Dual Batteries for dummies

[rds_929]

it has some interesting refinements and sounds good, but all sales pitches sound good, keep us informed how it performs.

There will always be companies that add bells and whistles to existing products, some people like it and some prefer the out of sight out of mind principle. I rely on the fridge monitor to tell me the voltage of the second battery and the fridge conditions.

which fridge is that ?? waeco ??

[martynvella]

Yes, the waeco CFX range, you have to buy the unit separately and it is fairly short range but a handy feature.

[Richolux150]

Mmmmm $300 ish dearer than the DCDC solar unit I use.........that ip67 wil come in handy if I am ever up to the hood lining in water.......but then I guess some other issue may also occur........I wonder though what temperatures batteries explode ........If the Ctek cuts out at 50 degrees.

Good looking unit....but I'm sure the much cheaper dcdc units will do a similar job......

[rds_929]

Yes, the waeco CFX range, you have to buy the unit separately and it is fairly short range but a handy feature.

what's the unit in question ?? iv'e got a cfx aswell is it expensive ??

[martynvella]

Not sure what they are called. Bcf have them but cheaper on ebay

[martynvella]

http://www.ctek.com/au/en/chargers/SMARTPASS

where does it end, create a need for something and someone will make something to sell to fill the gap.
for those that cant decide between vsr or bcdc, this does both, but how much it costs and the space and wiring is it worth it.

No matter how simple or sophisticated your 12 volt system is there is always a scenario that will leave you with hot beer,for the price and space it takes for all these gadgets it would be worth considering a Honda 10i and a gallon of unleaded for when your aux gets a bit light on for volts, but then that will run out of fuel too.

Simple answer......learn to enjoy hot beer.

[xychix]

Why is it so rare in 4x4 land to use a 3way fridge? I've got an Electrolux that runs on 220AC 12DC or Butane/Propane.

In the house while packing I'm powering it on 220, when leaving I plug it in the back in a 12V socket that only supplies power on iginition and once on our off-grid home I switch to a 907 Camping gaz bottle that I take with me or to the bigger local 13Kg Butagas tanks which are already there.

I live in Europe, regulations / availability / prices etc might differ, that might cause the difference.

[martynvella]

They are bulky, heavy, need to be on level ground, have a very heavy draw on 12 volts when travelling.
They are popular in caravans but not practical to use inside a vehicle.
Also they have different zone ratings, if you don't have the tropical zoned type they will lose efficiency when ambient is above 35 degrees.

When long term stationary camping they are on there own if you can keep them out of the wind that blows the flame out.

[Richolux150]

Why is it so rare in 4x4 land to use a 3way fridge? I've got an Electrolux that runs on 220AC 12DC or Butane/Propane.

In the house while packing I'm powering it on 220, when leaving I plug it in the back in a 12V socket that only supplies power on iginition and once on our off-grid home I switch to a 907 Camping gaz bottle that I take with me or to the bigger local 13Kg Butagas tanks which are already there.

I live in Europe, regulations / availability / prices etc might differ, that might cause the difference.

Cause its F$#&*@# hot here and no man should have to put up with hot beer.......

Just jokes.......tried a 3 way finch fridge here years ago and our pleasant East Coats breezes kept blowing out the flame... very disappointing experiment......solar wins hands down every time here..... but we all welcome your opinion

[Qwerty]

Hey guys wanting some opinions.

Purchased a supercharge d70z lead acid flooded wet cell deep cycle. I don't believe it's calcium hybrid at all.

It states on top max charge voltage 14.4v.

Supercharge said the "wet" setting on chargers will be fine.

However my acdc charger in wet mode charges at 14.7 , and my redarc dcdc in wet mode is 14.9?

Both have an agm setting which will do at 14.4v. Battery is def not agm.

Why would the Chargers output 14.7/14.9 for a lead acid when the widely stated standard is 14.4.

I also have an mppt victron blue solar input, its output is 14.4.

Another thing , it's stated as maint free , yet it has openable cell hatches to inspect fluid level.

last concern is we get extreme heat here and a very hot engine bay (1grfe runs very very hot).

