Battery Ah size recommendations

[roadtripper]

The other path to consider is selling on your current battery (if already bought) and buying one with a BMS that has either cutoff and/or heaters.

This is the reason many choose the Fogstar or similar. Yes it costs more but it's often easier than ensuring all 3 chargers (DC-DC, 240v, Solar) do the right thing and has the added benefit that the heaters will warm the battery and allow charging in freezing conditions (which charger cutoffs will not do)

 

[TallPaul_S]

Yeah I don't have a smart shunt so I need a temp reading for the mppt. Would a shunt be a better option than the battery sense?

A shunt is a good idea as looking at your system you won't have any way of telling what your state of charge is. The temp sensor is an extra but that would enable the low temp cut off in the MPPT (if it had that feature).

A shunt basically counts all current in and out of the battery to calculate the charge level.

The other path to consider is selling on your current battery (if already bought) and buying one with a BMS that has either cutoff and/or heaters.

This is the reason many choose the Fogstar or similar. Yes it costs more but it's often easier than ensuring all 3 chargers (DC-DC, 240v, Solar) do the right thing and has the added benefit that the heaters will warm the battery and allow charging in freezing conditions (which charger cutoffs will not do)

Yeah, a shunt is £80, then you might need something extra to enable cut off on the DC-DC charger, and all of a sudden the £200 you saved by going for the battery without a heater or low temp cut off, or a BMS to show battery charge has gone...

 

[pdid]

Thank you for all the replies, I've got some working out to do....

Fortunately it shouldn't be cold for a few months....

I'll come back with a solution!

 

[pdid]

Yep, that’s good for the MPPT. You could leave the iP65 unplugged and manage that easily enough, especially if you are not camping in winter. You will need a way to prevent charging from the DC-DC when the battery is frozen as well. I’m not familiar with your charger but it’s possible you could rig up a temp sensor on the battery that switches the DC-DC on/off. Loads of YouTube videos showing how to do that with a cheap eBay/Amazon sensor. Or they may do a probe as an option.

Back to this sorry. If I put a temperature sensor switch between the DC-DC charger and the battery terminals, and set it to be off below 1c, would this achieve the desired outcome? Or would it likely break the DC-DC?

Thanks

 

[ginkster]

Back to this sorry. If I put a temperature sensor switch between the DC-DC charger and the battery terminals, and set it to be off below 1c, would this achieve the desired outcome? Or would it likely break the DC-DC?

Thanks

Not ideal and it would need to be a switch/relay of a suitable power rating. Having the DC-DC not feeding anything won’t break it. I’m not familiar with your DC-DC but Victron models have a specific switch circuit to enable you to turn the DC-DC on/off. Maybe yours has similar?

I’d be more cautious with the temp settings too as it’s the middle of the battery that’s the important bit and not what you are sensing. I’d have it stop charging at say +1deg and not allow charging to start again until +5deg (or a bit more). If set too close to zero the outside of the battery could be warm enough but the cells still frozen. It’s always going to be a non ideal solution as you are measuring the temp from the outside rather than the middle of the battery as an inbuilt system would. There are loads of YouTube videos on this subject showing the sensor (a W1209) and how to set it up.

 

[roadtripper]

Back to this sorry. If I put a temperature sensor switch between the DC-DC charger and the battery terminals, and set it to be off below 1c, would this achieve the desired outcome? Or would it likely break the DC-DC?

Thanks

The issue here is it's only charging that needs to stop below freezing, it's fine for most lithium batteries to discharge down to around -20c that you are never likely to see.

You also need to be very careful to set up good hysteresis as @ginkster points out. Having the relay chatter on and off rapidly as the measurements vary about naturally is going to damage something and likely end up with welded relay contacts.

These are all electrical engineering problems that have been considered and solved in the temperature protection implementations in the chargers or the BMSs.

 

[ginkster]

hysteresis

That’s the word I was looking for….

