Sterling BB1270 temperature sensor

[PaulW2]

I have a Sterling BB1270 under my RHS front seat, in front of a 150ah LiFePO4 leisure battery.

The leisure battery doesn't have a heater. If the temperature drops below zero and I drive off with the van, the B2B charger will kick in, charge the subzero battery and potentially damage it.

It is possible, as I understand it, to fit an optional temperature sensor to the BB1270. I've identified the item on the Sterling website. This would then prevent the charger from charging the battery when it's below zero, as long as the charger is in the lithium setting.

This sensor simply plugs into the charger at one end. This is reasonably accessible and looks fairly straightforward.

Then the other end is meant to be connected to the negative terminal of the leisure battery. This is tricky to access near the back of the seat, immediately in front of the louvred plastic panel.

I am trying to avoid having to disassemble everything, i.e. I prefer not to take the seat apart if I can avoid it. (I have to go back to VanBitz at some point, and if this becomes too complicated I may simply ask them to have a look at it for me.)

However, I may be able to get things connected according to the instructions without too much trouble if I can remove the plastic louvred panel at the back.

It looks like this may entail pushing down two plastic tabs at the top of the panel and pulling it away from the seat. Can anyone confirm that this is the correct method?

And I would be grateful for any other comments, especially about my reasoning and the solution I've identified.

Thanks
Paul

 

[bigtwin]

Is there much risk that:

1. The internal temperature of your van will be at zero degrees when you’re occupying it, and
2. In the unlikely event that the internal temperature of your van is at zero degrees, you would start the engine and drive off?

I must say that I’m somewhat surprised that the protection that you refer to wasn’t fitted at installation.

Ian

 

[PaulW2]

Is there much risk that:

1. The internal temperature of your van will be at zero degrees when you’re occupying it, and
2. In the unlikely event that the internal temperature of your van is at zero degrees, you would start the engine and drive off?

I must say that I’m somewhat surprised that the protection that you refer to wasn’t fitted at installation.

Ian

There is a modest risk, yes. The battery temperature (it has Bluetooth) was 3 degrees at midday with an ambient temperature of about 5 or 6. As the nights get colder I think there is a risk that I may want to drive off when the battery temperature is below zero. In practice, and because I'm aware of the problem, I may not do it, but turn the van heating on first (it can draw current down to -20 even though it should only be charged above freezing). I tried that today and it took about an hour to increase the battery temperature by a degree, whereafter it started warming up a little more rapidly. But it is a big old lump which, when it is cold, takes a long time to react to air temperature changes.

 

[Spriddler]

Presumably the makers of EV's already have an 'intelligent' solution otherwise the EV's motor drain wouldn't be replaced for a period of time, and in cold weather the passenger heater would also be in use.

 

[PaulW2]

Presumably the makers of EV's already have an 'intelligent' solution otherwise the EV's motor drain wouldn't be replaced for a period of time, and in cold weather the passenger heater would also be in use.

I'm sure you're right. They presumably have on board heaters to ensure that the battery never dips below freezing?

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[autorouter]

I think the temperature sensor doesn't need to be electrically connected to the leisure battery. It just needs to be in a place where it will be at the same temperature as the battery. So stuck on the side of the battery with duct tape would be a reasonable place to locate it.

 

[PaulW2]

I think the temperature sensor doesn't need to be electrically connected to the leisure battery. It just needs to be in a place where it will be at the same temperature as the battery. So stuck on the side of the battery with duct tape would be a reasonable place to locate it.

Cheers, that makes it a lot easier given the layout. I've established that physically connecting it to the negative terminal will definitely require seat removal, as shown in this picture. But duct tape on the side of the battery? That should be a doddle!

 

[PaulW2]

Sterling agrees - as long as it's in the vicinity of the battery (including on the casing), and at the same temperature, it should work fine.

The potential issue may be that after prolonged cold the core temperature may remain below zero while the surface temperature, where the sensor is, rises above zero. Charging happens and related damage potentially ensues.

