(The battery and monitor thread )Car dead in the middle of the woods

MarkH said:

See my reply just above re why it might've failed for das mo.

The Smartpass and 250SE become one unit. Current is supplied to the 250SE from the alternator via the Smartpass, current passes thr

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trobex said:

This is a nightmare I would like to avoid in the Oz Bush!

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MarkH said:

See my reply just above re why it might've failed for das mo.

The Smartpass and 250SE become one unit. Current is supplied to the 250SE from the alternator via the Smartpass, current passes through the 250SE back to the Smartpass and on to the aux battery. On the way through, the 250SE boosts the voltage per it's charging regime (dependant on the aux battery's SOC), but it can only supply a max of 20A charge. The Smartpass unit itself also attempts to charge the aux battery directly across its terminals but relies solely on the voltage the smart alternator is producing, it can't boost voltage so outputs 3/5ths of bugger all if the alternator is supplying less than required voltage, especially once the aux battery SOC rises above around 75%.

I won't be fitting the 250SE as I'll replace the OEM auxiliary with a lithium battery. Lithium can be discharged without effect down to ~10% SOC so have a greater capacity than lead acid with the same Ahr rating. They also hold voltage above ~12.8V all the way down to that 10% so it doesn't affect fridges or inverters that cut off under load when voltage falls below ~11.8V, as with the EFB batteries. Lithium are also lighter and charge substantially faster as they have very little internal resistance right up to full charge. They will accept everything you throw at them until they reach ~99% SOC. This is a big advantage when relying on engine time to charge the aux battery. I figure the Smartpass will also charge directly at a much higher rate to the lower resistance of lithium, we'll have to see. I don't expect it to charge at over 14.4V as most alternators seem to stop there and typically you get losses due to cabling and distance from alternator to starter. 14.4V is still fine though for LiFeP04 lithium drop-ins with a built-in BMS. Depends how it plays with the Victron 30A BT Smart DC charger I'll be using. These can be custom programmed correctly for lithium and offers BT monitoring / switching and a 50% higher charge rate than the 250SE. I also carry a 5kg 200W folding solar panel I can deploy when camped up for a few days. This supplies 10-15A so can replace 50-75Ahrs/day in good weather. It'll run through a dedicated Victron 12V/20A MPPT Smart BT controller via an Anderson plug connected to the aux battery. This is all still in the planning stages so could change as info comes to light on the Smartpass. I'll put a post up down the track once the system is up and running.

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MarkH said:

You might be aware but allowing the battery to drop this low regularly is not wise for battery life. Best practice is to maintain as close to 50% SOC (state of charge) or ~12.2V as often as possible as batteries have a finite cycle life.
By running it down under 12.0V often, you dramatically reduce the life of the aux battery. The AGM chart below shows what happens to cycle life when the batterys depth of charge is regularly taken to 30, 50 & 100%. The same chart can apply to these EFB batteries as they have similar characteristics.

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KDJDGrenadier said:

Isn't the auxillary battery used to help charge the main battery?From what i understand the AUX battery is only being used to top up the main battery. The external power outlets and the 12V socket in the cargo area use the main battery, or am i wrong? Question is why is none of this explained in the user manual?

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KDJDGrenadier said:

The whole reason i went with the auxillary battery was to use it to power my fridge and camp lighting etc. Bit of a shame i can't use it for that purpose but perhaps there will be a work around in the future

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AnD3rew said:

Just run a cable from the load terminal of the Smartpass and you will achieve that.

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KDJDGrenadier said:

Thanks Andrew. I also bought the D250SE and plan to connect that into the system then charge with Solar. I have a 300W panel. A bracket is the next thing on the list

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KDJDGrenadier said:

Mark, i have a 250SE which i will be installing. Is there a way i can run the fridge and the camp lighting off the auxillary battery when stopped? Keeping the main battery isolated and hopefully prevent the current situation where all batteries are depleted?

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AnD3rew said:

Yep me too. Black Sheep bracket without the D250 is now a very reasonable price. I will order when he has sorted out the shipping cost error

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MarkH said:

Yes, the fridge being by far the main consumer can be run directly from the aux battery via a simple fused Anderson plug connection, the starter is isolated. Or, you could use the output terminal on the Smartpass, starter is still isolated. Pros and cons of doing this though. Pro is, the fridge is powered directly by the alternator when on the move leaving the 250SE to correctly charge the aux battery faster and without the interruption of the fridge cycling on/off, which can continually knock it out of the preferred charging regime and back into bulk mode. The con is the fridge load will be cut if the Smartpass detects the aux battery voltage dropping below 11.8V, or thereabouts. You may not notice the fridge is off, say you've left camp away from the vehicle beach fishing all day - disaster strikes and you come home to warm beers! It'd be prudent to wire in a cheap easy-to-sight digital voltage readout for the aux battery to give you at least a rough guide on SOC. Best viewed after the fridge has cycled off so the load doesn't skew the voltage. Stick the chart attached below somewhere nearby for quick reference. EFBs behave similar to AGMs.
If your fridge has low voltage cutoff you may as well run it from the Smartpass thereby letting the 250SE do its thing more effectively while on the move. If the fridge doesn't have volatge cutoff built-in you might want to run it direct from the aux. This way in a pinch you can keep the fridge running below 11.8V, but once you see 10.9V battery damage accelerates. OK once in a blue moon but best avoided where possible or the cells start turning up their toes.

Don't rely on the % display in the infotainment unit to monitor the battery/s while camped, it's likely far from accurate.
Until I have the vehicle and can suss out the wiring I'd just be leaving the roof outlets as they are and running a couple of LED camp lights from the starter. It's the same EFB 105Ah battery (think AGM) so should handle small loads like that no problem, as long as it wasn't 50% when you rolled into camp. You could add a 2nd voltage readout to the starter. Worse case you carry a compact jump starter for justin'. I have the Gooloo GT3000 which starts my 3.0L V6 Jeep no problem. see attached.

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KDJDGrenadier said:

Does that come with the connecting bars Andrew or have you managed to find them elsewhere?

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Highwayman said:

Car started as normal with no indication of problems (no warning lights etc).

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Tazzieman said:

The best stories come from "when things go bad"
You don't want a bland life do you?

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trobex said:

I want bland when the family is in the car and vehicle is working to start with haha!!! I need to read this all in full later tonight!

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