voltmeter/ammeter on dual batts

[rockcrawler31]

Hey all. I am re-installing a dual batt system and i'm wanting to put in some guages to monitor what is going on with the batteries/charge state.

firstly can anyone tell me how ammeters are usually wired in. are they just a pos and neg wire from the battery in question to the guage or are they put in line on a power wire? It should tell me whether i'm charging or draining the battery in question by how many amps per hour right?

I'd like to have a single ammeter and a single voltmeter in the cab to measure both batteries/circuits switchable via a rockover switch or something. The deepcycle batteries will be in parallel to the main via voltage sensitive relay. If the VSR is in parallel is there anyway to make sure that i isolate the charge/draw readings on the deepcycle batts from fridges etc.

can anyone send me or show me an example of a wiring system to make this happen.

Also i upgraded the bulbs in my highbeam headlights to 130 watters, i'm wondering if its worth putting a relay into my high beam wire to feed the high beam via a heavier cable like spotlights normally are.. Am i likely to get the most out of the bulbs this way? I'm pretty sure that my lights are positively switched so i guess i would just put the original highbeam wire on one side of the relay switch terminals and earth the other side.

finally, would a pair of gel deep cycle batteries be adversely affected by running a decent air compressor off them. what if i ensured that the motor was alway running and in parallel with the main when i did it.

[-Scott-]

Good question - after recent events, I'm thinking about monitoring my aux battery a little closer.

Cheap ammeters are wired in series. Getting the current from the battery, through the ammeter, and back to where you need it tends to be a hassle. Switching one ammeter between two batteries could be a little tricky - off the top of my head, I'm not sure there is a nice solution.

More expensive ammeters clamp a sensor over a wire in the circuit you want to measure. They (typically) don't like cranking/winching type currents, so you can only measure charging/accessories current.

One voltmeter/2 batteries is quite simple - it's called a switch (SPDT, if you want more information.)

I don't have any wiring diagrams handy - hopefully, drivesafe can help there.

Yes, relay for your 130 watters is a good idea. Wire them EXACTLY as you would spotlights (without the switch, of course. )

I wouldn't think twice about running an aircompressor off a pair of deep cycle batteries. (OK, unless it's a HUGE compressor, or the batteries are pathetic little excuses...)

I hope that helps,

Scott

[drivesafe]

Hi Rock and Scott, unfortunately Rock, I don’t have a diagram for what you are intending to do but because the use of amp readings are actually more useful than volt readings when trying to see how a battery set up is working, it’s good to see someone going that way.

Now for the bad news, as Scott posted, the standard in-line type amp meters are both fiddly to fit and either cover only a basic current range so don’t like high current situations or if they are designed for high current operations, they tend not to be very useful for reading small currents like those required by a fridge.

The other major problem with in-line type amp meters is just that, they require being fitted in the cable to be monitored and this then poses the problem that the full sized battery cable has to be run to the meter, so if the meter is to be mounted in the dash, you have to run the positive cable from one battery to one side of the meter then run the battery cable from the other side of the meter to the other battery’s positive terminal.

This is not only messy but means the cable run will need to be much longer and this means greater voltage loss.

There are some excellent high tech metering system that can do exactly what you want ( and a lot more ) with out all the extra battery cable runs BUT to get a reasonable set up will cost you around $500 and that’s before you install it.

As for the headlight wiring, I have to be up front here and state that I now make a range of Headlight Wiring Upgrade Kits so it’s in my best interest to push you that way but in all honesty, you DO need to upgrade the wiring BEFORE you fit higher wattage globes as the wiring in most vehicles is only just good enough to run the lights supplied with the vehicle and in most cases the installation of a new headlight wiring loom will make a big difference to the existing headlights.

Putting higher wattage globes in means that you will usually cause a bigger voltage drop in the power getting to the new globes and this has two problems. The first is that the new globes will never run at anywhere near the best light brightness and second, you are now overloading you existing wiring which was never designed to handle the extra current.

In addition to these problems, if your vehicle does not have headlight relays, upgrading your headlight globes means you are most likely going to burn out your headlight switch in a short period of time. One of the not so obvious advantages of fitting a new headlight wiring loom which includes relays, is the fact that the new loom will takes the current load off your headlight switch , which will mean a lot long life for the headlight switch and as these headlight switches are normally much, MUCH dearer than a new headlight wiring upgrade, they pretty well pay for themselves.

Now that doesn’t sound much like a product promotion, does it

Cheers.