Sterling Power LiFePO4 (Lithium) Leisure Batteries

[arthur49]

mikefitz - 2021-07-01 10:46 AM

 

Lithium batteries do not need temperature compensation of the charge voltages so unless the chargers are using temperature monitoring for low temperature charge disable, ( less than 5C) or battery overheat ( over 45C), they are not needed.

 

Mike

 

Thank you Mike.

 

The B2B, solar regulator and mains charger all have a lithium setting and the temp sensors are to monitor the low and high temps and therefore regulate/terminate the charge should such temps be encountered. The mains charger (Victron) in fact will not operate on a lithium setting without temp sensor being fitted.

 

Whilst the battery BMS monitor and adjust temp, charge etc etc, I've taken the view the BMS should be the "fall back" and as much as possible the B2B, solar, mains charger should take a primary role in presenting the batteries with ideal volts/current?

 

(With apologies to Veletron/Karen, I'm not usurping this thread but we have identical lithiums!)

[veletron]

Hi

 

I an leaving the BMS to handle any temperature-based compensation, this is on the recommendation of Stirling Power. For their own B2B temp comp is disabled for LifePO4 anyway, and for my EPSolar I have simply removed it.

 

The BMS will do a good enough job on its own and having both connected will lead to competition between compensators!

 

Karen

[arthur49]

Thank you Karen

[Pete7]

Karen, how are you getting along with the Sterling Lithium?

 

We have a 120Ah from Sterling which has done sterling work this summer enabling us to use the electric kettle and toaster rather than gas which given the calor gas fiasco has been a life saver. However, we have one cell that races away above the others when then reach 3.4v per cell.

 

Pete

[veletron]

They did not set the BMS up properly i'm afraid so the balancing never kicks in. To resolve this, I changed the settings on the BMS (via the bluetooth app), and also changed my mains charger settings to make it slow charge the battery at 5A - this gives the BMS more time to balance the cells.

 

The Daly BMS has a number of weaknesses including the fact that the password cannot be changed from the default - this potentially means that someone else could change the settings on your batteries!

 

See screenshots for my settings. PW is 123456 IIRC

 

Karen

[weldted]

Hi our van at the moment is at RV Installations, Mullacott, North Devon, having

 

*4 x 175 watt solar panels, Victron mttp 60 amp controller

• Victron 2Kva Multi

• Victron GX touch control panel

• 230 amp upgraded split charge

• Victron battery protects for the charge and loads

• Victron Cerbo control system

• Victron BMV battery shunt

• 2 x Transporter Energy batteries

 

these batteries carry a ten year warranty. So will see how it goes, it should be an improvement on 2 x 95 amp AGM’s and a 100 watt panel.

[veletron]

Crikey, I bet that wasnae cheap! You'll be running your house off the van once that lot is in!

 

I'm born and bred in Braunton, so I know Mullacott well.

 

Karen

[Mickt]

You sure that's enough

[Pete7]

Karen, yes we had the same problem, but the password was easy enough to Google. I have been watching Andy on the YT channel Off Street Garage and plan to use some of his settings over the next few days. Particularly setting the charge to 3.45v per cell and the float slightly less, the MPPT offset to just 0.1v so the MPPT switches back in early to enable power from solar to run day time domestic items rather than drawing down the LFP. The trail current will be set to 1A per 100A battery. That's on the Victron, then similar settings on the Sterling LFP.

 

I did pop into Sterling to pick up the LFP but they wouldn't say who the cell manufacturer is other than they are plastic cased, so probably not Eve types.

 

However, over all we are impressed and wouldn't want to go back to a pure-lead acid solution.

[weldted]

We off grid a lot in the winter (hopefully) down to Portugal, with this set up we will or should be able to run the hab air con. We also have a Dometic cx35freezer which runs at -18c. Admittedly not much chance of needing it during the winter but in the summer of 2020 we were glad of it.

Having had Tom fit our underslung gas tank and was very impressed with the standard of work. Also when discussing the Lithium set up it was clear to me they are very knowledgeable.

[arthur49]

veletron - 2021-11-23 10:05 PM

 

They did not set the BMS up properly i'm afraid so the balancing never kicks in. To resolve this, I changed the settings on the BMS (via the bluetooth app), and also changed my mains charger settings to make it slow charge the battery at 5A - this gives the BMS more time to balance the cells.

 

The Daly BMS has a number of weaknesses including the fact that the password cannot be changed from the default - this potentially means that someone else could change the settings on your batteries!

