batteries

[blackrose]

47 minutes ago, WotEver said:

Corrosion resulting in soft shorts. Plus they were probably somewhat sulphated anyway so weren’t holding much charge to start with. 

Corrosion of the terminals? No they were still clean.

[cuthound]

2 hours ago, dmr said:

I don't know anything about how batteries behave on float charge, or even if Trojans are suitable for this. The people on this forum who do back up power supplies might know more but I don't think Trojans are the usual choice. I reckon they do need to see 14.8 volts quite often to keep them happy, maybe your charger just stayed in float and never gave them a good voltage.  

 

I don't think over-filling would hurt them, it might even help as I believe acid strength contributes to plate corrosion. Batteries will only have a finite life even if never cycled but I haven't got a clue how long this is. The fact that they went down quickly after removing them must be a clue as to what the failure mode was....any suggestions anyone???? The acid in my old ones was very murky when I removed them.

 

................Dave

 

The old wet cell batteries BT used prior to the 1980's were floated at 2.27 volts per cell (13.62 volts for a 12 volt battery). They were capacity tested and equalised once every 2 years and usually lasted 20 years plus. However they used thick pure lead or lead/antimony plates. Plates made with a lead/calcium alloy need higher charge and equalizing voltages.

 

Murky acid results from the plates shedding active material, usually do to poor construction, over charging or being physically vibrated.

 

The shed material drops to the bottom of the cell and increaes the self discharge current. Eventually it causes short circuits between positive and negative plates.

[peterboat]

2 hours ago, OldGoat said:

!aha! the tricks is to buy them second hand (if you can find them...). Because they are indestructible / difficult to ruin, a used set at a reasonable price can be good value.

I listened to a 'mad professor' some years ago when I was building my boat and bought a trailer load. They're still going strong some 20+ years later.

Folks in foreign lands love them  for domestic wind and solar farms - thus they can be as rare as hen's teeth.

Big ad bulky, though.

 

Bimble sometimes have used ones on sale...    

You have to wait - which, of course, folks don't do nowadays....

 

I bought my low cycle LifePo4s cheap as well secondhand, so as they are light easy to charge and should do over 6000 cycles, they will do for me for many years to come

[Dr Bob]

21 hours ago, Alan de Enfield said:

Indeed it was, but as knowledge has evolved over the last few years it is considered that ANY level of discharge will result in a level of sulphation - keeping batteries at 85% for a couple of weeks will be degrading their capacity.

 

Battery chemistry has also changed - the 'new' calcium based batteries (sealed) seem to me to be very prone to loss of capacity.

 

The ideal is to fully charge immediately after use (as per an engine starter battery) not practical in reality but 95+% SoC should be aimed for.

It is all a balancing g exercise between cost of batteries & cost of fuel & engine wear - there is no correct answer.

 

My Father replaces his batteries every 5-6 months because he cannot be bothered (or forgets - he is in his 90's) to recharge them.

 

Batteries are disposable items.

We've now had LiFePo's on board for 3 months......and I am blown away with how 'good' they are. I went into this thinking that they would take a lot of managing. How wrong could I have been!

Siiiiiimple.

Dont have to worry about getting them full. EVER! I check em once per day (just a quick look at the voltage and current draw) and guess the SoC. Now we are in a routine it is simple. We are a heavy power user and now using circa 120-140Ahr per day.

The debate about are lithiums good for boats, to me, is about 2 things. The benefits and then the costs. You have to understand the benefits first before trying to compare costs as they are VERY different to Lead acids. However, I would NEVER dream of getting a pukka Victron system in as the cost is ridiculus. A DIY system using 2nd hand Li's is doable.

I posted a thread in Jan which has the details of my system.

The benefit to us is not having to run the engine for hours to fully charge the batteries. On our cheapo lead acids, we used to try and get to 100% every other day or at least twice a week which is quite difficult when the solar is on strike (Oct-Feb). We managed to keep our capacity up to 90% on the 6 LA's over a two year period (so not too much deterioration) but it took effort to think about when to run the engine and DMR's tactic of running the engine once per week for 6 hours is typical. We probably did it more. This has to be an issue for CC'er (and more so CM'ers).

Li's get you out of this rut. If you are using 100Ahrs a day then less than 2 hours per day is needed. You could save 100-150 engine hours over the winter. That is a lot of noise to stop making - and diesel - and engine servicing......and faffing.

