BATTERY TENDER

Can a battery tender be hooked up to more then one battery at a time. I have 10 batteries and only 4 tenders, so I would like to hook up more the one to a tender. I have 4 of the Schumacher speed charger 1.5 amp.

Bob

Good question- I wouldn't think so since the maintainer senses when a battery is fully charged. How would it sense a multiple hookup? (but I could be wrong)

I would think it'd work as long as you hook all positives together and the same with the negatives. May take a while to get 'em all up to 100%.

Gee Bob, you need to a) Sell some tractors b) Buy more tenders c) Come with us and haul em all down to Florida d) ORDER your bride go out each day and alternate the tender among different batteries (my bride Cricket would) e) BEST Take those batteries over to your brother in laws nice warm garage and make him keep them all charged. Tell him you would do it for him!!!!! so he being a good brother ought to do it for you, tell him I said so.


Okay, you can THEORETICALLY put batteries in Parallel and place a single tender onto the parallel bank HOWEVER that may not be the absolute best possible solution because:


1) The tender only has X amps available, and even if all batteries were perfectly balanced (Yeah Right lol) that only leaves a certain share or potential charging current for each, and it may not be enough since its so cold where you live. Don't Owls breed witch Chickens where you live???

2) If two batteries are in parallel the weak one may canniballize off the strong one and BOTH may not fare well in the long run

3) Theres no way so many different batteries would be very well balanced due to different brands and ages and types and sizes so when you start connecting them in parallel its like a circus and I don't see a small tender (depends on size and amps and design) doing a bang up job.

THAT BEING ALL SAID Heck I wouldn't consider connecting anymore then two in parallel and pick the best possible matched (size, type, brand, age) and hook a tender up n see what happens. Worse is the tender may blow up or both batteries discharge BUT IF ITS ONLY TWO AND THEY ARE SOMEWHAT BALANCED IT MAY JUST GET YOU BY FINE I WOULDNT HESITATE TO TRY IT (especially on your batteries)

DISCLAIMER not knowing the size and rating and specs and design of the Tender nor anything about the batteries or their condition, NO FREAKING WARRANTY but I still might try two batteries per tender n monitor the voltage and the electrolyte levels and hydrometer readings AND HECK IT MAY GET YOU BY. If not see (e) above.

John T Hope to see you in January, its Ying Ying time yayyyyyyyyyyyyyyy

There are tenders made for multiple batteries.
Do a search and You will find them.

here's a link for one.
battery tender

I have done it but I dont think it works as well as having one on each battery. I have purchased quite a few of the cheapo HF maintainers which are $9 on sale. They are very consistent at 12.5-12.6 Volts but you have to be certain the batteries are up before you place them on the maintainer.

I've had a Schumacher 1.5 amp battery maintainer hooked to three batteries, all hooked in parallel. Been done every winter, all winter, for four years now. Also have another 1.5 amp Schumacher maintainer hooked to my Ford diesel truck (with two batteries in parallel).

The issue is this. A battery maintainer must have enough charge rate to make a battery reach the voltage shut-off level. Usually around 13.8 volts. When you stick a small charger on a big battery or battery bank -at some point the charger cannot keep up and will stay in "full charge" mode all the time. All depends on the conditions of the batteries being charged. A 1.5 amp battery maintainer CAN keep three, 80 AH size-range batteries charged when in good shape. As soon as even one starts to wear out and need more charge - the maintainer will likely be on full charge mode all the time and eventually burn out.

I use one HF maintainer on my diesel truck which doesn't get used much. Dual batteries, but seems to be OK. Both matched batteries grew old together, so pretty well matched. Would strongly hesitate to do more than two, and definitely if they were not Siamese twins from birth.

In a perfect world, it would work. But, if one battery is sick, (depending on what's wrong with it), it could bring all the others down along with it, in turn causing the charger to cook all the good ones while trying to keep the bad one happy.

I don't think it would be worth the risk. Move the charger from battery to battery. If a battery refuses to hold a charge for a month or longer, usually much longer, it's time to replace it.

1.5 amp battery maintainers are meant to be used with no more then 33 amp-hours of 12 volt batteries or 12 amp-hours with 6 volt batteries. That is not very much. I have used successfully on much more but they are NOT designed to do that. Note that a typical 12 volt car battery is around 50 amp-hours. I.e. too big for use with a 1.5 amp maintainer, according to manufacturer's specs.

Just a comment about matching batteries. I doubt it makes any difference matching types. Ages -yeah. When batteries are mis-matched by type/size and hooked in parallel - they will equalize until voltage is the same with all. Not a big deal when similar vintage and able to be charged easy. If different ages though - the nominal voltages can vary a lot (voltage when sitting awhile not being charged). When hooking batteries in parallel and hooking a small battery maintainer to them? All it needs to do is achieve the desired shut-down-to-trickle voltage which is around 13.8 volts. It's all about the batteries ability to reach the threshold high volt limit with the amount of charge being provided.

