Battery chargers

[Maynard Rupp]

I know this subject has been tossed around before, but I still don't get it. We have the original 1986 battery charger on our 36'C. It seems that we get about 2 years out of those heavy 8D batteries. Our boat is plugged in at the dock and I keep the battery charger on. I am concerned that the bilge pumps could quit if the boat leaked badly and the charger was off. The paper work for the charger seems to indicate that the charge rate lessens as the battery becomes fully charged. Am I ruining my batteries by leaving that charger on? Would a more modern charger help this situation? Can anyone recommend a good, (better than we have), charger? These batteries work fine until they suddenly stop puting out voltage at all. BAH!!

[OBXTucker]

There's a great thread ongoing right now about Outback's and Analytic's.
I'm assuming you're using the old Sentry's and I can speak from authority in saying that they WILL cook your batteries if left on 24/7. How much distilled water are you going through (you are using distilled, correct)?

Join the other thread, a lot of information there.

[SKYCHENEY]

Some seem to have good luck putting a timer on those old chargers so they only run a few hours/day.

[spcoolin]

I've said it before...Even written long posts about it...But a properly operating SENTRY charger WILL NOT BOIL Batteries...
(Hatteras also installed LaMarche chargers that would boil batteries)

If a Sentry does boil batteries...
Either someone has put it into the manual mode (switch) where it won't shut off...
Or...It's control board is out of calibration or bad... It can be replaced for less than $200...

No...A Sentry is not new technology that will charge batteries as fast as the newer technologies will, but it's a set it & forget it charger, it's practically bullet proof, and every part inside is still available for replacement if needed...

Be aware that most of the newer smart chargers are a circuit board inside a box...Generally that board can't handle much abuse, and once it fails you have no manual bypass mode/switch...The board is also very expensive...

I'm not putting down the newer chargers but what I'm suggesting is:
You may want to think about leaving a Sentry intact & installing the newer charger if you want...Just keep the reliable, repairable Sentry installed as a standby.

Steve~

[fissioneng]

I've said it before...Even written long posts about it...But a properly operating SENTRY charger WILL NOT BOIL Batteries...

If a Sentry does boil batteries...
Either someone has put it into the manual mode (switch) where it won't shut off...
Or...It's control board is out of calibration or bad... It can be replaced for less than $200...

Or you have bad cell in the "control" battery, then the "non-control" battery gets the heck charged out of it when it doesn't need it. The Sentry can't detect a bad cell.

Or if the "control" battery needs charge, the "non-control" battery gets too much charge.

The problem with some Sentry's (my old one) is that they can't discriminate between the batteries. Whatever the "control" needs, the other one gets too.

I have never heard of a smart charger failure, but I'm sure it has happened. I have owned one for 10 years.

[REBrueckner]

You are using lead acid, not AGM nor gel batteries, right?

If they are using a lot of water, then they are being overcharged....It could be becaause an appliance is running and the Sentry may provide too much charge...more current than is needed to run the appliance....I do not know how good a job they do in that situation, which is abnormal.

Any significant overcharge would cause loss of water. That's a goof first test. When I ran my Hatt cruising full time for six months, and used 12 power full time, I found my 7 x 8D wet cell/lead acid batteries would take over a gallon of water...say 5 quarts at the end of the season. Not a lot for that much liquid capacity. Sitting mostly idle during about five mos of winter with light use, they would still use maybe 2-3 qts and I always topped them off before departing.

Over 11 years of use, several different brands would fail at about four years....maybe three years on on occassion. and it was usually because of a weak cell of two...most cells seemed fine, but one weak cell per pair or one per battery significantly altered power and I learned others would fail sooner rather than later....several times a majority of the cells cells got weak. When I replaced my Sentry with Statpower smart charges, the batteries charged faster, and I had three 40 amp chargers for genny use, but the batteries did not seem to last longer. So I ended up often buying two new 8D's every year among my three battery banks, that way I always had one bank of new batteries aboard.

Last fall, I checked three car batteries...my wife's and mine and my daughter...each tested just fine with a hyrdometer...about 3/4 or so charge as I recall. This spring, just six mos later, BOTH my and my wife's batteries failed!!!! (One was Duralast, from Pep Boys, another Exide.) (about three or four years old) So about six months after testing ok, each battery now had several virtually "dead" cells.

If the batteries are NOT being used when you are away, the normal situation, try feeling them for warmth...by hand or an infrared thermometer...idle batteries should NOT be warm to the touch.

You can also check the voltage at the battery terminals when systems are idle,,a voltage of 14, for example, is way too high if you detect that repeatedly....I've forgotten what normal idle voltage for a Sentry would be no more than 13 and 12.6 is likely better ....

[REBrueckner]

You are using lead acid, not AGM or gel batteries, right?

If they are using a lot of water, then they are being overcharged....It could be becaause an appliance is running and the Sentry may provide too much charge...more current than is needed to run the appliance....I do not know how good a job they do in that situation, which is abnormal.