 

See screenshots for my settings. PW is 123456 IIRC

 

Karen

 

Thank you for posting this Karen. I found balancing did kick in but seemed later than I would have expected. My protection parameters are the same as yours. I've now changed the coil characteristics to yours. Am I right in thinking Balanced Open Start Voltage is the figure at which balancing will start if any cell is at that level, or lower?

 

And Balanced Open Diff Voltage is obvious I think? This was sitting at 0.03v now changed to 0.01v

 

Love these batteries by the way.

[Pete7]

Karen, you have the cell reference voltage at 3.6v. Surely it should be 3.2v? Though I am not sure if it actually makes any difference.

 

Pete

[mikefitz]

After reading through all the posts I have a number of suggestions.

 

BMS settings.

 

The BMS is a last resort protection device for the battery and in not intended to control charging, all charging devices should programmed to operate within the safe working area of the battery.

 

The protection limits of 14.6 volts for the battery and 3.65 volts per cell voltage are considered safe limits.

With balancing, this should occur only when the battery is under charge and in a high state of charge so needs to be over 3.4 volts per cell,

Balancing start voltage = 3.4 volts

Balance open difference volts = 0.015 volts.

Thus balancing will not occur unless the voltage delta between cells is greater than 0.015 volts and the cell voltage is over 3.40 volts.

 

Charger settings for lithium.

 

Ideally the battery should be charge to almost full state of charge and then used. Where the battery is continually in a high state of charge service life is reduced. I have seen reports where lithium batteries lost considerable capacity within two years due to being continually under high charge and float voltages.

Ideal charge voltage is 13.8 to 14.2 volts, 14 volts is a good compromise. Higher voltages will apply more stress to the battery.

Float voltage should be set to the rest voltage of a fully charged battery, this will be 13.35 to 13.4 volts. A often used voltage of 13.8 volts will keep the battery fully charged and is not recommended.

If the charger has a 're boost' setting this needs to be 0.1 volts lower than the float voltage.

 

Sterling Batteries.

 

Issues are being found on some batteries.

BMS state of charge reporting.

The DALY protection circuit, the BMS, does not report the SOC correctly and my also not report charge and discharge currents correctly. This is a known fault with the DALY BMS . I recommend you return the battery for a replacement.

Cells with significant imbalance.

Under charge some batteries have the charge path disconnected by the BMS when one cell goes over volts, that is exceeds the safe 3.65 volts across the cell. This should not happen despite what Sterling Technical tell you. The battery should be assembled with cells reasonable balanced before assembly. The BMS cell balancing is designed to compensate for small cell imbalance and cannot deal with this issue.

If cell over volts stops the charge process then you have two problems, firstly the battery will never reach full capacity and secondly both the BMS and the cell are being over stressed. With the cell this results in accelerated capacity loss in that cell over time, and thus battery loss in capacity.

If you find the battery is shutting down the charge current when under charge, ( the BMS will report a fault with cell over voltage), lower the charge voltage if possible. If the problem continues ask Sterling for a replacement battery.

 

Sterling Batteries are excellent value however the quality control needs to be improved.

 

Victron Battery Protect.

 

There have been a considerable number of failures due to incorrect application of these units. This is partly a fault of Victron who did not stress that they are unidirectional and that they will also fail if subjected to excess over current.

The Victron battery protect must not be connected between the battery and an inverter. The input capacitors in the inverter take a very large surge current that /will damage the Victron unit.

Thus whilst using a Victron battery protect between the battery and consumers ( without an inverter) is OK, or between chargers and the battery, its not possible to use between the battery and an inverter/charger.

 

Split charge and lithium batteries.

 

With the low internal resistance of the lithium battery using a split charge is not recommended as a method of alternator charging. The only thing limiting the charge current is the resistance of the cables and components in the circuit charge path.

A battery to battery charger is needed to safeguard the alternator and cables from damage and to ensure the lithium battery charge current is within specified limits and to terminate charging when the battery reaches a high SOC.

The alternator used on most vans is not designed to deliver more that about 50 amps over the normal power needed for van electricals. It would be prudent to design the charging circuit to ensure this limit is not exceeded.

 

Mike

.

 

 

[Pete7]

Mike thanks, some interesting comments.

 

One of the problems of the Daly BMS is the balance is only 0.030v hence why people are starting the balancing lower down.

 

Pete

[arthur49]

Intending to go away in van in a few days so thought I'd check all OK.

 

No 12v at control panel. All fuses appear OK.

 

Its cold here - frost overnight - so took lithiums out into house after finding no 12v at panel.

