I got my MONGOOSE JLR up and running but it requires my battery to be at 12.5v or better. As it sits in key position 2 I'm at 12.3v. Since the 3 is a sensitive beast I'm hesitant to use the "Battery Tender Plus" charger I have on hand. Can anyone make some recommendations around the $50-$200 range?

 

Since the battery voltage across the terminals should be 13.8 - 14.4 when running, just engine; you should be fine. If your voltage when not running looks low, switch on head lights. If it drops like a stone, dead cell in battery. 12.3 seems low to me, if no load, but you said in position 2, so there is some load. With key off, battery volts may be where the charger needs it to operate.

On my D1, with battery unplugged for a month, it reads 12.59

On my other ride, it reads 12.67 off, 12.4 on but not cranked, and 12.01 with head lights on. Crank, and it rises to 14.31.

So putting some charge to your battery won't hurt. If non running and moderate load dips less than 11 battery is past time to swap out.

Most batteries will last 3 years. Then weaken quickly. They are designed to do this because the battery companies wanna sell you another one. They make stationary batteries for the telecom industry that last over 20 years, living a regal life in air conditioned comfort. Under the hood of a Rover is a tough place to live.

 

For most of the tests, resets, option customizing etc, the key needs to stay in position 2/engine off. The SDD requires the 3 to be hooked up to a charger and the voltage to be at or above 12.5v in order to proceed with the a fore mentioned procedures. The battery is less than a year old and is a duralast. I'm looking for a battery tender/charger that is safe to keep the battery above 12.5v without blowing up the electrical system.

 

Sorry. On the D1 position 2 is key turned one click, dash lit up, but not cranked. At that point engine electronics has powered up. Yours may be different.

So back to my original point, if your battery reads 12.3 without a load, then you have other problems, regardless of age of battery.

Battery float charging is not going to blow it up, certainly if just a trickle charge with a smart charger.

This season of the year, above 70-80F, and you have to keep a charger on the battery overnight, I'd be having it tested, maybe by more than one place (the parts stores have good free testers they use, but the noobie holding the tester may not know how to operate).

The issues will be where to place charger, if you plan to build it in, or attach it with hood open and leave cord run to it, as the cigar lighters are usually off when key removed. The 1.5 amp Battery Tender Plus will automatically switch to very low float rate once battery is charged.

Since the truck electronics are built to deal with 14.4 or so charging voltage, and much higher amps, no burn up is likely.

 

On the 3 when the key is in position 2 the nav, radio, and I think the headlamps (daytime running) are on. So I figure the myriad of on board computers and modules are as well. Just with the multimeter I'm getting 12.46 with everything off.

 

On the disco three co uk site, those folks using Faultmates or SDD tend to hook up one of the battery maintainers from CTEK which you can buy on Amazon. You really don't want to be reprogramming modules and have the battery voltage drop away mid update. The official LR SDD guide I think mentions a heavyweight 20A version but for domestic use you can probably get away with something in the sub $100 bracket. Do a keyword search for CTEK and I'm sure you will get a list of recommendations on that site.

BTW, if it's a "chinese" mongoose then be cautious about letting the SDD try a firmware upgrade on it - forum posts suggest that can toast and kill the interface. The only way I know for sure to check the parentage is to open up the interface and look to see if the tops of the IC chips have been scrubbed to remove markings...the amount you paid isn't a good guide as I have seen the clones selling on eBay for about the same price as the genuine article. Caveat emptor.

 

I got CTEK multi us 25000 a few years a go when it first came out on american market.I was probably the first customer who bought one from CTEK, right after they decided to produce one for US market running on 110 V a model that was already very popular in Europe back then.It might be an overkill for some, but since I own Foultmate and do some software updates, in which some take almost an hour ,believe it or not,this unit delivers constant 13.6 Volts and 25 AMPS in Supply Mode and it comes very handy for such procedures and just regular long diagnostics or horsing around with CCF data or air suspension.
Since LR3 draws from20 to 25 Amps with keys in position II, it is nice to know , that during they important updates I get constant juice back up from my multi charger.
I paid around 300 dollars, but you can get one know for around 200 now, on some websites .Good luck

 

Now I understand the issue, the long use drags battery down because truck isn't running. And the 1.5 amp one won't be enough to keep up with demand. One work around is battery jumpers from another vehicle.

Also keep in mind that a lot of things that plug in to the OBDII and sample power may be showing a different value than what you find across the battery terminals. One reason is the use of a diode in series with power inside the gizmo, this polarity protection will drop maybe a half a volt sometimes.

 

Will the CTEK MULTI 7002 get the job done? Sorry, I'm a victim of public education and I'm not understanding the specs too good.

 

The 7002 has a spec of 7 amps current, so that is better, but no where near the 20 amps previously mentioned. If trying to keep up with basic demand, that could be 25 -30 amps on some trucks, before you start flipping on AC, wipers, lights, a little background music [ Ghostbusters! ], etc.

BTW, the definition of "programmer" is a person that takes caffeine and pizza and turns it into software.