battery not achieving full charge

[tjfmmaes]

Hi all

I've just spend a good part of my weekend poking around the boat with a multi-meter with limited (or should I say no) success. I have recently bought an 1987 oceanis 350 with shore power, a rather vintage (1990ish) battery charger with 2 outputs and amp meter and two 135Ah batteries (service and engine). It also has an adverc charge regulator connected to the alternator. I found that, when using the charger, 1 battery measured 15.3+v (and burpled gently), the other was stuck on whatever voltage it had beforehand (12.3v). I swapped the charger outputs around and the reverse happened. When charging, the amps on the charger start at about 20 and then rapidly drop of to about 5 or 6. I had 2 observations here: 1) 15.3v is a bit much for charging a battery isn't it? (I thought around 14.5 is normal) and 2) my charger looks knackered - only 1 output working and 20Amps*15.3V=300W is a lot of output.

I then ran the engine for quite a while and measured the voltages on both batteries - both showed 14.3v which seemed fine (at least the adverc is working, phew). The problem is that the service battery (which has now connected to the over-charging charger ) seems to lose its charge v, quickly or never actually attains anything over 12.3v. I checked the water level in 2 cells (someone clever had tried to open the others with a blunt instrument and buggered the screw holes), which looked fine.
The engine battery, which used to be connected to the overcharging charger output, also dropped off quite quickly, but not as bad as the other one.

Also, another funny thing seems to happen in that the voltage drops, and then slowly regains its voltage (a bit) after switching off the charger over a period of an hour or so. Could that have anything to do with the voltage being "soaked up" (for want of not knowing a technical term) by the charger and then being released again?

To cut a longwinded story short: Has overcharging (is 15.3v overcharging?) wrecked my batteries? Is there anything I can do to rectify this? Is there anything else I should check? If I need to change my charger do you have any recommendations? I saw some with one output and a 1A trickle charge for the engine battery - are they any good?

All help is greatly appreciated as my wife is getting v bored with me going to the aft cabin, lifting the bedding and prodding around with a multimeter grunting inane comments such as "rise you b*****d"

Thanks, Thomas


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[Talbot]

Throw away that charger as it is ruining your batteries. I suspect it has boiled your electrolyte and probably warped some of the plates. 14.4 should be the maximum at normal temperatures, a stepped charger will not provide that except in one of the steps (the following is an adverc picture and differs from the steps on my mobelec charger)

Having replaced your charger, also replace the batteries that are not performing.

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[gert]

I would suggest to replace your charger and batteries immediately!

I just bougth a new charger from the swedisch company CTEK.
http://www.ctek.se/index_GB.htm
They have a (comprehensive) charger university on their website, with everything in detail about charging and batteries.
Please read this before buying anything.



<hr width=100% size=1>So Long, and thanks for all the fish..

 

[Anthony]

Hi, suggest you replace charger and batteries. Go for one of the multi stage chargers (sterling, adverc etc, there is no real consensus on which one, personally I have the sterling).

This could also be a good time to review the battery situation. Does 135AH prived the power that you need (running them down to below 50% capacity kills them quite quickly), so realisticaly you have about 65 AH of domestic. The reason I mention it is how much battery power you have on board would define what size charger you get, so best to plan ahead now rather than buy somthing you will replace with a bigger model in 6 months. You also dont want to kill your new battery by over discharging it to often.

Fridge and laptop are the main consumers for me, so have just replaced 105AH domestic with 405AH, a bit extreme for most, but you get the idea.

As for new batteries, dont pay swindalry prices, I got Numax Marine 135AH for £56 ea (+vat) from totton autofactors in Southampton, compared to abput £95+vat from Adverc.

Oh and as a side note, manbat, the distributers of Numax told me there is no difference between their leisure battery and marine battery, except the price!

Anthony

<hr width=100% size=1>The difference between men and boys, is just the price of their toys...

 

[tcm]

i agree with the others. Chuck out the batteries, get new ones. In technical terms, they are surffering for a lack of "newness"

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[William_H]

Just a few quick comments here. A digital multimeter can over read if the battery is flat. 15.3 volts @ 20 amps on charge is ok for a short period say up to an hour but longer periods can over heat the battery.
The battery is dead if it won't start the motor or will not give you the voltage current over time that you need for your services. If either battery will perform those tasks then it is ok. It does however sound like both are dud. Take heart batteries don't last for ever. The charger sounds like it is dead in one output. You could however use it with both batteries connected in paralell to the one working output. If the charge current drops from 20 amps after a short period that may be ok. I appreciate other respondents reckon the charger has killed the batteries but I am not so sure. A sure sign is loss of electrolyte and warm battery. You will probably go for a new charger but if you are really tight like me you may be able to manage with the old ione.
Regards will

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[willothewisp]

have a look at this site: www.victronenergy.com. The downloads are worth a try.

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