Do I Need a New Converter?

[rcolman]

Again, I must ask for help on my newly acquired 2002 Sea View 8310.

On 50 amp AC service, measuring charging voltage at the house battery terminals of 12.8 - 13.1 makes me think that the converter is having a problem.

At this voltage, the batteries will hardly ever achieve a full charge and will have problems in the long run.

I am not sure what type of converter came stock in the RV? Is anyone doing any converter upgrades.

Any info much appreciated.

Rick.

[wardy]

If your converter reads that low right after you apply gen or shore power then yes-problem. However if your coach has been plugged in a while then no, it's just maintaining. You should get voltages as high as 14.8 VDC when you first apply 120 VAC (50 amp service so 220-240 but the inverter only runs off one leg). So, how long was your coach plugged in before you took the measurement?

[rcolman]

Batteries were low after attempting first boondock .... 11.9 V or so

Plugged into AC power, and I read 13.1 V at the battery terminals. After several hours, it drifted down to 12.8.

seems low ...

[wardy]

Well you're right then, there is a problem. But it may not be the converter just bad batteries (two 6 volt in series? Really though it doesn't matter if they are 12VDC in parallel ). Anyway you could disconnect the batteries then apply shore power and see if you have ample 12 VDC power under load (turn a few lights on). The light's may flicker some as most converter's are do not supply filtered DC but are they bright? If so you likely have bad batteries.

[wardy]

Oh, BTW 11.9 volts indicates a fully discharged battery (flooded cell). You could remove & try to charge by an inexpensive plug-in unit. My guess is that you've got bad batteries.

[KIX]

It may just be one battery in the bank. So, disco them and check each one separately. Before checking each one let them sit discoed for at least 30 minutes.
As a side note........some batteries have a manufacture code stamped on the top of the post. It may read a letter that corresponds to month and two digits that correspond to year. Not all batteries are coded. If they're over 5 years old they're very suspect but even newer ones can be defective like Wardy says..

[Skip426]

Before you run out looking for a new convertor; first as other poster have said; check the batteries; second get the spec sheet on your convertor. My unit has a manually installed plug to to raise the charge volts, from 13.2 a maintenance charge ( for units that are plugged in most of the time). Up to 14.2 volt fast charge, ( for low battery, seldom hooked up to shore power). If you don't have the spec's, post all the info you can on the convertor ( picture if possible) someone here will have what you need for info , or how to get it.

[rcolman]

What would a bad battery read in terms of voltage, after sitting disconnected for a while?

[wardy]

Hey KIX, two fellow Floridians, a little insomnia like me?

rcolman: You've got good advise here but your last question is a good one. As KIX stated, charge the batt(s) and let them sit for 30 mins or even overnight. This way they will loose their "surface charge". Then measure voltage & let us know. Better yet would be to place the batts under load, i.e. a 12 volt light bulb-then read.
My thoughts are you need new Batt(s). Since you're into this (RV thing) now you maybe should purchase a specific gravity gauge for testing all wet cells, they are cheap. This instrument will give you the health/charge of all the cells within one battery. All cells (where the caps are) should read the same.

[Skip426]

Quote:

Originally Posted by rcolman What would a bad battery read in terms of voltage, after sitting disconnected for a while?

After a good charge , and 3 hrs off the charger, 12.4> 12.6.
If you test when you first disconnect the charger and get , say 12.9/13.2 volts a good battery with no load on it should stay very close, to that voltage as it cools from the charge.( 12.6 ) Remember if you are charging the battery out of the unit , do not set the battery down on concrete to charge it . Most part stores have testers and will run a free load test on the battery for you, or you can pick up a battery hydrometer, $10.or so. The hydrometer will come with instructions. for use; only works on batteries with removable caps ( lead acid)

[rcolman]

TNX. for the advice.

I tried the following test:

fully charged batter at 12.7 volts.

Ran my inverter/antenna/TV for two hours on battery power.

batter voltage went down to 12.2 volts.

measured specific gravity. All cell read in the GOOD category with little variation.

This makes me think the battery is good.

HOWEVER< I am still only seeing around 12.9 volts at the battery terminals while charging on AC power.

??????

[M&EM]

Quote:

Originally Posted by rcolman TNX. for the advice. I tried the following test: fully charged batter at 12.7 volts. Ran my inverter/antenna/TV for two hours on battery power. batter voltage went down to 12.2 volts. measured specific gravity. All cell read in the GOOD category with little variation. This makes me think the battery is good. HOWEVER< I am still only seeing around 12.9 volts at the battery terminals while charging on AC power. ??????

What type converter is in your coach? If it is Parallax ferro resonant converter, what you are describing may be normal dependent on other dc loads being run at the same time that the battery is trying to be charged. This is a common converter used by NRV in your year coach. Unless previous owner changed it out.

Here is a truncated description from Parallax:

900 Series Converter/Battery Charger Owner’s Manual
Questions & Answers:

Q. What happens if I leave the converter/charger on for long periods of time, unattended?
A. The converter charger is designed to function as an integral part of the battery system. The output
voltage of the unit is designed to charge the battery fully without going high enough to overcharge. The
ideal situation for prolonged battery life is to turn the converter on for ten hours a month during long
periods of no use. This will keep battery gassing/fluid loss to a minimum, non-sealed batteries should be
checked for fluid level once a month. Battery failure is most often caused by leaving the battery in a
discharged or partially discharged state. Even a completely charged battery will discharge itself if it is not
maintained or recharged periodically.


Q. What happens when I leave the converter/charger fully loaded for long periods of time?

This is the part that I am referring to in my post above!!


A. At full load, the output voltage of the converter/charger will be approximately 12.0 volts. If the system
is loaded to full converter rating, the battery will supply part of the current to the load until the battery
terminal voltage is the same as the converter charger voltage. At this time, the battery would simply be
floating and acting as a filter to the system. The converter/charger would then be supplying the total current
to the recreational vehicle. At the time, the battery would be slightly discharged condition and will return to
full charge when the load is decreased. In this type of system, the battery would help absorb sudden
changes in output voltage due to sudden changes in load current.

So if your total dc loads were enough to lower the converter voltage, then you may want to try turning all 12 volt power usage off while charging to see if better results occur. You may need to let this type charging system run for quite a long while to see higher recharge voltage..


Hope this helps,

Marty