Batteries draining quickly

[Rum Runner]

I have a 1987 340 Sundancer with three deep cell house batteries, run in a series. The batteries are charged by the original smart battery charger installed by Sea Ray. They show a charge of 12.6 volts when fully charged, but drain within an hour or so. I did not have this issue until I recently had the boat hauled and the bottom painted. When the boat was returned to the slip I discovered the problem. The batteries are about 18 months old. Any suggestions would be helpful.

 

[Lazy Daze]

Your batteries are connected in parrelel, not series. If they were in series, you would end up with 36v. OK, on to the problem at hand.

When the charger is on, do you see about 14.5v at the batteries?

First thing you can do is do an amp draw test to see how much draw you have. Remove the end negative cable and connect a DVM inline between the cable and the post. With no accessories on, you should have minimal draw - maybe an amp or less. If that is good, then I would check the cables/connections for looseness and/or corrosion. Next, disconnect the batteries from each other and charge independently then check voltage after an hour. You may have one bad bettery pulling the others down. Is the fluid level full in each battery?

 

[Rum Runner]

Thank you for your reply Dennis, I appreciate the help. Regarding your first question; Currently, no the charger will not charge the batteries any higher that 12.6 volts. Last week I had the boat hauled and the bottom painted, prior to that the charger produced about 13.8 volts, sometimes better. I have considered the possibility that something came loose during the haul out. Additionally, the batteries charge well above 14 volts via the alternator, but discharges quickly.
Not quite sure about "DVM", I'm assuming that means Digital Voltage Meter. If I'm right about that, once I disconnect the the neg. cable from the end battery, your saying to connect the positive lead of the DVM to either the post or cable and the negative lead to the other? And I intend to follow your other suggestions as soon as I can get down to the boat. Thanks again for you help Dennis.

 

[kaz911]

First thing to do is check and clean all battery connections. I had 0.5v go missing from my system on one battery bank - only due to a dirty battery connector. While the connectors are off - measure voltage on each battery. If they are the same age and same type - they should be around the same voltage. The best way to measure is to take all connectors off the battery - leave the battery to "calm" for about 30 minutes - and then measure.

I would not recommend putting your AMP loads through your multimeter unless you know what you are doing. Most meters can measure a maximum of 10 amps for current flowing through them. And on a boat 10 AMPs are not a lot. So if you have a defective component using a lot of Amps - you will fry the fuse in your meter. But I consider a AC/DC clamp meter an absolute essential thing to have - you can find AC/DC clamps with built in "multimeter" for $60-$160 and they make debugging much easier since you can measure APMs by clamping the meter on the cable without taking any cables off. And they do not "blow" if current is too high.

I have also just found out my charger is fried - or partially fried due to the fan not operating as it should - so some of the power transistors has "pooped" out. So my 30 amp charger is now a 10 amp charger.

 

[Lazy Daze]

Yes, that is the correct way to do an amp draw test with the DVM. I think it would extremely unlikely that anything is pulling more than 10 amps - my "guess" is that the problem lies elsewhere - (some meters can do 20 amps, too) - but a clamp meter is good idea, too. Some of them can get quite pricey (although good equipment) but that would be more of an anomaly -- that's a joke/play on words... for those that get it :grin: -- for those that don't, it's just a really bad joke.

Clean connections are always a good place to start (sort of standard practice when it comes to electrical gremlins). But don't stop at the battery - follow the ground to the engine and follow the positive, too. Remember, sometimes a connection can appear good and tight, yet corrosion has wicked it's way up inside the sheathing. Regardless of the outcome, seeing your boat is an '87, you might consider replacing your cables.

Assuming good connections...

Anywhere around 14v is what would be expected from either the charger or the alternator. And once the charging is "off" it would be normal for the batteries to settle down to somewhere in the low to mid 12v range. If they're going lower, one of the batteries is either low on fluid or bad. Check them individually.

IF the charger is indeed hooked up to the batteries (you're correct to wonder about it not being hooked up), and you're not seeing 14v-ish, then you've narrowed the culprit down to the charger-side. Is the breaker for the charger (might be labeled AC converter) on? Do the charger's lights come on? Breakers can "tire out" over time and sometimes only partially trip - pressing the "on" side will feel a little spongy. Does your charger have an internal fuse?

 

[kaz911]

Dennis - I don't really want to correct you but a fully charged LA, Gell or AGM battery must show (with very little load) 12.6 volt or MORE to be 100% charged. 12.5 volt = about 10-15% discharge.

1 engine room blower takes about 5-7 amp. 1 light (20 watt) takes 1.7 amp - you quickly reach 10 amp on a cruiser....

 

[Lazy Daze]

No worries - you are entirely correct. I think I was just being too general, trying to take into account possible inaccuracies in inexpensive DVM's (or simply using the dash gauge) and assuming that Rum is referring to voltage much less than even that. "Assumptions"... :smt101

As far as the amps go, yes, you're right that things can add up quick - but it's going to be very, very unlikely to have multiple errant draws. Especially considering that it shouldn't be too hard to figure out if everything is turned off or not. BUT, Rum, the way to properly do this would be to turn everything off at it's switch, and then check the draw. You should get very minimal draw at this point - things like auto bilge pump sensors, CO monitors, radio memory - miniscule amounts. If you're getting a higher draw, then turn the breakers off one at a time until the draw lowers - that at least narrows it down to a particular circuit. But I think you can wait on doing this till you check out the batteries/charger.

