Power issue, help?

[Ricco1]

Apologies for this post being so long, I've tried to include as much information as possible.

 

I've had an issue with my batteries for 2 years, just can't seem to sort it out:

 

First, I use very little power. My fridge is gas, t.v. is 16 watt, I use a netbook that draws around 2 amps. I only ever have one light on and don't feel the need to have a long shower every day. I calculate my daily usage to be around 30 amp hours.

 

I have 375 watts of solar and a wind turbine. Other charging is either via the engine or more recently, a petrol generator through a 20 amp charger.

 

During the winter months I charge my batteries every day without fail, with the generator.

 

I don't have a smartguage or similar so I am guessing about charged state. When I run the generator volts increase (2 separate meters) up to 14.6 then drop to 13.6. I assume this is when the batteries are reasonably well charged. I then run the generator for a further 20 minutes or so. As I said I do this daily.

 

The problem I have is that, with little power usage, the voltage of the batteries drops much quicker than I would expect. For example: Yesterday, after my charging regime, I connected my netbook (fully charged) for 2 hours. No lights on or anything. When I disconnected it after 2 hours, having used around 4 amp hours my single leisure battery showed a voltage of 12.3. This suggests to me that I've used around 40 amp hours rather than the 4 I'd expected.

 

Another example: Charged again later yesterday, switched the generator off at 8.00 p.m. it having run on 'float' mode for 20 minutes. 2 1/2 hours later with just a single 8 watt light on voltage showed as 12.4.

 

When I leave the boat without any power on the batteries maintain their charge so there doesn't appear to be a short or anything.

 

I replaced my then 2 leisure batteries in September 14. Then, thinking they were knackered I decided to just have one leisure battery, because my usage is low. My current battery is 3 weeks old.

 

Any ideas what might be going on?

[bottle]

Battery voltage will vary depending on load, higher the load, lower the voltage, battery will then 'recover' to show higher voltage when load is removed.

 

To use voltage to indicate SOC the battery needs to be rested, (minimum one hour) ie. not being charged and not being discharged, for the voltage reading to be any indication.

 

Voltage reading when the batteries are in use does not give any indication of SOC

 

The charger may be going into 'float' to soon and the batteries are not being fully charged.

[Richard10002]

 

I don't have a smartguage or similar so I am guessing about charged state. When I run the generator volts increase (2 separate meters) up to 14.6 then drop to 13.6. I assume this is when the batteries are reasonably well charged. I then run the generator for a further 20 minutes or so. As I said I do this daily.

 

 

 

My charger has some kind of algorithm which checks how long the "bulk phase" is, and calculates how long the "absorption phase" should be, before going into float. The absorption phase has a minimum of 1 hour.

 

This is rarely/never enough to reach a full charge, ( identified by the batteries drawing a low enough current, often stated as 2% of capacity at 14.4V, but better if less than 2%).

 

Thus, I often have to reset the charger after an hour, in order to keep charging until the current is low enough.

 

You cant really do this without a means of measuring Amps and AmpHours, although many seem to survive using a Smartguauge.

 

The upshot is that you will almost certainly not be charging for anywhere near long enough.

 

If I were you, I would invest in a NASA BM1 battery monitor and, if funds allow, a Smartguage as well - in that order.

[Paul C]

Apologies for this post being so long, I've tried to include as much information as possible.

 

I've had an issue with my batteries for 2 years, just can't seem to sort it out:

 

First, I use very little power. My fridge is gas, t.v. is 16 watt, I use a netbook that draws around 2 amps. I only ever have one light on and don't feel the need to have a long shower every day. I calculate my daily usage to be around 30 amp hours.

 

I have 375 watts of solar and a wind turbine. Other charging is either via the engine or more recently, a petrol generator through a 20 amp charger.

 

During the winter months I charge my batteries every day without fail, with the generator.

 

I don't have a smartguage or similar so I am guessing about charged state. When I run the generator volts increase (2 separate meters) up to 14.6 then drop to 13.6. I assume this is when the batteries are reasonably well charged. I then run the generator for a further 20 minutes or so. As I said I do this daily.

 

The problem I have is that, with little power usage, the voltage of the batteries drops much quicker than I would expect. For example: Yesterday, after my charging regime, I connected my netbook (fully charged) for 2 hours. No lights on or anything. When I disconnected it after 2 hours, having used around 4 amp hours my single leisure battery showed a voltage of 12.3. This suggests to me that I've used around 40 amp hours rather than the 4 I'd expected.

