Battery recommendations

Tranona

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though your windlass will love you deeply and truly for the nice high voltage liFePo4 can supply even when nearly empty. First use for me on new LiFePo4 it was "Oh now you're awfully keen today" 😎
The windlass does not care what supplies the current. Why would you let a battery go almost empty and then use it for a high current demand piece of equipment? Sounds like bad management to me.
 

GHA

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The windlass does not care what supplies the current. Why would you let a battery go almost empty and then use it for a high current demand piece of equipment? Sounds like bad management to me.
The windlass very much cares what the voltage is. Why would you assume a flat battery? Sounds like you don't really know much about internal resistance or Ohms law. 😜

Pull a load of amps from a couple of trojans the voltage will be way down. Just tried it. At rest with just house loads, (smartgauge says 93%) - 12.6V, run the windlass - 11.7V. Measured with a Fluke onto terminals.

LiFePo4 @ 25%SOC doing the same > 12.6V. For a motor that's huge. Which anyone who runs a windlass & swapped to LiFePo4 knows already just by the sound.

1707660074286.png
 

Graham376

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The windlass very much cares what the voltage is. Why would you assume a flat battery? Sounds like you don't really know much about internal resistance or Ohms law. 😜

Pull a load of amps from a couple of trojans the voltage will be way down. Just tried it. At rest with just house loads, (smartgauge says 93%) - 12.6V, run the windlass - 11.7V. Measured with a Fluke onto terminals.

LiFePo4 @ 25%SOC doing the same > 12.6V. For a motor that's huge. Which anyone who runs a windlass & swapped to LiFePo4 knows already just by the sound.

You're assuming windlass is powered by Trojans whereas in my case it's powered by the engine battery, usually with engine running.
 

Graham376

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LiFePO4 batteries are now cheaper than AGM per usable AH.

Haven't compared for a long time and it seems you're correct. UK supply to here out of the question so just had a brief look at Amazon Spain for quick comparison. No doubt cheaper than Amazon elsewhere. Think @GHA bought his from Spain?

3 x 100ah (300ah) LiFePO4 £564,
4 x Trojan T105 (450ah) £1280.
 

Alan S

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Just checked the specs for the 2 LiFePO4 batteries in Zing's post 54.
Max discharge current is 50A, no good for a windlass.
As Paul Rainbow and many others have said lead acid is much better in this case.
 

geem

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Haven't compared for a long time and it seems you're correct. UK supply to here out of the question so just had a brief look at Amazon Spain for quick comparison. No doubt cheaper than Amazon elsewhere. Think @GHA bought his from Spain?

3 x 100ah (300ah) LiFePO4 £564,
4 x Trojan T105 (450ah) £1280.
Some of the cheap lithium should be treated with caution. I would consider Trojans to be premium batteries. Compare them with premium lithium such as Fogstar where the internal components are known and reputable and the difference is not so obvious. A 300Ah will cost you £850. You then have to add on all the other components such as smart shunt, fuse and holder and possibly a dc/dc charger
 

Graham376

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Some of the cheap lithium should be treated with caution. I would consider Trojans to be premium batteries. Compare them with premium lithium such as Fogstar where the internal components are known and reputable and the difference is not so obvious. A 300Ah will cost you £850. You then have to add on all the other components such as smart shunt, fuse and holder and possibly a dc/dc charger

As many lithium batteries come with built-in BMS any reason why they can't be directly alternator charged? Solar appears OK as well via Victron MPPT Smartsolar.
 

JBPa

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Most of the run of the mill 100Ah batteries we see in the US have a BMS capacity of 100A, but 200A is pretty common too. Smaller batteries seem to be about 1C: you'll see 50A max on 50ah battery, 10A on 10ah. You can also get starting batteries capable of up to 1000A for brief periods, but these are not very common
 

Tranona

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The windlass very much cares what the voltage is. Why would you assume a flat battery? Sounds like you don't really know much about internal resistance or Ohms law. 😜

Pull a load of amps from a couple of trojans the voltage will be way down. Just tried it. At rest with just house loads, (smartgauge says 93%) - 12.6V, run the windlass - 11.7V. Measured with a Fluke onto terminals.

