Conversion of 12V to 6V Deep cycle, done, nice! - Page 3

Journey39n · 11-21-2011, 02:25 AM

Back to batteries. I have no battery slides in my current coach. But Winnebago designed lots, and I mean lots of room in the battery compartment. I just replaced my ailing 12v coach batteries with two Costco Golf Cart batteries.

They look so small in the compartment, but according to the meters, lots of amps and voltage.

I am going to make a hold-down bracket to secure the batteries, just to keep things tight.

FIRE UP · 11-21-2011, 12:22 PM

Quote:

Originally Posted by Journey39n

Back to batteries. I have no battery slides in my current coach. But Winnebago designed lots, and I mean lots of room in the battery compartment. I just replaced my ailing 12v coach batteries with two Costco Golf Cart batteries.

They look so small in the compartment, but according to the meters, lots of amps and voltage.

I am going to make a hold-down bracket to secure the batteries, just to keep things tight.

Right on bud,

Looks good. I think you'll be real happy with those Costco units. I can't really tell but, it looks like you could have gone with four, but, hard to tell. Nice job. Did you make up your own cables?
Scott

Journey39n · 11-22-2011, 01:31 AM

For the 39n, there is lots of room for batteries. Four 6v with the footprint of these Costco batteries would easily fit, with room to spare.

If we get to a point of doing lots of boondocking, I might add two more.

I just used the cables that were part of the oem setup, and arranged the batteries for the best fit. If I added two more, I would have to make some cables.

Its been over a day, dark and rainy, we are plugged into shore power, but still using 12v lights and such nearly all day, and I can't say I have heard the charger even run yet. (with one ailing 12v, used to hear it run about every other hour it seemed)

KJINTF · 11-22-2011, 07:14 AM

Fire Up

Sorry for the delayed response - You asked about the "Voltage Sense" line
Good to see there is a temp probe in your installation
Originally Posted by KJINTF

Looks like a nice clean install
A few questions
I see no voltage sense line - your charger even a high end converter should be using voltage sense line to compensate for the line loss
What about a temperature probe in the battery compartment - where are you measuring the battery temperature?

KJINTF,
Well Sir, there is the temp probe from the Dimensions 2000 watt inverter. It's positioned on the negative lug, on the right hand, inner battery. For the most part, you can't see it in the pictures. But, I assure you it's there. I've never heard of a "voltage sense line" but, that doesn't mean anything, it might be common on a lot of coaches but, I'm pretty sure it's not on mine. I did however, re-arrange a ton of parasitic wires that were all over the terminals on the chassis batteries. So, it's possible maybe it's in that rearrangement.

A Voltage sense line is a direct (fused) connection to an external device. This connection draws close to NO current thus no difference in voltage, it's there to measure precise voltage at the source aka batteries. Typically the wire size is small makes the line a bit easier to install again no current is being drawn thus no voltage loss. Are you are using a battery monitoring device (If not I suggest you get one) such as the trimetric RV-2025 or similiar. To operate properly they need to be connected at the battery. Additionally devices such as solar PV controllers use the voltage sense function to compensate for the slight voltage loss in the cable from the controller to the battery bank. They use this measurement to increase their output voltage compensating for the loss in the cable. Remember a voltage drop of as small as 0.3Vdc aka 300mV makes a large difference in charge time. Suggest you measure with a high quality 3 or more digit DVM the voltage at the charging device and then again at the battery bank - My guess you will be surprised at the amount of loss.

Just a friendly suggestion - trying to help

FIRE UP · 11-23-2011, 10:03 AM

KJ,
Thanks for getting back to me on this. I do have a question on your response though. You say a voltage sense line is an "electronic connection between the batteries and a device. May I ask, What device? I'm certainly no expert in this field. So, always trying to learn, even at my age. My "One place" panel, states my house batteries are at 13.2V when we've not used them for any length of time, i.e. sitting at home, in its parking spot, plugged in, and nothing on.