 

Another example: Charged again later yesterday, switched the generator off at 8.00 p.m. it having run on 'float' mode for 20 minutes. 2 1/2 hours later with just a single 8 watt light on voltage showed as 12.4.

 

When I leave the boat without any power on the batteries maintain their charge so there doesn't appear to be a short or anything.

 

I replaced my then 2 leisure batteries in September 14. Then, thinking they were knackered I decided to just have one leisure battery, because my usage is low. My current battery is 3 weeks old.

 

Any ideas what might be going on?

 

 

Basically, the highlighted bit. There's no proper substitute for a decent battery monitor (we'll leave to one side amp-hour counting vs smartgauge!!!) but one alternate is if your charging regime means the batteries are definitely fully charged and a bit more - for example most hireboats have no battery monitor, but the way they're used means that the batteries are typically fully charged because of the amount of cruising vs the amount of not cruising. Many leisure users would also have a similar pattern if they used the boat to cruise long(ish) days rather than stopping for long periods of time.

 

Personally I went for an amp-hour counter because I also wanted the facility of the ammeter so I can measure what's going into and coming out of the battery, which the smartgauge doesn't have, but I think I'd recommend smartgauge to others based on anecdotal evidence from users (I don't have one though so can't personally recommend it from experience!!)

[Ricco1]

Thanks for the replies.

 

I'm happy to upgrade to a decent battery monitor if that's the solution but I'm struggling to get my head round the whole thing!

 

Let me give another example of what's happening.

 

Watching t.v. with one light on; a couple of hours after charging. T.v. is 16 watts, light 8. Total 24 watts or just over 2 amp hours. The voltage of the batteries always reduces on both of my meters by .1 in between 45 and 50 minutes. I understand that .1 of a volt equates to around 10% of battery capacity. I have one 110 amp hour battery, pretty well brand new.

 

A quick calculation suggests that: My 50 minutes of usage should be around 2 amp hours but the battery voltage suggests that 11 amp hours, or say 10 assuming the battery wasn't completely charged, have been used up. So it seems that my devices are using 5 times more power than I'd expect. I guess that's what I'm trying to understand really, before throwing money at making sure my batteries are fully charged.

 

Thanks.

[Theo]

Thanks for the replies.

 

I'm happy to upgrade to a decent battery monitor if that's the solution but I'm struggling to get my head round the whole thing!

 

Let me give another example of what's happening.

 

Watching t.v. with one light on; a couple of hours after charging. T.v. is 16 watts, light 8. Total 24 watts or just over 2 amp hours. The voltage of the batteries always reduces on both of my meters by .1 in between 45 and 50 minutes. I understand that .1 of a volt equates to around 10% of battery capacity. I have one 110 amp hour battery, pretty well brand new.

 

A quick calculation suggests that: My 50 minutes of usage should be around 2 amp hours but the battery voltage suggests that 11 amp hours, or say 10 assuming the battery wasn't completely charged, have been used up. So it seems that my devices are using 5 times more power than I'd expect. I guess that's what I'm trying to understand really, before throwing money at making sure my batteries are fully charged.

 

Thanks.

You don't say in that post if you rested the batteries befor taking the voltage reading.

 

It may be that your batteries have lost capacity due to ageing or misuse. Some idea of how old they are and how they have been treated would help.

 

There are endless threads on Equipment some of which may help.

 

Nick

[Ricco1]

You don't say in that post if you rested the batteries befor taking the voltage reading.

 

It may be that your batteries have lost capacity due to ageing or misuse. Some idea of how old they are and how they have been treated would help.

 

There are endless threads on Equipment some of which may help.

 

Nick

 

New battery, 3 weeks old.

 

The .1 drop in voltage is the same whether under load or not. 12.1 became 12.0 under load, 12.4 became 12.3 with everything switched off. Starting figures taken 2 hours after charging had stopped. Cheers.

[nicknorman]

This is a fairly common problem and it always boils down to failure to charge properly. You have a small battery bank but also a small chargrper and even regardless of that it takes quite a long time to properly charge batteries of any size simply due to the chemistry - it takes time for the charge to penetrate deep into the plates.

