How long to charge batteries

[techie1]

I understand we have to say hypothetically since we don't know exactly the SOC. As a reference, I have read to buy a charger that matches the amp charge to at least 10% of the Ah ( 226Ah @20 Amps). So in my case, I would look at buying a charger that outputs at least 23 amps at full output. So my question is, given this statement, which is probably debateable, if I discharge my batteries at exactly 50%, my charger can output 25amps then what is a general guideline to how long will the batteries take to charge?
My problem is ending my hunt at 7pm and starting my hunt at 4am does not give the charger long enough to fully charge (15amp powerdrive charger). So I would like to have something that will fully charge the batteries on a hunting night for the next day and then let my onboard lower amperage charger maintain my batteries or charge when I am not hunting the next day. I have looked at a QuickCharge unit that is 48v 40amp as a last resort. I have also seen one that is a 25amp charger the current powerdrive unit I have max output is 15amps so that would be a 60% increase in potential amps for charging.
Please keep in mind we are talking hypothetical and I am just trying to obtain a standard of thought for charging times given at least three stage charging, consider Ah and charger Amp rating.
Thoughts?

[scottyb]

Your charger may do okay, but a standard Lester 25a stand alone unit would be preferred in my opinion due to the heavy replenishment charge available initially, but most of the charge time is the float or 5a type charge which they all will do...... which is why your charger may be enough. In the morning, has the charger completed it's cycles and shut off? What is the pack voltage at 4am?

[simple man]

I have heard that " quick charging " can be harmful to the batteries. You'll have to wait for one of our electronic techs to help you on this! I do know that the average cart charger is 25amps. Some of the 48V ones are only 15amps. Personally, I would try and get a 25amp charger. If your batteries are good, they should be able to fully charge in 9hrs, with a 25-30amp charger.

[techie1]

Originally Posted by scottyb

Your charger may do okay, but a standard Lester 25a stand alone unit would be preferred in my opinion due to the heavy replenishment charge available initially, but most of the charge time is the float or 5a type charge which they all will do...... which is why your charger may be enough. In the morning, has the charger completed it's cycles and shut off? What is the pack voltage at 4am?

OK. So going forward the standard thought is to have highest reasonable amperage for the 80% charge cycle and the next cycle is normally 5amps which is the topoff charge which the timeframe cannot be reduced because of the slow charge absorption requirement.
The red light is steady and it is a powerwise. However, I just bought new batteries since I could only go on one AM hunt and the batteries were dead. I have not used the powerwise charger on the new batteries. I will try it this weekend and measure the voltage in the AM.

[techie1]

Originally Posted by simple man

I have heard that " quick charging " can be harmful to the batteries. You'll have to wait for one of our electronic techs to help you on this! I do know that the average cart charger is 25amps. Some of the 48V ones are only 15amps. Personally, I would try and get a 25amp charger. If your batteries are good, they should be able to fully charge in 9hrs, with a 25-30amp charger.

I thought the norm was around 15amps peak charging on most chargers.
good to know, that is what I was looking for "a good reference" charge time. So now I know I am not unreasonable to expect the charger cut off in the 10hr range.

[JohnnieB]

Originally Posted by techie1

I understand we have to say hypothetically since we don't know exactly the SOC. As a reference, I have read to buy a charger that matches the amp charge to at least 10% of the Ah ( 226Ah @20 Amps). So in my case, I would look at buying a charger that outputs at least 23 amps at full output. So my question is, given this statement, which is probably debateable, if I discharge my batteries at exactly 50%, my charger can output 25amps then what is a general guideline to how long will the batteries take to charge?

<Snip>

General guidelines are simple.

You obviously have to put back as many Ah as you take out, but the recharging process is only about 80% efficient, so you actually have to put back about 1.25 Ah for each one taken out.

At 50% SoC it'll take about 5.5 hours at 25A and about 9.0 at 15A.


Note: Other than the charger output voltage having to match up the pack voltage, the voltage of the pack is more or less irrelevant since it is a string of 2V cells in series, 18 for a 36V pack, 24 for a 48V pack.

[scottyb]

Originally Posted by techie1

OK. So going forward the standard thought is to have highest reasonable amperage for the 80% charge cycle and the next cycle is normally 5amps which is the topoff charge which the timeframe cannot be reduced because of the slow charge absorption requirement.
The red light is steady and it is a powerwise. However, I just bought new batteries since I could only go on one AM hunt and the batteries were dead. I have not used the powerwise charger on the new batteries. I will try it this weekend and measure the voltage in the AM.

I disagree with this thinking entirely.

New batteries need to be completely charged by a GC battery charger BEFORE use.

New batteries are only at about 75% of their potential capacity until cycled about 20 times. Full strength may take up to 150 cycle times.

During the initial break in some experts suggest you not deplete the batteries below 75% capacity. And there-after never below 50% for the longest battery life although they will recover from 80% discharge, but, this does reduce their useful lifespan.

In conclusion I think you are doing your batteries a disservice which will result in poor performance and shortened life span. My suggestion is get them on a GC charger stat and run them 5-10 minutes a day and recharge until said GC charger cuts off for about 3 cycles like this before you try hunting again.

What I have expressed is my opinion & the opinions of Major GC battery manufactures engineers. This is only meant to help.