Quickest way to charge battery

db_cooper

I'm sure the answer is here somewhere but I haven't found it this morning.

I haven't used the generator yet while boondocking (ran the TV once for a bit to get through a morning).   I was planning on running the generator (2400w Westinghouse) plugged into the T@B to recharge the battery,  but I don't know the charge rate of the on board converter.   Would it be quicker to plug in my Battery Tender Plus (1.25 amp) and connect direct to the battery?  Should i get a higher amp charger?   I'd like to take full advantage of the generator to charge as quick as possible.  Current battery is a Group 24,  but planning on upgrading to a Group 27 AGM this spring. 

Thanks for any insight!

ScottG

All other things held equal, charging time is usually a function of charging current (amperage), with higher currents resulting in faster charging. That said, slow charging is generally considered better for the battery, and charging current should never be so high as to overheat the battery. I think the maximum recommended charging current is something like 10-20% of the battery's amp-hour (aH) capacity, depending on the type of battery being charged.

Regardless, 1.25 amp is pretty low for a typical 80-100aH capacity deep-cycle battery. I've never been able to find the charging current for the converter, but I suspect it's not all that high either. My guess is you would do better (at least in terms of time) with a separate high-capacity charger connected directly to your battery.

I know this is pretty general, but that's about the limit of my battery charging knowledge. Hopefully somebody else can chime in with more specific info.  

Nomad

I've got this one...



7.2 amp. Came with 2-3 different cables that have their proprietary plug on the end. Direct wired one to the battery so all I have to do is grab the charger and plug it in. It's a smart charger.
I've never timed how long it takes to get a good charge but at 7.2 amps it's reasonable.
It's also relatively small and compact.
Amazon - https://www.amazon.com/gp/product/B004LWTHP2/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

JohnDanielsCPA

I have that same charger.  Bought at Batteries Plus a couple of years ago.  It handles all of my batteries great!  (2 X 6V, 2 X 12V AGMs and 2 X 12V wet cell).  I can't recall what I paid for it, but was well under $100.  I recommend it as well.

JohnDanielsCPA

Oops, rewind.  I have the G3500.  Not sure what the difference is, but it looks exactly like the G7200 above.

db_cooper

Thanks y'all,  that's what I expected.  Was hoping to not have to purchase another charger,  but I don't want to run the generator more than a couple hours at a time.

TabberJohn

JohnDanielsCPA said:

Oops, rewind.  I have the G3500.  Not sure what the difference is, but it looks exactly like the G7200 above.

3.5 amp instead of 7.2, ~$60: https://www.amazon.com/dp/B004LWVEKS

wizard1880

The CTEK is a great way to charge up.  Like others have said, the built in converter is a poor charger.  Your battery needs 14.4-14.7v to charge correctly, but the converter only supplies 13.7v.  It is capable of 35A, but the low voltage output negates any usefulness of it.

The other charger options like CTEK, Battery Tender, Battery Minder, and any other microprocessor-controlled smart charger will give your battery the 14.4v it needs.  And these are your best choice for charging and long term battery health.  The lame part is, they're slow.

If you really want the best of both worlds, you're going to need to spend some money.  The Xantrex 20A dedicated charger is an excellent choice for your group 24 or 27.  Two golf-cart battery setup?  40A is for you.  So are a myriad of other marine-grade battery chargers on the market, but these are all in the $300-600 range.

Another option would be to replace the WFCO 8735 converter with the Progressive Dynamics model PD4135, a direct replacement.  It offers true 14.4v charging and converter functions for your T@b.  It runs in the $120-150 range.

Let me know if you have any questions about these setups or any others you may have seen.  I'm not a vendor, but just someone who's researched this stuff more than I care to admit . I'd be happy to help.

Ratkity

A generator is a very inefficient way to charge a battery. The Honda 2000i's have an onboard charger, but burn lots of gas to charge a battery (but good in a pinch). Batteries charge at a fixed rate depending on their state of charge at the time or they get very hot and discharge hydrogen gas. There are many threads here that talk about batteries and their differences (plate thickness for deep cycle vs an automotive battery - AGM vs GEL vs Lead-acid). In the end, it takes 24 hours to fully charge a battery and takes 2-4 hours to charge it to 90-95%. That last little bit needs to be done slowly. The onboard T@B converter has a 3-stage charger and is just like most chargers on the market.

I don't think the answer is to buy another charger, but to understand the dynamics of your manufacturer's battery and how to keep in top shape, even if you have to do a few 2-hour charges to extend a trip running solely on battery. Also following jkjenn's (and PXL and Verna's - full timers) recommendations on using other charging devices for iphones and small electronics, having solar or small battery lights, limiting use of battery hogs (the fantastic fan) - among other things. You can even put in a switch for the Jensen radio to turn off the display and phantom charge (someone here did it).

Nomad

JohnDanielsCPA - They have several models getting higher priced as the amps go up.
Ratkity - Takes 24hrs to fully charge...Is that from a dead battery? Or starting from what charge?
Ratkity - The builtin charger on the Honda requires a special cabel and the has no limits, it's a straight charger so you can overcharge from what I understand from a previous thread. Better off connecting a seperate charger with the stages.

