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Topic: Charging Batteries with battery charger AND Converter

Posted By: ibyers on 02/17/12 07:02pm

Hey everyone,

I was talking about dry camping at work today and we got on the topic of the fastest way to charge the batteries.

Some background

We do half of our camping trips with no services (Dry)
I have 2 6 volt GC (Costco) batteries
I have a PPS Parallax 7155 (55 Amp) Converter
When charging my batts at home I use a intelligent charger THIS ONE
I have a Champion 2000 inverter genny

My question is what is the fastest way to charge up my batteries when dry camping.

Should I unhook the Converter and use the intelligent charger? or can I leave the converter charging the batteries and hook up the intelligent charger at the same time? (i suspect this wont work as the intelligent charger will read the voltage from the converter and think the batts are charged and shut off)

Or should I ditch my converter and buy a better one?

Thanks everyone!

2011 Trailmaster 265BHS by Gulfstream
2005 Silverado 1500HD 6.0L/4.10 4x4
Tekonsha P3 Brake Controller.
2 Champion 2000w Inverter Generators with parallel kit
2 6volt GC2, 400w Solar, 3000 watt inverter, Trimetric 2025-rv

Posted By: ibyers on 02/17/12 07:06pm

Maybe I can just convince my wife to let me get a solar system.

Posted By: Sandia Man on 02/17/12 07:22pm

We prefer drycamping/boondocking and have a similar set-up of two 6 volt GC2 batteries from Samsclub. We also have a BD 40amp external smart battery charger but we haven't needed to bring it with us as our Iota IQ4 converter gets our battery bank back up to 80%-90% in 2 hours or less. Nothing wrong with adding external chargers, but we like to keep it simple while camping and are happy with the results thus far.

Posted By: time2roll on 02/17/12 07:25pm

I would set the portable on 40 amps and then plug in the RV to use the converter also. Truth is the converter will taper off as the portable raises the voltage to 13.8 at which point it will be just the portable.

Solar is a great idea if you are parked in the sun.

2001 F150 SuperCrew
2006 Keystone Springdale 249FWBHLS
675w Solar pictures back up

Posted By: Golden_HVAC on 02/17/12 07:36pm


The 55 amp converter is designed to put out 55 amps all day and night, while the portable charger will put out 10 amps all day and night, I don't think it will last very long at 30 amps, and according to the reviews, those using it to charge large battery banks find the charger fails within a year.

I would suggest plugging in the trailer to power up the converter. If you still desire a little faster charge, then plugging in and hooking up this charger will speed the process, however the charger might not last long when set to charge faster than 20 amps. And it will fool the factory converter into thinking the battery is closer to fully charged, and will probably lead to longer charge times, as the most charging happens when the converter is still in the absorption charge mode, at 14.4 volts. Once amperage drops, then the converter will drop to 13.8 or 13.5 volts.

I have a E-Meter that I can watch the amperage going into the battery. With it, you can easily measure the amperage going back into the battery, and check what works best in a couple of hours know how many amp hours came in with both chargers or just the converter. Yet without the DC amperage monitor, you will really have no idea if the charge happens faster with both or just the converter.

You can buy a Kill-A-Watt meter on e-bay for about $25 - $30 and plug in the converter or charger and monitor how many amps the charger is pulling, then determine if that amperage drops when the charger is plugged in and the converter moves into the float 13.2 volt mode.


Posted By: Golden_HVAC on 02/17/12 07:48pm

ibyers wrote:

Maybe I can just convince my wife to let me get a solar system.

If the portable charger catches fire (it is chineese) while she is there, she might be more happy to embrace solar power that is silent, uses no gasoline, and no smell or noise! Did I mention I don't like listening to generators?

This panel is 195 watts, 18 volt output (12 volt nominal) and can be controlled by a $53 controller (12 amps to allow for more amperage due to cold panels making more power than a hot one) that has 12 volt input and output, regulating around 13.5 volts before shutting off. 10 amps per hour of good sunlight X the 10 hours a day you get in the summertime equals a lot of power each day!


Posted By: jauguston on 02/17/12 07:57pm

You can charge your battery bank with multiple charging devices at the same time with no issues and they will all contribute to the total amperage going to the battery bank. Been doing it for years.


2005 Coachman Sportscoach Elite 402 40'
350hp Cat C-7 w/MP-8
7500w Onan quiet diesel generator
6-Kyocera 130w solar panels SB3024i MPPT controller
Pressure Pro TPMS
1987 Suzuki Samurai tintop Toad w/VW 1.6 turbo diesel power

Posted By: BFL13 on 02/17/12 08:08pm

The 7155 is a slow charger with constant voltage 13.8v. You will get much faster charging using that 40amp portable. If the portable "sees" the converter and won't start, just start the portable first and then plug in the RV so the converter comes on second. The portable will keep going.

If there is a draw on the batteries from the rig while you are charging them, this lengthens the time for a recharge, since the batteries will charge at the net amps.

To beat that, disconnect the battery bank and plug the Rv into the gen so the 7155 supplies the 12v for that draw. Meanwhile the portable can charge the disconnected batteries at 40amps for best charging time.

The 7155 will do little to no charging with the portable, since the portable will be at 14+ volts and quickly gets the batteries over 13.8v when the 7155 cannot provide any amps since it is no longer any higher than the batteries in voltage. In fact as soon as you start charging the battery voltage will spike to say 13.5 so there is hardly any differnce in voltage even at the start.

On charger quality, since you know yours works ok from using it already, don't worry about it.

* This post was edited 02/18/12 06:47am by BFL13 *

1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI

Posted By: ibyers on 02/20/12 08:44am

Thanks everyone for the suggestions!

I have been doing a lot of reading on solar solutions and sounds like the best solution.

Looks like solar is very cost efficient for our American friends but is still rather pricey for us Canadians. (thanks for the site Fred, but shipping to Canada makes this deal not so much of a deal anymore)

I did find this place That has a "RV Kit" that I can pick up locally.

Posted By: jauguston on 02/20/12 09:06am

Solar is dandy if you live where the sun shines most of the time. It is not a dependable source of power in areas where the sun doesn't shine all the time. Here in NW Washington the days when my system sees 40+ amps output it is capable of are few and far between. There are way more days I am lucky to get 10a. We use out coach 12 months of the year not just in the short sunny season. If you want to know you will always have power buy a generator first. A Honda EU 1000i will charge your batteries at up to 40a with a good three stage smart converter. If your solar system is meeting your power needs you don't need to get the generator out but if not it will always give you power.


Posted By: BFL13 on 02/20/12 09:16am

I like dealing with wegosolar here. Good people. Note that 125w "kit" is composed of a $350 panel and an $85 controller plus some bits and pieces, so $500 isn't a rip-off like a lot of those kits that are sold for twice what their components cost bought separately.

They got that particular panel on some deal and they said it is only "allowed" for non-grid applications like Rvs so that is why it has a lower price than their other panels at the same size watts and has a shorter warranty.

I use a similar set-up with a 130w panel and it does extend the time it takes to run down the batteries before the next recharge using gen and charger. It could turn a long weekend from needing a gen recharge to one that you can last till you get home and so not have to do a gen recharge while camping.

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