Charging only on 50amp?

[Rocketsled]

Trailer had a grumpy winter. After replacing the 5 year old water pump, in turned my attention to the charging system and the new Renogy BMS…the voltages seemed low, but agree with my multi tester…running a 15amp cable with 50amp dog bone has always been all I needed the night before to top off the batteries and get the fridge cold, but now it doesn’t look like that’s the case. Get to the camp site with full hookups and the BMS is now counting up, but still only 30% after charging all night. (That could be a red herring, you need to charge the system all the way, then tell the BMS ‘this is full’)

But still, not being able to charge the batteries on 110 needs to be addressed…

[snoobler]

Originally Posted by Rocketsled

Trailer had a grumpy winter. After replacing the 5 year old water pump, in turned my attention to the charging system and the new Renogy BMS…the voltages seemed low, but agree with my multi tester…running a 15amp cable with 50amp dog bone has always been all I needed the night before to top off the batteries and get the fridge cold, but now it doesn’t look like that’s the case. Get to the camp site with full hookups and the BMS is now counting up, but still only 30% after charging all night. (That could be a red herring, you need to charge the system all the way, then tell the BMS ‘this is full’)

But still, not being able to charge the batteries on 110 needs to be addressed…

What battery?

What voltages "seemed low?"

What converter?

[Rocketsled]

Ugh...Something swallowed my reply to you (Internet, phone, forum. hard to say)

Trailer has two 220AH 6v Batteries.

With the 'dumb' voltage meter, 12.78 was 'full' and after a night of furnace and fridge, it'd show 12.2

Charging in call cases was up around 14.4v

After having the trailer plugged in on 110v overnight, it was showing 12.2v on battery power and after a morning of messing around with the water pump, was showing 11.8v.

At camp today, the BMS was showing up 30% (which doesn't mean much, it hasn't been fully calibrated) 13.6V....when we're done watching TV and making coffee, I'll unplug and see what resting voltages are running off battery.

It'd be annoying if I couldn't top off at home for whatever reason. I guess I could throw a battery charger on it, but that'd be...sub-optimal.

[snoobler]

What is this BMS of which you speak? "BMS" is typically reserved for use with lithium batteries where a device literally manages the individual cells.

Do you have something like a Victron Smartshunt that actually counts current in and out of the battery and calculates a % SoC based on used vs. known capacity?

Many converters charge to the 14.4-14.6V range, absorb at 13.6-13.8V and float at 13.2V.

If you registered 12.2V on the battery after an overnight charge from 15A shore, that says either the converter wasn't getting power (shore power fuse/GFCI popped), or the converter wasn't working, has a blown fuse, wiring issue, etc.

Note that "resting voltages" and "running off battery" are mutually exclusive. Resting voltage for lead-acid means it's had no charge or discharge for at least 2 hours - preferably more.

[Rocketsled]

It’s a https://www.renogy.com/500a-battery-monitor-with-shunt/ renogy battery monitor, not a management system…it’s supposed to integrate over time to give an idea of state of charge, I wanted something to give me an idea of use without redoing the whole thing. It all feeds into a progressive dynamics panel and a 90 amp charger (also replaced last year)

[JRTJH]

Is it possible that your OEM battery cutoff switch is either turned off or corroded and not working properly ???

[Rocketsled]

Possible. Positive terminal could use some wire brushing, I unplugged shore power and it was showing 12.7, but I didn’t wait long enough to see what it settles at.

There’s just two lines going to supply the 12v system, so it’s not like it’s one leg or the other. I’m also noticing that the fans for the converter haven’t come on lately.

[Rocketsled]

One hour later and it’s back down to 11.7v…would a bad cell account for that?

They’re interstate batteries I bough at an RV show last year, no telling what it would take for a warranty claim…

[JRTJH]

Any car parts store should be able to load test the batteries for you. Or, you could use a hydrometer to check the specific gravity of each cell. That's the "old fashioned way" to do a half-hearted test... (see, I didn't use "half a**ed") LOL

But the "gold standard" is a load tester to confirm the battery status.

Interstate "ought to honor their warranty" at any Interstate dealer, regardless of where you bought them, provided you can confirm the purchase date.

[jasin1]

Originally Posted by JRTJH

Any car parts store should be able to load test the batteries for you. Or, you could use a hydrometer to check the specific gravity of each cell. That's the "old fashioned way" to do a half-hearted test... (see, I didn't use "half a**ed") LOL

But the "gold standard" is a load tester to confirm the battery status.

Interstate "ought to honor their warranty" at any Interstate dealer, regardless of where you bought them, provided you can confirm the purchase date.

Does anyone know of a good portable battery load tester ? Is that something worth buying? …I have so many different battery’s in all the different vehicles and boats,tractors etc

[snoobler]

Originally Posted by Rocketsled

One hour later and it’s back down to 11.7v…would a bad cell account for that?

They’re interstate batteries I bough at an RV show last year, no telling what it would take for a warranty claim…

When the converter is plugged into AC, does the Renogy show a current going into the battery?

