battery upgrade questions

[Merlin]

GaryM, interesting point about shunt based battery monitors, that is, where voltage is measured matters. And perhaps this concept is the key behind the PD 4000 series converters and their positive reviews.

I now understand that the most accurate place to measure battery voltage is at the battery itself. If a battery is healthy, there should little difference between load and at rest, maybe even fully so. Given that the power center is located downstream from the battery, voltage measured there will be influenced by distance from battery, wire AWG, not to mention a load on somewhere. Is it possible that 12.2 VDC (using Gary's parameter) measured by a shunt based monitor could be 11.8 at the power center?? GK

There is no particular relationship between the health of a battery and the load-no load voltage. A completely healthy battery may dip very low in voltage under short-term heavy loads-----even down into the single digits. Put a volt meter on your car's starting battery while someone cranks the engine and you'll see what I mean! Voltage is a rather coarse way to measure battery health and the only possibility of it being valid and reliable is to either check voltage at the battery while at rest or using a meter hooked up to a shunt. Since the voltage will vary a lot with load, you cannot determine the health or charge state of a battery while it is under a load without using a shunt meter.

I'm leery of the "boost mode" concept because just boosting the voltage isn't going to help much until the battery gets to the absorption stage in charging. What a discharged battery needs to recover is current, not voltage. Read the "Battery Charging" section at this site and you'll see what I mean. I would need to know a lot more about what the boost mode does in a particular 3-stage brand of charger to be able so say it's more than just marketing hype.

https://www.solar-electric.com/learning-center/batteries-and-charging/deep-cycle-battery-faq.html

[ADR]

I'm leery of the "boost mode" concept because just boosting the voltage isn't going to help much until the battery gets to the absorption stage in charging. What a discharged battery needs to recover is current, not voltage. Read the "Battery Charging" section at this site and you'll see what I mean. I would need to know a lot more about what the boost mode does in a particular 3-stage brand of charger to be able so say it's more than just marketing hype.

https://www.solar-electric.com/learning-center/batteries-and-charging/deep-cycle-battery-faq.html

The PD boost mode increases voltage AND current-   say normal bulk charge is putting 5A into a battery- activating boost may put 25A into the battery.

Of course the voltage HAS to go up to increase the charging current.   

Obviously a lot of current and higher voltage may decrease long term battery life some-  but as I said earlier when you only have a short window in which to charge- you do what you gotta do

I'd venture to say in a week of dry camping and running a generator a few hours a day  my pair of paralleled 105AH AGM batteries is never charged properly and fully.
So when I either get home or to a site with hookups (very rare for me) I let it do the full normal charge and skip the boost charge.

[Gary M]

Yea, amps increase as well. I had the same concerns about the boost mode initially Merlin, until I did some more research on the battery specs, etc..

For example, the recommended charging current for my AGM's is 30-70a for 2 of them. Boost mode would still be in specs. His charger is a 45a so it's not going to put out more than that. (my stock WFCO 8735 charger would never put out more than 15a in bulk mode!)

Also, the batteries themselves will limit the incoming amperage and slow it down around 75-80ish% SOC. I see the amperage on mine start dropping down at around 80% SOC while charging.

GK- The Trojan 6v 225ah T-105's are actually at 50% when they are at 12.1v(for 2 of them). I said 12.2v earlier because I don't even like taking mine down that low. 12.2 would actually be closer to 60% if you're measuring SOC by voltage.

[GrampaKilt]

If a battery is healthy, there should little difference between load and at rest, maybe even fully so.

What a learning experience this has been and continues to be! Thanks all for your contributions.

To clarify my quote above. I meant if voltage is measured at the battery. I think GaryM found this to be accurate while boondocking. It's obvious what I really need now is my battery monitor to arrive! GK

[Gary M]

which monitor did you end up getting GK? I would install the monitor before replacing the converter, so you can compare the amperage/performance between them.

[GrampaKilt]

I purchased the one in the link below. Liked the round format and the lack of complicated functions. I don't need Bluetooth capability. Perhaps a Victron knock off or made at the same factory? Who knows these days.

Had ordered a Drok, but it couldn't handle heavy gauge wire at the shunt, a good indication it wasn't designed for what I needed it for. GK

https://www.ebay.ca/itm/Battery-Monitor-detector-80V-50A-Capacity-Tester-lithium-lead-acid-12V-24V-car/183258431923?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

[nhlakes]

Good news: I have a pile of new Battleborn LiFePO4 batteries at my place with a bunch of big solar panels and boxes of controllers and accessories.  Bad news: They're for my brother in law's new 5th wheel and not for me.     He and his wife are boondocking in AZ all winter and setting up right. He may have more $ into his solar setup than I have in my whole camper.   They're already on the road and will be swinging by here soon to pick up all the goodies and having them professionally installed by one of the top solar guys out there.

