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Lithium battery install


Johny London

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16 hours ago, Detling said:

Two things not yet mentioned.

1 lifepo4 hate float charge it very slightly charges them until they expire, so when full, charging has to STOP. This is particularly difficult with the alternator.

2 also alternator related, most alternators on boats are not designed to chuck out full power for more than a few minutes, and most are inadequate!y cooled to do it.  Remember the 'alternator fryers' of a few years ago until they learnt to put a temperature sensor on the alternator. (Adverc and Sterling) to name a few.

Yes there can be great savings in fuel costs particularly in winter, but solar in the summer is more reliable as well as cheaper.  Dead alternators can usually be repaired for tens of pounds, dead batteries ...... 

 

I have a friend who is an engineer on hybrid bus systems and he has had several expensive accidents with lifepo4 battery packs, they are totally unforgiving, one tiny error and they curl up and die, so far always silently, they just stop.

I have had mine on the go for over 6 months with no issue and they effectively re on float. During the very hot and sunny summer I left them for 2 weeks when we came back they were sat at 13.8 volts, when I pluged them in they were showing just over 80% full, so no increase in charge using solar and a quality MPPT controller. James who has an all electric boat has been using these batteries for well over a year with no issues as well, yes we have all fitted max and minimum cut offs but as yet they havent been needed. The thing is I dont have an alternator charging these batteries, JohnV does but he has Lead acids in the system as well. All three of us use solat to charge and all of us installed a quality Controller which is maybe the reason we have no issues.

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3 minutes ago, peterboat said:

yes we have all fitted max and minimum cut offs

 

This remains a mystery to me. How exactly did you do this?

 

I know you mentioned using "a PCB from Amazon" or something like that, and some relays, but what PCB exactly, and what relays, please!

 

Many thanks...

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5 minutes ago, peterboat said:

I have had mine on the go for over 6 months with no issue and they effectively re on float. During the very hot and sunny summer I left them for 2 weeks when we came back they were sat at 13.8 volts, when I pluged them in they were showing just over 80% full,

 

I think you've been lucky. Charging at 13.8v WILL overcharge them given enough time. Overcharging risks destroying the cells. Possibly the Valance software inside your batteries also intervened and limited the SoC.

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24 minutes ago, Mike the Boilerman said:

 

I think you've been lucky. Charging at 13.8v WILL overcharge them given enough time. Overcharging risks destroying the cells. Possibly the Valance software inside your batteries also intervened and limited the SoC.

Never likely to happen in the real world Mike. I have a 12/24 volt fridge, and the fan running in the composting toilet, so the reality is, life makes the batteries safe from overcharging

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We've had our lithium batteries installed for nearly 2 months now and very happy with them (by lithium, I'm talking specifically LiFePo4 as the only suitable type for our usage). Massive reduction in engine running, and due to charge efficiency makes very little difference if you use high power appliances such as washing machine etc with engine on or off. Never going back to lead acid now. Just spent 3 days moored in Birmingham, and didn't need to run engine once, batteries went from 97% to 28%, and charged back up after 2.5hrs cruising. 

 

As far as I can make out from reading lots of articles and posts about real world experience using lithium, this whole not charging to 100% is a bit misunderstood. It's ok to charge to 100% if your going to use the batteries straight away, but not keep them there (although we don't generally charge them to that unless going away and leaving fridge on as not usually needed). Probably not best practise to do this daily, and might give slight loss of capacity over a long time, but generally insignificant in the overall picture. 

 

Our set up is probably more complicated than needs be, and would be tempted to simplify it if starting again. Having said that, so far it's working flawlessly. Our setup is as detailed below, and as said, so far is working really well. Could be tempted to just use the alternative 1 - lead- lithium hybrid method as detailed half way through this article next time, as would be simpler and cheaper (lots of good advice and information about lithium installs on that site).

 

Batteries and control: 

We've used 8 Thundersky 160ah cells from this guy who I found very helpful. The BMS I used was this from Australia, nice and simple to install, and gives cell level voltage protection. Batteries are monitored using a Victron BMV-701 for SOC, and this device to monitor cell voltages, and set alarms for high and low voltage, and cell voltage difference (alarm is surprisingly loud for such a small device!). High and low voltage cut is achieved using 2 BEP-701 motorised battery switches, one for loads and one for charging sources. 

 

Alternator Charging:

Alternator is controlled using this regulator which is completely programmable for different parameters. Alternator does need modification, but controller handles split charge relay so start alternator contributes to initial charging, has ability to end charging based on current into batteries, and switches to float mode that keeps current into batteries as close to zero as possible. Alternator controller is set to charge at 14v until current drops to 15A (5% of battery capacity) which we treat as fully charged. It also has a switch to force it to operate in float mode - ideal for long cruises e.g. (BCN Challenge!) to keep batteries from spending too long at 100%, and alternator and battery temp sensors to reduce alternator overheating, and prevent charging if batteries are below freezing or above 50c (defaults to float mode).

 

Other charging:

500W solar is via Tracer MPPT controller, with bulk set to 14v, absorption duration set to 60 mins, and float set to 13.3. This will be monitored and might need tweaking next summer, but we've not been overly impressed by solar this year due to shading from trees. Sterling pro charge ultra is set to bulk 13.9v, float to 13.2v, but received very little use as is limited to 30A on generator whereas engine can easily put 110A in!

