Of Generators and Batteries

Page 1 of 2  

Oh great and all-knowing men among men, wordy, worldly and wise. Please bestow upon me your deep knowledge, your passing proficiency, sense of the common and not so much common. I humbly ask for guidance...
A friend, really my wife's manager, has a cabin, in the woods, near St. Helens. No electricity and runs the cabin off a Honda generator hooked up to 4 auto-style batteries, on a plywood shelf, connected in series. The generator, below the plywood shelf, is run through an inverter to charge the batteries - when they're full, the generator is turned off, switches are switched and the needed electric comes from the batteries.
Problem is that the batteries, on the plywood shelf, don't seem to hold a charge as they did a couple years ago when he bought the cabin, in the woods. His father-in-law, uncle, neighbor, or grocery checkout clerk told him that one battery might be dead and sucking the juice from the others.
Last summer when he loaned us the cabin, in the woods near St. Helens, I checked and filled the cells with distilled water, and cleaned and tightened all cable connections. Seemed as though we were still running the generator, under the plywood shelf, a lot - considering that practically all of the house is run off propane except for a TV/VCR and a few lights which are religiously turned off when not needed.
We're headed up there for a week and the friend asked my wife if I might know how to check the batteries on the plywood shelf. Bless her heart, she said that I would indeed, probably, know how to test the batteries on the plywood shelf. Having a digital multi-tester at the ready, I am turning to you for guidance and awaiting further instruction.
How to test for a faulty battery? What type of replacement battery would be best for this use? What winterizing steps to help ensure long battery life?
Thank you, oh wordy, worldly and wise ones.
--
Owen Lowe
The Fly-by-Night Copper Company
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Well, that lets me out, but ...

Here's one link that might be useful:
http://www.uuhome.de/william.darden /
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Owen, are you sure this isn't a troll????? However . . .
Buy a battery hydrometer, check the cells for specific gravity. This is the best way, other than having a "resistor pile" to load test each battery. You say series connection, so you're using 48VDC to power the cabin, right? Possible to have a bad cell or two hindering things. Are you sure you don't mean they charge the batteries with generator, then the batteries run through an inverter to supply 110VAC for the cabin?
With your digital meter, you can come close by putting one lead on a post, then put a piece of wire on the other lead, remove the caps and dip the wire in the acid in the cell. Just far enough in to get the voltage, don't touch the plates! Voltage should progressively increase 2VDC with each progressive cell. Find one that doesn't, it's a bad cell.
Replacement? I would suggest a marine style "deep cycle", as they can take being drained very low & recharged better than a regular auto type.
Winterizing, make sure they are fully charged and cover them any time the cabin won't be in use for a while.
--
Nahmie
Those on the cutting edge bleed a lot.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Yep, the Harbor Freight battery tester is a good thiing to have anyway. It contains a big resistor to apply a test load. It doesn't tell the whole story, but is a good start to find the bad ones.
Making the voltage readings, even across each battery, after they are half or so run down will tell you more about which is the weakest.
My guess is that they are all in fairly bad shape and you'll end up buying a new set. Considering the cost of a vacation home, $250-300 probably isn't a big deal. Maybe some of the guests could pitch in on them.
I'd probably just buy the best marine battery WalMart has. Otherwise you are into special stuff and doing some research.
Care is important. It's a good idea to run them down pretty far occasionally...keeps them in more uniform condition. Also leave them fully charged when not in use.
Wally gives a good guarantee, especially on their best batteries, so keep the paperwork. I've actually received free replacements during the initial guarantee period. They didn't even check the old ones!
Wilson

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Best way is to put a load on each battery in turn (sperated from each other) and monitor time vs voltage. I would put at least a 200-300watt load on (12 v light bulbs work great for loads when testing batteries)
Lead Acid batteries typically have about a 100x charge/discharge to 500x charge/discharge lifespan, depending on how deeply they are discharged before recharging. Might be a better idea to double or tripple the # of batteries so that the same usage will NOT drain them as much as now, and keep an eye on the voltage and base the recharges based on those measured voltages
Also, lead acid batteries do best if they are left on a maintenance float charge when not in use, and a solar panel to help trickle/float the batteries when the residence is not occupied would be a good idea
John
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Snip

1. It does not matter if a modern battery sits on plywood or concrete. Modern batteries have plastic cases and this works much better than the wood and tar batteries of years ago that would discharge on a concrete surface. 2. If a battery does have a shorted out cell it can discharge itself and those connected to it rather quickly.

