hooking up a charger to house battery

[popshumphrey]

I was wondering if it is okay to hook up a battery charger to the house battery without disconnecting the house battery while it is hooked up to land power. Will it help the speed of the charge if it is a small charger? Will it damage the electrical system or heat up the battery? Just wondering.

[A32Deuce]

Would be no different if you also had solar. Won't hurt.

[Flybob]

Suggest you use a good battery maintainer such as Battery Tender or CTEK vs a charger. A maintainer will adjust the charge current as needed.

[valleyduo]

Originally Posted by popshumphrey

I was wondering if it is okay to hook up a battery charger to the house battery without disconnecting the house battery while it is hooked up to land power. Will it help the speed of the charge if it is a small charger? Will it damage the electrical system or heat up the battery? Just wondering.

I've never heard of charging batteries in this fashion. I would believe it's possible to damage either your plug in charger or your converter as there is the chance they would be applying different voltages to the battery causing one to back feed. I may be wrong on this as I'm not an electrical expert, but I wouldn't do it.

[TitanMike]

Originally Posted by Flybob

Suggest you use a good battery maintainer such as Battery Tender or CTEK vs a charger. A maintainer will adjust the charge current as needed.

So will the converter's built in charger. If power is available, just plug the RV in and let the system that was designed to do the job ----- do the job.

Most converters are a lot better battery chargers than most of the "household garage" type, both in charging profiles and max current capabilities.

Can't see the advantage of hooking up a piddly 10-15 amp charger when the converter is more likely than not capable of 40, 50, or 60 amp. Also switches to maintenance mode when batteries are charged.

[Adrian Gordon]

Originally Posted by popshumphrey

I was wondering if it is okay to hook up a battery charger to the house battery without disconnecting the house battery while it is hooked up to land power. Will it help the speed of the charge if it is a small charger? Will it damage the electrical system or heat up the battery? Just wondering.

I have a sense that I don't understand what you want to do. If you have shore power available why do you want to hook up a battery charger? Won't your shore power charge your batteries through your converter?

[camaraderie]

If it is OP's goal to charge faster than the house converter it is likely a futile quest.
Batteries can (when depleted significantly) only accespt a maximum of about 20% of their RATED AMP HOURS as charging current.
For example...a 75 amp hour battery (Group24) could be BULK charged at 15 amps FOR A LITTLE WHILE. After the battery gets somewhat charged it developes internal resistance to further charging and accepts far less current.
Using the same more than adequte charger...it takes just as long to put the last 10% of charge in as it does to get the battery to 90%. (And NOT going to 100% kills batteries way earlier).
So...adding MORE chargers will not benefit you one bit if you are already capable of charging at 20% of the battery rating.

[D W]

I wouldn't do it. It won't charge the batteries any faster, matter of fact it may take longer. You will be pitting two micro-processors against each other. Both fighting for dominance of the charge rate. Possibility of damaging the electronics is real.

[TitanMike]

Originally Posted by D W

I wouldn't do it. It won't charge the batteries any faster, matter of fact it may take longer. You will be pitting two micro-processors against each other. Both fighting for dominance of the charge rate. Possibility of damaging the electronics is real.

Not necessarily. Once the voltage on the batteries reaches the set point for switching to the next lowest charge rate on one or the other battery chargers It will for all practical purposes just shut down or go along for the ride.

The higher voltage charger will handle any charging current.

Now if one is trying to use an Old School "Battery Boiler" like service stations used to have, capable of forcing excessive current at voltages over 16 Volt into batteries, then damage is certainly possible.

In reality most converters, event he dreaded WFCO's, are better chargers than the type I described. Like camaraderie said in his post, the converter will put as much charge into a battery as it can accept without being damaged.

[A32Deuce]

Hay, don't knock the WFCOs! They can fry a battery better then the old gas station type! Ask me how I know!

[rlh1957]

I don't understand why you would want to hook up an outside charger maintainer if the RV is hooked to land power? The converter gives you DC from the land AC which keeps the house batteries charged. I can see not having land AC and thus no DC to maintain batteries, then a Battery Tender makes more sense.

[NMWildcat]

Oh now. I would bet the majority of RVers use WFCO converters with no problems. Can you buy a better after market converter? Sure, but why, if the WFCO does the job?

We boondock most of the time and our WFCO handles the charging duties just fine for weeks at a time. When at home, we usually just leave it plugged into shore power to keep the batteries up. No problems. So I would advice the OP to do that. Why fix what isn't broken?

Are there bad factory converters out there that cause battery problems? Yep, just like every component. But the majority work fine, so no need to label all of them as bad

[TitanMike]

Originally Posted by NMWildcat

Oh now. I would bet the majority of RVers use WFCO converters with no problems. Can you buy a better after market converter? Sure, but why, if the WFCO does the job?

We boondock most of the time and our WFCO handles the charging duties just fine for weeks at a time. When at home, we usually just leave it plugged into shore power to keep the batteries up. No problems. So I would advice the OP to do that. Why fix what isn't broken?

Are there bad factory converters out there that cause battery problems? Yep, just like every component. But the majority work fine, so no need to label all of them as bad

I agree. I suspect that most "fried batteries" connected to WFCO converters have been ignored long enough that they've outlived their useful years or have been allowed to go dry due to lack of maintenance.