A question that then arises is how much damage charging below zero causes. Does the LiFePO4 battery undergo a state change similar to water? The zero cut-off suggests the possibility. Above zero, drinkable water, below zero ice? And is any related damage therefore based on something akin to the stepwise progression of a state change?

Or is it more continuous - a small risk of a tiny amount of damage at -1, a huge risk of massive damage at -20 - and so on?

 

[Kannon Fodda]

Regardless of the B2B charger trying to operate, does not the BMS in the battery limit charging if the battery itself is out of parameters, i.e. too cold?

I would have similar concerns to the OP that it would take a while for the battery to be brought to temperature a long while after starting the engine and driving off, especially as I use my van as a daily vehicle over winter instead of having another car. Worse the solar system is also trying to keep the lithium leisure battery topped off, which does make sense when I've got the battery master fitted.

Yes I know ideally the lithium should be stored at around 80% if not being used, but there is nothing on either B2B or solar to allow that to be controlled and I have no access to the BMS in the battery as it's bluetooth system was incompatible with my phone.

 

[PaulW2]

Regardless of the B2B charger trying to operate, does not the BMS in the battery limit charging if the battery itself is out of parameters, i.e. too cold?

I would have similar concerns to the OP that it would take a while for the battery to be brought to temperature a long while after starting the engine and driving off, especially as I use my van as a daily vehicle over winter instead of having another car.

I don't know. Ideally BMS should do that, but it is my suspicion that it doesn't. Otherwise the warnings would be superfluous, Sterling wouldn't need to sell a temp sensor to prevent charging below zero and so on. Maybe some do and some don't?

While I don't use my van as a daily vehicle you describe my problem in a nutshell - the risk that I head off in it in cold temperatures and get to the other side with a ruined battery.

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[paddymcc]

My Roamer battery has a BMS that detects the temperature of the battery directly and won't charge it at just above zero or below. ( This morning the temp was 0C and I could see on the app that the charging was disabled). I did also fit temp sensors to the battery negative connected to the B2B and the solar controller but this is definitely belt and braces .
Re attaching a sensor to the battery casing, I think it would be fine , why not attach it behind some insulating material so air temp won't affect it?

 

[AdrianChen]

I think the temperature sensor doesn't need to be electrically connected to the leisure battery. It just needs to be in a place where it will be at the same temperature as the battery. So stuck on the side of the battery with duct tape would be a reasonable place to locate it.

Certainly the case with mine - worth a call to Sterling to see if it the lug is electrically isolated if it is either post will do - Victron do both types. The battery post is supposed to be acurate since it is "connected" to the insides (I get that with LA batts but Lithium?)..... I compared the measurements from a Smart sense connected to the case and the battery post type, and the Smart sense reacts far more quickly to the ambient temperature than the post connection jobby.

 

[PaulW2]

I compared the measurements from a Smart sense connected to the case and the battery post type, and the Smart sense reacts far more quickly to the ambient temperature than the post connection jobby.

Excellent - you've experimentally established an answer to that question!

Thinking about all the inputs, I would expect that if I attach the sensor to the battery casing with some duct tape, then put a patch (say 4 x 4 inches) of silver insulation material over the sensor to protect it from changes in ambient temperature in the cab, then it should pretty closely mirror the temperature of the battery.

 

[Ian_H]

Certainly the case with mine - worth a call to Sterling to see if it the lug is electrically isolated if it is either post will do - Victron do both types. The battery post is supposed to be acurate since it is "connected" to the insides (I get that with LA batts but Lithium?)..... I compared the measurements from a Smart sense connected to the case and the battery post type, and the Smart sense reacts far more quickly to the ambient temperature than the post connection jobby.

Presumably that means the post sensor is more likely to be closer to the internal temperature which will respond slowly cos its a big heavy lump, and the case sensor less so?

 

[AdrianChen]

Presumably that means the post sensor is more likely to be closer to the internal temperature which will respond slowly cos its a big heavy lump, and the case sensor less so?

I guess so, and at least some of the post/lug thing is inside the case and connected to the gubbins inside. The smart sense is destined for my generator battery at home, which might means it'll start when needed!

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