# Rate of chargers

Registered Users Posts: 11
Quoting from the battery FAQ:

"These are sometimes called "taper charge" - as if that is a selling point. What taper charge really means is that as the battery gets charged up, the voltage goes up, so the amps out of the charger goes down. They charge OK, but a charger rated at 20 amps may only be supplying 5 amps when the batteries are 80% charged"

I'm wondering if there is a ballpark way to estimate how long it will take to charge your batteries after factoring in this "tapering". So for the example 20A charger above, what would the average rate be approximately? Maybe 10 or 15 amps?

P.S. - I will be using a Powermax charger if that makes a difference.

Thanks

• Banned Posts: 17,615 ✭✭
Re: Rate of chargers

Peukart at work here, and every battery is different (so to speak). So are various chargers.

There's quite a difference between the preferred charge regime for deep cycle batteries and how most battery chargers perform. The taper charge refers to the battery being brought up to a "stop" Voltage (like 13.8 for automotive chargers) and the current dropping off to a certain minimum as a result (often 2 Amps). That's not very close to the deep cycle process of giving as much current as possible up to a capacity percentage maximum while bringing the Voltage up to over 14, then holding it there until the current drops or sufficient time elapses, and then letting it settle down lower.

You can conduct your own experiment monitoring both current and Voltage while the battery charges and see what figures/times you get. If you can compare this to specific gravity then you've got some reliable data.

It's all relative anyway. Minor discrepancies don't make that much difference. True, it will shorten battery life from the ideal maximum, but usually not enough to worry about. It's the major differences that will cause quick and expensive problems, like too low or too high charge Voltage, current, or time. Don't sweat the one percents.
• Registered Users Posts: 11
Re: Rate of chargers

It almost seems like you're saying that the Powermax chargers don't follow a normal deep cycle process. Or maybe Powermax chargers don't fall under this "tapering" category. I could be using the wrong terminology. Or am I reading you wrong?

What I'm trying to do is decide which size of charger to buy, but it depends on how much the charge rate is going to drop off. The longest the charger can take to recharge my batteries is overnight, and I might be willing to buy a bigger charger to charge them faster but only if I have some sort of a guesstimate on how much faster it would be. I'm using SLA batts so I don't have access to specific gravity.

Also, do those Powermax chargers have adjustable voltage settings?
• Solar Expert Posts: 5,183 ✭✭✭✭
Re: Rate of chargers

look at the specs on this one..scroll down to page 3 or so http://www.meanwell.com/search/pb-1000/pb-1000-spec.pdf

hth

KID #51B  4s 140W to 24V 900Ah C&D AGM
CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM
Cotek ST1500W 24V Inverter,OmniCharge 3024,
2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
• Banned Posts: 17,615 ✭✭
Re: Rate of chargers

From the "blurb":

The PowerMax deep cycle battery chargers are very similar to the Iota brand chargers. The PM3 series is a three stage charger (Float, Absorb & Bulk Modes). A three stage charger is much more efficient than a standard battery charger and can also increase the life of your batteries versus using a standard charger.

So it is a 3-stage charger, eliminating the main drawback of most chargers. But its specs don't indicate that the Voltage points are adjustable (a problem with almost all stand-alone chargers). You can read through the manual here: http://lib.store.yahoo.net/lib/wind-sun/PowerMax-PM3-manual.pdf

The Voltages seem to be set for middle-of-the-road where they'd work for either AGM or FLA's, but are a bit low for some FLA's.

As far as the size is concerned, just don't get one whose maximum capacity exceeds 13% of the battery bank's total Amp hours (some exception with AGM's). Targeting 10% or so will give you about the fastest charge rate you can get without exposing the batteries to excess current.
• Solar Expert Posts: 407 ✭✭✭✭✭✭
Re: Rate of chargers

The first analogy for battery charging that made sense to me was trying to fill a 5 gallon can of gas.

When it is empty, you can fill it with a high flow rate.
If you don't slow the filling rate as you get close to the top, after you finish and the bubbles settle, it will not be completely full.
If you want it to fill completely, you need to slow the flow to a trickle to top it off.

Alex Aragon
• Solar Expert Posts: 2,490 ✭✭✭
Re: Rate of chargers

Sounds like you already have a PowerMax, keep a eye on it if you have any load on the batteries if you keep it plugged in. It's basically a Power Converter made for the RV Industry with a kind of " Me Too " that lets them claim it's 3 stage. If you have a load it will never drop into the 3 rd stage. The absorption phase is for a fixed 7 hr period. Yes, I own one, my first and last.

Bulk 14.2
Absorb 13.6
Float 13.2

What you'll find is it'll hit the bulk trigger then it drops to the 13.6 Absorb for 7 hrs and it'll never charge your batteries correctly. Maybe mine is a bad one, I'd just never buy another one, cheap, but it'll cost you in battery life.
• Solar Expert Posts: 3,738 ✭✭✭✭
Re: Rate of chargers
As far as the size is concerned, just don't get one whose maximum capacity exceeds 13% of the battery bank's total Amp hours (some exception with flooded).