 

According to app voltages are approx 13.1v on each and approx 86% charge.

 

Putting a meter on the terminals gives reading of 9.48v on one and 9.47v on the other. BMS temps set at 0 degrees charge and discharge. The charge and discharge sliders show not activated.

 

I take it this is the BMS doing its job and disabling charge/discharge? (though temp is +2 degrees)

[mikefitz]

Depending on the BMS settings, 0C disable and 5C enable may be set, thus the battery will need to warm to above 5C before the BMS activates the charge path. The battery should/will be able to provide power out if a current is drawn. The BMS will then activate the discharge path. Normally the BMS will/should allow discharge down to -20C.

When the charge path is disabled and discharge is still allowed the BMS will only switch the discharge path 'on' if the current is above a certain value, ( around 0.5 amps). A multi- meter takes so little current you will 'see' a low voltage at the terminals.

If may be useful to check the BMS settings for low temperature discharge disable, the battery should still be able to power the van circuits down to -20C.

 

13.1 volts and 86% SOC seem slightly out of sync. The Daly BMS used in Sterling batteries may give incorrect SOC readings.

 

Mike

[Hans]

Be aware that the loading is very tricky. At low Ambient temperature. It take me weeks to understand their loading cycle. And Their Result.A Solar now does not do Anything to battery power. Proven last weekend on dog agilyty. Whit 75 RV. standing. A Webasto does not start At 11.8 volts. Just start the engine and it runs. Just in Case. To survive The Cold.

[arthur49]

mikefitz - 2021-12-06 11:58 AM

 

Depending on the BMS settings, 0C disable and 5C enable may be set, thus the battery will need to warm to above 5C before the BMS activates the charge path. The battery should/will be able to provide power out if a current is drawn. The BMS will then activate the discharge path. Normally the BMS will/should allow discharge down to -20C.

When the charge path is disabled and discharge is still allowed the BMS will only switch the discharge path 'on' if the current is above a certain value, ( around 0.5 amps). A multi- meter takes so little current you will 'see' a low voltage at the terminals.

If may be useful to check the BMS settings for low temperature discharge disable, the battery should still be able to power the van circuits down to -20C.

 

13.1 volts and 86% SOC seem slightly out of sync. The Daly BMS used in Sterling batteries may give incorrect SOC readings.

 

Mike

 

Thank you Mike. I took the batteries out and left them in kitchen. Within a couple of hours temp was showing 13 degrees, voltage 13.1v.

 

Put back in van - not a hassle really as they are light - and everything working great.

 

Thanks again Mike. I had a horrible feeling something was wrong but BMS was only doing its job

[arthur49]

Mike - for info

 

I love these batteries and I've found Sterling Power very good if you contact them for help but you're right quality control is not great.

 

Just found that low temp discharge was set at 0 degrees so I've reset to -20 degrees.

 

And I didn't realise that starting the engine wakened the BMS as it wasn't in instructions

 

When the batteries arrived 6 months ago the settings were different on each!

 

Every day's a school day even at 70+

 

KAREN - this is your thread and I don't want to take it over but we have identical batteries!

[veletron]

Hi

 

Don't worry, we are bouncing info off one-another. Its early days for lithium, and they are clearly not yet fit+forget - mainly due to easily remedied quality issues. We are beta-testing this tech for the masses, within 5 years, I cant imagine lead-acid for motorhomes still being a thing, and by then LiFePo4 will be fit+forget, and under £250 a pop!

 

Still liking mine as well, esp now that winter has come along and I can do 4 days off grid without moving, watch telle and boil a leccy kettle. Thus far I have drawn 180AH out of mine (2x100AH) during a long weekend. I'd have needed 4x100AH Lead-Acid weighing over 100KG for similar real-world, no-damage capacity.

 

Off the back of comments here, I have reduced the voltage of my mains charger to 14V/13.4V (boost/float). I am using a Sterling 40A Pro Charge Ultra off their surplus page - which has a custom mode. Hopefully this solves any cooked battery potential and limits the possibility of single-cell run-away.

 

Karen

[arthur49]

Sorry another question!

 

Mains charger is Votronic 25A with lithium setting. Its approx 30cm from batteries so short cable. I used 70A interconnect cable as that is the same as rest of van.

 

Fuse is 30A, fuseholder rated at 30A. BMS says batteries are receiving 24.5A. All contacts are clean and secure.

 

Cable is only very slightly warm but fuseholder/fuse is fairly hot to the touch.

 

Is this normal or should I beef up fuseholder and fuse?