Any significant overcharge would cause loss of water. That's a good first test. When I ran my Hatt cruising full time for six months, and used 12 power full time, I found my 7 x 8D wet cell/lead acid batteries would take over a gallon of water...say 5 quarts at the end of the season. Not a lot for that much liquid capacity. Sitting mostly idle during about five mos of winter with light use, they would still use maybe 2-3 qts and I always topped them off before departing.

Over 11 years of use, several different brands would fail at about four years....maybe three years on on occassion. and it was usually because of a weak cell of two...most cells seemed fine, but one weak cell per pair or one per battery significantly altered power and I learned others would fail sooner rather than later....several times a majority of the cells cells got weak. When I replaced my Sentry with Statpower smart charges, the batteries charged faster, and I had three 40 amp chargers for genny use, but the batteries did not seem to last longer. So I ended up often buying two new 8D's every year among my three battery banks, that way I always had one bank of new batteries aboard.

Last fall, I checked three car batteries...my wife's and mine and my daughter...each tested just fine with a hyrdometer...about 3/4 or so charge as I recall. This spring, just six mos later, BOTH my and my wife's batteries failed!!!! (One was Duralast, from Pep Boys, another Exide.) (about three or four years old) So about six months after testing ok, each battery now had several virtually "dead" cells.

If the batteries are NOT being used when you are away, the normal situation, try feeling them for warmth...by hand or an infrared thermometer...idle batteries should NOT be warm to the touch.

You can also check the voltage at the battery terminals when systems are idle,,a voltage of 14, for example, is way too high if you detect that repeatedly....I've forgotten what normal idle voltage for a Sentry would be no more than 13 I suspect....

[REBrueckner]

You are using lead acid, not AGM or gel batteries, right?

If they are using a lot of water, then they are being overcharged....It could be becaause an appliance is running and the Sentry may provide too much charge...more current than is needed to run the appliance....I do not know how good a job they do in that situation, which is abnormal.

Any significant overcharge would cause loss of water. That's a goof first test. When I ran my Hatt cruising full time for six months, and used 12 power full time, I found my 7 x 8D wet cell/lead acid batteries would take over a gallon of water...say 5 quarts at the end of the season. Not a lot for that much liquid capacity. Sitting mostly idle during about five mos of winter with light use, they would still use maybe 2-3 qts and I always topped them off before departing.

Over 11 years of use, several different brands would fail at about four years....maybe three years on on occassion. and it was usually because of a weak cell of two...most cells seemed fine, but one weak cell per pair or one per battery significantly altered power and I learned others would fail sooner rather than later....several times a majority of the cells cells got weak. When I replaced my Sentry with Statpower smart charges, the batteries charged faster, and I had three 40 amp chargers for genny use, but the batteries did not seem to last longer. So I ended up often buying two new 8D's every year among my three battery banks, that way I always had one bank of new batteries aboard.

Last fall, I checked three car batteries...my wife's and mine and my daughter...each tested just fine with a hyrdometer...about 3/4 or so charge as I recall. This spring, just six mos later, BOTH my and my wife's batteries failed!!!! (One was Duralast, from Pep Boys, another Exide.) (about three or four years old) So about six months after testing ok, each battery now had several virtually "dead" cells.

If the batteries are NOT being used when you are away, the normal situation, try feeling them for warmth...by hand or an infrared thermometer...idle batteries should NOT be warm to the touch.

You can also check the voltage at the battery terminals when systems are idle,,a voltage of 14, for example, is way too high if you detect that repeatedly....I've forgotten what normal idle voltage for a Sentry would be no more than 13 I suspect....

[bobk]

I had this issue with the OEM Newmar charger on my trawler. Newmar sold me a 'CCB', Charge control box, for about $100 about 20 years ago and it solved the problem.

[rsmith]

I know this subject has been tossed around before, but I still don't get it. We have the original 1986 battery charger on our 36'C. It seems that we get about 2 years out of those heavy 8D batteries. Our boat is plugged in at the dock and I keep the battery charger on. I am concerned that the bilge pumps could quit if the boat leaked badly and the charger was off. The paper work for the charger seems to indicate that the charge rate lessens as the battery becomes fully charged. Am I ruining my batteries by leaving that charger on? Would a more modern charger help this situation? Can anyone recommend a good, (better than we have), charger? These batteries work fine until they suddenly stop puting out voltage at all. BAH!!

I had a sentry on the boat for 30 years worked great I did have a timer on it for when I left the boat. since then I ve been thru 2 ferro chargers and both have been cooking the batts out.
As far as the pump I was always worried about the 32v pump so I mounted a 110v submersible pump from grainger above the dc pump. I got a fiberglass pump with a built in float switch. its got its own thru hull and is far greater capacity than the dc pumps. since its above the normal bilge level it wont come on unless its a emergency. like all backup stuff I test it once in a while to make sure its still works