If you can check the cells individually, use a battery hydeoneter to look for consistancy in each cell. A reading that is far higher or lower will indicate a bad battery. Low readings on all cells ususlly only indicate a discharged battery. If you have a volt meter you should have 2.2 bolts per cell when the battery is fully charged and has a surface charge from not being used at immediatley after full recharge. After putting a load on the batteries for 10 minutes or so this surface charge should be gone and the battery voltage reading should be that of the battery spec. If the battery shows below 11 volts you probably have a shorted out cell. Be sure to check batteries individually and disconected from the others. Also, these batteries should be of the marine/motor home variety. If you are using regular automotive batteries they will fail in a short period of time. Automotive batteries are designed to give out lots of energy in short bursts and not be run down to a dead state. OTOH marine/motor home batteries are designed to provide a consistant LOW demand and can be safely run down to total didcharge with out harm to the battery. Typically these batteries have caps for maintence on each cell although this is not a guarantee that it is a marine/hotor home style battery.

Marine/motor home style. Do not mix with automotive style batteries.

Do not let them freeze and keep them DRY and charged with a trickle charger.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Oops, I was tempted to suggest a trickle charger as well. The only way that will work is to remove these batteries from the cabin and take them to a location where full-time power is available. If the generator isn't running, there's no power in the cabin.
Try to find a friend in the area of the cabin who will keep these units warm, dry and charged so hauling them back and forth to your home is not required.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
They make inexpensive solar chargers for autos. You can get a few and hook them up. max

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 14 Mar 2005 13:14:33 GMT, "Leon"
[snip]

Really? How?

Actually to acertain charge condition, the battery should remain unloaded for 24 hours before measuring the voltage.
This is a topic that's been beaten to death in rec.outdoors.rv-travel.
Recommended reading:
http://amplepower.com/primer/index.html
Some of this is self-serving but it is probably the most comprehensive site around that deals with the subject.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Yeah, A battery is simply a serieries of cells and adding another battery simply adds another series of cells. A fully charged 12 volt battery will have a voltage of 13.2 volts. With a slight load for a few minutes the voltage goes down to 12 volts. A shorted cell works the same on the battery as leaving the head lights on with the motor not running. Basically a battery with a shorted cell will run itself down. Other batteries connected in the series will also run down through that short. With automotive type batteries there are some times 2 batteries under the hood when the car has a diesel engine. Late 70's and early 80's Oldsmobiles with diesel engines had 2 batteries. Almost with out fail if one battery went bad the other battery would go bad as a result of being run down to a dead state. Automotive batteries do not hold up long when fully discharged repeatedly.

This is true if you do not have the right type of testing equipment. A fresh charged battery will have that surface charge that I mentioned earlier and will reflect 2.2 volts per cell totaling 13.2 volts. Better HD battery testers can draw a load on the fresh charged battery for a few seconds to remove that surface charge and the voltage on the battery will drop to just at or just over 12 volts. The condition of the battery can then be checked successfully.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 14 Mar 2005 18:34:58 GMT, "Leon"

Baloney. Look at a 12V (nominal) battery in isolation. It is comprised of 6 cells connected in series (aiding). If one cell shorts (i.e. provides zero volts) the series connection yields ~10 V. There is no mechanism resulting from this that affects the remaining 5 cells in the slightest. Period. End of story. There is no additional discharge path. Unloaded, the battery sits there providing 10V.

One or more of them with shorted cells *will not* affect the others.

