Xantrex Low Voltage Alarm/Trojan T-105s

Hey guys. Thanks to your help, I built a wooden battery box for my two Trojan T-105s, ran them in series, and vented the box out a hole I cut in the side of my conversion van. Works great!

So I've only used my inverter (Xantrex Pro Wat 1000) for charging my computers and hot spot. I also hooked my rear 12-volt receptacle to my Trojans so I can run my roof vent fan and other 12-volt van off of it. I have a digital volt meter I can plug into the 12-volt receptacle for a reading. It got down to 11.6 volts so I hooked the batteries up to my Yamaha ef2000is for an hour. When I was done, the volt reading was 12.8. I used my inverter all night, again, for just my computers and hot spot. This morning I took a volt reading. It now reads 13 volts. But my inverter is chirping like crazy and gave me a an E01 (low voltage) warning, and read that its only bringing in 11.1 volts. I don't want to charge my batteries again because of the reading I got already.

Any ideas? Also is there a such thing as a 12-volt "surge protector," which I can plug into my 12-volt receptacle and create multiple outlets? Thank you in advance.

Yes there is such a thing as a 12 volt surge supressor however I doubt you need one.  There is also a multiple outlet adapter, NO electronics at all, just multiple outlets  Several kinds of those..  I will try to give you a link.

Now: What size wire did you use for that Inverter>  Small wire will result in low voltage.. You need at the very minimum starter cable (4ga) for a 1,000 watt, And I would recommend doubling that (2 parallel starter cables or bigger still 2ga),, Buy cables in both red and black, (RED for the positive side) and tape the wires together or use a split loom so they lie side by side. (That last bit about taping them.. Direct from Xantrex support).

Also do not use a 40 foot run, 4 feet is in fact farther than I 'd like to go.

NEXT: you said you put the generator on for just an hour.. One hour is not nearly long enough.. How the batteries got to 13 volt I have no clue.. Epically since you do not have a charger hooked up.  12.6 is the theoretical maximum unless you have a charger hooked up and operating, for the morning (Resting) test.  I suspect your volt meter is ... Not accurate.  The Reading on the Xantrex panel is more likely what you had.

With a good size converter (Output = Battery capacity C/20 rate (Amp hour rate for 20 hours to discharged) times 0.3 you need at least 4 hours, six would be better, to insure FULL charge, 2-3 to get it up to a safe level for shutdown. (It all depends on how bad you need that last 10%)

I seriously suspect your voltmeter of being off a volt or so.

Thank you John. Is there a such thing as overcharging? So whenever I charge (when the volt reading drops below 11.5-ish on the XANTREX display), I should charge for 3 hours minimum when it gets to that level? I have no problem with that. My cables are 4#, so should be ok. But I'll think about adding second cables. Just don't want to damage my batteries. And you're probably right...this volt meter just plugs into the 12-volt receptacle. It cost $20 and is probably off. Guess I need to buy my THIRD one in 3 weeks. Thanks for your help.

Yes you can over charge, IN fact you should from time to time. (it is called equlization)

Normal voltages, Resting, no load, fully charged there is a chart you can look at that shows state of charge for most Lead Acid batteries.. But think around 12.6 (Trust me one tenth of a volt is significant here)

Float is normally around 13.6

Charging is higher than that. Like 14

You need to push over 14 volts to overcharge in most cases, though 14 might do it given enough time.

I do not have the voltage to State of charge chart handy.  But others will link to it I'm sure, plus you should find one on Trojan's web site.  You will also find the charging specs.

This I will say. For RV use your max charge rate for flooded wet cells should not be more than 30% of your 20 hour rate amp hour capacity.  T-105's are what. 225 amp hours.. So 0.3 times 225 is 67.5  You can round that up to 70 or down to 60-65 safely..  Trojan recommends more like a 10% charge rate (22.5 amps) but for RV use that is going to take forever to recharge.

This is the BULK charge rate.. And how you choose your converter if upgrading/replacing.