[xychix]

I personally prefer open cells that can be refilled. Batteries often break down due to to little charging (as that is the safest way to go) and oxidation on the plates.

On my self build system I've chosen to charge up to 15.2, depending on the battery temperature that might be on the limit of gassing a bit, however when properly levelled up this is no problem at all.

I must add this is my personal preference for my little offgrid home and shouldn't be done without properly monitoring temperatures, hoewever in a moving car I can imagine you don't want a catch bottle next to the battery in order to catch fluids, nor do you want the risk a cell gets opened or not tightly closed down and starts leaking.

I can't find any info on the battery you mention but as per you description it sound like a regular (semi) traction cell. In France I'm paying 1 Euro per 1 Ah for such batteries in the size ~60Ah - ~120Ah.

back to your questions:

* will the battery be harmed when charging at a slightly higher voltage:
In my opinion NO if you keep an eye on the temperature and refill in time

* The battery is getting hot is that an issue:
there you go already, this might be a reason not to raise the voltage, monitor more often and make sure you connect a tube to the hole that the battery will gas out of when to hot.
There might even be a fire hazard involved in the gasses that leave the battery, maybe someone else here can help us on that. I'd try and make sure IF gasses escape the are forced down trough a tube and get the time to cool off before leaving the tube (it will just drip out and should only be a little tiny bit)

[Qwerty]

Thanks. Here in wa we regularly get 40-45c days. Often I am out in that at slow speeds , so under the bonnet would be getting up around 70c I reckon.
So on that aspect , heat is an enemy here.

I was more wondering why chargers classify wet cell charging as 14.9 when the standard is meant to be 14.4?

[Qwerty]

http://www.supercharge.com.au/amp-tech-d70z

[xychix]

Thanks. Here in wa we regularly get 40-45c days. Often I am out in that at slow speeds , so under the bonnet would be getting up around 70c I reckon.
So on that aspect , heat is an enemy here.

I was more wondering why chargers classify wet cell charging as 14.9 when the standard is meant to be 14.4?

well there's multiple phases in charging / multiple charge methods http://www.powerstream.com/SLA.htm
just a random example of charging voltages and temperatures of the environment.
So basically it's not just 1 voltage you are charging at, it's a bit more complex with a proper charger.

http://www.nrel.gov/transportation/ener ... 7paper.pdf
an interesting (but very in depth) paper on charging using the so called zero delta voltage. basically you keep charging till the Amp's approach zero and the voltage won't rise anymore over a certain amount of time. Use that measurements to determine that the battery is charged. This would mean a different voltage for different batteries.

there's a hole world to explore if you want to skip to the practical part my advice would be not to charge the battery with higher voltage due to your environment temps and check the water levels on a regular base (you'll learn soon enough if you loose water.

I've put a glass jar on a cold floor next to my battery and have the tube in there reasonable sealed. If I see condensation in that pot it's a sign I've lost some water. I'll fill up about once a year. However temperatures here are about 0 to 25 degrees celcius and the battery are places in the north side of the house (shady, quite constant temperature)

If the charging protocols (bulk float etc.) are roughly the same I'd consider putting the DC DC charger in 14.4 (as you'll be using that on the go and don't wan't to gass while driving) and leave the Ac-Dc charger on the higher 14.7 assuming you'll only charge using that when stationary and the hood in the shade (not bloody hot).

This way you choose the safer charging without gassing on the move and ensure a proper top up when near an AC point.

** Note: I'm not a battery doctor, it's just my opinion / how i would do things **

[xychix]

that's quite a lot to have 3 chargers around how come? is the battery going to stay under the hood or is it a 'mobile' battery pack that you want to be able to hookup anywhere?

Thats what I'll make, a box containing 1 60Ah semi traction that I can pop in the tub hooked to a DC charger, for camping trips a 100Wp solar + simple PPM charger will join the club. 1 thin AC charger to keep stuff working over winter / indoor as a backup.

Will put the battery in a box with a small voltage reader / 2x usb / 12V
http://eu.banggood.com/Wholesale-Wareho ... 9591.html#

This would mean I can also grab it and place it in the tent and still use my car.

