I'm a Battery Killer!

[Richard10002]

Posted this on canalworld a few weeks ago, and wonder what the opinions here are:

This is longer than I expected - apologies. It's an age old story, but I would be grateful for some input to my specific situation.

Bought 3 x Varta Hobby Leisure 110Ah batteries last May. Well recommended for a domestic bank.

I have a NASA BM2 battery monitor
Battery charging is via engine alternator, or Honda Eu20i generator via a Sterling Pro Combi S inverter charger with 80A charging capability.
No access to shore power.

When on board, I use between 50Ah and 70Ah per day, and generally charge with the genny each day for at least a couple of hours and much longer for a couple of days a week. Each day I am usually able to reach the point where the batteries are only drawing 3 or 4A on charge. I use the 14.4V Absorbtion setting.

Given 330Ah when purchased, a useage of even 70Ah a day, is less than 25% of capacity, and voltage readings would tend to confirm this until depletion of capacity started.

(I recall somebody either here, or in another place, suggesting that the above regime is likely to sulphate batteries quite quickly - which I didn't deny )

I can't remember exactly when but, around November/December, the batteries seemed to be reducing in capacity to the point where, over the past month or so, from fully charged in an afternoon, using about 40Ah by the next morning would reduce voltage to about 11.9V.

Bought a Hydrometer from Halfords and took readings of the 6 cells of each battery today:

Battery 1: 1180 to 1200
Battery 2: 1155 to 1180
Battery 3: 1125 to 1175

This was after charging for a few hours at 14.4V, to the point where the batteries were drawing less than 2A, having drawn about 70A when starting the charge. I'm guessing they are pretty much knackered.

A similar thing happened with a cheap set of batteries bought the previous March, (2012), so it would seem that my useage and charging regime kills batteries.this is despite the fact that I have what seem to be good charging equipment, and that I am quite anal about monitoring what is going on.

I think I now have a couple of specific choices (along with some other possibilities):

1) buy 4 x Trojan t-105 for about £430. This would give me a bigger bank, (450Ah), and a more tolerant battery, which might survive my. I suppose I could buy 2 for just over £200. My useage shouldn't take them below 50% if they arrive full, so I would be risking only half the money

2) buy 3 x cheap non branded 110Ah batteries, (say £65-£70 each), and accept that this will probably be an annual cost, (£4 a week, so not the end of the world).

I have a 100W solar panel fixed flat on the roof. This obviously doesnt do much to help. As prices drop, I could add another 200W for about £100 or so.

What do true liveaboards, without access to shorepower, do to keep their batteries charged, maintain their capacity, and make them last for years?

 

[Otter]

I'm not tremendously knowledgeable, but putting 80amps into a 300amp bank seems like you're charging it really hard, I had thought he maximum recommended charge was 10-15% of the bank.

 

[GHA]

Batteries are buggers, knee jerk is that yours aren't getting fully charged each time.
The 14.4v and amp readings, we're they by the batteries? If from a meter downstream a bit the voltage can be quite a bit out so the actual voltage at the batteries can be much lower when charging than the meter shows, makes it look like the batteries are closer to a full charge than they are.

 

[john_morris_uk]

Batteries are buggers, knee jerk is that yours aren't getting fully charged each time.
The 14.4v and amp readings, we're they by the batteries? If from a meter downstream a bit the voltage can be quite a bit out so the actual voltage at the batteries can be much lower when charging than the meter shows, makes it look like the batteries are closer to a full charge than they are.

My thought as well. I really wonder whether the charger is working effectively or whether your calculations about usage are out somewhere.

We have a bank of batteries with a total domestic Ah of 405 Ah and like you I usually only use about 70 Ah before recharging. Our batteries last over five years and maybe much longer...

We do have a wind generator for when the boat is on the mooring and I KNOW the smart charging system is working as we can monitor volts, amps AND Ah in and out so we know exactly what is going on. I am not familiar with the Nasa monitor. Does it just measure volts? Are you measuring all the parameters?

If you do get more batteries, measure the specific gravity and monitor it? Its the sure fire way of knowing what is going on.

