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markdoane · 12-05-2004, 08:20 AM

G,

My biggest blind spots are differential equations, interpersonal relationships, and organic chemistry.

wlj1943 · 01-09-2006, 11:30 AM

Hi to all.
In following this thread I see all have had the same experience as I; IE
1. Univolts and Megnetec converters kill yellow top Optimas.
2. The new technology convertor/chargers do a much better job of keeping batteries alive.
3. There is no subsitute for the weight of the battery when it comes to energy storage.
My solution was DIY like others; I use the battery disconnect switch while storing and 3 stage solid state charger. My lifeline G31 works great and only needs charging every 60 days or so.
WJ

Swanny · 01-09-2006, 11:50 AM

After all of the equations flying around, I was beginning to think we were running an '12-step' program for electricians.

I've been having problems with keeping a brand new deep cell battery charged. Someone recently told me that the Uni-Volts either work or don't work, is that true?

Mitch

**azflycaster** · 01-09-2006, 12:07 PM

Quote:

Originally Posted by Swanny

Someone recently told me that the Uni-Volts either work or don't work, is that true?

Mitch

Mitch, You could say that about everything

. Uni-Volts are still around after many years, but the newer convertors are much better. The Uni-Volts do not offer 3 stage charging like many of the newer replacements. The problems most often with the Uni-Volts are they hummmmmm alot and they will tend to over charge a battery if left connected for long periods (days). I am not sure how many amps are supplied to the charge circut, but it will take many hours to charge your battery. Have you put a volt meter across the battery and checked the voltage with city power and no city power?

Swanny · 01-10-2006, 06:56 PM

What's happening is the when I'm hooked up to city power, the interior lights will come on bright. Than after a while they will slowly dim to nothing.

When I listen to the Uni-volt it sounds as though something 'clicks' and than the lights come back on. As for the battery, I replaced it about 2 months ago and during a recent camping trip we used our generator.

It seems that the uni-volt will keep the lights on and operate everything when I take the battery out of the circuit, but once I put it back in we have the same problem. Could it be a bad battery already?

Mitch

**azflycaster** · 01-10-2006, 07:06 PM

I would have te battery tested. It sounds like it may be pulling everything down. Just a guess.

Swanny · 01-10-2006, 10:04 PM

When I tested the converter with the battery removed, there was about 13.5 volts coming out of the leads.

Although I replaced the battery in November, when I put it in the loop all of the lights come on brightly and than dim.

So here's my question. When we went boondocking 2 weeks ago, I think we used the battery to a very low level. It appeared to recoup while we towed the AS home, but after leaving the AS hooked to shorepower overnight, the battery still pulls down the system. Is it possible for a battery to go bad that quickly?

Mitch

**azflycaster** · 01-10-2006, 10:26 PM

Mitch,
Yes, it can happen

. Any auto parts store should have a tester that they can hook to your battery and tell you in a few minutes if it is bad. Batteries do not like to be bounced around a lot and sometimes that will make them short out a cell. I have had batteries last for several years and others for a few months. In my autos I average less then 2 years, the Phoenix heat is tough on them.

bryanl · 01-10-2006, 11:02 PM

Quote:

What I am saying is that the effect is much more pronounced at higher current draws.

That follows from the logarithmic nature of the phenomena. Or think resistance losses going up with the square of the current.

Quote:

I think you will find the Lifeline AGMs have a similar Peukert coefficient to the Optima AGM, certainly less than 1.2 for flooded cells.

The Optima coefficient is about 1.06 last I checked, while the Lifeline was 1.19. That rather surprised me. What it says is that the Optima amp hour rating for the 20 hour rate should be fairly close to that for its 5 hour rate, especially when compared to Lifelines or wet cell batteries.

But all that isn't really a significant issue when you have batteries run nearly flat and then poorly charged days or weeks later with the typical Univolt.

Best way to test for a defunct battery is to note when the lights start getting dimmer sooner. That is a practical load test.

Swanny · 01-11-2006, 09:20 AM

Quote:

Originally Posted by azflycaster

Mitch,
Yes, it can happen

. Any auto parts store should have a tester that they can hook to your battery and tell you in a few minutes if it is bad. Batteries do not like to be bounced around a lot and sometimes that will make them short out a cell. I have had batteries last for several years and others for a few months. In my autos I average less then 2 years, the Phoenix heat is tough on them.

As always you guys/gals always come through. I'll take in the battery to have it tested.

Mitch

rfield54 · 01-11-2006, 08:12 PM

Quote:

Originally Posted by andoboba

I need to have my '69 Ambassador plugged in full time. Has anyone figured out how to safely charge the battery while leaving the Univolt constantly plugged in?