The full charge cycle starts with BULK, this is fairly high current (See above) voltage may vary.

Once the battery is close to the 90% SOC mark you cut down on current, perhaps 10% or less of what you were running,, This is the absorption stage.. And it lasts like 4 hours.. NOTE: in this one the size of the converter is not as important, even a small converter will properly do the absorption charge and it will be nearly as fast (Like 4 hours 10 mintues) as one that is too large,, In fact TOO large may switch early and take longer.

Finally, once topped off it drops to "FLOAT" which is usually around 13.6

For exact settings consult Trojan and your converter manufacturer since there is some brand to brand "Wiggle".

If I read your description right you had the batteries down well below 50% (11.6 volts) and ran the generator for an hour and then used the inverter again?


The 12.8 volts you read right after charging was likely just the residual voltage from the charge.  A pair of T-105s that are down to 30-40% charge will probably need at least 2-3 hours to reach full charge. I'll bet you just need to run the generator longer.

Here's the math.

2 Trojan T-105 batteries = 225 amp hours @ 20 hr rating

Xantrex inverter has no 12v charging capability

Yamaha EF 2000IS generator has 8 amp 12v charging capacity for "charging batteries"

Batteries down to 11.6v = more than 50% discharged, let's just say 100 amps gone......... let's just say.........

100 / 8 = 12.5 HOURS OF CHARGING!!!! AT LEAST!!!!!

This assumes no other battery charger. None is mentioned by OP. Please, please, please, read some articles about battery use and charging. There is no free lunch. You can't live on batteries for free.

Ken

Ken is correct. My 2-3 hour estimate was for a 100 amp charging system.

Thank you guys so much. Yes Jeff, that is exactly what I did. Well I'm at a park right now with the genny running (and charging my computers and DVD player as well while its running). I had planned on sitting here for about 3 hours until the park closes, but even that won't be enough to fully charge the batteries right Ken? Well hopefully I didn't damage them? But from what you're saying...should I even use the inverter again until I can charge for a full 10-12 hours? Yes you're right Ken. I do need to read up more on charging. Thanks for the knock on the head. I'm a TOTAL newbie with electricity and living off-grid. Read A LOT and watched several hours of video on electricity just to build up the courage to install this system, but obviously need to read more. I'm probably not going back to the place that cut the hole in the side of my van for venting, as the manager there said running the batteries down to 10 volts was ok. Think he may be wanting an additional sale by me killing the cells.

How do I know when they are fully charged? What is the limit as to how low I should go before charging as far as voltage? Is the Xantrex display of input voltage enough to know the state of the batteries...or do I need an additional volt meter? I've already spent $30 on apparent junk volt meters. $5 for a Harbor Freight thing that doesn't work at all...another $25 on the one that plug directly into the DC socket that apparently is junk too. The RV store manager sold me that too...it gave a 14 volt reading right before I started charging...yet the inverter still chirped if I plug my computer into it...and read 11.1 volts when my computer was plugged in...11.5 when it was not. So both those are now in the garbage can.

John, you gave A LOT of technical language. I'm watching videos and reading now (per Ken calling my laziness out). Also John, yes I was looking for a multiple outlet adapter for that 12-volt receptacle. Any ideas?

Thank you guys so much. This forum is better than any class I think you could take!

UPDATE: 3 hours of charging and Xantrex still only reads 11.8-11.9 input voltage. Not even going to bother using it until I can charge for another 8 hours minimum...which will be today.

Does your RV have a converter?  If so what model?

We generally tell folks that the 12 volt terminals/outlet on the generator is good for little more than a trouble lamp or work light, I'd never use it for battery charging.

I use the converter, which in my case is a nice 80 amp job.. But ... If all you have is a magnetek 6300 series or equivalent... Go with the generator's 12 volt terminals.