Cariboocoot, Don't you mean to say that the exception to exceeding 13% is AGM batteries?
4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
• Registered Users Posts: 11
Re: Rate of chargers
westbranch wrote: »
look at the specs on this one..scroll down to page 3 or so http://www.meanwell.com/search/pb-1000/pb-1000-spec.pdf

hth

@westbranch:
That converter looks pretty sweet. I've been very happy with Meanwell's stuff in the past. Does anyone else have experience with this piece or are there other recommendations?

@Cariboocoot:
Thanks for the info. I would expect the inability to change the charging voltages would have a relatively small impact when compared to other issues, like not using a 3-stage charger in the first place. Or is it a big problem that will significantly reduce my battery life?

@SolaRevolution:
Great analogy.

@Blackcherry04:
Of course you tell me this the day the converter ships Too late at this point but I'll definitely keep an eye on it. The good news is that I never charge the batteries with a load (unless you count the 3-4mA draw from permanent voltmeters). These poor batteries have been so thrashed already.
• Banned Posts: 17,615 ✭✭
Re: Rate of chargers
vtmaps wrote: »
Cariboocoot, Don't you mean to say that the exception to exceeding 13% is AGM batteries?

Yup; you're absolutely right!
May you never get as confused as me.
• Solar Expert Posts: 5,183 ✭✭✭✭
Re: Rate of chargers

Just to be clear , that is a charger, converters are an RV contraption . Some quick reading at http://www.smithae.com/rv.html re converters.

KID #51B  4s 140W to 24V 900Ah C&D AGM
CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM
Cotek ST1500W 24V Inverter,OmniCharge 3024,
2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
• Solar Expert Posts: 3,738 ✭✭✭✭
Re: Rate of chargers
tanders12 wrote: »
That converter looks pretty sweet. I've been very happy with Meanwell's stuff in the past. Does anyone else have experience with this piece or are there other recommendations?

A forum member, SteveK, commented extensively on the Meanwell in this thread:

In another thread a couple of days ago SteveK indicated that he was about to go backpacking, so I don't know if he will chime in or answer any PM's for awhile.

--vtMaps
4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
• Banned Posts: 17,615 ✭✭
Re: Rate of chargers
tanders12 wrote: »
@Cariboocoot:
Thanks for the info. I would expect the inability to change the charging voltages would have a relatively small impact when compared to other issues, like not using a 3-stage charger in the first place. Or is it a big problem that will significantly reduce my battery life?

For most batteries it will not significantly affect lifespan. The tall case batteries (L16) will not like it, as they need lots of higher Voltage activity to remix the electrolyte properly. Obviously you will not be able to do an equalization charge with one of these.
• Solar Expert Posts: 2,490 ✭✭✭
Re: Rate of chargers
tanders12 wrote: »
@Blackcherry04:
Of course you tell me this the day the converter ships Too late at this point but I'll definitely keep an eye on it. The good news is that I never charge the batteries with a load (unless you count the 3-4mA draw from permanent voltmeters). These poor batteries have been so thrashed already.
Well, thats the story of my life " a day late and a dollar short ".

I actually have mine working pretty good. I drilled the case open and cranked the output pot wide open and it's output is 15.5 V. I have it hooked to a Xantrex C 30 charge controller. That allows me to have full output and control it without the weirdness they built into it. Only problem, it added about \$90 to the cost, for that I could have had a real charger.
• Banned Posts: 17,615 ✭✭
Re: Rate of chargers
Well, thats the story of my life " a day late and a dollar short ".

I actually have mine working pretty good. I drilled the case open and cranked the output pot wide open and it's output is 15.5 V. I have it hooked to a Xantrex C 30 charge controller. That allows me to have full output and control it without the weirdness they built into it. Only problem, it added about \$90 to the cost, for that I could have had a real charger.

I can understand why you did this, but it's not a good idea. The output from most chargers is not very "clean" and charge controllers may not like it. A PWM controller would be more tolerant than an MPPT.
• Solar Expert Posts: 2,490 ✭✭✭
Re: Rate of chargers
I can understand why you did this, but it's not a good idea. The output from most chargers is not very "clean" and charge controllers may not like it. A PWM controller would be more tolerant than an MPPT.
The Xantrex C 30 is a PWM controller. I use it 24/7 for over a year with no issues. It allows me to control all voltages and Equalize with it. I am stuck with a 2 hr fixed Adsorb, but I can live with that.

Again, I could of had a better charger for the amount I have in both of them. My choice for a cheap charger is the IOTA IQ4 as a plug in unit, I have two of them and couldn't be more pleased. I do believe a PF corrected charger is the best for the long haul. The best a IOTA or PowerMax is going to be is around .67 or so.
• Registered Users Posts: 11
Re: Rate of chargers
vtmaps wrote: »
A forum member, SteveK, commented extensively on the Meanwell in this thread:

In another thread a couple of days ago SteveK indicated that he was about to go backpacking, so I don't know if he will chime in or answer any PM's for awhile.