But that doesn't help me...  My wife and I have been doing more camping without power and will be doing 4 days  in a NP without power next week.   I've gone 3 nights before with just a little help from my gen, but I'm now seriously considering adding a second battery.   

I'd love to go the LithiumIon route, but cannot justify the expense, since we do not do THAT much boondocking / drycamping.  For now I'm simply considering adding a 2nd battery.   Perhaps another Cabela's group 27 lead acid deep cycle - not a bad cheap battery especially when found on sale.

(Finally, my question) I have a 2016 with a single battery tray up front.  Does anyone have a link for an aluminum double tray that I can easily swap out on the Aframe?  Or will I have to do a custom deal?

[DavidM]

Norco makes a very solid battery box for two GC batteries, your best choice if you want two batteries.

The existing aluminum frame is obviously too small. So remove it. The Norco box is strong enough if supported by two aluminum angle cross support members. Use 1-1/2" angle and notch the ends so you can bolt to the top of the trailer frame with heavy self tapping screws.

Two GC batteries will give you triple the AHs of a single, so if you went 2+ days with one, you should be able to go for about a week on two GCs.

David

[Gary M]

Depending how old your current battery is, I would just buy a matched pair of 6v golf cart batteries. Problem with mismatched batteries is that the weaker one is always draining from the stronger one.

[nhlakes]

Norco makes a very solid battery box for two GC batteries, your best choice if you want two batteries.
...

Assume you are referring to this?

https://www.amazon.com/NOCO-HM426-Commercial-Automotive-Batteries/dp/B003VAUG5A

Depending how old your current battery is, I would just buy a matched pair of 6v golf cart batteries. ...

Yea, the current Cabela's DC 27 was new this spring.  It's in real good shape so was considering pairing with the same, but I hear you both on the GC batteries.  Have considered those in the past, but was thinking I might possibly make the jump to Lithium Ion some day, so have kept my battery investment to a min so far.

Decisions decisions... I have not shopped GC batteries yet, what's a reasonable price for a reasonable GC battery?

Just bought an Andersen NoSway this week (should arrive this weekend) so trying not to go too crazy all at once.    Also still considering a solar suitcase...

[DavidM]

Yes, that is the Noco box.

Costco has GC2 batteries for about $100 each, maybe with core trade in though. Batteries Plus has them for a few bucks more than that, maybe about the same as Costco with no trade in. Both are Deka or similar. You can't buy a bad GC battery, the market would run you out of business if you didn't make a decent product, unlike so called dual purpose batteries.

You can do all I described above for $20-30 of aluminum, $62 for the Noco box, and a couple of hundred for the batteries. Li will cost many times that much, probably a thousand plus when all is said and done.

David

[nhlakes]

Thanks - I was googling the same and saw that Costco should be under $100 and Trojan 105's under $150, if I go this route I'll go for the Costco flavor based on the data I've gathered so far. 

Aware if the Lithium Ion cost, the Battleborns I'm holding for my BIL are around $900/each.

My next question will be will my stock Progressive PD4045 converter charge it OK - and what kind of portable charger would best to charge them quick from the generator...?  Need to pickup a new portable charger anyway.

Never played with 6V in series so will need to also figure out if I will still be able to use the Blue Sea 6006 single circuit on/off switch that I've been planning to install.

[DavidM]

Two GC batteries in series act like one big 12V, so the PD charger will work fine and the disconnect switch will also work fine. Although it would be better to install a 30A circuit breaker instead of a switch and accomplish two purposes. Amazon has them, see https://www.amazon.com/gp/product/B00DIGK346/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

Why do you need a portable charger? Just hook up the shore power cord to your generator with an adapter and let your PD charge it at 45A max. That will pull 6-8 amps from the generator, so you can't run any other heavy loads with the generator at the same time, assuming it is a Honda EU2000 with a maximum continuous rating of 13 amps..

David

[Gary M]

PD is better than WFCO for charging. You should be ok with what ya got 👍🏻.

[Merlin]

I installed a Lund truck box on my trailer tongue for the 2 batteries and it gave me lots of extra outside secure storage too. I keep all my electrical stuff in there; shore power wire, solar wire, charge controller, extension cords, adapter, etc. I fastened it with u-bolts to the trailer frame and bolted 2 battery trays inside for the batteries. Here's an example, but you'd need to find one that fit the space you have on the trailer and the batteries inside (but 2 group 27 would fit in this one).

https://www.amazon.com/Lund-4448FM-Brite-Aluminum-Flush/dp/B009VZX8DG/ref=sr_1_2?ie=UTF8&qid=1537491119&sr=8-2&keywords=lund+48+side+mount+truck+box