 

You give a lot of information but you don't say how long you typically run the genny for. To properly charge (which you should do at least occasionally) will take at least 6 hours with the last few hours at a low current.

 

HOWEVER there is no point in doing that with the charger in float mode. In fact I'd say there is no point in running the genny at all with the charger in float mode so your +20 mins is a bit pointless. As has been said lots of chargers go into float prematurely. You might be able to get it back into absorption mode by briefly switching it off and back on again, different chargers have different algorithms but it may stay in absorption for 30 mins or so. Then switch it off and on again, or get a charger that you can control more comprehensively. Or maybe switch from genny to engine once the charger goes into float.

 

As has also been said, without any sort of monitoring at all you (and we) are working in the dark. At the very least get a Clampmeter so that you can see what the charge current is. Uni-t UT203 £30. With the charger still in absorption (14.6v or so) you should get the current down to 1A at least once a week. The Clampmeter will also allow you to check what the actual current drain is.

[MikeV]

It's also just possible you new battery is duff. I bought 4 cheap batteries once and they rapidly showed all the symptoms of sulfation with very low charge current even when they were 50-75℅ SoC according to my Smartgauge. I've now got 4 Trojan T105's and they will take all the amps my 90amp alternator can throw at them until the SoC comes up. After 2 years they're still performing like they were when they were new.

[Ricco1]

Thanks again.

 

I appreciate I might not be charging the batteries properly. But if I was, then usage dropped the soc to what I'm achieving charged at the moment, wouldn't the batteries behave as they are now i.e. depleting around 5 times quicker than I would expect? In other words, from 100% to 90%, from 90% to 80% and so on, will take the same amount of power usage?

 

I understand that batteries become sulphated if not fully charged and this shortens their life. The batteries are effectively new and seem to be behaving, to me, as if they are 20 amp hours rather than 110.

 

How might I put a complaint in to the supplier, the battery is sealed, can I measure anything?

 

Thanks for your patience!

[nicknorman]

Thanks again.

 

I appreciate I might not be charging the batteries properly. But if I was, then usage dropped the soc to what I'm achieving charged at the moment, wouldn't the batteries behave as they are now i.e. depleting around 5 times quicker than I would expect? In other words, from 100% to 90%, from 90% to 80% and so on, will take the same amount of power usage?

 

I understand that batteries become sulphated if not fully charged and this shortens their life. The batteries are effectively new and seem to be behaving, to me, as if they are 20 amp hours rather than 110.

 

How might I put a complaint in to the supplier, the battery is sealed, can I measure anything?

 

Thanks for your patience!

 

Undercharging causes sulphation which causes major loss of capacity (and ultimately death due to very low capacity). With standard leisure batteries I found that, even as non-liveaboard and on shore power in the marina between cruises, our batteries suffered from sulphation such that after only 6 months they only had 50% of their original capacity. 100% capacity was recovered by a relatively short equalisation charge (couple of hours at 15.5v) for a while, then process repeated. They were dead after 2 years (although to be fair we are pretty hard on them).

 

Now we have Trojans and they are a different kettle of fish altogether, no loss of capacity after 2 years. Although I know that some people are happy with ordinary leisure batteries, personally I think they are not fit for purpose (they are rebadged starter batteries) and I would never go back to them.

 

In your case I suspect the capacity is way down due to sulphation. 20AH is not unfeasible. You might be able to recover capacity by doing an equalisation charge but since yours are sealed, you would need to be careful not to overdo it and check the manufacturer's recommendations on the matter.

 

Once they are dead, get Trojans or the equivalent!

Edited January 3, 2016 by nicknorman

[Ricco1]

Undercharging causes sulphation which causes major loss of capacity (and ultimately death due to very low capacity). With standard leisure batteries I found that, even as non-liveaboard and on shore power in the marina between cruises, our batteries suffered from sulphation such that after only 6 months they only had 50% of their original capacity. 100% capacity was recovered by a relatively short equalisation charge (couple of hours at 15.5v) for a while, then process repeated. They were dead after 2 years (although to be fair we are pretty hard on them).

 

Now we have Trojans and they are a different kettle of fish altogether, no loss of capacity after 2 years. Although I know that some people are happy with ordinary leisure batteries, personally I think they are not fit for purpose (they are rebadged starter batteries) and I would never go back to them.

 

In your case I suspect the capacity is way down due to sulphation. You might be able to recover capacity by doing an equalisation charge but since yours are sealed, you would need to be careful not to overdo it and check the manufacturer's recommendations on the matter.

