Alternator regulators - are they worth fitting?

[wuntenn]

Been having some electrical problems with my Land Rover 110 which has a pair of batteries connected with an IBS Split Charge Battery Monitor system. My Eberspacher has been flashing up low-voltage cut-out warnings and shutting down, even when the battery is supposedly fully charged. Charge seems to drop off very quickly on the battery when monitored with a meter. I'm in the process of checking all the Eberspacher wiring to see if there's an obvious problem in the circuits, and fitting a small digital voltmeter so I can compare battery voltage and voltage at the Eberspacher in real time and watch for voltage drops.

However in getting in about all of this I've realized the CTEK Intelligent charger which I've been using to maintain the batteries is knackered and although has been flashing up various lights suggesting it's working and knows what its doing, it's actually all over the place and has finally totally died (just out of warranty!). So I have no idea how long its been defective and what havoc it has wreaked on my batteries charge retention abilities.

This was compounded by realizing my alternator was doing some strange charging behaviour (possibly voltage rectifier dying) and fitting a new alternator in mid-December and it being defective too! It suddenly died last week a hundred miles from home in a blizzard which was a tad inconvenient. When it arrived the box was damaged slightly, suggesting some rough handling but it looks like it might have been sufficient to have caused some damage.

So I've possibly had a combination of inconsistent charging from both the CTEK and alternator(s).

Anyway new CTEK has arrived and is working a treat, and a replacement alternator is on the way.

It's possible that my batteries have had the guts knocked out of them by the combination of duff charger and alternator so it may be that I need to replace them. However in reading up on electrical stuff recently as I try to get a handle on all of the complexity of electrickery I came across 'alternator regulators' and their benefits in charging efficiency and battery maintenance. This, for example, Sterling Advanced Digital Regulator - seems like a useful bit of kit.

So, my question - are these things worth it? And do I need to beef up the wiring to accommodate their output? And crucially, would they play nice with the IBS Monitor/Split Charge system?

 

[Martyn]

Load test your batteries first and then go from there.

 

[wuntenn]

Load test your batteries first and then go from there.

Did some tests:

It was about -1 deg. and frosty. Van had not been started/run for a few days.

Aux battery at rest = 12.68v
Main battery at rest = 12.61v

Pulled apart heater multiplug (Eberspacher unit's main connection loom, 12 inches cable-length from heater unit) to take voltage reading: at rest reading at plug = 12.44v

Reconnect plug, start heater, it draws current for start-up cycle and cuts out immediately, low-voltage error code 11 shows. (error code 11 indicates voltage at heater is <10V )

With heater switched off again, the meter now reads:

Aux battery = 12.35v
Main battery = 12.28v



With the meter connected and taking readings in real time at the aux battery terminals during the start-up cycle, the voltage reading drops to 11.82v

I still need to bare some wires at the heater end and see what the reading is there when it's under load. Waiting for a small LCD meter to arrive so I can install. It should be here tomorrow.


Meanwhile I did another test, charged both batteries to 'full'. Then left overnight, off the charger. Its got warmer today so not sub-zero.

At rest, engine off:

Aux battery - 12.57v
Main battery 12.34v

Reading at Eberspacher unit - 12.56v

Attached a mechanics 12v trailing light with a 55w bulb across aux battery and switched on:

Aux battery dropped to 12.45v, then 12.40v and so on until after exactly 3 minutes it was steady on 12.15V.

Reading now at Eberspacher - 12.15v


I'm no expert but that looks a tad unhealthy to me. Aux battery is 86AH deep cycle unit.

 

[DiploStrat]

Depends ...

Typically, the advantage of a secondary regulator, like your CTEK, for example, it to allow you to run one charging profile for your starter battery and one for your camper battery. Battery to battery (B2B or DC to DC) devices work by throwing away amperage to gain voltage, thus (partially) compensating for long wires to the camper battery and for alternators which do not run at the higher voltages required for some deep cycle batteries. As many vehicles already run at over 14v, these can prove to be very expensive alternatives to a simple relay or an intelligent relay, the latter being my personal favorite. These allow you to harvest the full output of your alternator as opposed to the typical 20-40A of a B2B. But, if the normal charging voltages of your truck never reach 14v and you have long, small wires, a B2B can be a lifesaver. Many Toyotas, for example, limit to 13.9v.

Assuming, however that your Landcover charges in the range of 14 - 14.5v (at 20C), a secondary regulator isn't going to do much for your starter battery. And the CTEK is already performing the same function for your camper battery. If you want a faster charge for the camper battery, look into the CTEK SmartPass, an intelligent relay specifically designed to integrate with the CTEK D250S.

Bottom line, the first thing you need to know is the output voltage of your factory alternator. Remember, charging voltages vary by type of battery - FLA, AGM, etc. and dramatically by temperature. Most charging voltages are given at 20 or 22C, but climb into the stratosphere at freezing or below. Consult the tech manual for your battery.

Hope this is comprehensible and useful.