Ratkity

PXL, I only know the Honda 2000i had a battery charger cuz you said it was there lol. I have no idea if it's 3 stage, but it does require special cables. I agree a 3-stage charger is the way to go. I didn't know the Honda 2000i didn't have a 3-stage charger. I'm surprised (given the price of the generator). I have the companion one. Still a good generator! I love mine.

24 hrs to fully charge was from a half or slightly below - 12.2 - it depends on the amp capacity of the battery too (and only read that was for deep cycle while I was researching). I was just researching deep-cycle lead-acid battery care too. AGMs charge at a lower bulk voltage (13.8V) so the hydrogen gas doesn't make the sides bulge. Most cheapo consumer chargers just have a top bulk charge state at 13.8V for consumer protection. Lead acid can go to 14.4V (manufacturer dependent) and good chargers have selections for the battery type. Many cheapo "smart" chargers won't even begin to charge a battery under 11.9V for "safety" reasons and don't care if it's AGM or Lead acid - they top out bulk charging at 13.8V. There's a way to get around charging a fully discharged battery that doesn't have dead cells using a cheapo charger (Youtube video).

db_cooper

Sounds like replacing the converter is the best use of $150 compared to a new charger.   I plan on using solar in the summer,  but for some ski trips in cold weather I want to be able to top off the battery with a few hours of generator use at the max.  

I'm assuming the PD 4135 is pretty straightforward to install even if you're not a wizard?? 

Ratkity

db_cooper said:

Sounds like replacing the converter is the best use of $150 compared to a new charger.   I plan on using solar in the summer,  but for some ski trips in cold weather I want to be able to top off the battery with a few hours of generator use at the max.  

I'm assuming the PD 4135 is pretty straightforward to install even if you're not a wizard?? 

db, a battery tender (after re-reading your post) won't charge your battery, but will maintain it's current charge. The "Battery Tender" brand makes a full 3-stage smart charger (which is compact and I like) that will charge your battery to full (use it on my motorcycle). I also have a humongous charger that has lots of trouble-shooting lights and can be tailored to your battery type. I can hide the little compact one under the bike cover (plus it has the SAE pigtail for my bike). I'm afraid the monster charger would walk away if I left it there unattended.

Dalehelman

What kind of charge rate does the average tow vehicle alternator put out?

TabberJohn

wizard1880 said:

The CTEK is a great way to charge up.  Like others have said, the built in converter is a poor charger.  Your battery needs 14.4-14.7v to charge correctly, but the converter only supplies 13.7v.  It is capable of 35A, but the low voltage output negates any usefulness of it.

What year T@B has what converter model?
The WFCO 8735 may be a slow charger, but specs indicate it is a 3 stage unit.
3 Stage Converter/Charger Voltage Output: 13.2 - 14.4 VDC Range  
Normal mode: 13.6 VDC
Trickle charge mode: 13.2 VDC
Bulk charge mode: 14.4 VDC

rfuss928

The built in WFCO 8735 converter will output up to 35 amps charging a deeply depleted battery.  It is a good 3 stage charger that works well for most T@B owners.  Typically it runs 10 to 15 amp rate (bulk charge) during mid state of battery charge.  Voltage switches up to 14.4 - 14.8 and much lower amps (<3) during the final saturation stage of charging.  It takes a large external charger to get charge rates this high.
Most any generator will provide enough power to run the converter or any other charger to it's capacity.  Two or three hours should easily replenish 50 - 60 amp-hours using the on board converter.  Absolute saturation to 100% rated capacity of the battery will take much longer with any charger because the rate falls to 1-2 amps during the final stage of charging.
A couple hours of generator every day or two should keep up with conservative power use including the T@B's 12v refrigerator.

Jltab

Hi,
I bought this one from amazon, can I use this charger connected to generator?
Thanks

https://www.amazon.com/gp/aw/d/B000H961YI/ref=mp_s_a_1_24?ie=UTF8&qid=1483837453&sr=8-24&pi=AC_SX236_SY340_QL65&keywords=battery+charger

wizard1880

Oops, there's some misinformation out there-- The battery tender is capable of fully charging your battery.  At 1.25A however, it's very slow.  It is a true 3-stage microprocessor controlled battery charger with 14.4v charging rate.  It may take 2-3 days to fully charge if the battery is low, but it will fully charge.  Flooded lead acid batteries love slow charging, as long as it reaches 14.4v during the bulk charge phase (1).

No lead acid battery will get a full charge at anything less than 14.2-14.7, depending on the battery style.

There's literally hundreds of threads, over the last decade or so, with complaints about WFCO converters and their supposed 3-stage charging.  It is not possible for it to enter bulk charge mode (14.4v) with the default wiring in our T@Bs.  To explain why goes beyond the technical depth of this forum.  Please, I promise I'm not making this up--google for yourself--if you are dependent on your converter to attain a full charge, you're not getting it.  Watch your voltmeter or connect one to the battery during charging, and you'll see it never goes above 13.7 or 13.8!  WFCO converters are used by most RV manufacturers only because they can produce them quickly enough in China for everybody.  Almost all competitors are made in USA.