 

[Andrew G]

Richard, may I humbly suggest that before you invest in new batteries you find out why the old ones have died. They should last for years, not months. Seems to me that 1) they are not being fully charged and 2) they are discharging too low. (I have killed a top of the line AGM battery in months by undercharging it – you are not alone).
Can you afford (£ and space) some solar panels?
My (3 x 120ah AGM) house batteries get up to, and sit on, 13.8V most days. My 34’ yacht has a 96A alternator and 160W of solar panels – in Australian sun. I rarely use my wind generator (and one is possibly not suited to your environment??).
My hard and fast rule is to never let them get below 50%. If they (very rarely) start getting near that I’ll turn gear off or start the engine. The following table might help – it’s for wet batteries. It suggests you are getting near 0% charge – not good.
http://www.trojanbattery.com has good reference material (I'm not otherwise promoting them - my batteries are a different brand).

Specific Wet Cell
Gravity Voltage %Charge
1.265 12.65+ 100%
1.225 12.45 75
1.190 12.24 50
1.155 12.06 25
1.120 11.89 0


Cheers, Andrew

 

[charles_reed]

For some reason your batteries, despite the gear, are not being charged. I also suspect your daily usage is a gross underestimate.
From the smidgen of history given, I suspect that there is a ineffective connection somewhere which is giving a resistance,
and cutting the current to the batteries and fooling the chargers into thinking they've reached a higher voltage than they have.
Really a painstaking step by step check through the whole circuit, cleaning and remaking all the connections is the (fortunately inexpensive) route to correcting your problem.
It's pretty typical of a dirty battery-terminal connection.

 

[Andrew G]

Charles makes some good points. The other thing to check is whether it is all, 2 or just one? Can you take them out of line and see how they each hold their charge after resting for 24hrs when fully charged - unloaded over several days and then loaded. All 3 should be similar. Better still, then get them “tested” eg at a garage /auto-electrician or with you own gear, to confirm your suspicions.
This only checks that they are or are not dead - not the underlying issues of charging regime, discharge and dodgy connections. Throwing new batteries at it will only solve the problem until those too die. Andrew

 

[Spi D]

Agreed.
Bear in mind, that 'intelligent' charging systems like yours need to perform a complete run though all stages to maintain batteries in best condition. If that can not be accomplished within the time you allow the system to run at a time, you wont get the benefit from your well considered setup.

Did you ever hook up to shore power while visiting marinas and see any difference?

 

[Poecheng]

Agree that it appears (from this distance) that the batteries are not being fully charged.

Assuming (but don't !) that all the connections are clean etc then I consider it arises from a number of factors

a) The charger is turned off far too early - a smart charger needs to be left on for a long time on "float" in order to fully charge up. (See Spi D above) This does not ever seem to be happening.

b) the alternator is likely to be fairly ineffective in your circumstances and should be converted to a larger alternator (you don't say what size it is so I am guessing) with smart charger so that your engine hours really count. I like Adverc and if you are not upto spending £ for new (Spring offer for £150 +VAT http://www.adverc.co.uk/page/6) , there is one going on fleabay at the moment and they generally go for about £50. You will need a little work on the alternator and wiring but nothing that cannot be done readily on the canals if you are not a diy man.

c) the consumption calculations are notoriously difficult. That inverter/charger will take Ah even when it is doing "nothing".

My suggestion in the very short term is that you get hold of a CTEK battery charger and get onto shorepower for a couple of days charging each (individually) fully through the cycle and then put all three together on charge and leave it on as long as you can whilst consuming nothing (paint the boat, go to the pub!). What you want is for them to reach the end of the cycle (shown by the leds) and then keep it on for as long as possible in your circumstances. This doesn't need to be a massive CTEK charger (eg the 20A to 30A ones) as a smaller one (eg 7A) will do the trick if you give them enough time.

Good luck

 

[skenn_ie]

I believe that you are only likely to get back 50% of what you put in, and unless you are using deep-discharge batteries, you should only use 30% from fully charged before recharging. If depleted below 60 - 70%, permanent damage will occur, and the longer they are left depleted, the more damage done. You should also check the voltage at the battery when charging, that is a better indication that saying "charging at 14.4v"
Having said that, I would be interested in people's opinion of De-sulphator devices. Some swear by then, some say they are a complete waste of money.

