Conversion of 2003 EZ-GO TXT Series Golf Cart to OGRPHY LiFePO4 Batteries 

Just be careful about temperature limits on lithium batteries. Check the specs for max operating temperature and max charging temperature to make sure the weather in your area doesn't go over those limits... It can completely break lithium batteries.

How did the installation and results go? I have the same cart and wondering about how well this is working for this particular 100aH solution, mainly if the BMS ever shuts down because you're drawing too many amps.

Glad to help. But I'll warn you, there will be no range test coming from me... I run it for 50-60 amp hours and then I recharge it. I have no plans of triggering a low voltage BMS trip, because it degrades battery life to run it all the way down. Other folks have done capacity tests on this battery and shown that its capacity exceeds the rating, so that's what you'd have to rely on. Distance is entirely based on the amp-hour capacity of the battery, the top speed of your cart, and its operating current at top speed. As I calculated in the video, this puts my cart at about a 35 mile max distance, but your distance will depend on your cart. Unless these batteries fail, there won't be new info really to add.

Thanks!

Hope he does a update video.....

In short, no, the issue you have had in some other case has not been an issue here. Having the ammeter shunt connected only to the ground end of the system does mean that the meter only sees charging of the lowest battery, and since the charging occurs in parallel there is no guarantee that the other two batteries are experiencing the exact same charge profile. Because of this, it's fairly important to fully charge all the batteries until the charger stops on all batteries, to be sure that each battery is fully charged. Ensuring that the meter determines this as full charge requires that you set a proper full-charge voltage setting (for me, it's something like 40 V across the entire bank) and you need to make sure that you set a proper amp-hour capacity in the meter settings. Putting three 100 A-h batteries in series does not yield a 300 Ah capacity, it yeilds still only a 100 Ah capacity at triple the voltage of a single battery. If both of these are set correctly, then when the charger sees you've hit the full-charge voltage across all the batteries, it should switch the display to indicate full charge and a 100 Ah capacity remaining. Again though, even once it says this, your true full capacity is only reached when the charger ceases charge on all batteries. On the discharge end of things, the reading for current flow is only from the lowest battery ground, but since the discharge is occurring from batteries in series, this current is identical from each individual battery (as long as you don't have any 12V loads being pulled off of a single battery) so it is accurately reading the discharge state of each battery.

Set the amp hour capacity to 100 AH. As for the full-capacity voltage setting, you'll know what to put there once you run a full charge on your battery set. For example if it goes to 39.9 V on a full charge, then make this setting be 39.9 or 39.8V (this will cause the screen to show 100 percent charge when crossing that threshold during charging). These two settings are the most important. Everything else is personal preference. If you want alarms for low remaining capacity, you can set that to 20 percent or 10 percent or whatever you want. As for low voltage trips, use the OGRPHY manual as a guide. I don't have the voltages memorized but for example if it says that 10 percent remaining battery corresponds with a voltage of 12.1V, then you can set your low voltage alarm at 36.3 Volts to get a warning at that point. But again, that's personal preference.

If it is just a single initial spark, and if you have a stepdown converter, it's possibly the capacitor charging on the initial connection. Happened to me too. But if it's a continuous spark that makes you really question the situation, I'd recommend checking for a wiring issue by bolting all the positive leads together, bolting all the negative leads together, and then checking resistance from the positive side to the negative side using a multimeter. If the key is off, the multimeter should read as "OL" (open loop) or possibly on the order of mega-ohms when measuring across the leads. If you get something more on the order of a few ohms, then you might have accidentally gotten a lead mixed up, or there could be a "ground" in your system that was responsible for killing your old batteries and now threatens your new ones.

That NOCO charger is for 12V nominal batteries, which are actually well above 12V at full charge. The output by the NOCO therefore is a higher voltage, because you need a voltage difference to drive current into the battery. I don't recall the exact maximum I've seen it at, but it esablishes a voltage that drives a 10A charging current, which for me I think has been on the order of 14V per channel. Even without an installed meter, it's easy to check with a multimeter while charging but I've had no issues at all and I've been running it for over a year at this point.