[Moiv]

If you're worried about the chargers in wet mode being too high a voltage then just set them to AGM mode so your charge voltage is reduced.

I thought calcium batteries needed a higher charge voltage though

[martynvella]

If it is a conventional vented type battery don't worry about the extra little bit of voltage, just regularly check the electrolyte level, it will just cause it to go through it a little faster, just as the higher temps will. As the battery ages it will go through the electrolyte faster, this is normal.

A lot of suppliers are not putting calcium on the batteries now if they are fully sealed, they just assume everyone knows they are. Yours mustn't be or the stated chg voltage would have been higher than that so it is most likely a lead antimony alloy just with thicker plates.

In my opinion that is the best choice of battery types for extreme heat, just hope the vibration issues have been sorted, but only time will tell that.

Set your redarc to its lowest setting for heat reasons, it wont be hot when it is on your ac charger.

Remember the suppliers create their own specs for the lables and data sheets, the exact same battery with a different brand name on it could vary considerably.

[Qwerty]

yeah both the charger and battery makers got back to me today and said put on the 'softer' AGM setting which max charges at 14.4

More so due to the extreme heat my engine bay gets.

I presume though the AGM profile won't ramp in higher amperage or anything? I.e. the voltage level is the only factor (in a 3 stage DCDC charger)

Nah def not calcium ... previous one was, and it demanded a 16v charge ... even so , i left my redarc set to WET for that due to heat ... and just gave it an intermittent 16v run with ACDC charger on a cooler night with bonnet open.

My concern is /was that the AGM profile may have lower voltage, but dumps in a higher amp rate? (coz AGM generally can be fed pretty hard) ... or is that up to the battery/charger to negotiate during charging? the resistance etc would be same?

Dont want to choose AGM profile for the loewr voltage, if that in turn means the charger feeds harder on the amps?

[Qwerty]

either way AGM is gunna be the mode ... other two are too high a voltage.

Althogh confusingly, the battery maker just said "please set it at 14.7 wet lead acid mode. AGM setting is configured for a different plate design"

confusing!

[Qwerty]

Set your redarc to its lowest setting for heat reasons, it wont be hot when it is on your ac charger.

.

On a different tangent. So rewind a week, my old CA CA Allrounder battery died a big death.

It was hissing and boiling, 14 moths old.

THey said they tink it dropped a cell or two.

However , i was charging at the time with my AC-DC charger (set to calcium mode up to 16v) ... which started at 8pm the night before. I came out at 8am and it was still in bulk mode! ... hissing and boiling.

I am not sure, but i have a suscipicion the AC charger might occasionally lose its marbles and "stick" in boost mode.

my other concern is i also have a 5amp (capable of 15amp, but the panel is small) MPPT victron blue solar charger... it would have come online at 5am ... and started floating immediately at 13.8v ... i wonder whether the MPPT solar charger artificiailly brought the voltage down to 13.8 ... which confused the ACDC charger into thinking it was time to bulk charge again ... over-charging the crap out of it?

I have the same concern if my solar is inputting at same time as my redarc DCDC (they are independant) ... both victron and redarc didnt think their products would hassle each other... basically as soon as my redarc is on, the mppt goes into float mode .. but the voltage def gets ruled by the redarc (i see my volt meter on 14.5 - 14.9 pretty much constantly, unless extremely hot day).

can't be assed rewiring or upgrading the DCDC to include a solar input ... too hard basket, ill chalk this one up to a bad battery (super charge allrounder... been quite a lot of reports of them dumping cells) buckling under stress.

Going to limit and closely monitor any use of my Projecta ACDC

my other mistake was having load running when charging with the projecta... they say to use "PWR SUPPLY" mode , NOT a charge mode, if there's any load. It'll still provide some charging, just not as good.

Projecta manual does state that load (or anything bringing voltage down) will screw up charging profiles.

The redarc i am not sure... but given it's designed for in-line use... it must have some more smarts to not get confused by load. They do state they use timers and cutouts to not over-charge, regardless of what volt level is telling the unit.