S.

 

[RichardS]

My suggestion in the very short term is that you get hold of a CTEK battery charger and get onto shorepower for a couple of days charging each (individually) fully through the cycle and then put all three together on charge and leave it on as long as you can whilst consuming nothing (paint the boat, go to the pub!). What you want is for them to reach the end of the cycle (shown by the leds) and then keep it on for as long as possible in your circumstances. This doesn't need to be a massive CTEK charger (eg the 20A to 30A ones) as a smaller one (eg 7A) will do the trick if you give them enough time.

I just bought a CTEK 7A charger and was messing around with it earlier today. It seems to work well but the big advantage for me over the Halford smart charger which has just packed up after 3 years is that after a power outage, and we have a lot of them out here in the sticks, the CTEK simply restarts its detection and charging cycle rather than shutting down.

Richard

 

[john_morris_uk]

I believe that you are only likely to get back 50% of what you put in, and unless you are using deep-discharge batteries, you should only use 30% from fully charged before recharging. If depleted below 60 - 70%, permanent damage will occur, and the longer they are left depleted, the more damage done. You should also check the voltage at the battery when charging, that is a better indication that saying "charging at 14.4v"
Having said that, I would be interested in people's opinion of De-sulphator devices. Some swear by then, some say they are a complete waste of money.

S.

Sort of true mostly: I understand that 85% of what you put in is a more likely return....

 

[Richard10002]

Thanks to all for the input.

I don't have access to shore power, so don't want to create an artificial situation by hooking up as a one off.

The NASA BM2 shows instant amps, accumulated amps, voltage, (checked at battery terminals), so I'm pretty sure I'm getting reasonable monitor readings.

The problem seems to be that I'm not getting up to 100% when charging so, each week, there must be a bit of extra sulphation.

I'm tempted to add an extra 200W of solar, (total 300W), and an MPPT controller as a first step. Then try a couple of Trojan T105s, perhaps charging them at home for a few days, before fitting them on the boat.

If I spend 3 or 4 days on the boat a week, with 3 or 4 days at home, the solar should have the chance to top up the batteries to pretty much 100%, and my useage, with some daily charging, shouldn't take them below 50%, or even 65%, which Trojans should handle better than cheap "leisure" batteries.

 

[Pete7]

Richard, is there a chance the BM2 is out of sync with the state of the batteries? so you think there is only 3 - 4 AH of charging left to go whilst in fact it could be 30 - 40 AH. The battery monitor can't tell how many AH are in the batteries, all it can do is calculate the amps going in and out, add a fudge factor because to charge a battery you need to add slightly more amps than you take out and then it gives you an estimated figure of whats left in the batteries. After a while this figure could become out of sync. We have the Sterling equivalent and disconnect it from the batteries a couple of times a year to reset it after a really good battery charge.

Also why are you using the 14.4 voltage setting for flooded lead acid? crank it up to 14.8 and let the amps flow :encouragement:

You should be able to recover the Varta Hobby batteries. Notice they weigh 5-6 kgs more than the cheaper models of the same size and rating. Since the volume is the same it must be extra lead to account for the weight, no bad thing having thicker plates which is probably why they quote a depth of discharge to 60%. Previous owner managed 7 years with a set of Hobbies and we managed 5 but a worn battery master switch took out one when it didn't quite disconnect over a winter, two new batteries later and I am hoping for 6 - 7 years as we have added lots of solar to keep them topped up.

Pete

 

[Richard10002]

Thanks for that Pete.

To assess whether the batteries are close to full, I generally monitor the Amps they are drawing. At the moment, I have an assumption that the capacity is around 130Ah so, when they are drawing about 2A, I assume they are close to full. At this point I generally zero the Ah counter, so it's never out of sync.

I used 14.4V because that is what Alpha Batteries suggested. With my previous batteries, (which died a similar death), I used 14.8-15V, and I have recently started using 15V on these. Every now and then, I run the equalising facility at 15.6V, but it doesn't seem to make a difference, even if I give it 6 hours or so.

I probably won't do anything serious until mid/end of May, so a bit of time to see what I can do.