One advantage of using the rig's 3-stage converter (if it has one) is that it knows when to stop charging. (The magnetek is a single stage and does not know when to quit, nor is it fast, Less than 10 amps)

Your generator is a very poor battery charger - only 8 amps (max) and not enough voltage to do a good job either. I doubt if you are pushing more than a couple amps/hour into those batteries.  Buy yourself a decent auxiliary battery charger and plug it into the generator 120v outlet and the batteries will charge both faster and better. If you want to fully charge in 2-3 hours, I would suggest at least a 50 amp sustained charge rating, but we are probably talking a $300 charger. Those auto store chargers rated 10/30/50 amps are not 50A chargers - they just have a brief 50A boost mode. Their sustained rating is only 10 amps.

Here is a quality 20 amp charger:
http://www.westmarine.com/mounted-battery-chargers/professional-mariner--prosport-20-plus-heavy-duty-marine-battery-charger-20a-12-24-36v-3-bank-charger--14152177

Even one of the 10 amp Walmart chargers will do a better job of charging than your generator.

The solution as I see it is to add a higher amperage charger to your system. Something that your generator can handle and will shorten your charging time. The longer you run the genset the more fuel you burn.

Something like this unit http://www.invertersrus.com/powermax-pm3-45.html looks like it may fit your needs. It looks like it's maximum draw is 10 amps at 108v so your genset should handle it.  45 amp bulk charge will bring you back to 80% in a reasonable amount of time. 

Your research will tell you that the most efficient charging is in bulk mode. I use my batteries down to 50% and then charge to 80% at the bulk rate for days on end, never letting the genset run long enough to top the batteries off because it's the least efficient charging. If your capacity/use ratio is adequate for that, just top them off every couple of weeks and use the bulk rate range for day to day use.

Please don't take offense at my sometimes blunt method of providing information. Sometimes wakeup calls come in the middle of dreams.............

Ken

Ken: No offense taken at all. I appreciate the knowledge and motivation. My genny is due for its first oil change (after 5-6 hours of break-in). I used the inverter a little last night and now it reads 11.5 again (with a load plugged in). I'm just going to fill the generator with gas and run it dry charging the batteries...or at least for 10-12 hours until the batteries are fully charged. But as both you and Gary alluded to, this is obviously not efficient and puts unnecessary wear-and-tear on my generator. Your method of charging a little every day sounds best, especially in the morning when I start the genny to make coffee.

John I have a Chevy Van I converted into a camper (of course after investing a couple thousand getting it mechanically sound), not an RV. The whole electrical system is custom installed. Don't know anything about converters. Pardon my ignorance! My next investment is one of those auxiliary chargers.

Thanks for everything gentlemen!

Ok,  Weill I will tell you all you need to know about converters.

A "Converter" in RV parlance, goes by other names in other places, but it is a box that converts 120vac to battery voltage,,, Basically it Converts shore power into alternator power... A good 3-stage job will first charge the batteries as fast as they can be safely charged (See information below) to around 90%, then slow down and SLOWLY top them off over the next 4 or so hours, then float them till they are run down by either running without shore/generator power or by demand grater than the converter can convert.

Then it kicks back into bulk.

A 3-stage PLUS, is a 3 stage converter with at least one additional feature.

The Progressive Dynamics 9200 line is such a converter, One of the best made.

Now how to replace the "00"

Your maximum safe charge for most battery types is around 30% of your 20 hour capacity rating (C/20 amp hour rating)

For a Group 24, C/20 is roughly 75, Max charge rate is thus 22.5 amps

For a group 27,,  Rounds up to 100 and thus 30 amps
for a group 29 rounds down to 100 and thus 30 amps

Note rounding is allowed

Group 31 is 130 amp hours so rounds to 40 amps

Muliple batteries in parallel... ADD,  So two G-31's 80 amps.

Six volt pairs are 220-230 amp hours (usually) and both 8D and 4D (12 volt) round to teh same size. 70 amps.

So for a pair of GC-2.. 9260 is likely your best bet.

You wire it in parallel with the battery, USE good heavy cable (like starter cable) plug it in and ... it works.