Redarc dc-dc 12/40

Trevor law · Senior Member

Redarc dc-dc 12/40

JeffRae · Guru

We have a RedArc 12/25 that charges one 120ah Full River in the car. Not had any problems with ours. Only thought is the 12/40 suitable for charging 2x120ah batteries ?

JeffRae

Trevor law · Senior Member

We had the redarc for 3 years now no problems ,but had to renew batteries ,and as I asked the battery specs say 13.7 float but the float voltage of the redarc is 13.2 just wondering if it is too low of a float voltage ?Going to give it a test run today and see what happens .We have had to replace the battery because the batteries have been wired up wrong and one battery has been as been doing all the work and is stuffed so one battery is ok the other won't hold a charge,so can't replace one as it will draw the new down.We have a Projecter 50/240 volt charger hard wired in the van which as a float voltage of 13.7 volts so no problems when on power .Thanks for any input

Trevor

Cupie · Guru

I'd contact Redarc & see what they say.

I think that 'under charging' leads to sulphation & consequent inability to 'hold a charge'.

Here's a useful site

http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

For what it's worth the auto settings for my AGM are

Absorption 14.4v; Float 13.7v; Maint 14.4v (perhaps an OK compromise going by the table below)

Here's an interesting extract from the above site .. (sorry .. the first row should be one column to the right. A copy & paste /operator error)

2.30V to 2.35V/cell	2.40V to 2.45V/cell
Advantages	Maximum service life; battery stays cool; charge temperature can exceed 30°C (86°F).	Higher and more consistent capacity readings; less sulfation.
Limitations	Slow charge time; capacity readings may be inconsistent and declining with each cycle. Sulfation may occur without equalizing charge.	Subject to corrosion and gassing. Needs water refill. Not suitable for charging at high room temperatures, causing severe overcharge.

Your 13.7v is just under the lowest V listed above ie 2.28v/cell ... their lowest is 2.3

-- Edited by Cupie on Monday 20th of November 2017 05:23:36 PM

Trevor law · Senior Member

Thanks Cupie,I have emailed Redarc and we will see what they say what I have read on redarc site it is because of heat so I will see what they say

Trevor

swamp · Senior Member

hi
Some chargers have float then a secondary float/storage mode . In storage mode its all about keeping the battery in good condition with as little stress on it as possible . You are still maintaining 100% capacity so sulphation should not be problem .

I guess this happen s for Redarc because they donot want a 10stage charger electronically [to big complex ] and have condensed version .

Delta18 · Guru

I have just discovered I have a concern in my ute battery system.

I have just fitted a Scangauge2 to the car mainly to monitor coolant and auto trans temperatures.

I also can monitor battery voltage an I've noticed that the alternator holds the battery at around 12.6v - 12.7v most times after the initial 13.6v after engine start.

This concerns me for 2 reasons,

1. the low voltage is surely too low for a Float stage so will shorten the battery life and,

2. I have fitted a Narva Voltage sensitive relay on my Andersen Plug circuit and this unit cuts out if the battery voltage goes below 12.7v .

You can see the problem, a lot of travel time I will have no fridge running in the van!

Is there anything can be done other than replace the VSR with a ignition triggered relay?

Cheers Neil

Bill B · Guru

.
You can see the problem, a lot of travel time I will have no fridge running in the van!
I

You have a compressor fridge don't you, so it would be wired to run off your van battery system which is in turn charged by your solar array along with whatever charge is provided from your anderson plug.

Delta18 · Guru

Bill B wrote:
.
You can see the problem, a lot of travel time I will have no fridge running in the van!
I

You have a compressor fridge don't you, so it would be wired to run off your van battery system which is in turn charged by your solar array along with whatever charge is provided from your anderson plug.

Thats right Bill, I worded it such so as to not overcomplicate things.

The Andersen Plug is to charge the van battery via a 40A DC-DC charger in conjunction with the solar n the event of copping days of little solar input.

Cupie · Guru

I think that my Thunder DC to DC charger chooses between the input from the tug's alternator & the Solar. Always gives preference to the tug. I had thought that it accepted both inputs at once. I'll have to read the manual more closely to confirm.

So I am going to wire in a couple of anderson plugs that will enable me to connect the tug's input straight to my 3 way fridge or to the DC to DC Charger as I choose.

The alternator output is connected by a simple 30A relay off the accessory feed to the cigar lighter.

-- Edited by Cupie on Tuesday 21st of November 2017 04:59:08 PM

Trevor law · Senior Member

Just had a reply from Redarc (about the float voltage) and according to their technical department there is no worries about the 13.3 voltage,so if they say it is ok I will just have to go with what they say

Just movin dust .Trevor

vince56 · Senior Member

In response to Delta18's concern re low voltage after start up, I have just bought a 200 Landcruiser and the auto elec says that they run at quite low voltage once the engine is up to temp. He suggests a redarc BCDC charger to bump charge rate up whilst on the road to aux batteries otherwise they will be constantly under charged. Apparently this is an issue for a lot of vehicles post 2015.