--vtMaps

There's a lot of good info there. Don't understand most of it. I will most likely need another charger in addition to the Powermax. After I get done evaluating it I'm going to seriously consider one of those Meanwells
• Solar Expert Posts: 2,490 ✭✭✭
Re: Rate of chargers

I have no reason to bash the Meanwell charger, but it's a 2 bank charger. Being from the Boating world and having many, many chargers, a multi bank charger is something I stay away from. 2,3,4 bank chargers just seem to have problems with whatever circuitry controls the way it skips from bank to bank. Again, I don't know if it's just my luck and my many friends, but they can have issues. If you don't have 2 banks to charge, don't invite a problem. You can end up with one bank way over charged and one way under charged. If you only hook up one, it may not be as big a problem, it will still skip and check the open bank.
• Banned Posts: 50 ✭✭✭✭
Re: Rate of chargers
As far as the size is concerned, just don't get one whose maximum capacity exceeds 13% of the battery bank's total Amp hours (some exception with AGM's). Targeting 10% or so will give you about the fastest charge rate you can get without exposing the batteries to excess current.

Many think that's snail pace charging (13%). It will shorten battery life.

How about charging at 100% of battery capacity when battery is at 100% SOD! That's one amp per battery capacity times SOD. That means if you got a 220Ah battery at 50% SOD, charge rate is 110A. Now that's flying!

http://evbatterymonitoring.com/WebHelp/Battery_Book.htm#Section_3.htm

Cal
• Solar Expert Posts: 3,738 ✭✭✭✭
Re: Rate of chargers
I do believe a PF corrected charger is the best for the long haul. The best a IOTA or PowerMax is going to be is around .67 or so.

Regarding the power factor of the Powermax, last December BackToBasics posted:
* A note on power factor*
I'll be using a 1200 watt generator in conjunction with my charger, once I'm actually off the grid that is. I asked Errin if there was any way at all the charger would ever draw more than the max they had listed on their spec sheet. It was very clear I'd be using a small genset and didn't have much AC current to spare. His reply was simply no it wouldn't and all the units have PFC built in.

Another source of info on the powermax: http://forum.solar-electric.com/showthread.php?12916

--vtMaps
4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
• Solar Expert Posts: 2,490 ✭✭✭
Re: Rate of chargers
vtmaps wrote: »
Regarding the power factor of the Powermax, last December BackToBasics posted:

Another source of info on the powermax: http://forum.solar-electric.com/showthread.php?12916

--vtMaps
The point is ?? Are you saying they are power factor Corrected ?? Even their selling features are tricky to figure out. There is a test someone here did on them and they were less than 70%, now what model that was , I have no clue, because their models are all over the place and change often. There instruction Manual has another companys name on it that went out of business, WFCO or something like that.

Power Factor Correction on 75, 80, and 100 amp models.

http://www.bestconverter.com/PowerMax-Boondocker-Converters-_c_154.html
• Solar Expert Posts: 3,738 ✭✭✭✭
Re: Rate of chargers
Are you saying they are power factor Corrected ??Even their selling features are tricky to figure out. There is a test someone here did on them and they were less than 70%, now what model that was , I have no clue, because their models are all over the place and change often.

Blackcherry, I have no idea if they are PFC. One of our forum members claims they are. I have not seen the test you refer to on this forum. Your point about their models being all over the place is certainly consistent with the review at http://forum.solar-electric.com/showthread.php?12916

One thing in favor of the PowerMax is that a very reputable dealer (NAWS) sell them.

Personally, I am looking for a PFC 24 volt charger. I am hoping that SteveK will give us some followup on his Meanwell charger that he wrote about: http://forum.solar-electric.com/showthread.php?10123
--vtMaps
4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
• Solar Expert Posts: 2,490 ✭✭✭
Re: Rate of chargers
vtmaps wrote: »
Blackcherry, I have no idea if they are PFC. One of our forum members claims they are. I have not seen the test you refer to on this forum. Your point about their models being all over the place is certainly consistent with the review at http://forum.solar-electric.com/showthread.php?12916

One thing in favor of the PowerMax is that a very reputable dealer (NAWS) sell them.

Personally, I am looking for a PFC 24 volt charger. I am hoping that SteveK will give us some followup on his Meanwell charger that he wrote about: http://forum.solar-electric.com/showthread.php?10123
--vtMaps
As always, The Dealer is the key. The guy at PowerMax is a nice Guy " Errin Tipple " or something like that. I talked to him trying to make some sense of what the charger was supposed to do. As I said, it's a almost 3 stage charger of sorts.

I am adding this from their owners manual, this NOT a normal 3 Stage charger profile.