Parallax Power Supply 7345

Thank you all for your thoughts and advice...

Another thing about converters with temp comp that came out of the Paramode experience, is that if the converter is inside the warm rig and the batts outside in the cold, as is common, then you must have that temp comp on a wire going to the outside.

The issue is finding a route for that wire. Not easy at all in many rig's. Was hopeless in our 5er.

As it happens, the converter was deck-mounted out near the batteries so no problem with wire routing. Paramode does offer an in-place replacement for the older type 7300 converters, though which would have to have that wire routed to the outside somehow.

I notice many solar controllers have an ambient temp sensor on the controller itself. (some do have wires for remote to elsewhere) If the solar controller is near the batts and so outside the rig's heated area, no problem. But some get mounted inside the heated area.

bigfootford wrote:
I disagree with measuring the ambient air temp around the battery.
It makes no sense.

Please provide your source for this statement.

The source for this statement is the dozens of battery tables we've all seen of terminal voltages and/or charging voltages of lead acid batteries versus degrees Fahrenheit. All tables like this I've seen have never mentioned the temperature of the electrolyte or the temperature of the battery's terminals or case. Of course attaching the probe to the terminals or the case is convenient, but is going to be some kind of average of the temperature of the battery's mass versus the air around the case in the immediate area where the case-air heat transfer is taking place. I guess I've always assumed that the table temperatures meant the temperatures of the air in the immediate vicinity of the battery (i.e. the temperature of where one was camping) - hence my talking about a probe from a temperature compensating charger being placed very close to the battery(ies) right in the compartment where you have them.

Here's a typical writeup for us laymen that talks about the charging voltages applied to lead acid batteries depending upon some kind of temperature ... it sure reads like they're talking about the temperature of the environment that the battery is in:

http://batteryuniversity.com/learn/article/charging_at_high_and_low_temperatures

Yes the Paramode Vabs was 14.2 which is lower than ideal for many RV type batteries, especially 6s which really like 14.8 or so.

I did break into the Paramode and use its internal adjustable pot to jack up the Vabs and it worked great after that. Except now the Float voltage was too high. (I didn't do float with it anyway.)

Also mine only lasted a year and then it ate itself for unknown reasons, and Mena's did something similar. An easy fix for a tech apparently, but the warranty procedure looks like a hassle, with you sending it in paying the shipping and then if it is agreed it comes under warranty it gets sorted out. So if shipping is $50, might as well blow that on a new $150 unit and not bother in case they refuse warranty. That's what I did, only I got a PowerMax as a replacement eventually, since I wanted to try one of those.

Temp comp may not matter for charging unless you are in extreme temps or have really fussy batteries. It does matter for the best Float voltage though. 13.2 is for 80F and 13.9 is for 50F so if you have that PD for your winter Float at 49N, doing 13.2, you will still need to do something extra. I don't know if the periodic shot of 14.4 would do much good there. 6s need a periodic run of 15.5 to keep them happy.

On the location of the temp probe, the Paramode had a ring terminal with the temp sensor next to that. So it went on the post. But what happens if your connection with other wires on that post is not perfect? It will heat up! :) So much for accurate temp comp.

PowerMax has a decent line of converters too, I really like mine.

Battery temperature is measured on the posts of the battery.
That is the only place on a battery to get a true battery temperature reading and thus adjust the charge voltage.

I can add that with the Prosine 2.0 Xantrex says that mounting the sensor on the negative post "provides the most accurate results", and stuck to the side of the battery "also provides good results in most situations". The Outback temperature sensor has no provision for post mounting, just adhesive to stick it to the battery case, and of course the adhesive tends to fail in pretty short order.

Paramode has temperature compensation but as tested by BFL13 the bulk voltage is a bit weak unless you put the thermistor in the freezer. No thanks.

pnichols wrote:


By the way, what MEX and myself mean by "temperature compensation" is a probe mounted in the air, close to the actual batteries, that measures the air temperature around the batteries and then feeds back through wires to the charger's circuits so as to have the actual charger output - no matter what stage the charger is in - automatically adjusted up or down. This minimizes the long term risk of damage to the battery(ies) in high air temperatures and more accurately optimizes the speed of charging in cold air temperatures.

I disagree with measuring the ambient air temp around the battery.
It makes no sense.

Please provide your source for this statement.

Battery temperature is measured on the posts of the battery.
That is the only place on a battery to get a true battery temperature reading and thus adjust the charge voltage.

It takes hours for a battery to equal changes to the ambient air temperature.

When charging takes place the battery temperature will rise. The greater the charge current the more rapid the battery internal temperature will rise. So if the ambient temperature is 40 deg f. and the battery's internal temperature = ambient then the Temp compensated charger will increase the charge voltage... As the internal temperature rises in the battery the charge voltage will begin to decrease, compensating for the increase in temperature of the battery.

Jim

MEXICOWANDERER wrote:
The more dry camping / generator recharges you are into the more you need a true multi-stage temperature compensated charger ...

Carefully notice what MEX is saying above. Think twice and check three times before jumping onto the "PD as a replacement for the Parallax" bandwagon that so many above are encouraging.

I don't think that the Progressive Dynamics ("PD") line of multi-stage RV battery chargers have temperature compensation - which is a very important feature for really taking care of your batteries correctly under the widest possible set of camping conditions. Read these specs again to be certain that temperature compensation comes on these (I don't see it, but maybe I'm not reading these specs clearly):

http://www.bestconverter.com/4600-series-Upgrade-Kits_c_133.html

I'm not saying that the PD chargers are not "good enough" ... just saying that they're "not the optimum" RV chargers, in accordance with what MEX is recommending. Best Converter does carry other multi-stage RV chargers that are temperature compensated.

By the way, what MEX and myself mean by "temperature compensation" is a probe mounted in the air, close to the actual batteries, that measures the air temperature around the batteries and then feeds back through wires to the charger's circuits so as to have the actual charger output - no matter what stage the charger is in - automatically adjusted up or down. This minimizes the long term risk of damage to the battery(ies) in high air temperatures and more accurately optimizes the speed of charging in cold air temperatures.

I'm starting to see a trend here!!!!

Sam

Yet Another Nix Here On The Paradox Perverter

The more dry camping / generator recharges you are into the more you need a true multi-stage temperature compensated charger with a potential to serve up 40 amperes of charge rate for EACH RV battery. 2-batteries using an 80 amperes charger would not be overkill.