Batteries ??

[seanoo]

Hi , haven’t been on here for a while ! I’m in need of new leisure batteries and was thinking of lithium iron but what’s bothering me is the charging in cold weather. My leisure batteries live in a external locker. I was looking at the 2x tn100 from battery megastore with a 30 amp dc to dc charger and I have 200 watts of solar with a mppt charge controller. How do people get on in cold weather charging these batteries (below 4 degrees) ? Is my only option to bring the batteries inboard ? Cheers sean

 

[XxAnthxX]

Just thinking outside the box, any chance you could insulate the battery locker???

I don’t have such luxuries as an option ( ) so have never looked into it sorry.

 

[Campervan_man]

Maybe you could insulate the external locker ?
24MM thick Celotex etc

These batteries seem like a good buy { Charger included }.

https://rover.ebay.com/rover/1/710-...0001&campid=5338547443&icep_item=122423724952

There was 20% off them the other day with ebay promotions.

 

[seanoo]

Thanks , I thought about that and ducting blown air in there as well or maybe some sort of heater mat under the batteries that is powered from the alternator?

 

[seanoo]

Maybe you could insulate the external locker ?
24MM thick Celotex etc

These batteries seem like a good buy { Charger included }.

https://rover.ebay.com/rover/1/710-...0001&campid=5338547443&icep_item=122423724952

There was 20% off them the other day with ebay promotions.

I think the insulation will only hold off the cold for while and it will still drop too low especially if it’s cold for a few days.

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[poppycamper]

I think the insulation will only hold off the cold for while and it will still drop too low especially if it’s cold for a few days.

The other disadvantage of insulation on its own is that although it will take longer for battery to cool down it will also have same effect when temperature rises and therefore taking longer for battery to get back up to a rechargeable temperature
That is why I have a much bigger reserve of power than I would normally need so I can survive for longer in winter without needing to charge batteries.

 

[seanoo]

The other disadvantage of insulation on its own is that although it will take longer for battery to cool down it will also have same effect when temperature rises and therefore taking longer for battery to get back up to a rechargeable temperature
That is why I have a much bigger reserve of power than I would normally need so I can survive for longer in winter without needing to charge batteries.

Good point ! So what stops the batteries being charged by my solar or alternator when it’s 0 degrees? Will the management circuit in the battery keep them from being charged in low temperatures?

 

[Two on Tour]

My LifePo4 battery sits on a low heat output heat mat which is controlled by a thermostat that turns the mat on at 5c and my Victron battery monitor tells my Victron Battery Protect to disconnects the battery at 0c

 

[Raul]

Some batteries have internal protection built in the bms for low temp charging and high temp discharging protection. I don’t know if TN power has this features, usually if they are not in the spec, they don’t have them as this is a selling point to. Is all down to how the battery is built and what bms has. Some don’t have this protection and you need to add a temp sensor that communicates with the charger. Victron chargers communicate via ve network on the smart enabled devices. That’s how I charge. I use a smart solar charger networked with the temp sensor. And for B2B I use a Victron Orion dc-dc 30a. I wired a switch via remote switch terminals, to switch it of when NOT needed. By default I leave this off, and only when needed I turn it on. The alternator supplements only on bad weather and never to full charge. Only to get out of it. Solar does the charging for me.

 

[Lenny HB]

Good point ! So what stops the batteries being charged by my solar or alternator when it’s 0 degrees? Will the management circuit in the battery keep them from being charged in low temperatures?

Solar chargers like the Votronic and Victron have an optional temperature sensor and when on the Li setting they won't charge if the temperature is too low, same for the B2B when charging from the alternator.

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[Raul]

My LifePo4 battery sits on a low heat output heat mat which is controlled by a thermostat that turns the mat on at 5c and my Victron battery monitor tells my Victron Battery Protect to disconnects the battery at 0c

How does the Victron battery protect knows the temperature? And why disconnect it?

 

[Two on Tour]

How does the Victron battery protect knows the temperature? And why disconnect it?

The Victron battery monitor, Battery Protect and Battery Sense are all networked so relay info between the devices.

I disconnect a 0c as that is the norm with LifePo4 cells as they are not supposed to be charged at 0c or below.

 

[Raul]

Does your charger communicate with the batt sense? All you need is to stop charging, not disconnect the battery, unless you’re using the battery protect to disconect the charging sources only, ie solar B2B etc. The battery protect usually is intended for low and high voltage disconnect.
What happens to loads if you disconnect? You can still discharge well below 0 deg.

