Battery gets Hot but not Full

[Ex-Calif]

Yes never below 50% or about 12v.

You don't mention where you are but I would take the batteries to a battery shop and have them tested. You will likely be buying new batteries anyway and you can trade them in at the same time.

In the US one of the big shops can do it.

Not sure you can get to the individual cell voltages by yourself.

[conachair]

Have a read here..... http://batteryuniversity.com/learn/a...internal_short

In fact, read the whole site
Sulphation is a different process to shedding.

[h the boat]

Hi Sam, Most of the replies you have had have been on the right track, BUT have you checked each battery by charging it on its own. If the originating fault is in one of the batteries, it will show a different charge or voltage rate to the other. If they both appear to give a similar result, you could have a rectifier (diode block )fault in your charger, which is allowing a substantial volume of A/C current direct to your batteries. If this is the condition, your battery's may have already been destroyed..AND the same will happen to any new ones. There is a relatively simple way to check, but you will need to borrow an analogue volt meter which can read both A/C and DC. A digital one will not display a correct result. First connect the one battery which you think may be good. switch the meter to DC Volts, in the 12 v-20v range. switch on shore power charger, you should see about 12-14 v across the battery. Switch off charger, turn meter to A/C volts switch on again you should see very little or nothing.. If it is still showing almost the same voltage, then the problem probably lies in the charging unit. Not to mislead you, it may be a poorly made volt meter giving you this effect but you can easily check this by repeating the operation on a neighbours boat... h the boat.

[btrayfors]

Sealed flooded batteries do not belong on a boat, especially not for "leisure" or house batteries. These are not deep-cycle batteries, no matter their markings.

The Victron Centaur is a capable charger.

As was suggested, replace the batteries you have....both of them...with golf-cart batteries which can be found most anywhere. Trojan T-105s are the "gold standard", but there are many others. A good U.S. brand is Crown...made in Ohio.

Two 6V golf-cart batteries in series will give you about 225AH capacity @ 12VDC.

They should be charged at 14.6-14.8VDC in the absorption phase, and when fully charged should be floated at 13.4-13.6VDC.

Treat them well and you'll get 5-7 years from them.

Do NOT discharge below 12VDC. Better, keep them as fully charged as you can, and don't discharge below 12.2VDC (50% SOC).

Use only distilled water to keep the electrolyte about 1/2" above the plates. Be careful not to introduce contaminants when you fill them. Keep them clean.

Get a good multimeter and clamp-on ammeter, and learn how to use them. Don't believe the onboard meters unless you have checked them against a reliable standard.

Bill

[Scott Berg]

What Bill said


Sent from my iPad using Cruisers Sailing Forum

[thinwater]

I probably missed it in an earlier post, but check the SG or RI on the fluid (state of charge). Voltage tells only 1/2 the story. If the SG is up, that's all your getting (filly charged) regardless of voltage (some detailed adjustments apply).

[Sam the Sailor]

Thanks for the answers! The other battery (the one that didn't heat up) is receiving charge as usual but the voltage goes down to 12.0 V after drawing only 45 amp hours (135 Ah battery) so obviously it's not working perfectly anymore.

I will try to find golf cart batteries but I don't know how readily they are available in Greece. Currently I'm in Corinth and soon going to Athens and I hope to find them there. If anyone has experience where I should ask those batteries here I'd be more than happy to hear.

I think I need four golf cart batteries to be able to use ~200 Ah without dropping voltage under 12.2 V. I like to anchor but I don't have solar panels yet so the energy is a bit of a problem.

[donradcliffe]

I bought 8D lead acid batteries from a shop in the district between Marina Zeas and the Port of Pireaus. Nice folks, good prices, and they delivered them to the marina.

[savoir]

Even though the battery problem is consistent with a faulty battery cell that is not the only possibility. If the PO can sell you a boat fitted with truck batteries he might also have sold you an incorrectly programmed charger. A charger at the wrong setting can cause the same problem.

You have to tell the charger what type of battery you are using by adjusting the selector switch which is at the front/bottom of the unit. It seems like you are going to buy lead acid so you should check that the switch is at " LA ".

[Sam the Sailor]

Originally Posted by donradcliffe

I bought 8D lead acid batteries from a shop in the district between Marina Zeas and the Port of Pireaus. Nice folks, good prices, and they delivered them to the marina.

Thanks! Do you happen to remember the name of the shop or whether they had golf cart batteries? If not I guess other deep-cycle batteries also work.

[Sam the Sailor]

Originally Posted by savoir

Even though the battery problem is consistent with a faulty battery cell that is not the only possibility. If the PO can sell you a boat fitted with truck batteries he might also have sold you an incorrectly programmed charger. A charger at the wrong setting can cause the same problem.

You have to tell the charger what type of battery you are using by adjusting the selector switch which is at the front/bottom of the unit. It seems like you are going to buy lead acid so you should check that the switch is at " LA ".

Thanks for the tip! I checked the switch and it was correctly set to "LA". However, according to manual absorption voltage for LA is 14.5 V and Float voltage 13.5 V. Currently my remaining battery is charged with 15 A and 14.0 V.

If I have understood correctly my 30 A charger should have following steps when charging the battries. Please correct me if I'm wrong:
1. Charging with 30 A, voltage lower than 14.5 V since charger is the bottleneck
2. Current stays at maximum 30 A while voltage keeps increasing until it's 14.5 V. After that charger is no more bottleneck
3. Voltage is fixed 14.5 V and current starts to decrease.
4. When current is under some threshold (what it might be?) charger switches itself to Float mode and voltage is decreased to 13.5 V

Have I understood the charging process correctly? If yes then there should not be a moment when current is 15 A and voltage 14.0 V, shouldn't there?

[Sam the Sailor]

Just a quick status update. I found few battery suppliers in Athens from ybw forums and got very good service from Dimitris Kapetanakis, Automotive Solutions Ltd. They delivered four Trojan T-105 batteries to my boat so now I have 450 Ah capacity which is vast improvement to previous situation.

I also installed Nasa Clipper BM-2 to monitor new batteries to make sure they won't drop under 12.2 V or 50% SOC.

Thanks for help everyone, especially Bill for the valuable hints!