My guess is leaning towards (1) something wrong on the charger side... not hooked up/bad breaker/fried or (2) A bad battery/connections.

Rum - It's true that when one battery is bad it will draw the others down and if you check the voltage while they are still connected together, you will see a lower average. BUT, another quick check can be to simply disconnect them and recheck voltage on each one individually. Often, if only one battery was bad, it will start to read lower than your initial reading and the other two will start to read higher.

 

[Rum Runner]

Thanks Dennis and Kaz, I'll give all of your suggestions a try this week. If you don't mind, one last question and then I'll let both of you get on with your lives. My on board charger is the original one installed you Sea Ray in 1987. According the manual, it is a smart charger and should be left on. As I mentioned in my earlier post, prior to last week it would charge the battery bank up to approximately 13.4 volts. Now, it does not seem to charge above 12.6 volts. I am certain that the charger is on, but not sure of its output. There is a meter on top of the charger that does not register, never has, and I am not sure if it's a volt meter or amp meter. If, after I disconnect the batteries, can either of you tell me what the range of output would be normal for this charger, and if it only produces 12.6 volts, would that be a good indication the charger has gone bad? Thanks again for all your help. R

 

[Molson]

put your volt meter on the battery and check the reading. Plug in the charger and check it, you should know right away if its charging or not.

 

[electricaldoctor]

put your volt meter on the battery and check the reading. Plug in the charger and check it, you should know right away if its charging or not.

+1 k.i.s.s.

 

[Lazy Daze]

I'm not sure if you've actually measured the 12.6V at the battery with a DVM yet, or not. BUT... regardless of battery condition, you should still see somewhere around that 14v reading. Even if a battery is bad, you should still see that higher voltage that the charger is putting out since when the charger is on you're measuring what the charger is putting out - a bad battery won't lower that number. Only when the charger is turned off will the battery voltage start to come back down to normal (or lower/worse).

 

[2texoma]

First thing to do is check and clean all battery connections. I had 0.5v go missing from my system on one battery bank - only due to a dirty battery connector. While the connectors are off - measure voltage on each battery. If they are the same age and same type - they should be around the same voltage. The best way to measure is to take all connectors off the battery - leave the battery to "calm" for about 30 minutes - and then measure.

I would not recommend putting your AMP loads through your multimeter unless you know what you are doing. Most meters can measure a maximum of 10 amps for current flowing through them. And on a boat 10 AMPs are not a lot. So if you have a defective component using a lot of Amps - you will fry the fuse in your meter. But I consider a AC/DC clamp meter an absolute essential thing to have - you can find AC/DC clamps with built in "multimeter" for $60-$160 and they make debugging much easier since you can measure APMs by clamping the meter on the cable without taking any cables off. And they do not "blow" if current is too high.

I have also just found out my charger is fried - or partially fried due to the fan not operating as it should - so some of the power transistors has "pooped" out. So my 30 amp charger is now a 10 amp charger.

I have searched for such meter in this price range and thus far the one's I saw below $100 will only read AC. The one's in the $175 price bracket test on 600 amp scale with +- 1% accuracy at best making it almost worthless for the type work discussed here. Will you please be more specific regarding source of DC clamp on amp meters with built in multimeter capiable of reading in the 10 amp range? No intent to hi-jack but thought op might run into same difficulty locating a suitable meter. Thanks

 

[kaz911]

I have searched for such meter in this price range and thus far the one's I saw below $100 will only read AC. The one's in the $175 price bracket test on 600 amp scale with +- 1% accuracy at best making it almost worthless for the type work discussed here. Will you please be more specific regarding source of DC clamp on amp meters with built in multimeter capiable of reading in the 10 amp range? No intent to hi-jack but thought op might run into same difficulty locating a suitable meter. Thanks

The 1% is of the reading - not of the entire range.... So if you measure 10 amp - 1% is +/- 0.1 amp. Even if it was 0.5 amp out - that is not going to make a huge difference. You just need ballpark figures.

This $8 clamp meter would work fine: http://www.ebay.com/itm/EXTECH-MA22...577?pt=LH_DefaultDomain_0&hash=item338275b661

To measure voltages - you just need some cheap voltage probes - they are pretty much generic - and can be found for $2 for a set.

 

[doug5790]

I have 3 batteries total. one on the port side, two on the starboard. 1995 290 Sundancer. Which is house? which is port motor, which is starboard motor? My port motor battery is going dead. Out for a cruise, I can watch the port gauge slowly go from 12v to 11v to 10v and then not enough to crank the port motor. Will start with "emergency" jump switch. All three batteries were just replaced. I need to find a loose connection, or wire not connected. Which battery should I look at?

 

[src]

Unless someone screwed with the system, the port battery is for the port engine, the starboard battery bank is for starboard engine AND house. It sounds like your battery isn't getting charged from the alternator while running. Could easily be an alternator problem, but I don't know enough to give you the details on checking it out. Search for alternator on the forums for more info, or someone else will probably chime in with some good info.