 

Once they are dead, get Trojans or the equivalent!

 

Thanks for that. The battery is 3 weeks old. Would it sulphate that badly in such a short space of time, or is the battery faulty? I've charged it every single day to 14.6v with the generator and charger, plus the bit that wind and solar have given me.

[MtB]

 

Thanks for that. The battery is 3 weeks old. Would it sulphate that badly in such a short space of time, or is the battery faulty? I've charged it every single day to 14.6v with the generator and charger, plus the bit that wind and solar have given me.

 

 

I'm not expert but from what I've read on the subject, the voltage whilst being charged is meaningless for assessing how well charged the battery is.

 

to assess the state of charge you need to use a hydrometer to measure the specific gravity of the electrolyte, or rest the battery for an hour then measure the terminal voltage.

(Or best of all, measure the 'tail current', but for this you need a clamp meter.)

[bottle]

 

I've charged it every single day to 14.6v

 

If that reading was taken with the charger connected and working then the reading is the charger voltage, not the battery voltage.

 

You only at the moment have a volt meter to tell you the SOC and the voltage reading will only give an indication of the SOC when the battery has been rested.

 

Battery charging,

 

at the start voltage low, amperage high as the battery charges the the voltage will rise and the amps fall when the amps are reading 2% or less than the battery capacity, the battery is charged or near enough.

 

Battery charging is in your case by a charger, hopefully this charger is a three stage (bulk, absorption , float.)

 

So when in:

 

bulk the voltage will be low and amperage high

 

the voltage will gradually rise then it will go into the absorption phase

 

the absorption phase the voltage will remain at 14.6 in your case and the amps will gradually fall

 

it will then go into float (to go into float depends on the charger)

 

The voltage lowers to the set voltage and the amps are also low

 

Note: when the charger is in absorption ie. you have the high voltage (14.6v it will then take a few hours to actually charge the batteries depending on the original SOC

[Guest]

Instantaneous voltage readings can be misleading, depending on whether there is load applied at the time etc. As others have said, the voltage needs reading after resting the battery to get a realistic idea. What are you using to record the voltage, and have you tested this against another meter?

It takes a lot more effort to recharge a battery than discharge it, especially in colder weather.

[MtB]

 

If that reading was taken with the charger connected and working then the reading is the charger voltage, not the battery voltage.

 

You only at the moment have a volt meter to tell you the SOC and the voltage reading will only give an indication of the SOC when the battery has been rested.

 

Battery charging,

 

at the start voltage low, amperage high as the battery charges the the voltage will rise and the amps fall when the amps are reading 2% or less than the battery capacity, the battery is charged or near enough.

 

Battery charging is in your case by a charger, hopefully this charger is a three stage (bulk, absorption , float.)

 

So when in:

 

bulk the voltage will be low and amperage high

 

the voltage will gradually rise then it will go into the absorption phase

 

the absorption phase the voltage will remain at 14.6 in your case and the amps will gradually fall

 

it will then go into float (to go into float depends on the charger)

 

The voltage lowers to the set voltage and the amps are also low

 

Note: when the charger is in absorption ie. you have the high voltage (14.6v it will then take a few hours to actually charge the batteries depending on the original SOC

 

 

 

Sounds to me as though the OP is turning the battery charger OFF at the end of the bulk phase (i.e. when the charge voltage gets up to 14.6v) instead of letting the charge continue into and through the absorbtion phase (i.e. several hours at a steady 14.6v).

 

If so, the battery appears to have been charged to only about 70% every day but no more. No great surprise its knackered!

Edited January 3, 2016 by Mike the Boilerman

[Loafer]

His battery is never being charged to 100% innit. He needs to keep that voltage up and prevent his charger from going into float mode. There's no room for float mode with an offline boater.

 

A means of measuring charge voltage, and particularly current, is the only way of establishing full charge with any accuracy. Depends on battery type, obviously.

[Ricco1]

I'll describe what happens when I charge the battery..

 

Usually the battery voltage is around 12.3 rested, with no load. I fire up the generator and plug it into my 20 amp charger. Voltage then goes up to around 14. Over an hour or so the voltage slowly rises up to 14.6. Once at 14.6 it stays at this for around 10 minutes. It then drops suddenly to 13.6 and stays there, seemingly as long as I leave it.