The set of three batteries I've had all hooked in parallel and tied to just one 1.5 amp maintainer have worked well now going on the 4th winter. One is a small garden tractor battery, one is a large 12 volt cranking battery and the other is a type 24 deep-cycle battery. Pretty mismatched and have worked fine thus far on the one maintainer.

It is ALL about the size of the battery and age. Keep in mind that the "small print" with a 1.5 amp battery maintainer limits it to use with no larger then a 33 amp-hour battery.

If you have many big batteries and want reliability - you need something that costs a lot more then $20. Like this Guest marine dual output maintainer. This is what I use on my RV for winter storage. Has one large engine cranking battery and two large deep-cycle "house" batteries.

There ya go Bob, the DEFINITE answer you were looking for lol some think YOUR charger may work on more then one battery, others think maybe not. Indeed a higher rated higher quality unit stands a better chance, but I didn't see that was your question. As typical, you get plenty of opinions (including yours truly) anytime an electrical question is asked, and I enjoy them all.

The fact remains however and the bottom line is, a 1.5 amp charger isn't all that much, let alone hooking it up with TWO batteries!!!! I have no idea what sort of overload protection it has, so if you do try two batteries at once (I wouldn't bet the farm on the outcome, no data here), I strongly advise you match them to some extent. Its not hard to go there after some time passes and stick a voltmeter on them. I have also heard horror stories of some cheap tenders burning up so were not gonna sit them on top of a bale of straw now are we.

Try n let us know Bob, good luck.

John T

(quoted from post at 07:15:35 11/18/14) Can a battery tender be hooked up to more then one battery at a time. I have 10 batteries and only 4 tenders, so I would like to hook up more the one to a tender. I have 4 of the Schumacher speed charger 1.5 amp.

Bob

Click to expand...

I use the same tenders.
Will they do it? yes
Does it work them too hard? also yes, in my opinion

As an example,
I'm a 12v guy, so I usually have a lot of 6v batteries after changeovers.
I routinely wire two 6v batteries in series to power some of
my small 12v garden tractors (good ballast too...)
Using a battery tender on these when they are discharged a bit,
takes a very long time and the tender gets very warm..hot.
Hot enough where I don't like it.
So, I now use a closely monitored real charger on those setups
to top off the charge when they have been sitting.

same with two 12v batteries in parallel in the shop.
Yes, it works, but the heat thing again, so I use a real charger one at a time, and the alarm on my phone to remember to shut it off

I use this battery maintainer on my 4-group 31 batteries in my semi every winter. Batteries reach charged voltage and then the battery maintainer switches to the desulfatation mode.
batteryminder

No "guessing" or random "opinions" needed. Just about every company that sells a 1.5 amp battery maintainer states clearly, in writing, it's only rated to maintain a maximum battery size of 35 amp-hours for a 12 volt setup.

EXACTLY JD, you got it, go to the head of the class lol. If the specs and data indeed say Bobs Tender is ONLY rated to maintain a maximum battery size of 35 amp hours for a 12 volt setup I HAVE NO REASON TO DOUBT THEM (subject to you know how a company may hype their product???). No guessing or opinions needed if we had his specs and data in front of us. Maybe he can provide that then we can give a more exact engineering answer !!!!! Maybe you can find them (would need his make n model and other info perhaps and look it up on the net????)

As always I enjoy our sparky chats, you take care now and keep warm

John T

I've abused many of my little 1.5 amp maintainers. So far most have worked OK. I have however burnt out many of the Harbor Freight versions. Nice thing about them though - is they are made to be mounted permanently and hard-wired. Nice to have an AC power cord already attached to a tractor, truck or car. Just have to plug it in. WARNING !!!
Last summer before leaving my house for two weeks - I plugged in my tractor in a hurry and plugged in the 1500 watt tank-heater by accident. Here's some photos showing my IH B275 with the two AC plugs next to each other.

I always enjoy your pictures postings. As I teased my old friend Bob there, were not going to sit any Tender on a bale of hay now are we lol Not too long back I had the pleasure of a personal tour at his farm and saw all his tractors and batteries, wish now I had paid more attention to his Tenders and all that, but we had other things more "important" ???? and his Sis and Brother in Law were there, thats all I'm saying. One note, where he's at the extreme cold makes a difference concerning all our talk about his Tenders capacity and ability to keep any (let alone two) batteries maintained, subject to battery as well as Tender size and rating etc etc !!!!!

It would be fun to look at all your equipment someday, I used to give Seminar Workshops at the New York State Two Cylinder Expo then swing past Niagra Falls or take the RV upstate.

KEEP WARM UP NORTH THERE

John T

Maybe or maybe not some good news for Bob if you have the same charger he does. As I said somewhere below, only 1.5 Amps isn't all that much however and I wouldn't bet the farm on this lol.

Of course, the battery size and type and capacity and charge state and temperature and the tender itself all go into the mix as to whether it will work or not, I still wont bet the farm.

As noted below without all the data and specs on the charger and the battery info its hard to say.

John T