If you currently have 4 12V batteries, then 4 of these will provide the same voltage. However, to determine whether they are suitable will require that you figure out what the controller current is on your cart and figure out what the motor current is at full speed (and then follow the logic I covered in the video to identify if it seems like these current values are safely within the battery capabilities). Unless you can make this determination on your own golf cart, I wouldn't recommend moving forward with the swap. If your current cart has lithium batteries you will not need a new charger, but if your current cart has any other type of battery then you really should get a new charger suitable for lithium.

I don't recall looking at the 36V Epoch battery. OGRPHY and a few others offer 36V varieties, but I could not find one that was any more cost effective than going with three 12V batteries. It really all came down to cost. What I am about to say is true of all lithium batteries like this, not just this brand: -Charging with the stock golf cart charger may work in a dire situation, but the charging profile is not a good match for lithium batteries. It probably will undercharge your lithium batteries and degrade their life. -Yes, you can use a single 36V charger that's designed to charge lithium batteries. However this adds some additional requirements. Either you should also install a battery balancing system to make sure that the batteries maintain equal voltage to each other, OR you should manually balance them before you install them and then manually rebalance them about once a year. If you don't do this, then if the batteries drift apart in their charge status over time, you'll end up overcharging one or two of the batteries and shortening their life.

Thank you for the time to update all if us. As you can see, there are many interested in your project. It was well presented and thought out presentation and thoroughly explained in a professional educational manner. Greatly appreciated ! I like the charging system you have and the leads to each battery make complete sense. I had been doing the same process using Pulse Tech Xtreme Results for / Charging units. They seemed to extend the six 6 Volt lead acid Trojan batteries and stay hooked up 24/7 just in the desulfating mode. My question is: I don't have the space you had under your seat as my EZGO is a 92 Marathon so I would have to possibly lay two of the batteries on their side because of the frame configuration under there. I've emailed Orgraphy but never received a response. I assume they can be installed on their side but cannot confirm that yet. Thanks again, please keep us posted on how your set up is performing. Kind regards.

The 36V battery is over 1000 dollars. The 12V battery set is less than 700. There was not sufficient benefit to warrant the extra expense. Yes you can charge them with a single bank 36V charger, but as I discussed early in the video, this can result in the batteries ending up at various charge states over the course of time. If you decide to do this, I would recommend possibly adding on a battery balancing system to help maintain even charge states.

@@metalheadjc Oooh that’s why people always mention balancing these batteries ok never understood now I do. Yes the singles are way cheaper actually on sale right now. Thanks for the info.

That's what I was thinking. Just use a SS bolt with the head cut off with two nuts, tighten together and screw in and tighten down with some blue locktite or, just a drop of red locktite. Remove the nuts, then connect up your battery cables and other wires as you would on a regular battery with posts. Just use caution not to over tighten since the battery terminal holes are shallow and not as sturdy as on a traditional lead acid battery. These batteries are supposed to be coming with " prismatic cells" now, not " pouch cells" which had been the case on some RU-vid tear down videos I watched. I was just contacted by Ogrphy yesterday and advised of this change after contacting their customer service via email.and asking the question.

In short, it took less time to just deal with what I had in the moment than to stop, go buy threading or modify a bolt, etc. It would have replaced a small hassle with a bigger hassle and an extra cost. It also adds a secondary opportunity for the system to loosen, unless you add a threadlocker which is not desirable since it is both electrically insulating and it makes it difficult to remove the threading if I have to send it back.

I have not run them until completely dead, and don't plan on it. The meter I installed says that the cart is drawing about 40 amps when running wide open, so should get 2.5 hours of run time at 14 mph. That puts theoretical range at 35 miles if you run the batteries to nearly dead, but I would probably limit it to about 30 miles to add some safety buffer.