OK, I'll get off my soapbox now.

Nomad

wizard1880 - "To explain why goes beyond the technical depth of this forum" - I didn't know this forum had limits. Am betting some take that as an insult.

Subism

wizard - you say "with the default wiring"; does that mean it is capable if it is wired differently?

ChanW

wizard1880
I'm open to technical depth.

Seems lots of folks here are!

ColoradoJon

wizard1880 is correct, the WFCO converter that comes in our T@Bs is not very good.  My dual 6V system would not fully charge with the WFCO converter end I ended up using a battery tender junior to complete the job!  Yeah, it took over a week to top the batteries up but it worked

Excellent suggestions offered in this thread regarding external charges.  I would like to recommend the Pro-Logix PL2310 charger.  At $60 this charger does everything, and even has temperature compensation.  Selectable battery type, voltage, and charge amperage (2, 6, and 10 amp).  Also has float and exercise mode.  Amazon Link.

Nomad

Looked at the Pro-Logix - Was too big to fit in the T@B tub with all the other stuff. Got the smaller NOCO, fits with room to spare.

db_cooper

I'm glad I asked the question,  there is a lot of good information here for keeping.  It really seems like replacing the converter is the most convenient way to get a full and quicker charge.  No carrying other chargers, and the price is similar to a quality quick charger.

The original group 24 that I currently have drops to 12.2 overnight when running the Alde and Fridge on propane,  with minimal use of lights or anything else. I've read on here that it can stay at 12.2 for quite some time,  but I haven't tested how long ours does.  Sounds like I'll be taking a chance boondocking more than 1 night with the current battery, and trying to use a generator to get it back up to a level to go overnight again.

It was a year old when I got the trailer, so I don't know how well the battery was treated.  That makes me nervous about getting 2 nights out of it at a ski area without hookups.   I was planning on putting in a Group 27 AGM (Outback tub) come spring or maybe a Group 31 if I can make it fit (and pick it up)  

db_cooper

T@Bnero, 

I don't see any terminals on the WH 2400i inverter/generator,  I do have a 12volt 8 amp output,  so I'm assuming you're saying I should connect that directly to the battery for 8 amp charging?

I'm also assuming I should only do this for a few hours,  since this would be bulk charging, and no way to step it down?

TabberJohn

db_cooper said:

It really seems like replacing the converter is the most convenient way to get a full and quicker charge.  No carrying other chargers, and the price is similar to a quality quick charger. 

Bummer that the WFCO does not operate to spec. You'd think that WFCO would be subject to a recall or class action suit if the unit has never performed correctly unless "with the default wiring in our T@Bs" is the main issue.

I agree it makes more sense to replace the converter unless you want a smart charger for use elsewhere.
Progressive Dynamics squarely takes aim at the 8735: http://www.progressivedyn.com/pd4135_converter.html

On the other hand could you simply connect a $50 smart charger to an unused AC connection on the WFCO 8735 and have the smart charger service the battery instead of the WFCO whenever you're on shore power?

Nomad

db_cooper - Running Alde, fridge and the two reading lights till midnight I usually get a 12.2 at bed time. It stays at 12.2 thru the night most of the time. That's with 40 degree nights so the Alde isn't running constantly.

Ratkity

Very good distinction, boo. Until you and PXL said something about the Honda 2000i charger, I wouldn't have known since I opted to get the companion because I hate that adaptor plug. Speaking of which, I need to start it up soon. It's just too cold to go outside, turn on the heat in the camper and work!!

rfuss928

boo said:

I charged my T@B battery with my Honda generator and my Ctek charger from 12.1 to 12.6 in two hours.

The Ctek 7002 charges @ 7A max.  Two hours of charging replaced 14 amp-hours maximum - likely less.  That is about 30% of a 50 amp-hour batteries total capacity.  Probably from about 60% to 90% keeping in mind measured voltage is very sensitive to rest time and temperature.  
Ten to fifteen amp-hours over 24 hours is pretty conservative power use.

db_cooper

PXLated said:

I've got this one...



7.2 amp. Came with 2-3 different cables that have their proprietary plug on the end. Direct wired one to the battery so all I have to do is grab the charger and plug it in. It's a smart charger.
I've never timed how long it takes to get a good charge but at 7.2 amps it's reasonable.
It's also relatively small and compact.
Amazon - https://www.amazon.com/gp/product/B004LWTHP2/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

  Did you permanently mount this in the tub?   If not, did you get the SAE adapter to use with the Zamp port?  I have the Zamp adapter cable to use non-Zamp appliances through the Zamp port.

Nomad

No, I's not permanetly mounted. It just sits in there when I need it. I orderd one of their proprietary cords/plugs and wired that directly to the battery so all I have to do is plug it in.
I also wired a Zamp Type connector to the battery as a backup. Since I live off solar, my builtin Zamp plug is always in use.