No converter just battery charger?

I apply 14.8 volts until the battery cells start to bubble 2 per second. Then drop the voltage to 14.2 to finish up. Forty amps initially into a single 100 amp hour battery is not 30%* and it means a significant reduction in generator run time.

*What you can get without overvoltage initially

TIME (meaning a clock) how long it takes your battery to charge to 2 bubbles a second. Then get a timer and fine tune the time to get it down pat.

Time is MONEY and NOISE with a generator. I like to minimize it.

qwerty11 wrote:
So I keep getting different numbers. Could somebody clarify what is the maximum amps you can charge a lead acid battery?

Thanks!

5% or 10% is fine if you have the time.

30% is more practical when using a generator. Even this is fast to 90% then you still need 2 to 4 hours for the last 10% because the charging process slows significantly at the end.

Voltage is key. You want to be 14.2 to 14.8 for fast charging. No real amp limit.

30 amp IOTA converter would work well as a permanent solution.

You get different numbers because "it depends."

The battery itself has an "acceptance rate" which is the most amps it will take in at the state of charge it is at and the voltage it is at.

There are differences among battery types too, such as between Wet and AGM.

You start out at a fairly high charging rate until the battery gets up in state of charge (SOC) and then hold the voltage there while amps taper off as SOC keeps rising. So the charging rate slows down after that first part the more the battery gets charged up.

So it is no use talking about 10% or 20% charging rate unless you specify where along in the recharge you are measuring at. The charging rate will change from there.

So I keep getting different numbers. Could somebody clarify what is the maximum amps you can charge a lead acid battery?

Thanks!

Battery chargers like converters come in two basic types (Times a bunch on Chargers)

Smart and "Dumb"

The Magnetek 6300 series (As an example of a Dumb converter) was well known as a bnatery killer,, Why, because it did not have the "Smarts" to know when to quit so it kept on a-charging and a-charging even though the battery was full.

Many multi-amp chargers are like that (I do not know nor do I intend to research the one you have).

On the other hand the Progressive Dynamics 9200 line is a SMART converter/charger, it DOES know when to stop.

And so do the "Smart" automotive chargers.

Consider this brochure report from Progressive Dynamics on how long it takes to charge a deep cycle battery. This is battery science here not many short cuts around it.

"Progressive Dynamics ran this test on the amount of time it took a PD9155 (55-amp) converter/charger set to three different output voltages to recharge a 125 AH (Amp Hour) battery after it was fully discharged to 10.5-volts.

14.4-VOLTS (Boost Mode) – Returned the battery to 90% of full charge in approximately 3-hours. The battery reached full charge in approximately 11 hours.

13.6-VOLTS (Normal Mode) – Required 40-hours to return the battery to 90% of full charge and 78-hours to reach full charge.

13.2-VOLTS (Storage Mode) – Required 60-hours to return the battery to 90% of full charge and 100-hours to reach full charge."

This report is real good info if you want to re-charge your battery back up to its 90% charge state in a quick three hour generator run time if you are camping off the power grid.

Rule of thumb around the battery folks here is to use around 20AMPs charging source for each battery in your battery bank...

Just my thoughts
Roy Ken

10% is great with utility power. Makes for long run times with a generator.

Tom_M wrote:
As stated above, 12 amp is not ideal. It would take at least 9 hours to charge a typical 100 AmpHour battery from dead to full charge. A portable battery charger is a good idea. I used a Stanley 40 amp charger that worked well until it blew up. Both Stanley and Black & Decker make a 40 amp charger for about $100. I used the Stanley to supplement my solar on those cloudy days when solar couldn't keep up. With a portable charger you would have the flexibility of using it for other charging needs.

I thought the most you should charge a batter is 10% of rated Ah. So a 114 Ah battery should be charged no more than 11.4 amps. Am I wrong?

As stated above, 12 amp is not ideal. It would take at least 9 hours to charge a typical 100 AmpHour battery from dead to full charge. A portable battery charger is a good idea. I used a Stanley 40 amp charger that worked well until it blew up. Both Stanley and Black & Decker make a 40 amp charger for about $100. I used the Stanley to supplement my solar on those cloudy days when solar couldn't keep up. With a portable charger you would have the flexibility of using it for other charging needs.

mena661 wrote:
You could get a small DC-DC converter and save the charger for charging.

:H Not sure what advantage you'd have in converting 12 volt DC to 12 volt DC. The ONLY difference between a stand alone charger and an RV power converter is that the charger just isn't permanently installed. BOTH will charge the batteries only when plugged into 120 volt power and NEITHER will do anything when not plugged in. Using a low cost stand alone charger is perfectly feasable but you CAN go too cheap. Get one with a maximum charge rate that is equal to about 25% of your total amp hours in your batteries. It should also be a multi stage charger so it only inputs the correct voltage necessary determined by your batteries needs. You can find these chargers for under $50.00 at many locations.

Good luck / Skip