 

I have tried resting the batteries for 2 hours after charging the voltage reading without load is then 12.7.

[Loafer]

I'll describe what happens when I charge the battery..

 

Usually the battery voltage is around 12.3 rested, with no load. That's ok I fire up the generator and plug it into my 20 amp charger. Voltage then goes up to around 14. Over an hour or so the voltage slowly rises up to 14.6. Once at 14.6 it stays at this for around 10 minutes. It then drops suddenly to 13.6 and stays there, seemingly as long as I leave it.

 

I have tried resting the batteries for 2 hours after charging the voltage reading without load is then 12.7.

 

That's not fully charged - it's typical of most chargers that they only do the minimum effort possible to charge batteries over a long term.

 

An hour at 14.x and then weeks at 13.x is fine.

 

In your case, you need to keep the charge voltage at 14.x for as long as you run your generator.

 

Read the thread about charging T105s, lots of argument and opinion on there.

 

Edit: 'x' depends on your battery type. 4 or 8, usually.

Edited January 3, 2016 by Loafer

[nicknorman]

I'll describe what happens when I charge the battery..

 

Usually the battery voltage is around 12.3 rested, with no load. I fire up the generator and plug it into my 20 amp charger. Voltage then goes up to around 14. Over an hour or so the voltage slowly rises up to 14.6. Once at 14.6 it stays at this for around 10 minutes. It then drops suddenly to 13.6 and stays there, seemingly as long as I leave it.

 

I have tried resting the batteries for 2 hours after charging the voltage reading without load is then 12.7.

That is absolutely nowhere near fully charged. Not even vaguely close. It should stay at 14.6 for several hours, 3 or 4.

 

This is why your battery is screwed. Your charger isn't fit for purpose.

 

Edit: 2 hrs after charging, with no load, isn't enough time to get a true SoC voltage reading. I find that with zero load it takes a long time for the surface charge effect to die down.

Edited January 3, 2016 by nicknorman

[Ricco1]

That is absolutely nowhere near fully charged. Not even vaguely close. It should stay at 14.6 for several hours, 3 or 4.

 

This is why your battery is screwed. Your charger isn't fit for purpose.

 

Edit: 2 hrs after charging, with no load, isn't enough time to get a true SoC voltage reading. I find that with zero load it takes a long time for the surface charge effect to die down.

 

Thanks. The battery is 3 weeks old. Is it possible to screw it up so quickly?

[Loafer]

Yes but it should slowly recover capacity if you cane it a bit on charging. Watch the electrolyte level and keep resetting the charger. Maybe that will keep the charger at boost voltage for longer. A couple of desulphation charges might help too.

 

But it's definitely not being fully charged.

In the spring, your solar panels will do it all for you.

[ditchcrawler]

. Watch the electrolyte level and keep resetting the charger.

Its sealed

[nicknorman]

Thanks. The battery is 3 weeks old. Is it possible to screw it up so quickly?

Yes I think so, 3 weeks is 21 days and 21 cycles without approaching fully charged. However I'd say it's recoverable with a full and proper charge and careful equalisation charge (once fully charged). Sealed leisure batteries tend to have lots of calcium in the plates and can thus take fairly high voltages without gassing much, but best to consult the manufacturer. However I'd guess it could stand a few hours at 15.5v (more, if the batteries are cold) without losing that much water

 

I think I can see what's happened here. The charger has no idea what capacity the batteries are. It switches to float based on current - ie when the current falls below a certain value. With a large bank, it will switch to float when the current falls to a value that represents a low % of the capacity and thus close to fully charged.

 

But with a relatively small battery such as you now have, whilst it will switch to float at the same current, that current represents a relatively high % of the capacity and therefore a long way from fully charged.

 

So your charger was not too bad before but now you just have 1 battery it is not fit for that purpose.

 

So you need a means of maintaining the 14.6 (or preferably a bit more eg 14.9 if the batteries are cold) for several hours. I'd try that first and if that doesn't help you'll need a means of getting the voltage up to 15.5 or a bit more (16v for very cold batteries) for a few hours.

 

If the batteries are sulphated due to inadequate charging and you try to return them under warranty it will be obvious why they are problematic (low fully charged SG and I think you can see a colour difference in the plates).

[Loafer]

Removed- duplicate post.

Edited January 3, 2016 by Loafer