 

Total cost a bit over £1000, but includes several improvements and rewiring that was badly needed anyway. 

 

Happy to answer any additional questions on our install if wanted. 

 

 

20180916_183059.jpg

Edited by Tom and Bex
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2 hours ago, Tom and Bex said:

We've had our lithium batteries installed for nearly 2 months now and very happy with them (by lithium, I'm talking specifically LiFePo4 as the only suitable type for our usage). Massive reduction in engine running, and due to charge efficiency makes very little difference if you use high power appliances such as washing machine etc with engine on or off. Never going back to lead acid now. Just spent 3 days moored in Birmingham, and didn't need to run engine once, batteries went from 97% to 28%, and charged back up after 2.5hrs cruising. 

 

As far as I can make out from reading lots of articles and posts about real world experience using lithium, this whole not charging to 100% is a bit misunderstood. It's ok to charge to 100% if your going to use the batteries straight away, but not keep them there (although we don't generally charge them to that unless going away and leaving fridge on as not usually needed). Probably not best practise to do this daily, and might give slight loss of capacity over a long time, but generally insignificant in the overall picture. 

 

Our set up is probably more complicated than needs be, and would be tempted to simplify it if starting again. Having said that, so far it's working flawlessly. Our setup is as detailed below, and as said, so far is working really well. Could be tempted to just use the alternative 1 - lead- lithium hybrid method as detailed half way through this article next time, as would be simpler and cheaper (lots of good advice and information about lithium installs on that site).

 

Batteries and control: 

We've used 8 Thundersky 160ah cells from this guy who I found very helpful. The BMS I used was this from Australia, nice and simple to install, and gives cell level voltage protection. Batteries are monitored using a Victron BMV-701 for SOC, and this device to monitor cell voltages, and set alarms for high and low voltage, and cell voltage difference (alarm is surprisingly loud for such a small device!). High and low voltage cut is achieved using 2 BEP-701 motorised battery switches, one for loads and one for charging sources. 

 

Alternator Charging:

Alternator is controlled using this regulator which is completely programmable for different parameters. Alternator does need modification, but controller handles split charge relay so start alternator contributes to initial charging, has ability to end charging based on current into batteries, and switches to float mode that keeps current into batteries as close to zero as possible. Alternator controller is set to charge at 14v until current drops to 15A (5% of battery capacity) which we treat as fully charged. It also has a switch to force it to operate in float mode - ideal for long cruises e.g. (BCN Challenge!) to keep batteries from spending too long at 100%, and alternator and battery temp sensors to reduce alternator overheating, and prevent charging if batteries are below freezing or above 50c (defaults to float mode).

 

Other charging:

500W solar is via Tracer MPPT controller, with bulk set to 14v, absorption duration set to 60 mins, and float set to 13.3. This will be monitored and might need tweaking next summer, but we've not been overly impressed by solar this year due to shading from trees. Sterling pro charge ultra is set to bulk 13.9v, float to 13.2v, but received very little use as is limited to 30A on generator whereas engine can easily put 110A in!

 

Total cost a bit over £1000, but includes several improvements and rewiring that was badly needed anyway. 

 

Happy to answer any additional questions on our install if wanted. 

 

 

20180916_183059.jpg

This is the first post I have seen on Lithium batteries that is actualy possible to understand. The outlay also looks much more sensible than the fifty million pounds I have read elsewhere. You also have a damn good inverter there. One question please. How many a/h thingies do you have and how old were the batteries on purchase. Also is it possible to just leave the starter battery setup as is with LA battery on the other alternater or is the shared earth then a problem?

Taa

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6 minutes ago, mrsmelly said:

This is the first post I have seen on Lithium batteries that is actualy possible to understand. The outlay also looks much more sensible than the fifty million pounds I have read elsewhere. You also have a damn good inverter there. One question please. How many a/h thingies do you have and how old were the batteries on purchase. Also is it possible to just leave the starter battery setup as is with LA battery on the other alternater or is the shared earth then a problem?

Taa

Ahhhh smelly. you are being seduced by the dark side

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7 minutes ago, mrsmelly said:

This is the first post I have seen on Lithium batteries that is actualy possible to understand. The outlay also looks much more sensible than the fifty million pounds I have read elsewhere. You also have a damn good inverter there. One question please. How many a/h thingies do you have and how old were the batteries on purchase. Also is it possible to just leave the starter battery setup as is with LA battery on the other alternater or is the shared earth then a problem?

Taa

Inverter was given to me by a previous neighbour who was going to bin it after "upgrading" to a modern Victron one?

 

Total capacity is 320AH, of which I've used 220 between charges, and could probably push that towards 250 usable AH if I needed to.

 

Batteries themselves cost £600 with all bolts and connecting straps, but were old stock that although tested as still having very good capacity, dropped voltage slightly at high currents (over 200A) so not ideal for electric car use. 

 

I've retained the lead acid starter battery and alternator as standard, just with the addition of a split charge relay to make best use of the spare alternator capacity.

 

I did consider getting rid of the starter battery and running everything from the one bank, but decided against it in the end. I do have an emergency start switch though to start from the lithium bank if required, as I did with domestic bank on my last boat. It's quite noticeable how much faster the engine turns over on the lithium,  and how much easier it starts due to their ability to deliver high currents with very little voltage drop. 

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