With Lithiums, you know exactly what is going in. Start the engine and 50A is showing on the gauge....and keeps showing. On ours, I know 2 hours engine running will put in 100A. I dont need to think about 'when will they be at 100%'? If I set the alternator at a higher output then it would take less time (just cautious about overcooking the alternator). We cycle ours between 20% and 80%. Maybe I should back off a bit and stop charging at 70%?

I wont bore any of you here with my views on cost comparisons as I have some ideas on an affordable way of using lithiums. My system cost me £1500 for 480Ahr (at 12v) of which £500 was for the wiring/switching/protection which is way over the top of what would work. I will start another thread when I have time later in the week on that.

There is no doubt to me that lithiums are the way to go if you are CC'ing or CM'ing, but not if you spend months on a land line.

 

[WotEver]

13 hours ago, blackrose said:

Corrosion of the terminals? No they were still clean.

No, corrosion of the plates, resulting in paste laying at the bottom of the cells. 

[peterboat]

9 minutes ago, Dr Bob said:

We've now had LiFePo's on board for 3 months......and I am blown away with how 'good' they are. I went into this thinking that they would take a lot of managing. How wrong could I have been!

Siiiiiimple.

Dont have to worry about getting them full. EVER! I check em once per day (just a quick look at the voltage and current draw) and guess the SoC. Now we are in a routine it is simple. We are a heavy power user and now using circa 120-140Ahr per day.

The debate about are lithiums good for boats, to me, is about 2 things. The benefits and then the costs. You have to understand the benefits first before trying to compare costs as they are VERY different to Lead acids. However, I would NEVER dream of getting a pukka Victron system in as the cost is ridiculus. A DIY system using 2nd hand Li's is doable.

I posted a thread in Jan which has the details of my system.

The benefit to us is not having to run the engine for hours to fully charge the batteries. On our cheapo lead acids, we used to try and get to 100% every other day or at least twice a week which is quite difficult when the solar is on strike (Oct-Feb). We managed to keep our capacity up to 90% on the 6 LA's over a two year period (so not too much deterioration) but it took effort to think about when to run the engine and DMR's tactic of running the engine once per week for 6 hours is typical. We probably did it more. This has to be an issue for CC'er (and more so CM'ers).

Li's get you out of this rut. If you are using 100Ahrs a day then less than 2 hours per day is needed. You could save 100-150 engine hours over the winter. That is a lot of noise to stop making - and diesel - and engine servicing......and faffing.

With Lithiums, you know exactly what is going in. Start the engine and 50A is showing on the gauge....and keeps showing. On ours, I know 2 hours engine running will put in 100A. I dont need to think about 'when will they be at 100%'? If I set the alternator at a higher output then it would take less time (just cautious about overcooking the alternator). We cycle ours between 20% and 80%. Maybe I should back off a bit and stop charging at 70%?

I wont bore any of you here with my views on cost comparisons as I have some ideas on an affordable way of using lithiums. My system cost me £1500 for 480Ahr (at 12v) of which £500 was for the wiring/switching/protection which is way over the top of what would work. I will start another thread when I have time later in the week on that.

There is no doubt to me that lithiums are the way to go if you are CC'ing or CM'ing, but not if you spend months on a land line.

 

Same here Bob except I have even less controls than you do, as I watch 37amps are going in, its up to 13.6 V per battery, and my immersion heater is heating water for the day using the drive solar perfik

As an afterthought I fitted 3 solar panels to the electric truck yesterday 300 watts each, when I connected them up they were putting in nearly 900 watts!! they came from a guy that fits solar farms these panels are the business, wish all the panels on the boat were this type so good

Edited May 21, 2019 by peterboat

[peterboat]

And they have now stopped charging! Its like they hit a brick wall, the solar controller is dropping to zero even as I type  brilliant! have put the washer and dishwasher on to make use of the free lecce

Edited May 21, 2019 by peterboat

[frahkn]

19 minutes ago, Dr Bob said:

We've now had LiFePo's on board for 3 months......and I am blown away with how 'good' they are. I went into this thinking that they would take a lot of managing. How wrong could I have been!

.......

There is no doubt to me that lithiums are the way to go if you are CC'ing or CM'ing, but not if you spend months on a land line.

 

My boat spends about a third of the year on land line. At the moment mainly in the winter months but we are exploring the possibility of changing this to a better mixture of winter and summer.

 

I treat my lead acids as disposable but expect to get at least 3 years out of each set.

 

I rarely stay in one spot for more than 2 days but even then, have to run the engine for showers etc (we have a gas water heater but don't tend to use it).

 

I doubt (but of course am not certain) that LiFePos would help me much. I am however watching these threads with considerable interest.