Leisure Battery Charging system

Ta-da



All there. Take your pic of shunts. The brassy* one has an M6 hole and a M8 hole the silvery** one has two M8s.

They're both 250A 75mV as is the meter.

*Not brass
**Not silver

Dull yes, decent conductor though. I found some BZP hardware that came with the shunt I'll include these too but I'd recommend chucking them for stainless or brass because they're already showing signs of galvanic corrosion and will only cause you problems.

jace_da_face wrote: »

Here is the circuit powered and a current reading of 22.43 amps.

Blimey that's a good meter!
Driving her like a rental.

jace_da_face wrote: »

That's warm enough thank you. I shouldn't need to keep it going any longer.

Get worried around 50°C

jace_da_face wrote: »

Yeah well I still might. I might even settle for half the load with just the fridge on 12V should the Fluke let me down during calibrating. Will give this a go over the next day or two. :eek:

Swap the £10 HRC fuse for fuse wire. Cheaper than hi-tech fuses or new meters.

HRC is for >400V

jace_da_face wrote: »

So went through the calibration process this evening. There were times when I cursed and blinded, convinced the battery monitor is broken. When trying to increment and decrement voltage and current values, and either nothing happens or the parameter appears to change randomly, then it’s e-bin.com right? But I persevered....

Fair play!
No E-bin comes later when you press the wrong button sequence and then have to start all over.

Good meters (>€100) work outtov the box by the way. ..just sayin'



100% charge is what the specific gravity tells you. Not what a meter, and definately not what a charger says.
But you are down to ±10% error margin I'd expect.
FLA have a non linear efficiency, it'll manifest as drift over time.

jace_da_face wrote: »

If it gives me a good picture of my power usage without EHU then it will serve some purpose.fast recharge.

That's it that's what they do best and charger performance info.

Power a laptop from an inverter then power it from a car charger if you wanna see an interesting comparison.

jace_da_face wrote: »

My next step is to go through all my appliances one by one to see why my parasitic current is so high. I noticed this while installing the monitor. It’s up at about 400mA.

Yes that is high. Mine is 70mA. Less is more.
Instrument cluster usually, tank monitors, fixed alarms, radio.

Float charger? Disagree. I use my battery.

Simple solution is a good load compensating charger like a Ctek, ProNautic, Xantrex, MasterVolt, Victron, Sterling. Make sure it has ample capacity to power your shore 12volt loads and have 5% > 15% overhead of your battery capacity rating for battery charging. eg. 200Ah battery, 6A nominal running load = 25A Charger.

Low end generic brand or automotive chargers are going to give you problems.
If it has temperature compensation it's a good sign it's safe to leave on a battery indefinately and that it's a well designed charger.

Make it exclusive to solar charging.

Feeding solars controllers works great, you need a current limited input up to the task that doesn't exceed 50% your charge controllers rating or use MPPT and some passive protection is advised.

Sure a device that take inputs from all sources would be great but nobody makes one that's fit for purpose. Unless you go into >1kVA inverter combi charger changeover jobs with solar inputs land.

Does it matter at the end of the day? Replacing a battery every few years is a very economic way to power a motorhome. Always having a battery one foot in the grave...maybe that's annoying maybe it's not...

I whip out working Zigs. I wouldn't be resurrecting any.

jace_da_face wrote: »

It seems the smartest way at all might be a single charger which accepts charge from multiple sources but also supplies load current.

Found one from the land of Oz.



Overlanders seem to like them. Can't comment, never tested one, the external temp sensor and a 14.8V set-point speaks volumes to it's credibility though.
The fact it comes with a real monitor is also quite telling. Most of the market offerings would lose sales hand over fist if they did that because you'd see how poor the unit is outtov the gates without having to wait for your third battery replacement for the penny to drop.

Hmm interesting..
Ctek make a good product but I don't especially like them. I find them overpriced and conservative.

The Smartpass 120A is a Merlin Smartbank inna fancy wrapper.
The DS250A is an over- cold-rated Sterling B2B 20A with an odd MPPT solar charge controller attached.

It's not going to help with a poor performing mains charger/maintainer/battery boiler.

Having a look at the manual tripped the BS detector a few times.

Ctek, DS250 wrote:

• Power reduction: 30°C 16A, 50°C 13A

That's a 13A continuous unit! After 30mins most electronics' thermal design point is ≥50°C

Ctek wrote:

• SMARTPASS 120 supplies consumers from the alternator instead of from the service battery while the service battery is charging, which permits faster charging.

That's a naturally occuring property of a higher voltage source, in a correctly wired system the alternator powers loads never the battery. It's a fundamental principle of electricity, not something I would be claiming as an inbuilt feature.

Ctek wrote:

TIP 6 Heavy current consumers (more than 80A) must be connected directly to the service or starter battery.

That's an 80A continuous unit with 120A surge and 350A instantaneous.
They're relying on the alternator to throttle before the unit melts...yeah why not..that's perfectly ok...but it's an 80A unit!


Other things to be aware of;

• The Voc of the solar input forces you to fit expensive 12v panels because it can't handle bigger. The whole point of MPPT in my opinion is so you can use half the price domestic panels.
• The smartpass is not a boosting unit. So you'll never get 120A from it, the DS250 is only boosting 20A (derate to 13A after 30 mins) after that you are still relying on the not so useful alternator regulator. As such it will still require compensatory cable routing and gauge and possibly an external alternator regulator to get close.
• The temperature compensation is too conservative. 23 mV/°C from 25°. Standard is 30mV/°C
• 14.7V setpoint conservative & non-programmable. (14.8V + 30mV/°C kicks bottom)
• Absorption timeout 12hours = 95% charged for flooded batts = diminishing returns.
• Engine battery trickle charging feature, could be a double-edged sword. I'd call it a parasitic load, maybe it's useful to some.
• 13A continuous charge + alternator on a 300Ah battery?

No meter...no surprise there. No mains regulation other than to throttle other inputs.


Other than that they are using the wrong symbol for the ground and calling it an earth with an earth symbol depicted. An earth is an earth potential conductor that is staked to the planet earth with an electrode of some kind. A Ground is a reference point in an electrical system that is grounded to a chassis. A negative is an ungrounded or floating 0V potential with reference to the positive.

They can be and often are all connected at the same point but they are not the same thing.




Sure it works, and probably well enough for some, apples to apples though it's an overpriced half-a-solution.
Yer paying premium for the BS marketing.


In terms of versatile, high performing multi-input BMS from the manual alone I'd give it a speculative 6/10 where 0 is a Zig/Calira/blok-thing and 9 is my home-brew system*. :P


* when it's finished