LiFePo4 @ 25%SOC doing the same > 12.6V. For a motor that's huge. Which anyone who runs a windlass & swapped to LiFePo4 knows already just by the sound.

View attachment 172203
I saidd it does not care where the power comes from - just what it is. That is why you us a battery with a high CCA for a windlass - as suggested for the OP. No one has suggested using Trojans for this job so not a valid comparison.
 

JBPa

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As many lithium batteries come with built-in BMS any reason why they can't be directly alternator charged? Solar appears OK as well via Victron MPPT Smartsolar.
You can, but you should add an alternator protection device which are about $80.
 

geem

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As many lithium batteries come with built-in BMS any reason why they can't be directly alternator charged? Solar appears OK as well via Victron MPPT Smartsolar.
The lithium will take every single amp your 60A alternator can provide. It will do this constantly. The alternator is not rated for 100% duty. It will overheat and possible catch fire. There are some tricks to make it work but they are tricks on a suck it and see basis. Not where you really want to be. A new Victron dc/dc charger will do up to 50A, programmable. A way better solution
 

Tranona

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As many lithium batteries come with built-in BMS any reason why they can't be directly alternator charged? Solar appears OK as well via Victron MPPT Smartsolar.
Because you will fry the alternator unless you use a regulator or a B2B. Solar is OK with an appropriate regulator. It is a complete misconception that you can just replace LA with lithium, although now it is becoming more practical as the lower cost of batteries mitigates the cost of the additional charging management to fit them.
 

Refueler

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Most of the run of the mill 100Ah batteries we see in the US have a BMS capacity of 100A, but 200A is pretty common too. Smaller batteries seem to be about 1C: you'll see 50A max on 50ah battery, 10A on 10ah. You can also get starting batteries capable of up to 1000A for brief periods, but these are not very common


Just a comment ... make sure when checking C rating you are clear on which rating .... discharge or charge.

Most Li based have higher discharge C rating than Charge ..... and TBH - if a Li has a rating of 1C for discharge - its definitely not designed for any high power demand use.
 

Tranona

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LiFePO4 batteries are now cheaper than AGM per usable AH.
That is true but the vast majority of leisure sailors pattern of usage means they will never be able to benefit from that. so they are popular with heavy users such as liveaboards, particularly in sunny climes but not viable for many to go to the expense of changing.
 

geem

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Just a comment ... make sure when checking C rating you are clear on which rating .... discharge or charge.

Most Li based have higher discharge C rating than Charge ..... and TBH - if a Li has a rating of 1C for discharge - its definitely not designed for any high power demand use.
Its quite normal for lifepo4 cells to have the same charge/ discharge rate. In my case, my two lithium batteries can handle 385A at 24v charge or discharge. The 2 parallel BMS can handle 400A at 24v, in theory. We are limited by the 3000w inverter, which for most people is the limiting factor. For us that means about 125A but for most people on a 12v system, it is half that
 

Zing

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though your windlass will love you deeply and truly for the nice high voltage liFePo4 can supply even when nearly empty. First use for me on new LiFePo4 it was "Oh now you're awfully keen today" 😎
Yep, on the bow thruster particularly also. Wow! I didn't know it could work as well as that. On winches on the lot, even the ability to flush the loo.
 

Zing

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LiFePO4 batteries are now cheaper than AGM per usable AH.
Correct as I showed to the reactionary lead lovers above, and note that it is multiple times cheaper when proper account is taken of the increased life expectancy.
 

Zing

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Just checked the specs for the 2 LiFePO4 batteries in Zing's post 54.
Max discharge current is 50A, no good for a windlass.
As Paul Rainbow and many others have said lead acid is much better in this case.
Not so. That's a continual current discharge rate. You don't do that with a windlass, you use it for minutes only at that or maybe twice or three times that and such use is fine. A lithium battery also can give enormous current discharges when starting engines for example, but briefly, and that is also well within their discharge current limits.
 
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