Keeping batteries charged - help please

[Bester]

Hi guys, I need some advice regarding charging of 3rd and 4th batteries. I have read all posts regarding dual battery systems, but still have some questions I need answers for.
I currently have a National Luna portable box (battery #2) located in the back of my bakkie, charging from the alternator via the National Luna controls. This is used to run my Waeco 50 located in the back of my bakkie, as well as my tyre compressor. When we do have power at camp, it is charged from a C-Tek MXS 5.0
I also have another battery (battery #3) mainly used to power a trolling motor on a small inflatable boat, but also as a back-up to run my fridge should we not have power points at the camping site (in this case we have to use the oars for the boat ). This battery is charged at home, and not connected to any charging while travelling. If necessary, this battery is also charged with the C-Tek MXS 5.0, separate to battery #2 if power is available at camp.
Then I have another battery (battery #4) in my trailer used to run my National Luna 52 and 12V lights. Currently this battery charges directly from the bakkie alternator while travelling, and is manually disconnected when the bakkie is switched off. When we do have power at camp, it is charged from a C-Tek Multi XS3600.
So what I need is a practical solution to keep all batteries charged while travelling / camping.
I need some assistance with the following:
1. Can I charge all 3 additional batteries (4 batteries with cranking battery included) from the alternator while travelling?
2. If I can safely charge all batteries from the alternator while travelling, can I connect all to the National Luna box to be automatically disconnected when the bakkie is not running?
3. Can I charge both battery #2 and battery #3 simultaneously with the C-Tek MXS 5.0?
4. What would be the most cost effective way to keep these batteries charged, assuming no power point at camp for up to 3 nights?
Any advise would be appreciated!

[CasKru]

According to my knowledge it is a no-no to charge batteries in parrallel. The problem is the charger gets confused about the state of the batteries and they never fully charge.

An option for you might be to look at a few DC-DC chargers. This way each battery gets it's charge from the alternator and is charged properly. With the DC-DC chargers, you use much less current than the NL system.
m2cw

[ChrisF]

Jip would also look at the DC-2-DC options.

A "flat" battery can suck a LOT of current from the Alternator. Three flat batteries may well put a severe load on the alternator.


with dc-2-dc chargers you have various options though. :)

Battery "2" should be happy with about 10A charge rate - which is about one set of spot lights. Same for battery "4". You do get dc-2-dc chargers that limit the maximum current, so this is very easy to set up.


Battery "3" should require even less current, maybe limit it to 5A charge rate. Now your alternator only needs to supply 25A to all three, which it really should be able to do.


at night, with spots, and wipers going, I would diconnect these battery loads to not over load the alternator.

[Bester]

Thanks for the replies. Would the Ctek 250 DC to DC charger work to charge these batteries, or would I need a DC to DC charger on each battery. If it would be a very expensive set-up to charge all 3, I would rather keep battery #3 off the system and only charge when we have power available.

[CasKru]

Any intelligent charging system will not be able to charge 2 never mind 3 batteries at the same time.

[Bester]

I think I may have a solution that won’t break the bank (too much) at this stage – I would like to get some feedback from the guys that know more about this stuff than me.
From my cranking battery I have 16m2 cables with an inline fuse running towards to the back of my bakkie. Just behind my tow bar these cables split in two – one set goes to an Anderson plug at my tow hook, the other set goes into the control panel of a National Luna portable box (this will be removed from the box and mounted in the back of my bakkie).
The 16m2 battery cables coming from the National Luna control panel will then go into a battery selector switch with three settings - off, battery 1 and battery 2. I will then connect the two batteries which I currently have (one is a 100Ah and one is a 102Ah) to the selector switch. I can then select which one of the two batteries is in use or being charged when driving. When at camp and 240V is not available this should give me approximately 3 to four days between the two batteries without any driving. If 240V is available I can use my Ctek MXS 5.0 charger to keep the battery in use charged.
On my trailer, I currently have 8mm2 (I think) that connects to the Anderson plug at my bakkie tow hook, connected to a 75Ah battery in the trailer. This battery will be replaced with a Deltec 97Ah (largest I can find that will find in the space provided). Instead of replacing the 8mm2 cable, I will fit a Ctek 250 charger in the trailer. From what I understand this should then give the battery in the trailer some decent charge while travelling, and allow me to connect two 80 watt solar panels when at camp and 240V is not available. When 240V is available this battery can be charged from the Ctek XS 3600.
The new battery for the trailer and the CTek 250 charger will set me back just over R4000. Please send me your comments / suggestions – I don’t want to be penny wise pound foolish. Next on shopping list will then be the solar panels!

[Bester]

Or should I rather consider solar panels instead of CTek 250 charger for the trailer?

[LeonRogers]

Or should I rather consider solar panels instead of CTek 250 charger for the trailer?

Have you got the solar panels? I am thinking of installing solar panels so please help with some useful information..Waiting for reply thanks in advance:)