Batteries

[Burchie70]

I take my two batteries out of my 5th wheel for the winter and put them in my basement. Can I take a battery tender and maintain both batteries by hooking jumpers in parallel? Not sure if that makes sense but the same way I have them hooked up in the camper. Also how many amp tender would I need for two batteries? Thanks for any help

[RogerR]

Battery tenders are cheap compared to the cost of a battery.

I would call or email Deltran/ Battery Tender company and ask their opinion. If you start with a charged battery in good condition a battery tender used very little amps to maintain it.

Using battery tenders I have kept my garden tractor battery going for 4 years instead of annual replacement. Several years on RV batteries.

[us71na]

My Batteryminder Model 1500 instructions say this:
MAINTAINING MULTIPLE BATTERIES
Batteries should be charged individually. To properly maintain multiple
batteries they should all be the same type (gel, flooded or AGM) and condition.
It is OK to mix deep cycle and starter. Charge each battery individually before
connecting together. Never connect batteries at different states of charge. The
charged battery will rapidly transfer energy to the discharged battery possibly
causing catastrophic failure. Once the batteries are charged, use 18 gauge
or greater wire to connect the batteries or for greatest safety protection and
ease of use, consider investing in the BatteryMINDer Y-Connector Model
210AY with SmarTECHnology*.

[bankr63]

I have 6 batteries on the bench in my garage (2 RV, 4 Electric Mobility Scooter for Mom and MIL), and one tender. Every time I take the garbage out, I switch the tender to the next one in line. They don't need to be on a tender 7*24 and won't drain much at all before they get their next boost.

[Burchie70]

Thanks guys, just to try it I ended up charging both batteries then used 12 gauge wire to make jumpers so it’s in parallel. I put the positive from the tender on one battery and the negative on the other battery. Both batteries are the same make and size. The tender has stayed green showing its fully charged since this morning.

[dvspl]

If both are charged, I think the battery tender will work fine to maintain them in parallel. But if you're worried about it, probably not much more trouble to maintain them separately by switching the tender from one to the other once per week or so.

[billcf7]

Originally Posted by Burchie70

I take my two batteries out of my 5th wheel for the winter and put them in my basement. Can I take a battery tender and maintain both batteries by hooking jumpers in parallel? Not sure if that makes sense but the same way I have them hooked up in the camper. Also how many amp tender would I need for two batteries? Thanks for any help

Be careful charging lead acid batteries indoors , they will offgas hydrogen when charged

[Dogdoc]

The key facts here are that the batteries are the following

same voltage
same state of charge
same capacity
same age (this factors in with capacity as batteries lose capacity with age)
fully charged at onset

your connection pattern in spot on, doing so makes the batteries look like only one to the charger. If you put the leads on just on battery then there can be dissimilar charging of the batteries in the string.

The discharge rate will be minimal and almost any tender will maintain them through the winter. If you believe a maintainer can prevent or reduce sulfation then buy a brand which states it can deal with that. I have rejuvenated some sla batteries with that function.
As for gassing, highly unlikely with a maintainer functioning normally

[Dogdoc]

The diagram of the charging hookup for 2 12v batteries in parallel on the battery minder website is incorrect. It shows both leads on the same battery rather than one on each a pos and neg terminal. This issue becomes more significant the more batteries you have in the string.

[mjdcwo]

Because of the variation in batteries (state of charge, age, brand, degree of sulfation, etc) I believe it is always best to charge them separately. Battery maintainers are reasonably inexpensive (see link below) so I have one for each battery and use them continually when the vehicle/equipment is in storage. I have extended the life of the batteries in our golf cart, lawn tractor, classic cars, RV, etc. for a long time. It's good insurance for longevity.

https://www.harborfreight.com/automa...ger-64284.html

[saarf]

Make sure the battery tender you use is rated for deep cell batteries which have heavier internal plates. Unfortunately this info was in the enclosed booklet that came with the battery tender and not on the box.

[Bullitt6283]

Another way to do it-

https://www.autobarn.net/2-bank-battery-tender.html



.

[RallyAce]

As with people, batteries have their own 'personality'. While sitting on a bench the fully charged voltage can vary between the two batteries by a couple tenths of a volt and with a battery tender hooked to both batteries it will try to charge the lower voltage battery over its fully charged state. This will shorten the life of that battery. For the minimal cost of another tender, put one on each battery. In the long run it will save you the cost of a new battery.

[videoarizona]

Once again I seem out of step with others.
I have a trailer RV. Motorcycles. Sailboat.
I NEVER leave a battery tender on a battery over more than one night. I charge the battery, them let it sit. Once a month I'll connect up the battery tender and let it charge overnight. Then disconnect. Been doing that for over five years now and all batteries are still good. Just switched to lithium ion on trailer. Following advice on that by letting it sit half charged.

I used to leave bike, RV and boat batteries on tenders. No more! Was replacing batteries every two years. Learned my lesson.
A fully charged lead acid will not freeze over a winter. It will be fine until season opens. Charge up and good to go.
If you leave battery connected(and I do with motorcycles and sailboat), I always make sure I don't have a parasitic discharge going on so battery doesn't get drained.
You do you. But for me, no more long term battery tenders!

[joe w]

Originally Posted by RogerR

Battery tenders are cheap compared to the cost of a battery.

I would call or email Deltran/ Battery Tender company and ask their opinion. If you start with a charged battery in good condition a battery tender used very little amps to maintain it.

Using battery tenders I have kept my garden tractor battery going for 4 years instead of annual replacement. Several years on RV batteries.

I bought two battery tenders from HF and they have maintained both my batteries for three years now during the winter months.

[LittleBill]

When I put my unit in storage, I take my two batteries (that will be in some state of discharge - not completely though) off and put them on the bench, hooking them up to a battery tender in parallel. It will bring them up to full charge then go into maintenance mode.

Be safe -

[RPR]

2X. Even batteries that are “maintenance free” where you can not check the water have some type of vent.

[goatman]

I have used Harbor Frieght trickle chargers (one per battery) and have good and bad results. I upgraded from wet cell to AGMs to address out gassing problems and minimize maintenance requirements. I exhaustively researched battery maintainers and decided upon Noco Genius chargers because of their durability, reconfigurability (switch selectable 6v, 12v, standard wet cell, AGM...etc) and selection (1amp ,2a,5a,...etc). I have spoken to their engineering department to insure that my application(s) were realistic. I am currently automatically maintaining 4 each 6v AGMs (200ah) in a configuration as it is on the motorhome- 2 series pairs in parallel which then looks like a 12v load to the maintainer. The Noco is smart enough to determine when and if a charge is required as well as temperature sensing the environment to make adjustments. So far everything looks great . I do log results frequently and batts are looking great- individually and as a group.

[57gasser]

First thing I did was put a marine grade battery disconnect on the camper to eliminate any parasitic drain. That way, I can flip the switch on every few weeks and plug the camper in for a couple days. I've found that to be the easiest way out, but I realize not all of us are able do that, everyones situation might be different as far as storage options go. For me, its one less battery to pull out. Just leaves the 2 hot rods & mower to deal with!

[Falcon67]

Have 5 Battery Tenders here as I like spares. 3 in use right now with 4 batteries. One race car, one mower and two quad units on a single Tender. The deep cycle units on the trailers are kept up with the onboard equipment - both trailers are plugged in to the shop on their respective RV connections. The trailers are always on shore power when at the house.