Dc to DC battery charges.

Submitted: Tuesday, Jan 25, 2011 at 23:47
ThreadID: 83899 Views:4537 Replies:7 FollowUps:17
This Thread has been Archived
I'm looking into replacing my current dual battery system with a DC to DC charging unit. I have a V6 120 Prado and an aux battery that runs an 85lt Evacool fridge freezer.
I've found that my piranha dual battery system (fitted by ARB) isn't supplying the required charge to keep the fridge running on low after a 2hr drive per day causing it to fault after two days. So I'm currently looking at alternatives.
Can anybody please share there experience with dc to dc battery charges. There are two I'm currently looking at and both seem to do what I want...they are the Ranox and Sterling bb121250.
The Sterling seems to be more efficient in its charging capacity when it comes to wet cell batteries (trojan 115amp batteries x 2).
Your feed back would be greatly appreciated.


Back Expand Un-Read 0 Moderator

Reply By: _gmd_pps - Wednesday, Jan 26, 2011 at 02:57

Wednesday, Jan 26, 2011 at 02:57
I use the sterling with 2 banks of 4x6V Concorde AGMs with a total of 12V 440AH x 2 and it runs very nicely. I have a dual alternator system which delivers enough voltage at idle for the sterling.

I purchased the unit in Germany with a remote control unit at half the price (including shipping) of what it is here in Australia.
If you are interested I can give you the email address of the shop I bought it from.
You can email me at gmd@vk6gmd.com
good lcuk
gmd
AnswerID: 443055

Follow Up By: Luce1 - Wednesday, Jan 26, 2011 at 10:48

Wednesday, Jan 26, 2011 at 10:48
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?

0
FollowupID: 715132

Follow Up By: _gmd_pps - Thursday, Jan 27, 2011 at 13:00

Thursday, Jan 27, 2011 at 13:00
I think you got your facts mixed up.
Read again about B to B and A to B units ...
have fun
gmd
0
FollowupID: 715267

Reply By: siukalo - Wednesday, Jan 26, 2011 at 04:10

Wednesday, Jan 26, 2011 at 04:10
This is the best on the market right now I think. They are about $360 from ebay. http://www.ctek.com/EN-AU/dcdc/default.aspx
AnswerID: 443056

Follow Up By: Luce1 - Wednesday, Jan 26, 2011 at 11:00

Wednesday, Jan 26, 2011 at 11:00
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
0
FollowupID: 715133

Follow Up By: siukalo - Wednesday, Jan 26, 2011 at 13:53

Wednesday, Jan 26, 2011 at 13:53
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
0
FollowupID: 715149

Follow Up By: _gmd_pps - Thursday, Jan 27, 2011 at 13:06

Thursday, Jan 27, 2011 at 13:06
This is the best on the market right now I think - WHY ???
am curious !
have fun
gmd
0
FollowupID: 715269

Reply By: Member - Matt M - Wednesday, Jan 26, 2011 at 08:58

Wednesday, Jan 26, 2011 at 08:58
The Sterling has a higher output (50 amp from memory) than the Ranox which is 25 Amps. However the Ranox is no longer being manufactured so write that one off your list. It is a pity in many ways, but I believe they are gone.

Cheers,

Matt.
AnswerID: 443066

Follow Up By: Who was that again? (Vic) - Tuesday, Feb 01, 2011 at 22:04

Tuesday, Feb 01, 2011 at 22:04
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.
0
FollowupID: 715921

Reply By: vk1dx - Wednesday, Jan 26, 2011 at 09:16

Wednesday, Jan 26, 2011 at 09:16
We have two Allrounder batteries under the bonnet and never have any trouble. They are not split and we run two fridges, a 40Lt for non frozen stufff and a 21lt for frozen items. We were having trouble before getting the batteries replaced and can now quite safely run them without the motor started for a whole long weekend.

Phil
AnswerID: 443070

Reply By: trainslux - Wednesday, Jan 26, 2011 at 10:37

Wednesday, Jan 26, 2011 at 10:37
What size and type is your aux battery??


driving for 2 hrs is not alot of time for charge, but it should bring up your battery to near 80% or more if it was run overnight on the fridge.

Is the wire a good size, and are all the connections sound allowing all the current to get to the aux battery.

Great to get a dc dc charger, but lets see why its not working for you first.

Trains
AnswerID: 443077

Follow Up By: Luce1 - Wednesday, Jan 26, 2011 at 12:57

Wednesday, Jan 26, 2011 at 12:57
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.

0
FollowupID: 715145

Follow Up By: trainslux - Wednesday, Jan 26, 2011 at 21:49

Wednesday, Jan 26, 2011 at 21:49
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

0
FollowupID: 715222

Follow Up By: Luce1 - Wednesday, Jan 26, 2011 at 22:13

Wednesday, Jan 26, 2011 at 22:13
It's a wet sell battery...will check the voltage to the fridge as you suggested.

Cheers,

Luce1
0
FollowupID: 715226

Follow Up By: trainslux - Sunday, Jan 30, 2011 at 14:19

Sunday, Jan 30, 2011 at 14:19
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
0
FollowupID: 715611

Follow Up By: Luce1 - Sunday, Jan 30, 2011 at 16:57

Sunday, Jan 30, 2011 at 16:57
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



0
FollowupID: 715630

Follow Up By: trainslux - Tuesday, Feb 01, 2011 at 16:01

Tuesday, Feb 01, 2011 at 16:01
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


0
FollowupID: 715859

Follow Up By: Luce1 - Tuesday, Feb 01, 2011 at 20:23

Tuesday, Feb 01, 2011 at 20:23
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
0
FollowupID: 715899

Reply By: Member - Scrubby (VIC) - Wednesday, Jan 26, 2011 at 15:11

Wednesday, Jan 26, 2011 at 15:11
G`day Luce1,
I have a Sterling 121250 and cannot fault it, it supplies 2 x 6v x 200ah RV Gel batteries ( in series ) that run my 80 lt Trailblaza Fridge/Freezer.
I am unaware of any other DC-DC 12v charger that is capable of 50 amps output, this is a big feature for charging quicker thus less engine running time particularly if you have large capacity batteries..
Others on here like the Ctek but the biggest (25amp) only puts out 50% of what the Stirling does therefore I would think it takes twice as long to achieve a similar result.

Regards,

Scrubby.
AnswerID: 443115

Follow Up By: Luce1 - Wednesday, Jan 26, 2011 at 22:08

Wednesday, Jan 26, 2011 at 22:08
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.
0
FollowupID: 715225

Follow Up By: _gmd_pps - Thursday, Jan 27, 2011 at 13:04

Thursday, Jan 27, 2011 at 13:04
you need AGM's to utilise 50Amp charge current or parallel banks of wet cells.
have fun
gmd
0
FollowupID: 715268

Follow Up By: Luce1 - Sunday, Jan 30, 2011 at 17:07

Sunday, Jan 30, 2011 at 17:07
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
0
FollowupID: 715633

Follow Up By: Mike DiD - Wednesday, Feb 02, 2011 at 10:12

Wednesday, Feb 02, 2011 at 10:12
He did write "200ah RV Gel batteries".

Charging at 50 amps is within specifications.
0
FollowupID: 715953

Reply By: Bonz (Vic) - Wednesday, Jan 26, 2011 at 16:50

Wednesday, Jan 26, 2011 at 16:50
Ctek also do one that has a mppt solar input as well, and Redarc have a unit that I have heard good things about, you should pop those on the looking at list.
.
Time is an illusion produced by the passage of history
.

Lifetime Member
My Profile  My Blog  My Position  Send Message
Moderator

AnswerID: 443127

Sponsored Links