STERLING ULATRA PRO 50 ISSUE

[lmxr]

Originally Posted by Cpt Mark

Unit powered off.
Power on 14.1V amps (starts off 20's and goes down after a few seconds)
within 230 minutes (sometimes faster) it will settle to 13.6 V from the charger and maybe 4 amps. This would be fine if the battery is charged but it is not. Currently battery is at 13.2V.

The issue is it never gets fully charged. In fact, it would appear that if it goes onto bulk charge mode it's in seconds then going into absorbtion briefly the conditioning which is before float.

An LFP battery in good health that has a voltage of 14.1 V and accepts only a few A is fully charged, or at least very close to being so (within a few percent). A fully charged LFP battery in good health at rest for a few hours should show 13.5 V or at least 13.4 V.

I assume that only the battery charger is connected to the battery such that there aren't any loads that discharge it. Assuming the voltages and currents you mention are correct, there's an issue with the battery. If it's fully charged it should measure 13.5 V and if it's not fully charged it should be soaking up massive current when it is being charged with 14.1 V. What LFP batteries are you using?

To given an example from our bank, our bank is >90 % charged when we terminate charging at 13.8 V and 35 A (840 Ah bank). I know this because after doing the above I overcharged the battery to 3.65 V/cell and 2 A (top balance) and the required energy came down to a few percent of the capacity (and that includeded the energy required to balance the cells). For our bank, 13.2 V boils down to <70 % SOC, so for us 13.2 V does not mean fully charged at all.

I'm not sure whether I can blame the battery charger: if it sees that the battery does not accept much current (I guess less than the tail current) while it is being kept at the absorption voltage, it will assume that the battery has reached full charge and will therefore switch to float.

[baltic sailor]

I have a Sterling Ultra Pro 50A, 4 cells blue Lishen 280A and a JBD 120A BMS.
The charger charges the battery with 47A till the battery is fully charged. I have the older model which has no setting for Lifepo4. I have set it to open lead. Works fine. I get 295 A into the Lifepo4. I turn the charging off at 14,0 with the BMS. I have a bus bar across the 3 output posts on the Sterling and heavy cable.

[Cpt Mark]

Originally Posted by baltic sailor

I have a Sterling Ultra Pro 50A, 4 cells blue Lishen 280A and a JBD 120A BMS.
The charger charges the battery with 47A till the battery is fully charged. I have the older model which has no setting for Lifepo4. I have set it to open lead. Works fine. I get 295 A into the Lifepo4. I turn the charging off at 14,0 with the BMS. I have a bus bar across the 3 output posts on the Sterling and heavy cable.

Well, that gives me some hope. I reset the values to 14.4 and float of 14V. That made a difference. Only charges at 21a for a few minutes then drops down but one thing was very different. This time we have a time to absorb value of 59 minutes whereas before it was 0 minutes.

I've sent another email to Ben and see if I can change that 59 minute vale or get rid of it.

[Cpt Mark]

Originally Posted by baltic sailor

I have a Sterling Ultra Pro 50A, 4 cells blue Lishen 280A and a JBD 120A BMS.
The charger charges the battery with 47A till the battery is fully charged. I have the older model which has no setting for Lifepo4. I have set it to open lead. Works fine. I get 295 A into the Lifepo4. I turn the charging off at 14,0 with the BMS. I have a bus bar across the 3 output posts on the Sterling and heavy cable.

Hmm, let me get this straight. When you Sterling hits your preset max voltage your BMS shuts the battery off? Then what do you do? Turn off the Sterling, turn the BMS back on? Please elaborate. It doesn't make sense to me.
Thank you
Mark

[baltic sailor]

I use a JBD 120 A Common Bus BMS (same like the Overkill). This BMS has two Mosfet switches one for charge, the other for discharge. As you might know these are directional. If the Charge Switch is turned off by the BMS or the App, the discharge switch is still ON. If the voltage from the charger (14,2 V) is higher, then the Voltage on the 12 V Bus is the voltage from the charger in this case 14.2 Volt. Now many people are afraid of the load dump out of the alternator. I have a starter battery on the alternator which takes care of the load dump, but will install a Sterling Alternator Protector. The Lifepo4 is charged from the alternator via a Renogy 40A DC-DC Booster. So the 12 Volt Bus for the instruments has no direct connection to the alternator.
There is a lot of discussion not use a Common Bus BMS....truth is that the majority uses a common bus BMS. The other rumour, is that the BMS turns Charge and discharge off at the same time, have not seen this either.
The BMS switches at the set voltage the charge Mosfet switch OFF (14.0), therefore the Lifepo4 is disconnected from the charger, discharge remains On.
The voltage from the Sterling Charger was at max. 14.2Volt.
Perhaps I set the BMS higher e.g 14.4 V? Will experiment next season.