Reply
 
Thread Tools Display Modes
Old 06-28-2019, 10:13 AM   #1
Senior Member
 
Join Date: May 2017
Posts: 121
Managing batteries and switching/charging same

I recently took delivery of a new trailer which included a new group 24 battery rated at a paltry 75 amps. Additionally I own a older (2 y/o) but still working very well, group 27 battery that when new was rated at 105 amps.


I have enough room to mount on the trailer tongue beside the existing the g24, the older g27. I am of the belief that it is not a wise idea to parallel these two batteries due to the difference in size and age.


I plan to install a multi bank battery switch and thus isolate one battery from the other. My yet to be mounted, but in hand, battery monitor can monitor each bank (of one battery each) and alert me when to switch from one bank to the other.


My primary question is: when one bank (of one battery) becomes low and I need to charge it, how can I charge it while at the same time using the other full bank? I have available for charging purposes, (1) the trailer's onboard charger on either shore power or a generator. (2) a portable battery charger.


I posed the question above because if the battery switch is isolating the batteries, isn't it also isolating a bank from receiving a charge? Should I just plan on using the portable charger on the low and now, isolated battery?



TIA
__________________

mjacxx is offline   Reply With Quote
Old 06-30-2019, 09:05 AM   #2
Senior Member
 
SeaDog's Avatar
 
Join Date: Jan 2016
Location: Idaho
Posts: 5,706
If your reason for installing the switch is because of the difference in the batteries whey not just get two batteries of the same type and rating and operate your rig as designed?
__________________

__________________
Retired Navy
Jake my sidekick (yellow Lab)
2017 RAM 2500 CC 4X4 Cummins Diesel
2016 Flagstaff 26 FKWS
AF&AM & El Korah Shrine of Idaho
SeaDog is offline   Reply With Quote
Old 06-30-2019, 09:38 AM   #3
Senior Member
 
rsdata's Avatar
 
Join Date: Aug 2014
Location: Northern KY
Posts: 2,922
your isolater does isolate the batteries... charge from a separate charger not your built-in unit and hook to whatever needs to be charged... 8 amp electronic chargers are reasonable price

or buy 2 new group 27 Interstate battery at Costco for about $80 each and save your isolater and charger purchase money...
__________________
ďToo much of anything is bad, but too much good whiskey is barely enough.Ē Ė Mark Twain



2014 Shamrock 183
2014 RAM 1500 Bighorn Crew Cab, HEMI, 3.21 gears, 8 Spd, 4X4 TST TPMS
rsdata is offline   Reply With Quote
Old 06-30-2019, 09:48 AM   #4
Senior Member
 
Chuck_S's Avatar
 
Join Date: Aug 2018
Location: Richmond VA
Posts: 821
Mismatched pair of batteries will never provide what you want. You're correct they need to be separated from each other and the system otherwise the weaker battery will continually siphon power from the stronger. If run separately you're likely to over-discharge one battery before switching to the other. Note the dozen's of threads regarding discharging batteries too low and damaging them.

But you already own these batteries so why not just use them? The switching scheme, a simple Off-1-Both-2 switch (common on small boats) will work for the near future afterwhich you can get a pair of new matched batteries and run them combined as one big battery.

-- Chuck
__________________
2006 Roo 23SS behind a 2017 Ford Expedition
Chuck_S is offline   Reply With Quote
Old 06-30-2019, 09:59 AM   #5
Senior Member
 
Join Date: May 2017
Posts: 121
Quote:
Originally Posted by SeaDog View Post
If your reason for installing the switch is because of the difference in the batteries whey not just get two batteries of the same type and rating and operate your rig as designed?

To be clear;
1) I own the batteries and chose to use them. Some would consider me a cheap S*B
2) If were to get another battery, I would buy only one. It would match the newer G24 I have.
3) I have always installed a battery disconnect switch, irregardless of the style, type or age of the batteries. Goggle will yield many reasons its wise to do so. YMMV.


Charging in my chosen configuration was the question. Can you help with that?


Thanks
mjacxx is offline   Reply With Quote
Old 06-30-2019, 10:05 AM   #6
Senior Member
 
Join Date: May 2017
Posts: 121
Quote:
Originally Posted by rsdata View Post
your isolater does isolate the batteries... charge from a separate charger not your built-in unit and hook to whatever needs to be charged... 8 amp electronic chargers are reasonable price

I may wind up doing just that. Thanks


Quote:
or buy 2 new group 27 Interstate battery at Costco for about $80 each and save your isolater and charger purchase money...

I can't fit two 27's with out some surgery I don't want to do............Thanks
mjacxx is offline   Reply With Quote
Old 06-30-2019, 10:18 AM   #7
Senior Member
 
Join Date: May 2017
Posts: 121
Quote:
Originally Posted by Chuck_S View Post
Mismatched pair of batteries will never provide what you want. You're correct they need to be separated from each other and the system otherwise the weaker battery will continually siphon power from the stronger. If run separately you're likely to over-discharge one battery before switching to the other. Note the dozen's of threads regarding discharging batteries too low and damaging them.

But you already own these batteries so why not just use them? The switching scheme, a simple Off-1-Both-2 switch (common on small boats) will work for the near future afterwhich you can get a pair of new matched batteries and run them combined as one big battery.

-- Chuck

Thanks. My Victron can be set to alert of a over or lower discharge than a [%] event. Tested twice with success yesterday. Once with the onboard charger and once with a separate (very old) non automatic (no float) charger.

Yep. Using them is the plan and your near future remarks are well noted, that also fits into the bigger picture plan. Thanks again.
mjacxx is offline   Reply With Quote
Old 06-30-2019, 10:18 AM   #8
Senior Member
 
Chuck_S's Avatar
 
Join Date: Aug 2018
Location: Richmond VA
Posts: 821
A 6v GC2 (?) battery has the same footprint as a Group 24 battery and much more storage. Just a little taller. I've run a pair of these as one big battery for 15 seasons.

-- Chuck
__________________
2006 Roo 23SS behind a 2017 Ford Expedition
Chuck_S is offline   Reply With Quote
Old 06-30-2019, 10:31 AM   #9
Senior Member
 
Join Date: May 2017
Posts: 121
Quote:
Originally Posted by Chuck_S View Post
A 6v GC2 (?) battery has the same footprint as a Group 24 battery and much more storage. Just a little taller. I've run a pair of these as one big battery for 15 seasons.

-- Chuck

I have considered going that route but it will result in an appox 180 lb weight gain. Maybe down the road and after I lose some weight.
15 seasons? On the same set?
mjacxx is offline   Reply With Quote
Old 06-30-2019, 10:43 AM   #10
Site Team
 
Flybob's Avatar
 
Join Date: Oct 2014
Posts: 9,507
Choosing to use what you have, the best solution is to isolate the two batteries and use a separate automotive battery charger to charge the one not in use.
__________________

__________________

2015 Freedom Express 248RBS
TV 2015 Silverado HD2500 Duramax
TST Tire Monitors
Honda 2000I + Companion
2 100W solar panels
Flybob is online now   Reply With Quote
Reply

Tags
batteries, charging, switch

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



» Featured Campgrounds

Reviews provided by


Disclaimer:

This website is not affiliated with or endorsed by Forest River, Inc. or any of its affiliates. This is an independent, unofficial site.




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 08:13 AM.