 

[Two on Tour]

All the negatives of both the load circuits and chargers are connected to the shunt for accurate monitoring of the battery, so yes in my case all load circuits and chargers disconnect.
The Sterling B2B and 240 chargers are dumb and the 0c disconnect is only really a safety net if the battery heater or diesel heater fails and to date the lights have not gone out.
With the way we use our van we are unlikely to get to very low temperatures in the van and the frost guard settings on the diesel heater also prevent getting to 0c

 

[Pausim]

This is what relion say about their charging temperatures:
Charging Temperature LiFePO4 batteries can safely charge between -20°C to 55°C (-4°F to 131°F). However, at temperatures below 0°C (32°F) the charge current must be reduced, until the temperature is >0ºC (32ºF), as follows: 1. 0°C to -10°C (32°F to 14°F) charge at 0.1C (10% of the battery capacity) 2. -10°C to -20°C (14°F to -4°F) charge at 0.05C (5% of the battery capacity) LiFePO4 batteries do not require temperature compensation for voltage when charging at hot or cold temperatures. All Relion LiFePO4 come with a BMS that protects the battery from over-temperature. If the BMS disconnects due to high temperature, wait until the temperature reduces and the BMS reconnects the battery circuit before using or charging the battery. Please refer to your battery data sheet for the BMS high temperature cut-off value.

In effect this means a low charge rate of a few amps is ok at colder temperatures. I imagine in winter you are unlikely to exceed these figure using solar unless you have a huge array. I am comfortable leaving my Efoy in automatic mode. I can turn my B2B off if it is really cold when I set out but I am lucky that my battery space is heated so once things have warmed up I have nothing to worry about.

Relion also do an LT (low temperature) range. I believe these have built in heating elements and if it is too cold the incoming charge is diverted to the heating elements until a safe charging temperature is achieved.

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[Raul]

I have a battery protect that is installed on my house on a 48v system. Is to cut the loads LVD if battery is to low. But the solar chargers remain connected. I never knew a batt sense can work with batt protect. I have a separate temp sensor via ve bus connected to inverter charger coupled to the GX hub. This makes corrections on temperature compensated charging. Also the solar chargers pick up this via GX hub.

If you hit 0deg and disconnects the charger from the battery, then panels are still connected to charger but without battery. This scenario can blow your charger.

 

[Raul]

This is what relion say about their charging temperatures:
Charging Temperature LiFePO4 batteries can safely charge between -20°C to 55°C (-4°F to 131°F). However, at temperatures below 0°C (32°F) the charge current must be reduced, until the temperature is >0ºC (32ºF), as follows: 1. 0°C to -10°C (32°F to 14°F) charge at 0.1C (10% of the battery capacity) 2. -10°C to -20°C (14°F to -4°F) charge at 0.05C (5% of the battery capacity) LiFePO4 batteries do not require temperature compensation for voltage when charging at hot or cold temperatures. All Relion LiFePO4 come with a BMS that protects the battery from over-temperature. If the BMS disconnects due to high temperature, wait until the temperature reduces and the BMS reconnects the battery circuit before using or charging the battery. Please refer to your battery data sheet for the BMS high temperature cut-off value.

In effect this means a low charge rate of a few amps is ok at colder temperatures. I imagine in winter you are unlikely to exceed these figure using solar unless you have a huge array. I am comfortable leaving my Efoy in automatic mode. I can turn my B2B off if it is really cold when I set out but I am lucky that my battery space is heated so once things have warmed up I have nothing to worry about.

Relion also do an LT (low temperature) range. I believe these have built in heating elements and if it is too cold the incoming charge is diverted to the heating elements until a safe charging temperature is achieved.

Relion has low and high temp protection. Also a heat pad that is activated at low temps. Most of charging power is diverted to heat pad, then charging. A well built LFP at a price.

 

[poppycamper]

you hit 0deg and disconnects the charger from the battery, then panels are still connected to charger but without battery. This scenario can blow your charger.

That's why you need to put isolator between panel and solar controller

 

[Raul]

That's why you need to put isolator between panel and solar controller

Or, even better, tell the charger to stop charging and watch it on stand by when temp allows to resume. Hence the importance of batt sense to communicate with charger. But, there are many ways to skin a cat. The important bit is to protect against low temp.

 

[Pausim]

Relion has low and high temp protection. Also a heat pad that is activated at low temps. Most of charging power is diverted to heat pad, then charging. A well built LFP at a price.

The heat pad is included in the LT series only but not the more commonly used RB series batteries. I agree they are well built.

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