Lithium LifePo4 12v Batteries - Time For An Upgrade?

[Samiguel]

Low temp cut off is a must, and your covered there which is good.

For the heater - where's the van stored when you're not driving it, and it's it in regular use or is it just for summertime and trips away?

The heater might come in useful if it's stored during winter, as with an AMT-12 and a solar panel, you can basically keep the starter battery and leisure battery topped up with no hookup or additional chargers needed, provided it can get enough solar. If you regularly have cold days in winter, no heater might scupper this. Even 15w of solar is 1amp and might be enough to keep everything topped up over winter. It'll depend entirely on now much solar the van would get and how many days below zero you have.


On the BMS side, the Victron app is easier to access than the Fogstar app, and you're already going to be using it with your other Victron kit. 1 app Vs 2.

As for the BMS inaccuracies - that could be a bigger issue if you think you'll be running the battery down to 20% or lower regularly - even with normal use you'll very likely not see the correct % on the BMS, due to low solar days, or just using a few lights etc. so you might find that you're in a situation where you think you have 15% but the battery suddenly cuts off because it's actually at 0%.

Nice one, thank you. The van is a daily driver so the only time it doesn't get driven is the weekends basically. Should have said, the panel is one of the suitcase ones so it's not permanently connected.
I like the idea of having all the data in one app and, as I said, I do trust the Victron kit.

In the summer we went to Scandinavia and got quite good solar, but our AGM battery couldn't quite cope with the fridge so the battery voltage being available in the MPPT app was really handy. With more capacity in the lithium I imagine we are less likely to run it flat, but I suppose knowing an accurate SOC is important for us.

So, save up for a bit longer and get the 105ah battery AND the Smart Shunt?

 

[TallPaul_S]

Nice one, thank you. The van is a daily driver so the only time it doesn't get driven is the weekends basically. Should have said, the panel is one of the suitcase ones so it's not permanently connected.
I like the idea of having all the data in one app and, as I said, I do trust the Victron kit.

In the summer we went to Scandinavia and got quite good solar, but our AGM battery couldn't quite cope with the fridge so the battery voltage being available in the MPPT app was really handy. With more capacity in the lithium I imagine we are less likely to run it flat, but I suppose knowing an accurate SOC is important for us.

So, save up for a bit longer and get the 105ah battery AND the Smart Shunt?

I don't think you'll really see a benefit from a heater, in that case. There might be a couple of days a year when you've got solar out and it's too cold to charge but the fact that you've not got permanent solar means they probably won't be very often.

I'd go for the 100Ah drift ECO and the smart shunt. 5Ah is not worth worrying about.

 

[Samiguel]

I don't think you'll really see a benefit from a heater, in that case. There might be a couple of days a year when you've got solar out and it's too cold to charge but the fact that you've not got permanent solar means they probably won't be very often.

I'd go for the 100Ah drift ECO and the smart shunt. 5Ah is not worth worrying about.

Brilliant. Thanks for the advice...

 

[Samiguel]

Brilliant. Thanks for the advice...

Actually just triple checking - low temperature protection prevents the battery from being charged, so the DC-DC charger won't damage it if below freezing?

 

[TallPaul_S]

Actually just triple checking - low temperature protection prevents the battery from being charged, so the DC-DC charger won't damage it if below freezing?

Correct, the battery BMS will stop any charge coming in from actually charging the battery when it's below freezing. You can just leave the chargers to do their thing as normal, the battery BMS will block the charge.

You can still discharge the battery below freezing (so it'll power your fridge etc), that's all fine - but charging a LiFePO4 battery below zero is a big no-no.

 

[NicolasH]

We have the Fogstar Drift 105 and it has been brilliant. So much better than our traditional lead acid leisure battery. Fit and forget.

It can power the fridge, lights, diesel heater and phone chargers for days. It’s combined with a PV Logic 100w panel, PV Logic MPPT charger, Victron Bluesmart 30a charger, and an Ablemail DC to DC.

We had an issue with the battery not reporting the correct SOC to the app. Fogstar support were really good. We just had to charge the battery until it reached 14.2v and it reset the BMS.

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