how low to take batteries before re charge

[kMD]

I have a 2009 RXV (4 12 volt) batteries. I was told one of the worst things you can do is keep charging the cart when the batteries are still almost fully charged. Somebody said by doing this you are not using up the full cell of batteries its only using the top part of the battery cell and this shortens the life of the batteries. I have been trying to research, some say take battery really low others say 50% charged.

I found a chart in one of the posts it said 12.73 volts is fully charged and 12.1 volts is 50% charged for one battery or 50.93V fully, 50% 48.41V, does this sounds correct?

Also any recommendations on a digital read out volt meter? I wanted one that reads the actual voltage and I will keep a chart with me so I can calculate how much running time I have left. Right now I pop the seat and put a volt meter on each battery.


Thanks
KMD

[JohnnieB]

Sounds like you've been getting bad information from someone that knows absolutely nothing about lead-acid batteries or wants to sell more of them sooner.

Lead-acid batteries have no memory, so there is no need to discharge them before recharging them.

Your cart batteries ought to be recharged after each use, or at least in the evening of the day the cart was used. In other words, don't let the batteries sit overnight in a partially discharged state. In fact, the higher the average SoC (State of Charge) maintained, the longer the battery's cradle to grave lifespan.

Lead-acid cells do not discharge from top to bottom. The discharge occurs over the entire electrolyte to plate interface simultaneously.

It is true that the electrolyte will stratify as the batteries sit and the heavier acid tends to sink to the bottom of the cell, causing the lower portions of the plates to be more active, but the charging process mixes the electrolyte and driving the cart shakes the batteries enough to keep the electrolyte mixed.

RXVs have a very touchy electrical system, so the safest bet is to connect a DVM type battery meter directly to the battery pack's main positive and negative terminals and let it run all the time, or add a switch to one of the meter's leads to turn it on and off completely separate from the cart's electrical system. https://www.cartsunlimited.net/battery-meters.html

Also there are different SoC charts for different brand batteries. 50.93V is 100% SoC for Trojan brand batteries. What brand batteries do you have?

[cgtech]

Heres a chart to illustrate the relationship between average soc maintained vs battery lifespan.

[scottyb]

Hard to believe anybody is still out there spewing this myth. I thought we straightened all of those old school battery abusers out

[kMD]

I have crown cr-gc155 I just got them.

So I should plug it in after every use even a quick run and always keep them charged?

If I am out for a long run what is the lowest I should take the batteries without damaging them?

Thanks for the advice I am new to this.

[JohnnieB]

Originally Posted by kMD

1. I have crown cr-gc155 I just got them.

2. So I should plug it in after every use even a quick run and always keep them charged?

3. If I am out for a long run what is the lowest I should take the batteries without damaging them?

4. Thanks for the advice I am new to this.

1. Attached is a SoC chart for Crown brand cart batteries.

2. If it is convenient to do so, yes. Otherwise just put it on charge that night.

If the "quick run" is over a couple miles, I'd opt for charging.

My charger is located in a detached garage and if I suspect I'll be making another short trip in the next few hours, I leave the cart close to the back porch and don't put it on charge until I put the cart in the garage for the night.

3. Technically, irreversible physical damage starts occurring at about 1.50VPC (Volts per Cell), or about 36.0V for a 48V pack. During non-destructive testing, the cells are not dropped below 1.75VPC, or about 42.0V for a 48V pack. However, the recommended low voltage cutoff for some controllers is 38V for a 48V pack, so try to stay above 38V on the dash mounted DVM while driving cart.

If you are asking how low of a SoC % can you take the batteries to before recharging, about 50% is the typical max distance driven before recharging, but the SoC is based on an At-Rest voltage and you have to stop the cart and let the batteries rest (recover) for several minutes to get a voltage for a SoC estimate.

In a nutshell, battery voltage drops when amps are drawn. The voltage drop is almost instant, but the voltage recovery after the amp draw cease is slow. (Up to any hour or more.) When I'm out and about and want to know how much usable energy I still have stored in my battery pack, I let the batteries rest about 10 minutes. The SoC estimate will be on the low side since the voltage hasn't fully recovered, but that is good.

4. We all had to start someplace.

[kMD]

Thanks for all this great info a couple more questions.

1. The chart attached I want to make sure I am reading it correctly. For my crown batteries if I run batteries down to only 10% of charge (about 46 volts). The amount of charges I can get out of the batteries would be about 600. But if I only run batteries down to 90 % of charge (about 50.47v) left I can get 5200 charges out of the batteries. Is this correct?

2. The digital volt meter I assume I wire red to pos of first bat and black to neg of last battery? Do you wire it directly where it is always on, or ad a toggle switch or wire it to key on?

3. Should I always leave cart charger on even when fully charged or remove once charged. I have a ez go Power wise qe charger, model 915-4810

[JohnnieB]

Originally Posted by kMD

Thanks for all this great info a couple more questions.

1. The chart attached I want to make sure I am reading it correctly. For my crown batteries if I run batteries down to only 10% of charge (about 46 volts). The amount of charges I can get out of the batteries would be about 600. But if I only run batteries down to 90 % of charge (about 50.47v) left I can get 5200 charges out of the batteries. Is this correct?

2. The digital volt meter I assume I wire red to pos of first bat and black to neg of last battery? Do you wire it directly where it is always on, or ad a toggle switch or wire it to key on?

3. Should I always leave cart charger on even when fully charged or remove once charged. I have a ez go Power wise qe charger, model 915-4810

1. Yes, that is what the graph says, but there are several more factors that determine battery lifespan, so only interpret the graph as maintaining a higher average SoC means a longer lifespan with all other factors being equal rather than anticipating the number of charge cycles indicated.

Attached is a map showing a more realistic lifespan by region's climate. With dedicated attention to the battery's care, you can get more lifespan than that map indicates, but even under ideal conditions and care, getting the top numbers of=n the SoC chart is unlikely. (Suspect there was considerable PR influence on the upper numbers published by the battery manufacturers. Not saying they lied, but there are ways to favorably skew statistics. From 10% up to about 70% appear to be fairly reasonable, but they start getting iffy from there up in my opinion.)

2. Red is B+ and Black is B-. Do not connect to the RXV's electrical wiring in any way, shape or form or you may be paying out upwards of $2000 for a new controller. They are that touchy!!!

3. Doesn't matter. That charger most likely shuts off when it believes the batteries are charged and must be unplugged from and then re-plugged into cart to start new charging cycle.

[drewloker]

Hello.

I use my 1995 Txt Freedom a little on the weekends. Maybe 10-20 minutes on Saturday, 10-20 minutes on Sunday. And probably never more than a mile at any given time.

Should I still charge every night after use, or would it be ok to charge Sunday...or even every other weekend or so?

My strategy has been to charge when the battery meter goes down one bar from full...which is weeks of just a few minutes here and there. But reading this post has me concerned I have already damaged my 1 year old batteries.

Thanks for the advice.

[Mooncarter]

Originally Posted by drewloker

Hello.

I use my 1995 Txt Freedom a little on the weekends. Maybe 10-20 minutes on Saturday, 10-20 minutes on Sunday. And probably never more than a mile at any given time.

Should I still charge every night after use, or would it be ok to charge Sunday...or even every other weekend or so?

My strategy has been to charge when the battery meter goes down one bar from full...which is weeks of just a few minutes here and there. But reading this post has me concerned I have already damaged my 1 year old batteries.

Thanks for the advice.

Charge it. These batteries discharge a little on their own every day. Just charge it every day. Leave it plugged in.