Worth checking the individual 6V to see if they're the same. I would be concerned with any voltage difference > 0.05V.

I wouldn't be thinking about a warranty claim until I confirm the problem. I doubt you want to get new batteries and find yourself in exactly the same place a week from now.

I second the recommendation on specific gravity, but I assert that it's much more valuable than "old fashioned" or "half-a**ed." It's the best way you can confirm that individual cells are actually working. You want them typically above 1.265 for full charge all falling within 0.03.

A load tester isn't going to tell you anything meaningful until you've been able to fully charge the battery. A battery sitting at 11.7V will fail a load test even if it's in excellent shape.


Concerning test equipment, I have the following:

https://www.amazon.com/Schumacher-BT.../dp/B000AMBOI0

and

https://www.amazon.com/gp/product/B07Q6NBXQG

They both basically do the same thing, but they do it in different ways, and the information from each is meaningful.

The 100A load tester is just brute force.

The digital tester does something very important - measure internal resistance - something you can record and trend. It's also a little less sensitive to state of charge.

[Rocketsled]

I have a 12v tester I trust, and a Harbor Freight 6v tester I don’t distrust, I can isolate and charge them separate from everything else.

[snoobler]

Originally Posted by Rocketsled

I have a 12v tester I trust, and a Harbor Freight 6v tester I don’t distrust, I can isolate and charge them separate from everything else.

The more specific your testing can be, the better your results.

When plugged into to shore power, does the Renogy report a current going into the batteries?

[Rocketsled]

It's showing 62w consumption with the Fridge and Lights on, additionally, earlier in the troubleshooting, I measured the voltage across each battery isolated and they were both different...5.7v and 5.1v.

Seriously considering LiFEPo4 at this point as I'm spending more time grinding on this than if I just made the leap (it'd replace the charger and the batteries...the two things I'm currently troubleshooting)

[JRTJH]

Originally Posted by Rocketsled

It's showing 62w consumption with the Fridge and Lights on, additionally, earlier in the troubleshooting, I measured the voltage across each battery isolated and they were both different...5.7v and 5.1v.

Seriously considering LiFEPo4 at this point as I'm spending more time grinding on this than if I just made the leap (it'd replace the charger and the batteries...the two things I'm currently troubleshooting)

I'd include a third thing: the charge line/battery power line from the converter/power supply DC fuse panel to the battery cutoff switch and then to the battery terminals and the ground wire from the battery box to the frame. I've seen way more problems with bad crimp connectors, shorted/damaged wire "pinched to the frame" and loose/corroded connectors than I have failures of either the battery or the converter/charger.

You may well have a bad battery or a defective charger and installing the best you can buy might fix the problem, but installing a "big bucks system" consisting of new batteries and a upgraded converter/charger to those same wires will not "fix the problem" if the issue is under the trailer floor or at at that red switch in the battery compartment..... BTDT

[Rocketsled]

Hmm. [pause]

I did build a stub cable when installing the shunt. used Rosin and solder and a torch, but it's entirely possible that's a culprit.

[dutchmensport]

You lost me on the first post. Too complicated for me. All this electronics just to go camping?

[Rocketsled]

Originally Posted by dutchmensport

You lost me on the first post. Too complicated for me. All this electronics just to go camping?

All these electronics to figure out if there's enough power to run the furnace through the night when it's 25 degrees out...but mostly 'something doesn't seem right, I wonder what it is.'

Because waking up warm and having hot water to shower and food that's not spoiled with is kinda wonderful.

[JRTJH]

Originally Posted by Rocketsled

Hmm. [pause]

I did build a stub cable when installing the shunt. used Rosin and solder and a torch, but it's entirely possible that's a culprit.

I would make a SWAG that your soldered connections are "head and shoulders better" than the "quick build crimped chinese connectors" used on the assembly line. Some of the wiring harnesses are built "off line" and installed, but most of the electrical wiring is "strung through the walls and floor from big wiring spools" and then, after the trailer is partly assembled, somebody "crawls in the belly spaces" and starts crimping connectors on the ends and figuring out what to connect where...

Here's a couple of photos of what you'll see on the line. Crawl inside a cramped space on a hot day with a crimping tool a set of wire cutters and a handfull of connectors, drop a connector and the inclination is to use what you have, not crawl back out to get the correct connector and crawl back into that "hell hole"... So, lots of "make do with what's in my hand" rather than "stop and get the correct parts to do it right".... And, for many of the "electricians at the factory" the mantra is, "If it works great, if it doesn't, the dealer can fix it, it's too hot to stay in here and check my work"....

So, your soldered wire is probably not the worst part of the system !!!!!

[Rocketsled]

We're camping about 20 minutes from home. (I commuted to the home office today, matter of fact)...I'll isolate and charge the batteries separate from the trailer and measure...heck, I even have a spare 12v battery that's in mostly good shape, assuming the trailer needs a battery to safely power the 12v side of things.

Sure is a lotta bull**** troubleshooting. (plus the pump this weekend...and that delamination I'm still pondering.)

5 year old trailer.