[weldted]

I have a different take on this

 

The only reason for a B2B charger is if you have a smart alternator, as a Smart alternator is ECU controlled you are not able to add an unknown discharge current, as this could damage the alternator and the ECU. Without a B2B it could also spike the house batteries with a voltage higher than 14.6v which is not ideal. The main aim of a B2B is to fool the ECU into thinking there is a charge current needed by the vehicle battery, this charge current can then be used by the house battery.

 

The only advice is not to run the engine on tickover to charge depleted batteries for more than 15 mins as the Alternator could get hot.

 

The first comment insinuates that a B2B chargers have the capacity to stop a Lithium battery accepting a charge. This is simply not the case as there is no data transfer between the B2B and battery BMS. Even if you had a B2B you would still have to rely on the battery BMS to switch off the ‘allow to charge’ function when the battery is fully charged, a B2B is not capable of doing this. By installing a Cyrix and a battery protect we are performing all necessary features of a B2B at a far lower cost.

 

In answer to the 2nd statement. If you tried to regulate the amp draw from an alternator by reducing the cable size it would simply melt the cable, the cable sizing in my installation will allow the safe transfer of available power. As I mentioned before there has never been an issue with these systems damaging alternators.

 

Point to note these are not cheap batteries with a cheap BMS and are capable of accepting a C1 charge and carry a ten year warranty. All the other equipment fitted carries a five year warranty. Try looking on the Transporter batteries website

[veletron]

Hi

 

A depleted lithium will pull whatever current it can get hold off. If there is decent cabling and a connection to the alternator via a standard split/charge system, then you end up with the BMS in the battery being the only thing present to limit the current.

 

Not all alternators are built the same most will be just fine feeding massive currents (assuming the fuse allows this), but you are putting huge stress on the alternator particularly at tickover and possibly also on the BMS depending on the current flowing.

 

Additionally, basic alternator charging has no means to reduce the voltage to 'float' once the lithium's are charged, in fact as the charge approaches completion and the current drops, the voltage from the alternator at the battery will increase, and once again, you are relying only on the BMS to prevent the battery becoming damaged.

 

Given the price of these batteries, I feel that spending the extra on a BMS designed to charge them optimally is a reasonable investment.

 

Karen

[veletron]

arthur49 - 2021-12-08 12:32 PM

 

 

Cable is only very slightly warm but fuseholder/fuse is fairly hot to the touch.

 

Is this normal or should I beef up fuseholder and fuse?

 

Rule of thumb: heat is bad! Heat is caused when current passes through a resistance, current flowing through a resistance leads to a voltage drop across that resistance, that heat is wasted power PowerWasted=Current X Voltage drop.

 

Get everything running, and then with a multimeter, measure the voltage across the cable/fuse combo eg from the Victron output to the lithiums on the +ve (red) cable only this gives the voltage drop. You know the current 24.5A so wasted power is 24.5A X Measured voltage drop eg if you measured 0.25V drop, then you are wasting 6.125W.

 

Additionally, measure the voltage drop between the engine battery and the INPUT to the Victron B2B, work out the watts wasted here too and add it to the watts wasted above to get your total

 

On my van, I use 4AWG / 25mmSq Welding cable, and I overrate fuses as well. Fuses are there mainly to protect the cables. I would use 40A/45A+ for a 30A B2B also, not all fuses are equal. ANL fuses are superior to AGU fuses, and the wee small automotive blade type fuses are not appropriate for B2B application. A fuse close to its maximum current WILL get hot!!

 

With 4AWG and an 80A fuse, nothing is warm in my van charging @60A for several hours. I should also say that at 60A with 4AWG cables you still need to keep cable lengths 2.5M or less, for longer runs, you need to even thicker cable!

 

Karen

[arthur49]

veletron - 2021-12-08 7:19 PM

 

On my van, I use 4AWG / 25mmSq Welding cable,

 

Karen

 

Thank you Karen. For all the large power cables I followed your example and and used 4AWG cable.

 

Looking at the mains charger yes the fuse on reflection is poor. Cabling is 70A from charger to batteries but its a 30A fuse in a car blade type holder rated also 30A, so I suppose I should expect heat!

 

I have a midi strip/link fuseholder with M5 studs in my spares, I'll use that with 40A fuse I think.

 

Fuses to/from B2B and alternator and batteries, all 4AWG cable, are mega link with M8 studs and cable run to B2B is a little over 2m. I do plan to change the fuses from batteries to cube type but laziness set in

 

Thank you for your help again