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-   -   Charging Amps? (https://www.buggiesgonewild.com/showthread.php?t=29623)

BJustice 02-26-2010 02:14 PM

Charging Amps?
 
I have a 36V, ’88 Marathon that came with an old style, 36V charger. The charger has three options for charging - High, Medium, or Low. These equate to 20 amps, 16 amps, and 12 amps. The amperage does drop as the batteries are reaching fully charged.

Which selection would be best to use when charging my cart?

I'm getting ready to buy new batteries and want to make sure I treat them well.

Thanks!

dougmcp 02-26-2010 02:46 PM

Re: Charging Amps?
 
Any of the selections are fine. IMO, I would choose the 20 amp setting, my charger starts at 25 amps.
It will only cycle at that level for an hour or so before it starts to reduce in amperage as the voltage increases.
Most chargers have no option and start at the higher amperage.

golfcarfixer 02-26-2010 04:04 PM

Re: Charging Amps?
 
Dont think i have ever seen a charger like that only ones with timer dials on them.

Tech Support 02-26-2010 04:27 PM

Re: Charging Amps?
 
I was always taught that the gentler you pump the current in, the better for the batteries. If I had time, I would recharge at a lower amp rate and let it go, rather than starting high and slamming the current it right away. If I had time, that is.

sunking 02-26-2010 05:25 PM

Re: Charging Amps?
 
Quote:

Originally Posted by Tech Support (Post 368612)
I was always taught that the gentler you pump the current in, the better for the batteries.

That is not quite accurate and leaves to much guess work to know what gentle means.

As a generic rule no more than the C/8 rate which means the battery 20 hour amp hour rating divided by 8. So for a Trojan T-105 with a 225 AH rating = 225/8 = 28 amps is the highest current you want to supply and will fully charge the a completely dead battery in theory in about 10 hours for 5 hours for a 50% DOD.

Ideally the seat spot is from the C/10 to C/14 rate. This is why you see most cart battery chargers in the 25 to 16 amp range. There are two reasons for this:

1. is a condition of stratification. Stratification is where the heavier component of the electrolyte (sulfuric acid) will settle to the bottom of the battery leaving the lighter water on top which accelerates the formation of lead sulfate crystals on the battery plates. Lead Sulfate crystals are the death of batteries and the main cause of 90% of all battery failures. The higher charge rates literally cause a slight boiling action and mix up the electrolyte preventing or correcting stratification.

2. As mentioned above Lead Sulfate crystals is the death of batteries. The soft crystal formation start to form when the specific drops below 1.250 or roughly at 10% DOD. and if left for extended period of times will harden on the plates. Below 50% DOD and the crystals harden, and once they turn hard there is no way to remove them. Ok at a higher charge rate of C/8 to C/12 if you allow the voltage to rise to the Bulk charge voltage of around 2.45 volts per cell the soft crystals are disolved back into the electrolyte and all is well. If they are allowed to harden, there is no return.

Tech Support 02-26-2010 05:29 PM

Re: Charging Amps?
 
I forget we're dealing with deep cycle batteries, which usually end up way below 50% level and need to remove the sulfate. You are correct.

sunking 02-26-2010 07:20 PM

Re: Charging Amps?
 
Quote:

Originally Posted by Tech Support (Post 368665)
I forget we're dealing with deep cycle batteries, which usually end up way below 50% level and need to remove the sulfate. You are correct.

No problem I really did not disagree with with just added some details because slow does not have much of a meaning to me, and there is apoint where to low of a charge current is too low and will not do what you expect besides take forever.

I did forget to add one thing I would like to point out to folks and that is the charger themselves. I have never bought a new cart, I can afford to I just never pay retail for anything. All the carts I have bought I do not take the charger, so what I might say may not be true in all cases about them, but I do know about batteries and charging algorithms.

Most of the stock chargers i see, at least for EZ-GO are constant current types with timers. Correct me if I am wrong. That being the case they are pretty much useless IMO. I think the CC line uses constant current but the controller on the cart has a signal lead to tell the charger to turn off when the batery is charged?

Ok enough beating around the bush. If your charger is constant current with only a timer, chances are pretty darn good you are frying your batteries. As I said earlier Sulfation is the number 1 killer, but there is another killer even more deadly than sulfation, and that is plate errosion. Keeping batteries is a delicate balancing act betwen over charged and under-charged with a very fine line in the middle. On the under-charged side is sulfation already discussed. On the over charge side is plate erosion. The damage is accumulative and irreversible so when the plates erode they are gone and you can't get it back Cocaine. (Yes I am a Erric Clapton fan:lol:)

So how do you fix or control the problem if this is you. Well there is not a good answer, or at least one you will like. You have no real idea od what DOD your battery is in when you connect the charger. With a timed charged you would have to know exactly, run some calculations, and then set the timer. The other option is to get a hydrometer out and continually monitor the SPG level to se when they reach 1.277 for a Trojan, well that sucks.

Imo the real or at least best solution is to chunk the charger and get a real 3-stage battery charger. Just plug it in and forget about it until it is time to go ride. Fisrt stage is a constant current mode called BULK charge and that is applied until the cell voltage reaches approx 2.35,then it switches to ABSORPTION charge which is a constant voltage of about 2.45 volts until the charge current reaches about 3% of the C rate, then it switches to FLOAT mode which is a pure constant voltage of 2.25 volts per cell which is applied until you turn it off and go ride with a 100% fully charged battery.Even if you leave it on for a year your battery is in perfect shape assuming you keep the water level up. Heck you could leave it outside in a sub arctic winter and the battery will be just fine unless it drops below -77 F, then you got a problem of a frozen battery and cracked case.

Ok I will quit rambling on now. :shock:


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