Thread: Dual batteries?

Hi Folks and there is a slight delay in the delivery time.

The new isolators are made up and just need to have the specific cables bolted to them, but I am trying to develop a battery hold down for the rear battery mount in the L322.

If I succeed in producing a hold down for the kit, I will include this with all the prepaid customer’s kits at no extra cost.

The problem is, until I develop the bracket, if I can, I can not make up the cables till I know exactly how long each cable will need to be.

Please note, I have experimented with a few conventional battery sizes and none fit very well, other than the Optima D34, so I am designing the bracket set up specifically for an Optima D34 battery.

I am flat out at this time with some back orders I must get out over the next two days ( supplies finally arrived today ) so I will fill these back orders first and then concentrate solely on the L322 kit over the weekend and will ship them with or without a hold down bracket set up on Monday.

Sorry for the delay but I need to get this kit as a finalised set up before I list it on my web site, but hopefully you will benefit from the addition of a bonus hold down bracket.

Sounds good to me. No hurry for me.

Camo

X2

Works for me too. No hurry for me.

It would be nice if you could engineer a hold down for a D34 (since that's what I have). It is not going to be the end of the world if you can't or don't though.

So, all up, not a problem.

Cheers,
Iain

Thanks for the notice, I'm impatiently awaiting mine

Just got the battery today so was hoping to bugger up the install on the weekend.

Never mind, I can screw it up later.

The parts I need arrived this afternoon and I will test my test battery hold down set up over the weekend.

So far, the test unit is both simple and holds the battery securely, but I modified a standard hold down bolt to test the theory and now I have all the parts needed for the complete kit so they will be shipped Monday or Tuesday next week.

I have to finish the installation instructions and need some more pictures and once these are taken, I post some up.

I’ll be posting the full kit info in the Verandah section next week and once again, thanks again Summiitt for letting me highjack your thread.

Hi folks and sorry for the delay but I needed to make some changes to the software as there may have been a potential problem when attempting to charge a low Optima battery.

This problem will not occur with any other battery but because of the high currents an Optima can draw during a charge, I needed to make allowances for this.

A short explanation. About 6 or 7 years back, I was testing the ability of charging batteries down 10mm2 twin cable and I was using a very discharged Optima Yellow Top 55Ah as the current draw and the starting up current draw was over 60 amps.

Now to the dilemma this high current draw could have caused.

The DT90 isolator’s primary purpose is to allow for the charging of an auxiliary battery while protecting the cranking battery from being over-discharged.

In the normal charging state, the DT90 has three 30 amp relays all powered up together to allow for the safe handling of up to 90 amps to current from battery to battery. Each of these relays draws just 50ma while turned on.

The unique feature of my isolators is the ability to allow the use of up to 50% of the cranking battery capacity to be used for powering accessories while the motor is off. This is called the SHEARED mode.

Now the DT90 is specifically designed to draw even less power than the SC80 or the USI-160, while in the SHEARED mode it does this by reducing it’s own current requirements further while shearing the power between two batteries.

It does this, when the voltage at the DT90 drops below 12.75v, by randomly selecting any two of the three relays and shuts them down, saving an additional 100ma and while this doesn’t sound like much, over a few days camping, it can be a good power saving.

This is where the potential problem may have occurred if the Optima was in a very low state and the suspension compressor was running at the same time, the voltage drop at the DT90 could possibly drop below the 12.75v SHEAR mode threshold, causing the isolator to shut down two of the relays.

This under normal motor off type usage is exactly whats supposed to happen, but if it happened while the motor was on, because the Optima is in such a low state, it could be pulling as much as 60 amps through a 30 amp relay.

This situation could not be allowed to happen.

I have added some additional software routines to the program to allow the isolator to avoid the potential problem but I still needed to test both the current load capacity of the Range Rover’s rear power feed and that the new subroutines did what they were supposed to.

I carried out a worst case charge cycle for a single battery this morning, and the new programming does it’s job but while the drive this morning did not produce the low voltages I suspected it might, it did give a good idea of what the recharge capability of the new set up can achieve.

NOTE, the DT90 is not only capable of charging a single battery in the rear of the RR, it can easily handle the charging of a set of batteries in a camper trailer or caravan being towed behind the RR. Hence the potential low voltage scenario.

This is the basic results of the test which may be of interest:-

Both batteries had been in a rested state for about 15 hours and while the Optima was showing a State of Charge voltage ( SoC ) of 11.93v, it had actually been discharged down to 11.55v the day before.

The cranking battery was at 12.36v

Approximately 1 minute after starting the motor, the alternator voltage rose to 14.93v.

NOTE, I had deliberately keep the DT90 disconnected from the RR while I measured the start-up voltages at the cranking battery.

I then connect the DT90 and once it activated, the voltage at the Optima rapidly rose to 13.80v and there was a current draw of 47.7 amps, BUT, because the RR was idling, the voltage at the cranking battery was pulled down from 14.77v and as I was by myself, I did not have a means of increasing the revs to get the voltage back up to 14.93v.

If I could have lifted the voltage up to 14.97v, the maximum registered this morning, I would probably have measured as much as 55+ amps being drawn by the Optima.

After 20 minutes driving, the current draw at the Optima were still 41A and the volts were 13.91v with the motor idling. The cranking battery voltage was 14.77v at idea and was at 14.97 while driving.

At 25 minutes, the optima’s readings were 30A @ 14.21v.

At 30 minutes, 22.5A @ 14.35

A short time after 30 minutes from the starting of the motor, the alternator voltage dropped from 14.97v to 14.04 at the cranking battery while driving and 13.99 at idle

At 40 minutes, 12.7A @ 13.72

At 45 minutes, 10.6A @ 13.76

At 75 minutes, 5.6A @ 13.82. This last reading was just before the motor was stopped and the cranking battery voltage was 13.96.

Again note that if your were towing a CT or Caravan, with a few batteries being charged, the current draw would be higher but the resulting voltage drop would place a quasi current limit on the system to somewhere around 75 to 80 amps.

Anyway, with all testing and programming finalised, I will start shipping all the kits early next week.

Again sorry for the delay but I always prefer to be as cautious as possible when developing new systems.

I’ll post some more pictures this afternoon and I have also found another battery that will fit the L322 rear compartment.

It’s an Allrounder MRV48, a 60Ah battery.

Supercharge Batteries - Car Batteries, Maintenance, Expanded Grid Technology

Originally Posted by Camo

Thanks for taking my order Tim.

Is this the right battery?

OPTIMA YELLOW TOP BATTERY 12 VOLT NEW AGM D34 750CCA DEEP CYCLE ALPINE PIONEER | eBay

Camo

Why not go for the blue top OPTIMA - same price/ specs but has SS wing nut terminals in addtn to SAE posts.