Battery advice please

Saguday

Saguday

Well-Known Member
Joined
28 Feb 2006
Messages
3,263
Location
Me: Zummerzet Boat: Plimuff
Visit site
Dear Chaps and Chappettes

Have 5 x 100Ah AGM house batteries sitting at about 8V and wondered if it's safe to try and charge them up with a hefty 225AH battery charger? Or do I need to be more subtile wot do you fink?

Have been running engine to loosen things up and the house batts seem to be slowly responding but will take forever this way.

Dont know if I should disconnect them all and charge one at a time or can I do them all at once - any battery afficianodoes care to comment?

Ta

Neil
 
Saguday said:
Dear Chaps and Chappettes

Have 5 x 100Ah AGM house batteries sitting at about 8V and wondered if it's safe to try and charge them up with a hefty 225AH battery charger? Or do I need to be more subtile wot do you fink?

Have been running engine to loosen things up and the house batts seem to be slowly responding but will take forever this way.

Dont know if I should disconnect them all and charge one at a time or can I do them all at once - any battery afficianodoes care to comment?

Ta

Neil
Click to expand...

Ask VicS he knows most answers :D
 
Saguday said:
Have 5 x 100Ah AGM house batteries sitting at about 8V l
Click to expand...

Thay could be dead now, you need to get them checked by battery people.

You can try taking 4 out of circuit and charge just the one from engine, see if it takes a good charge, say 30 amps. If it only takes say 2amp it is almost certainly dead, in which case trying the big charger will not loose you anything.

Brian
 
Thanks Brian. Given where they are is trying the big charger likely to cause any issues? Is it possible just one of the batteries is duff and is dragging the rest down or would they all be in the same state?

Batteries were fine end last year but boat has been unused this year until this weekend. Only thing I found was bilge pump was accidentally left on auto (mea culpa) so probably culprit for running batts down.
 
I would be taking one out and plugging it into a modern multi-stage charger to see what happens. I wouldnt be surprised at all if they are fine - if they were ok when last used.

In days gone by I would have probably gone for the big amp charger as you suggest ............. from my readings, things have changed .........
 
Hi Folks, thanks for the response and here's an update.

Using the engine only I coaxed them from 7V up to 8.4V which led me to believe they were not dead. I phoned a couple of battery people to see what they said and the first said "they're busted chuck them out" and the second said "no, give them a good solid charge for 24 hours and you should be fine"

Given there is just shy of £1700 worth of batteries at stake I hit them with a 30A mains charger and in 6 hours they were at 11.9V. So we're functioning again and I'll continue with another day of charging to make sure everything's fine.

At least this has given us plenty of opportunity to clean the boat :)

Cheers

Neil
 
Batts

Hi Neil,

Once you have given them a much longer charge you may wish to check how much of that voltage is just a "surface charge".
Once fully charged (and batterys disconnected from everything, so there is no drain) - re-check the voltage. It should only drop a tiny amount.
If they drop a couple of volts (approx) there could be a prob.

Will keep fingers crossed for you

Ian

p.s £1700!!! ouch!!!!!!!!!!!!!!!
 
Hi Ian,

Overnight they only dropped about 0.2-0.3V so I ran the engine for an hour this morning (1500rpm astern tied to pontoon ) and the charger was dumping 60A into them at the peak of the charging cycle. They're sitting at about 11.8V at the moment so I dont think they're fully charged yet but I'm much more confident they'll get there.

Next, I need to find out why me solar panel charger ain't outputting :)

Yes, the house bank is 5 Lifeline AGM's 100AH which in the US is about $1500 and here £1700 !!!

Cheers

Neil
 
Saguday said:
Hi Ian,

............. They're sitting at about 11.8V at the moment so I dont think they're fully charged yet ..............
Click to expand...
They certainly aren't, Neil, you need to get them sitting at 12.7v an hour or so after stopping charging before you can breathe a sigh of relief.
 
dabsolute470 said:
wow... just googled them and they seem very good but soooo expensive.

could you not use normal ones ? sorry for my ignorance.

steve
Click to expand...

They served us very well when we lived aboard and four came as standard kit on the boat when we bought her. If I had to replace them now I'd have to go for a cheaper alternative but if I can get another year or two out of them I'll probably try and get the same ones - unless western civilisation has collapsed entirely by then of course... :)
 
I had replaced 3 blown Odyssey AGM batteries (permanently connected for two years to non smart charger) in 2006 with equivalent Squadron AGMs. The boat was then in Fox's overwinter for a major repair, and I left the batt switch on for 6 weeks... When I got back to the boat the domestics were all showing 4V. I charged them with a smart charger (lent by Fox's) for about a week, and they are still fine 5 years later. I think the sums work out for AGM's for me...
 
You must log in or register to reply here.

Share this page

Top