I got rid of my WFCO because I wanted the "Charge Wizard" that PD has on their Converters so I can force a bulk charge rate when I want the batteries to charge quickly. Also installed a larger converter than OE.

When I comes to converters I'd had some real "winners" in the past. The last one I had was a "Magnatek" that had only two charge voltages. 13.2 at ALL times unless you put a jumper between two terminals and then it jumped to 13.6. People hated them and according to online posts they were failing right and left. Mine? Was still in it's original place when I sold my trailer after 22 years. Never killed a battery that was still in it's useful life (5 year avg).

[A32Deuce]

Originally Posted by TitanMike

I agree. I suspect that most "fried batteries" connected to WFCO converters have been ignored long enough that they've outlived their useful years or have been allowed to go dry due to lack of maintenance.



I got rid of my WFCO because I wanted the "Charge Wizard" that PD has on their Converters so I can force a bulk charge rate when I want the batteries to charge quickly. Also installed a larger converter than OE.



When I comes to converters I'd had some real "winners" in the past. The last one I had was a "Magnatek" that had only two charge voltages. 13.2 at ALL times unless you put a jumper between two terminals and then it jumped to 13.6. People hated them and according to online posts they were failing right and left. Mine? Was still in it's original place when I sold my trailer after 22 years. Never killed a battery that was still in it's useful life (5 year avg).

Not always true your first statement!

[TitanMike]

Originally Posted by A32Deuce

Not always true your first statement!

Never used the term "always".

In my experience people are often quick to blame something other than themselves when something like a battery fails. Not "ALWAYS" but OFTEN.

[A32Deuce]

Mine fried with everything well taken care of. Batterys topped off once a week and terminals kept clean and sealed. It just decided it was tired of reducing power and stayed at full power. Just glad I was nearby when I smelled the bats. No neglect just a bad WFCO. Have a good 4 stage and bigger AGM bats now.

[Tom48]

Originally Posted by valleyduo

I've never heard of charging batteries in this fashion. I would believe it's possible to damage either your plug in charger or your converter as there is the chance they would be applying different voltages to the battery causing one to back feed. I may be wrong on this as I'm not an electrical expert, but I wouldn't do it.

Did it for years with the old trailer when the solar was not doing the job and needed to maximize my time on available electric source. Usually that was a generator that I did not want to leave running longer than needed. An hour or so with the secondary charger on 25 amp "Boost" watched the batteries to never out and out boil them. Never a problem. The batteries were over four years old when we sold it and still held a full charge 12.7 vdc, for days, when batteries were shut off at home.

[ScottBrownstein]

I am sure that there are 1000s of WFCOs that are performing admirably. However, most complaints that I have seen and read are, in fact, from WFCOs. Two issues. Out of the box, WFCOs seem to resist running UP to boost mode (>13.3 or so.) Sometimes you can cajole them but other times they just sit there. Interesting enough PD has a patent on their Charge Wizard, but it doesn't cover the multi level capability but rather a "dongle" that permits the user to manually select a specific charge mode for a timed period. On PD it will go into boost for 4 hours and then drop back (I have runs logs of this performance as well.) As another poster indicated, this is ideal for maximizing the value of genny run times when boondocking.

The other failure that WFCOs seem to exhibit occasionally is not dropping out of Boost mode! This will fry a battery in short order.

As others have said, you can't beat up batteries by failing to recharge them or letting them run dry...and then blame the converter. It does amaze me that WFCO continues to sell well (maybe $$$) as an OEM, so their reputation on forums like this can't be all that deserved. However, very seldom see a post like this regarding Progressive Dynamics, so they must be doing something right.

Bottom line, watch your voltages and make sure there is enough water in the cells! Again, must admit that my PD maintained batteries seldom need much water.

Never hurts to look over their shoulder to see that all is well.

Now, regarding two chargers. As others have said, two chargers can often result in less than one since the control circuitry is constantly monitoring battery back voltage and what it might be seeing is the other charger and not the battery itself. Solar charge controllers are specifically made to co-exist with grid tied chargers.

[MR.M]

the wfco's are installed in over 90% of rv's bound to have a few more issues since they are the majority out there in use in the real world . 4 yrs with mine never a hick-up full time

[pmsherman]

I was happy with the single stage WFCO converter in my 2011 Georgetown until I discovered that it had an internal electrical "leak" from the hot line to ground. This problem occurred only when the converter was outputting high amounts of current, something that rarely happened.

The place I was staying at only had the single GFCI outlet available, and it was powered only from dusk to dawn. I discovered the problem when, on the second night of being plugged into the GFCI outlet, I kept tripping the GFCI breaker. There was no issue the first night because the batteries were fully charged from the day's drive. The issue was validated as the converter by disconnecting it which eliminated the GFCI tripping problem. Reconnecting the converter brought the problem back. Unfortunately for me, I required stable AC power for the entire night so I ended up disconnecting the converter and hooking up my "smart" battery charger to the house batteries.

Unfortunately, the battery charger eventually detected a fully charged battery and went into maintenance mode. Once there, it only exits that mode by disconnecting it from the battery. By morning, my house batteries were well depleted.

My solution to the problem was to install the spare converter I already had. The replacement does not have the problem the WFCO had and I had no issues for the following few nights.

Phil