My digital VOM which, has at least 3 or more, decimal places, also says 13.2V. Now, I'd have to remove the cover off the Dimensions Inverter/Charger to see what the output voltage is at that point to see if there's any differences between the charge source and the batteries. I'll do that later and inform you of the results. Thanks again for you advice and expertise here. Very much appreciated.
Scott

SCVJeff · 11-23-2011, 10:20 AM

External Sense is a separate set of inputs on a large majority of commercial lab quality power supplies, but are also found in consumer devices like solar regulators, and a few inverter/ chargers with remote sense and current shunt functions like some Magnum Power equipment -The Dimensions does not have this feature.

But for those in Rio Linda, this is an extremely high impedance input that allows the power supply (or source) to accurately measure it's voltage at the end of the main supply cable and adjust as necessary. Even though I'm running 4ga. cable from my solar regular to the batteries, I'm also running external sense to compensate for ANY losses induced by the primary cable. If you have it, use it..

KJINTF · 11-23-2011, 10:45 AM

Scott

Sorry I was not clear with my earlier response
Sometimes (many times) I get involved in others things while typing out respones and do a bad thing as in "make assumptions". We all know what an assumption means.

The connected "devices" are the "Converter" aka battery charger, or Solar Controller "also a battery charger" in my earlier examples.

The important point I might not have got across the last few respones is the fact that a voltage loss requires a current flow. For example when your battery bank is sitting there, no lights on, no TV, Nothing on as in no power being drawn from the betteries, the voltage will measure the same everywhere you check it. No curent flow no voltage loss.

Now when the batteries are drawn down say 50% SOC "State of Charge" turn on the charger "Converter" and measure the voltage at the battery and then again at the charger. The charger will be putting out say 13.7 or even 14.7/8 if it is a proper multistage charger, check the voltage at the batteries it will be "lower". This is the voltage loss the connectors and wiring between the charger and the battery bank introduce. This loss only occurs when a current is flowing. The more the current the more loss just when you need the higher current to get the betteries back up quickly. Remember voltage does not and never has "flowed" (is that a word?) only current flows. My guess the voltage at the batteries will be at least 0.5Vdc lower than the earlier measured at the charger. The voltage sense line used, in many, if not most upper end batery chargers and solar charge controllers compensates for this loss by increasing the voltage output of the charging device.

Check your battery charge recommendations. There are several good references on multi stage battery charging.

I prefer not to run my on board generator at all if possible and when needed as short a time as possible. A higher voltage of only 0.5Vdc will make a huge reduction in the overall charge time.

A fully charged standing battery (no loads, no charger hooked up) 100% charged should be about 12.6Vdc and a fully discharged battery reads about 11.6Vdc, only 1Vdc difference. Not much! Any loss in the wiring, there are always losses in wires, should be compenstated for as much as possible. Thus the voltage sense line we are speaking of

Yes I am bit OCD maybe even a lot OCD - I monitor and log all my RV power consumption and change the charging configuration files of my charge controller depending on the seasons.

Hope this helps

KJ

KJINTF · 11-23-2011, 10:55 AM

Jeff

Well said

I found most "high-end" manufacturers of Solar Charger Controllers include the capability standard, most inverter / chargers have the option, most remote mounted battery chargers (not the portable ones) include the capability and only a few "converters" have the capability.

Agreed if you have it use it

FIRE UP · 11-23-2011, 01:14 PM

KJ & Jeff,
I certainly want to thank you two for some intelligent offerings of help on battery maintaining. I'm assuming I don't have any voltage sensing lines of any sort. The Dimensions 2000 watt inverter/charger does, in my opinion, have a darn good three stage battery charger. It even has (as you most likely already know) a cycle on it that, in every fifth cycle, it will "Equalize" the batteries. I've seen it do it a couple of times since we acquired the rig.

But, I'll keep an eye on all the batts and see if I can tell if I'm getting all the charge to them I should be. Maybe I'll turn something on and leave it on for a while so as to drop the battery condition down and then run a test on the charging sequence and we what's up. Thanks again. Very much appreciated.
Scott

SCVJeff · 11-23-2011, 02:24 PM

I think the Dimensions charger is fine and arguably beefier than my new one, although I would rather have had a EQ button on mine rather than relying on every (x) number of starts that I may not want to run the gen or be plugged in while it's doing it's thing. I just replaced mine with a Magnum, and that was one of the reasons why (the big one being PSW).