Thread: super charge batteries

<span style="color:blue">why not run it as an auxillary battery and have it isolated from the starting battery....

so you dont send both batteries flat if something happens....
drivesafes SC40 does a great job of making sure you have a battery that will
still work in the morning......and its the cheapest one around.....</span>

Thanks Zook for the plug.

Hi weeds, there are heaps of different myths around but unless your vehicle has an alternator that actually monitors the cranking battery ( and very few alts do ), there should be no problems while charging as the voltage coming from the alternator will at all times be higher than either battery, no matter what type or size they are.

So no matter what state the batteries are in, the alternator will just keep producing current and the batteries will, independently of each other, simply pull the amount of current that each battery needs.

Now it’s a bit different when it comes to using the batteries to power things once the motor is turned off. You should not leave different type of batteries permanently connected together while they are not being used.

By different types of batteries I mean you shouldn’t keep say a wet cell deep cycle connected to an AGM but there is no real reason why two similar type batteries of different sizes can’t be left together.

The only problem with any parallel battery set up is as Zook pointed out, if one dies, the other usually follows suit in a short time.

Cheers and hope this is of some help.

Anyone bought a sc battery in vic ? Interested to hear what discount was given. There is a guy selling sc bats on ebay with pickup in any state.

zook said:
<div class='quotetop'>QUOTE</div><div class='quotemain'>why not run it as an auxillary battery and have it isolated from the starting battery.... [/b][/quote]
i have three batteries installed, 1 x start and 2 x deep cycle aux. the rig had a manual isolater when i brought it which i'm happy with for the time being

drivesafe said:
<div class='quotetop'>QUOTE</div><div class='quotemain'>By different types of batteries I mean you shouldn’t keep say a wet cell deep cycle connected to an AGM but there is no real reason why two similar type batteries of different sizes can’t be left together. [/b][/quote]
they are all lead acid

thanks for the info

how the hell to you guys do the quote thing with the person name in it

Originally posted by weeds
how the hell to you guys do the quote thing with the person name in it

Press the quote button at the top right corner of the person's message. This will create a new message with the text enclosed. Delete unnecesary text but leave the quote and /quote (surrounded by square braces) in place.

If you press the quote button on this message, you'll see what I mean.


Ron

Hi weeds, by lead acid batteries, do you mean they are wet cell batteries, do they have plugs on each cell for topping up the water.

Cheers.

PS Thanks Ron, I can never get that to work either.

"i now have an 85Ah and a 120Ah connected in parralle, will the 120Ah fully charge or will it stop accepting charge or the alternator stop charging when the 85Ah reaches it max charge"

Electricity is like water, ie: it always takes the easiest path. Batteries have resistance within them, the larger the battery the greater the resistance, so if two batteries are wired up together of differant capacities then the smaller of the two will get more charge than the larger.

At work they once charged a pallet of small batteries and large batteries all hooked up together on the one charger. The charger was left on overnight as they usually do and in the morning they found that all the small batteries had been cooked and the larger ones were ok. When charging batteries we always try to keep all sizes together so that they all get an even amount of charge. We have one big charger that is connected to a distribution board so we can set differant charge rates for differant size batteries. Overnight we can charge 8 pallets of batteries, each pallet can be of differant size and all charged from one charger.

When you put two batteries together as mentioned above you in a sense have one large battery, they should both discharge and recharge at a similar same rate because they equalize, but that will only be to a point, when the small one has run out of puff then you will be draining just the large one and then you will find the small one will charge up faster and eventually the large one will catch up, but when this is happening the small battery will be getting more charge and causing damage to it. You really need a product between the two batteries that can monitor the charge rate between them and set the required amount to each of them. I think drivesafe is the man to talk to regarding that...cya

Hi bellaposs, I will lay money that your charger was a two or three stage charger and that’s why it cooked the batteries. Most of those work exactly the way you explained it and simply put, would only see the lowest charged battery and act accordingly

With exception to something like a D3 or RRS, where the alternator monitors the cranking battery, just about all other vehicle’s alternators are one state chargers and don’t put out a high enough ( at least they shouldn’t ) voltage to cook the batteries otherwise every dual battery set up, mine included, would have one of the batteries cook every time someone went away for a weekend.

The fact that the alternator only puts out a safe voltage level is the reason you can CHARGE different types of batteries and the size doesn’t matter.

But once the motor has stopped, if you have been charging different TYPES of batteries you should separate them or you can then have problems.

Batteries of the same type but of different sizes can be left in parallel.

In fact, while DISCHARGING the batteries of the same type, when connected up in parallel they should be left that way until they are charged again or if at any time during discharging, the batteries are separated, they should not be connected together again until they are being charged again.

I use a AC two stage charger that can charge up to three batteries at a time and they can be all different types and sizes but each battery is automatically charged separately and only one at a time as needed and the other two are kept on a maintenance charge.

BTW bellaposs, I’ll have to come and see you soon about finding a suitable battery for use in D3s and Range Rover Sports.

Cheers