@@deepfriedengineer have you done a full throttle test on it? Does it kick off the bms? I installed my 36v trolling motor battery on my txt and with full throttle applied it kicks off the bms.

@@Backyardpondboys I always drive the golf cart at full throttle when cruising. BMS is nowhere near tripping... The limit is 100A long term and the full speed full throttle current has been only 40A. When taking off, I don't stomp the accelerator straight down, I just drive reasonably. Takeoff current is typically 70-120A but only for a second or two. BMS has never tripped. Uphill I have had currents of 70-80A for tens of seconds. Again, this is less than the 100A BMS trip. The BMS has never tripped for me at all.

@@deepfriedengineer that’s the weird part.. my battery also states 100amp.. looks like I need to do some more reading! Appreciate the info!

All you need is any 4 channel, 12V per channel lithium charger. Here is an example: dakotalithium.com/product/marine-4-bank-40-amp-10-amp-per-bank-12v-onboard-lithium-battery-charger/ If your charge level meter just uses voltage as the way it checks charge level, no it will not give you the info you need. Voltage changes so little over the whole charge range that it would only show a significant voltage drop when your battery is almost entirely dead.

Still going the same as day 1. I have no idea about the internal construction or how it has changed over time, though.

If you could amplify, that would be helpful. I walk through all the wiring that was necessary in this video, mostly just reusing the existing wiring exactly as it sits, so which aspects do you need clarification on?

Sorry, I just saw your other comment saying you mostly got it sorted out. Glad to hear that.

I bought this cart 2 years prior with a working set of lead-acid batteries already installed in it for $2500. Yes, following these steps for a 1.49 kW cart would have the same result, provided that it is a 36V cart (which it probably is, given the low power).

I have no particular affinity for 3x12V. In general, a single 36V battery would be easier to deal with, and if the cost were similar that's the route I'd go so that you don't have to deal with interconnected jumpers and a multichannel charger. I don't have a pulse on all the prices at this second, but historically the cost of the 36V batteries have been too high to justify going that route, and I saved several hundred dollars (all inclusive, considering charging and everything) by going with 3x12V. If the situation were the same again, with the same cost savings, I would do again exactly what I did.

Still going strong! No change in performance.

A battery balancer is only needed if individual battery charge states would diverge over time. That occurs over the long term when the batteries are charged as a bank in series, which yields a guaranteed bank voltage but not a guarantee of any individual battery voltage, and over time the battery charge states may diverge. It can also happen in a short period of time if you pull 12V loads off of one battery rather than feeding those loads via a step-down converter which pulls power from the entire battery bank, as this imposes higher utilization of a single battery. However, when you charge batteries individually, they are explicitly re-balanced each time you complete a full charge, because each battery is returned to an identical full-charge state with the same individual battery voltage difference. Summarily, yes the concern of battery balancing was considered, but for the configuration I have created (particularly with individual battery charging), it would add a cost but no benefit. However, if you decide to charge the entire battery set as a whole using a 36V charger, you will need to separately invest in a balancer.

It could be connected to the same load distribution fusebox as all the other 12V loads. However if the winch current is very high, you'll need to make sure you get a stepdown converter with a higher load capacity. Alternatively, you could power it off of one 12V battery. However if you do this, you will need to ensure that the current doesn't exceed 100A and you'll definitely need to recharge your batteries independently (just as I have them in this video) as soon as possible to keep that one battery from running out of charge. It is important not to use this scheme while using a single 36V charger unless you also have a battery balancer, or else you will overcharge two batteries and undercharge the one that is being used as the winch supply.

Everything is still working the same as when I made this video. I haven't had one issue, and I have not done any maintenance or rework of any kind.

Hydrogen is produced during charging due to electrolysis, not due to a chemical reaction with the idle contents, so hydrogen and oxygen gas are not produced in any concerning quantities when the batteries sit idle: ehs.umass.edu/sites/default/files/Battery%20SOP.pdf