Dc to DC battery charges.

Hi gmd,
I'm looking at the Sterling battery to battery charger. It's a simple install and tricks the alternator into thinking the main battery is flat which then gives your aux battery its charge (40amp), is your sterling weather proof?

I think you got your facts mixed up.
Read again about B to B and A to B units ...
have fun
gmd

Went into Ctek sight and viewed there DC to DC chargers...they require a 22v input which I don't think a standard car alternator is capable of supplying. Do you have a product# which I can use?
Cheers

Hi

I think you might have read it wrong it does not require 22v but Max is 22v. Have a look at the manual http://www.ctek.com/files/manual/D250S-Dual_uk.pdf

This is the best on the market right now I think - WHY ???
am curious !
have fun
gmd

Pretty reliable bit of kit Matt. I think they weren't competitive price wise when their manufacturer put the charges up. The 25amp/hour output seems to be pretty solid.

It will be interesting if the Sterling puts out those amps for long as the inputs will need to be very strong. The fuses will need to withstand some heat.

Hi Trains,

The aux battery is a Trojan 115amp which was bought new under a year ago (fridge is new to car). Have checked all connectors and the install was professionally done by ARB. Not knowing the coorect terms for wire gauge, I would say the od is approx 10mm.
Alternator output is 14.3 volts measured at main terminals.

Is that an agm, or a flooded wet battery?

if its a wet battery, for want of a better term, then the few hours travelling will not be enough time to put back into the battery what you need.
an agm will accept, or absorb more in less time than the wet type of batt.

With the battery low on charge after a nights running, and then you start and run your vehicle, what is the volts you are getting back at your start batt, then the solenoid contacts both sides, and finally your 2nd batt ?

For interest, what is the voltage on the outlet to the fridge when its running as well.
Worth testing Just in case you have a faulty connection there.

T

It's a wet sell battery...will check the voltage to the fridge as you suggested.

Cheers,

Luce1

Hi Luce1,
Been away, and sadly having to travel in this 42 deg heat :(.

If you have had time, what have you found regarding your voltage, and if any voltage drop in your wires to the 2nd batt.

Im wondering if they just have not had enough time to be recharged from the short drive time.
With agm batts, you would most likely get away with those 2 hr trips.

Any way, lets us know what you find.
Would be good to find a fault and fix it if one is there.

T

Hi T,

Hope things have cooled off...an icy draught always helps.

I've checked the charge rates and this is what I found:

Resting Charging

Main 12.7 14.2
Aux 12.7 13.6
To fridge 12.6 13.5

I'm having my deep cycles checked by the retailer this week in case there not holding charge under load, they're 18 months old and should be o.k

Contacted Alan at Ranox who confirmed there no longer producing there unit:(
but he did recommend the Redarc as doing a similar job but not as many features.

I've been in touch with Ian at RV Power Stream who's been helpful. After explaining what I wanted, he suggested running the bb121250 sterling.
Must be an in cabin installation between main and aux battery, an easy install using no smaller than a 6D&S cable which I'm already using. :)

Asked Ian about the possibility of damaging the open lead acid batteries...suggested it wouldn't be a problem and explained why.
(To anyone who's interested you can call Ian on 0427648726).

I'm thinking I'm not giving the batteries enough time to charge hence my problem.

What are your thoughts.

Cheers,

Luce1

Hi Luce1,
When you tested the charge rate, the voltage drop is just over half a volt.
The other test would be to see how many amps are going into the batteries when they have been brought down.

At 13.6v, it will take alot longer than 2 hrs to bring the aux battery state of charge up, in fact I would guess that a good 14 to 14.5v would be what you would need to bring them back up, and would take more than 2 hrs of driving.
Best check the recommended volts charge, and amps they can take tho.

Having said that, and without seeing your setup, I dont think there is enough time for your batteries to be recharged in the time you specify.

If your alternator drops the voltage as the engine bay warms, and reduced the volts, you will notice the half a volt drop more then too.

Suggestions are, get the dc dc charger, than will ensure you will get metered higher volts and amps into the aux battery.
Get an agm, as it can accept more charge in less time than a flooded wet acid one if your continuing to do small top up trips.

T

Received a response from Trojan re battery charging:

The 27TMH battery should be charged to 14.8 volts with a maximum current of 15 amps. Ideally, the current would taper as the battery voltage increases with a finishing current of around 3 amps.

It seems I'm not supplying enough charge to satisfy the Trojans.

Luce1

Hi Scrubby,

There seems to be some discussion in other posts regarding a batteries capacity to accept high outputs (50amps) such as the Sterling offers.
Have you had any problems with your batteries and how old are they since the install?

Cheers,

Luce1.

you need AGM's to utilise 50Amp charge current or parallel banks of wet cells.
have fun
gmd

Hi Scrubby,

I've looked at the bb121250...it seems to be a good choice. I've read other posts which also indicate this.

Thanks for your input...if there's anything else I'd appreciate you feedback.

Cheers,

Luce1

He did write "200ah RV Gel batteries".

Charging at 50 amps is within specifications.