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Post by Telemachus on Sept 25, 2020 9:08:58 GMT
My lovely lithium batteries have arrived from China. This one is 200Ah at 3.3v and I have 12, which gives me 600Ah at 12v. Lots of lubbely juice!
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Post by Deleted on Sept 25, 2020 9:10:22 GMT
CALB cells?
That must have also been lots of money !!
£2k ish at a guess.
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Post by Clinton Cool on Sept 25, 2020 9:14:07 GMT
I love the idea of lithiums. If nothing else, if they become more popular, it should calm the perpetual engine runners down a little.
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Post by Telemachus on Sept 25, 2020 9:17:07 GMT
CALB cells? That must have also been lots of money !! £2k ish at a guess. Yes well spotted, about £1800. But hopefully will last 20 years or so, which makes it £90 a year for batteries. Probably cheaper than crappy leisure batteries that only last 2 years, plus all the advantages of lithium, if you can stand the up-front cost.
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Post by Deleted on Sept 25, 2020 9:22:42 GMT
You can have fun making the management system for that bank.
I actually just received some LiFePo4 as well this week but much more modest.
I found some mastervolt 20ah 12v batteries discounted to £100 each so had 4 of them. Built in BMS on each one can be paralleled up to 3 units.
60ah is enough for my purposes and the other one will be a general portable utility battery.
Sticking with lead acid for the engines for now as lithium looks a bit complex for that purpose.
The 60ah will be charged by my new 365w solar panel via Victron MPPT and be used as a secondary domestic power circuit separate to the existing arrangements.
I use about 15-20ah a day, if that. If there is surplus it can be used to charge the electric outboard battery via inverter.
All good fun.
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Post by Telemachus on Sept 25, 2020 9:33:10 GMT
You can have fun making the management system for that bank. I actually just received some LiFePo4 as well this week but much more modest. I found some mastervolt 20ah 12v batteries discounted to £100 each so had 4 of them. Built in BMS on each one can be paralleled up to 3 units. 60ah is enough for my purposes and the other one will be a general portable utility battery. Sticking with lead acid for the engines for now as lithium looks a bit complex for that purpose. The 60ah will be charged by my new 365w solar panel via Victron MPPT and be used as a secondary domestic power circuit separate to the existing arrangements. I use about 15-20ah a day, if that. If there is surplus it can be used to charge the electric outboard battery via inverter. All good fun. Yes still working on the management system, the alternator controller is mostly done, just need to add some code to limit charging voltage based on highest individual cell voltage. The hardware for the battery monitor is done but lots of software needed, driving the emergency isolation relay, the balancing resistors, putting the cell voltages onto CANBUS and adjusting the Combi charge voltage to limit maximum cell voltage / go to float at the desired SoC. I think it’s going to take several more months.
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Post by Deleted on Sept 25, 2020 9:35:33 GMT
CALB cells? That must have also been lots of money !! £2k ish at a guess. Yes well spotted, about £1800. But hopefully will last 20 years or so, which makes it £90 a year for batteries. Probably cheaper than crappy leisure batteries that only last 2 years, plus all the advantages of lithium, if you can stand the up-front cost. Can they be killed like cheapo leisure batteries if you don't look after them?
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Post by Telemachus on Sept 25, 2020 9:42:56 GMT
Yes well spotted, about £1800. But hopefully will last 20 years or so, which makes it £90 a year for batteries. Probably cheaper than crappy leisure batteries that only last 2 years, plus all the advantages of lithium, if you can stand the up-front cost. Can they be killed like cheapo leisure batteries if you don't look after them? Yes but in a different way. They like to be left partly charged, they don’t mind being deeply discharged and left for weeks at say 20% SoC, it doesn’t matter if you never fully charge them. But if you over-charge them, or let them go completely flat, they will die instantly. Hence the complicated management system. They also don’t like being charged below 0C but that is not normally a problem in a canal boat application.
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Post by Deleted on Sept 25, 2020 10:15:13 GMT
I like the sound of this, but I am lazy and will no doubt kill them in 12 months..
Do they charge like normal batteries, in terms of time and energy needed from sun/hook up/engine?
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Post by Deleted on Sept 25, 2020 10:22:07 GMT
Lithium are quicker to charge.
That's one of the good things they can take a full charge ie 100% of their capacity until almost full.
So if you had a 100ah battery and were charging it with an alternator capable of putting out 100 amps the battery would be full in about an hour or so.
That's the story anyway.
They take whatever you can give them.
That's why in theory if done right a lithium bank could end up saving considerable amount of fuel for someone who runs a generator or engine while stationary to charge up.
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Post by Deleted on Sept 25, 2020 10:23:56 GMT
Not quite sure how this works with Telemachus having 600ah because it seems to me they will be hungry and overload the alternator. I guess this is being taken care of in the management system. The usual story is that you need -less- not more because they like to be cycled ie used and can charge fast.
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Post by Telemachus on Sept 25, 2020 10:46:40 GMT
Not quite sure how this works with Telemachus having 600ah because it seems to me they will be hungry and overload the alternator. I guess this is being taken care of in the management system. The usual story is that you need -less- not more because they like to be cycled ie used and can charge fast. Yes if you look at the diagram, there is a temperature sensor on the alternator. If it gets too hot, the controller reduces the maximum field current thus decreasing the output. Otherwise yes the 600Ah could hoover up the full 175A for several hours, which would likely knacker the alternator fairly quickly. we have 450Ah of LA at the moment, I could probably have gone for 400Ah but decided to splash out on 600Ah in the end.
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Post by Telemachus on Sept 25, 2020 10:50:30 GMT
I like the sound of this, but I am lazy and will no doubt kill them in 12 months.. Do they charge like normal batteries, in terms of time and energy needed from sun/hook up/engine? No they take whatever charge you can throw at them until nearly fully charged. Not more hours spent putting in the last bit of charge at 5A or whatever. Charge efficiency is also 99% or better, 93% or so for lead acid. Power efficiency (which also takes into account charge voltage vs discharge voltage) is massively better, and much better efficiency at high discharge rates. If you don’t have a proper management system you will kill them in a lot less that 12 months. Couple of days, more like!
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Post by kris on Sept 25, 2020 10:59:53 GMT
My lovely lithium batteries have arrived from China. This one is 200Ah at 3.3v and I have 12, which gives me 600Ah at 12v. Lots of lubbely juice! Exciting times, I’ve just received my bmv 712 so ready to fit the lifepo4’s that I bought, finally.
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Post by Telemachus on Sept 25, 2020 11:04:26 GMT
My lovely lithium batteries have arrived from China. This one is 200Ah at 3.3v and I have 12, which gives me 600Ah at 12v. Lots of lubbely juice! Exciting times, I’ve just received my bmv 712 so ready to fit the lifepo4’s that I bought, finally. I recently got a BMV712 as well. Good bit of kit, very configurable. Not sure if I will fit it onto the boat (we currently have a Smartgauge which will become useless, plus the Mastershunt) or the caravan. I mostly got it to see how easy it would be to get it to send SoC data to the alternator controller - the answer is “not as easy as I’d hoped, but definitely possible, with a fair bit of code.“
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