 

[pdid]

Right just checking through instructions for the Sterling BB1230. If it's been installed correctly it should only work when the ignition is on and so should have a feed into the unit for this. If I put the sensor on this feed it should stop the unit powering up.

I can also install an easy access switch for if we ever get extreme temperatures, however unlikely this may be.

 

[ginkster]

Right just checking through instructions for the Sterling BB1230. If it's been installed correctly it should only work when the ignition is on and so should have a feed into the unit for this. If I put the sensor on this feed it should stop the unit powering up.

I can also install an easy access switch for if we ever get extreme temperatures, however unlikely this may be.

Quick look at the instructions shows that there is an option temp sensor available for the BB1230. In lithium settings this trips at 0deg but can be changed which I would suggest to something like +5deg.

 

[pdid]

Quick look at the instructions shows that there is an option temp sensor available for the BB1230. In lithium settings this trips at 0deg but can be changed which I would suggest to something like +5deg.

I've seen the sensor, I thought it was only for high temperature settings? Can I ask where you have seen the lithium settings? Thanks

 

[ginkster]

I've seen the sensor, I thought it was only for high temperature settings? Can I ask where you have seen the lithium settings? Thanks

Page 8:

Instructions

 

[pdid]

Page 8:

Instructions

I think there's 2 versions, I've got the 2017 instructions but they've been superceded by 2020 instructions...

I'll have a look at the 2020 instructions.....

 

[pdid]

Page 8:

Instructions

My BB1230 is the green stripe model with one lithium setting.... Reading between the lines I can fit the temperature sensor but it would not be adjustable so set at 0c for lithium. The manual you linked suggests a maximum of +2c anyway which isn't really high enough....

Thank you again for your help

 

[pdid]

Well this has turned into a nightmare....

Set out to get the battery installed today, managed to somehow reverse the wiring initially, realized and corrected my mistake. Now it seems that my diesel heater is dead, the victron mppt is on but not bulking from solar despite updating settings to lithium and the sterling appears to be dead....

12v fridge lights and sockets all okay though.....

No clue as to what is going on. The weird thing is that the sterling fired up when polarity was wrong and I did manage to set the lithium profile, nothing since wired correctly....

 

[ginkster]

Check all the fuses and breakers including any on/in the units themselves. Hopefully no lasting damage.

What state of charge is the battery? That may be why the MPPT isn’t in bulk. Post a pic of the MPPT data so we can see what’s what.

 

[roadtripper]

The Sterling chargers appear to have a fuse on every input/output/ground connection under the lower cover:


They also indicate those "tell tale" diodes. A common form of polarity protection is to place a diode and fuse such that if the connection is reversed the diode shorts and the fuse blows. It may be that in this case the fuses are also under sized so they also fail so Sterling can tell if a failure is outside of warranty:

 

[pdid]

Thanks for your help fellas, all sorted now. I'd popped about 4 fuses. 2 on what I assume is the feed to the diesel heater, 1 on the sterling unit and one on the victron unit........

Lessons learnt.....

 

[pdid]

Next issue.....

Has anyone gone from a CBE 516 charger to a Victron IP65?

I thought it was going to be a straight swap, just cutting plugs off and joining, but there is an extra wire (white) which I believe is something to do with the starter battery. I think the CBE charges the starter once the leisure battery is full.

I don't think the IP65 can switch between battery profiles so I won't be able to keep this function....

What did you do to install? Thanks

Phil

 

[roadtripper]

By the looks of it it's just a signal to other equipment that the charger is on - for instance it might put a "charger on" light on a control panel.

 

[pdid]

By the looks of it it's just a signal to other equipment that the charger is on - for instance it might put a "charger on" light on a control panel.

View attachment 249280

Thanks, yeah I think all it does is light up the EHU icon on the control panel I have. It's not really necessary but nice to have. Has anyone managed a workaround to get this connected?

Thanks