This situation had the two batteries in parallel. A shorted cell in one will cause the second to discharge to the 10V (nominal) level.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

That depends on which cell is shorted as to what voltage will be remaining. Not always will a battery with 1 shorted cell show 10 volts. I'll admit that it has probably been 20 years since I have done any battery testing. Given that, When I tested for a short, I would connect a lead to 1 battery terminal, I do not recall which, and another lead/probe would go down into the water in the cell. If the first cell was good the volt meter would indicate about 2 volts. With the probe in the next good cell the voltage would be about 4 volts. If the third cell was bad/ shorted out, the voltage would remain at about four bolts for the remaining cells and or if another lead was connected to the other terminal.

And I need to correct a statement that I made earlier. The second battery connected up parallel will also be run down by the bad battery. Having retired from the automotive industry and worked for Oldsmobile for 10 years I saw this often. One day the engins starte fine, the next morning, only a click from the starter solenoid. Oldsmobile always recomended replacing both batteries if one battery was bad as the second battery could often be recharged but would seldom hold up after having been discharged so sompletely. Oldsmobile/ Delco ate many batteries under warranty on cars equiped with dielel engines.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

How is that possible? A car battery is just 6 lead-acid cells in series, that happen to share a common case. Each cell has a potential of a little over 2 volts. The schematic looks like this (assuming I haven't gotten the anode and cathode symbols bass ackwards):
+ | | | | | | - ------||-----||-----||-----||-----||-----||------ | | | | | |
Since each cell produces 2 volts, the end-to-end potential is 12 volts. If you short out a single cell:
+ | | | | | | - ------||--*---||--*--||-----||-----||-----||------ | | | | | | | | | | +-------+
You're left with 5 2-volt cells in series, giving you 10 volts. It doesn't matter which cell shorted, you're still left with 5 2-volt cells in series. 2+0+2+2+2+2 is the same as 2+2+0+2+2+2.

Anybody who designs a system with two voltage sources in parallel or two current sources in series deserves what they get.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Many years have passed,, ;~( and I undoubatably have use the wrong termonology. Seeing was believing with the old style battery tester and my memory of the end result is probably inaccurate. That said however since a battery by definieion is more than one, and or several of any one thing, a battery of cells make up a higher voltage storage unit commonly called a battery. A D cell is technically not a battery but 2 D cells are a battery. I guess to help understand what I am trying to convey, cells in a series contribute to a higher voltage. If one of the cells in a series no longer allows current to pass through the voltage stops increasing at that point. I think similarly with cheap Christmas tree lights wired in a series if a bulb does not work the whole string quits working. If you terminate the strings of lights before the bulb that does not work and close the circuit the lights before the non working light will again light up. A bad cell will have a detremental effect on the remaining cells.

I totally agree but I suspect at that time a battery with enough cranking amps would have been too large to fit in one spot under a crowded hood. 2 smaller batteries could be more easily located. IIRC the combined CCA's were around 1500. The smaller V6 260 ci diesel used in the front wheel drive vehicles used a single larger battery rated at over 1200 CCA. The whole Olds diesel scenario had many weak points. Further, RV's use multiple batteries set up parallel for lighting and water pumps. When one went bad they all seemed to go bad. I was able to make some of them last a little longer by disconnecting them from each other during storage. Then only 1 would usually go bad at a time. I would check the voltage of each one before reconnecting.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
<snip>

Got any free plans?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 16 Mar 2005 11:08:57 -0600, Patriarch

Nope. But I bet Joat does.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

YOU send him the email. ;-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Oh, to go a bit farther as to how a cell shorts out, If you have ever seen in side the battery you have lead plates separated by insulators. The insulators can crack or break from excess cold or heat and eventually allow the plates to come in contact with each other. That causes the short.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 14 Mar 2005 13:14:33 GMT, "Leon" SNIP

In the described environment which does not have electricity to run a trickle charger you may want to check around for a solar based "battery tender". Assuming the cabin is not too deeply in the woods and gets sun at least to the roof you could probably set one up rather inexpensively that would be sufficient to keep the batteries topped off as long as you give them a good charge with the generator before leaving between visits. Of course a good snow on an unheated roof................
Dave Hall
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I had to include that and similar wood references, dear Leon, as I didn't want to be accused of posting an off-topic message. ;)
--
Owen Lowe
The Fly-by-Night Copper Company
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.