Well, back to the original question. If you choose not to go with the Intellipower/Charge Wizard, another option would be to use a timer between shore power and your AS. Adapt your 30 amp AS cord to 20 amp (3 prong) and plug in the timer. Mine is set to let current through for one hour a day. I leave the timer and AS cord in the bumper storage and run an extension to power. You'll have to check your battery with a meter for a few days to determine how much daily charge your battery will need.

**azflycaster** · 01-11-2006, 09:58 PM

Instead of an adapter and a timer, what about one of these: http://www.batterystuff.com/categori...ttery_chargers
It sounds like you could leave it attached and it would maintain the battery.

davidz71 · 01-12-2006, 09:04 AM

I can vouch for the 1 amp and 4 amp BatteryMinders. You can keep them attached year round without problems. My 2 Delco Voyager batteries were in excellent condition 4 1/2 years after I bought them when I sold my trailer. When away from home and boondocking, I used a 5 watt PulseTech Solargizer solar panel to keep the juices flowing. That worked fine when being conservative so I decided to add a 30 watt panel and splurged on fan use. Never a problem.

Swanny · 01-12-2006, 11:39 AM

On this topic...does a functional univolt have the ability to recharge a discharged battery?

My reason for asking is when I checked the Univolt output (without the battery), it read 13.5 without any lights on. However, when I left the 'dead' battery hooked up to the univolt for 12 hours, it wouldn't recharge the battery.

I than attached the battery to a battery charger and it regained a full charge after a full night of charging and I no longer have dim/dead lights.

I looked at the Univolt to see if there is a voltage regulator attached to it, since I'm beginning to wonder why I have the right voltage output, but it won't recharge a discharged battery. Am I missing something?

Mitch

GoldFever · 01-23-2006, 10:50 PM

So I've been following this thread all along and am closer to understanding the problem with the Univolt. Now I don't see anymore replies. Is this all there is? I may just decide to replace the univolt, switch to 6volt golf cart batteries like the Trojan T145 model replacing my dying Trojan 12 volt batteries, one of which seems to have been killed by the constant charging of the Univolt (see above). The bad one has been doing the boiling thing (see above) and leaking (see above). I think I need a better charging and converter system. I also have two 75watt solar panels that charge with a charge controller. And I carry a generator (actually two during summer: Honda EU3000 for running the aircon and a recently purchased used EU1000 for light use). We boondock all the time, almost never hooking to a power cord EXCEPT AT HOME. This is where the batteries get left on the Univolt (read: Magnatec) and do the dying routine. We hate the hummmmm so it may be gone by summer.
Enough.
(I just had to add some more words to this thread)

ticki2 · 02-21-2006, 11:38 AM

Before I read this thread I was sure I knew the univolt answer , now I'm sure I don't . I leave my '76 with original univolt plugged in all the time . First battery lasted 5 years , present battery 2 years old and still good . In the owners manual it says " The charging circut automatically controls the current ,reducing it as the battery increases in charge ". Are some univolts different than others? What is the real story . Thanks

PS I put a small computor fan on it to keep it cool, works great.

bryanl · 02-21-2006, 01:11 PM

An older Univolt is a constant voltage current limited power source. If the battery is low, the voltage difference between the univolt and the battery is large and a lot of current will flow to charge the battery. As the battery is charged and its voltage rises, the current to the battery will drop because there is less of a voltage difference pushing it.

If the voltage on the Univolt was set close to 13.2v it probably won't overcharge your batteries but will take a long time to get them fully charged. Many Univolts were set at 13.6v or higher. These charge faster (bigger voltage difference between univolt and battery) but have too high a voltage to float maintain the battery without causing overcharging and electrolyte loss.

New three stage chargers change their voltage output for optimum battery charging current to the battery. That is how they control charging and maintenance charging. The go up to 14.4 volts to charge quickly and then drop to 13.2v for maintenance when the charge is done.

ticki2 · 02-21-2006, 03:49 PM

Thanks Leipper , the fog is starting to clear

FrenchBern · 05-07-2006, 12:44 PM

Congrat Leipper, You rate a 100 percent in your answers as far as I am concerned.
I am not sure if this was mentioned before but there is a fuse between the Univolt and the battery. If the univolt is reading 13 volts and the battery is not charging make sure that 40 amps fuse is ok before blaming the Univolt. This fuse is located in the Univolt distribution fuse panel.

Pick · 05-07-2006, 02:44 PM

In the instruction sheet that came with my Charge Wizard, they have a charging chart, based on a 55 amp Intellicharger, hooked to a 125 Amp-Hour battery. In the "Boost" mode, (14.4 Volts) it looks like it could take 18 hours to fully charge the battery. In the "Normal" mode (13.6 volts) it looks like about 78 hours. "Storage" mode, (13.2 Volts) about 105 hours! So much for running your generator for "a couple of hours" to recharge your batteries!! So it looks like a plain old dumb Univolt can recharge a dead battery in about 3 days.