage, so it is going to display a very low SoC when first attached to the battery pack. Let it charge for a minute or two before reading the SoC.

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FWIW: The only way to accurately measure the SoC of a cart battery is to measure the Amp flow over time as it is being discharged. In other words, the only way to find out how much energy a cart battery holds is to empty it and measure what comes out.

There is coulomb counting (Amps in vs Amps out) but a cart battery's storage capacity varies with temperature and how much can be removed varies with the rate it is removed at. Charging efficiency is also a variable.

[B_Mo]

Thank you Johnnie. We don’t put it though heavy use. We don’t even use it daily. Just took it out and will plug it in after using it from now on. I just thought if we only use it to drive around the neighborhood a little, I should wait for about a week before plugging it back in instead of constantly keeping it plugged in. At least until I have 10-20 charges on it.

[DaveTM]

I would suggest that you pick up a Multimeter (cost around $15...you don't need an expensive one) for future diagnosis of any cart issues.

FWIW

[B_Mo]

Originally Posted by DaveTM

I would suggest that you pick up a Multimeter (cost around $15...you don't need an expensive one) for future diagnosis of any cart issues.

FWIW

It’s on the list for the next Home Depot run. 👍🏼

[Cobra,1]

Most agree charge batteries after every days use.
20 minute drive that day,mine goes on the charger.

The closer you can keep batteries to 100% charge is better for battery life.

If you were to drain batteries down to 80% capacity over a weekend oppose to recharging daily if only drained down to 90% capacity. Daily charging can help battery life.
Use it, charge it.👍

[JohnnieB]

Here is a number of charge cycles available vs average SoC for four of the most popular brands.

The numbers are from the battery manufacturers themselves, so I'd take some of them with a grain or two of salt, but the trend is true.

[cgtech]

If only more electric buyers understood what its really all about. Yep, no "gas engine noise" is not that simple.


And factory "lithium" isnt that simple either. Ezgo shares Nothing with us. Its "theres no problem, or, send it back". Quick turnaround is not a thing for the consumer. They literally give us nothing.