Battery charger

[Bill B]

Question for the electrical engineers... I have a generator with an on board trickle charger for the battery, does anyone foresee a problem with adding a second battery of the same voltage, via jumper cables 12 ga in size, to the trickle charger?  The second battery would be disconnected and used on another generator when needed, that does not have a charger.  Bill

[foakes]

Yes, best way to do it is in parallel (postive to positive, negative to negative) —- then connect the charger to negative on one battery —- and positive on the other battery.

Charging would take nearly twice as long —- which shouldn't be an issue when trickle charging at 2 amps.

Couple of things —-

Jumper cables will have some resistance in them and are notorious for not always having a solid connection.  Best to make up some dedicated cables (each the same length) for this operation.

A smart charger is your best bet nowadays.  A good one is only around $50 nowadays —- and will have 4 stages of charging plus the ability to choose the type of battery —- deep cycle, AGM, Gel, regular vehicle battery, lithium, etc..  And also the amps —- 2, 6, and full start. 

The older, traditional chargers will actually considerably lessen the life of your batteries by charging at full load all of the time.  The new smart chargers will restore, maintain, recondition, and ease off the power towards the end —- plus give you a screen indicator of where your battery is in the charging cycle.

Best, Fred

[Wally15]

Well said, Fred. I'm still trying to figure out the external power source for the generator trickle charger. And why you would need 12 ga on a 1-5 amp trickle charger.
Since I recently lost most of my tools in the garage fire, I've been researching chargers, along with a thousand other things. I ended up buying a couple of NOCO Genius1 smart chargers and a Motopower MP00207 smart charger. They both have quick connects to easily change from clamps to spade, ring, fork (or whatever) connections. They all have flexible 16-18 ga stranded wire.
Bill, a couple of potential problems I foresee with your proposed method:
1 - charging dissimilar types at same time - regular lead acid and a LiFePo4 (Lithium) battery, for example. Smart charger may get confused as each requires a slightly different charge voltage.
2- Batteries in different charging states. One is in stage 4 trickle mode and the other one requiring the full stage 1 charge. It can only select one charge state and you may never get the extra battery charged. Or shorten the life of the generator battery if the charger selects stage 1.
I think I'd just buy a stand alone smart charger for the 2nd battery.
Not to "toot their horn", but the Motopower MP00207 is a very versatile. And it's on sale from Amazon for $28. 7 charge stages, desulfator, 6 or 12V. Very handy to have around. Sorta like the workshop I no longer have.
GA Mike

[Keta]

I maintain 4 boat batteries in the winter by hooking them parallel to a trickle charger or a solar panel.  Do not mix battery types in the circuit.  If they are LiFePO4 batteries do not charge them if they are 32 degrees or lower.  I am in the process of figuring how to heat my LiFePO4 battery box so they can charge in the winter but they are only used to pump water and a few LED lights so it is not needed as much in the winter.

[Gobi King]

what is the output of the trickle charger? does it go to sleep ONCE charging is complete?

[Keta]

4A and yes. 

My stand alone battery maintainer solar panel has a Renogy Voyager charge controller.

[Bill B]

Thank you, I knew I could get an answer here.  I've said it before, if this group cannot solve a problem, then the problem might not exist 😁.  One battery is lead/acid the other is lithium, so another charger will be ordered, thank you Mike for the tip on Motopower.  A trickle charger is built into the main generator so I don't know if it goes to sleep and the manual does not give any specs on it.  I do have available power in the generator shed so plugging in the second charger won't be a problem.  Now if gas prices would drop some more, I need another 10 gallons to top off my strategic fuel reserves and another bottle of SeaFoam.  Bill

[Keta]

You need to get a charger designed for LiFePO4 batteries.

[foakes]

My "Doh" moment was when I was wondering why my batteries would fail prematurely —- although I had them on a trickle charger that I bought 20 years ago.

Finally figured out that the older charger was ruining the batteries because it did not have the new "Smart Battery Charging" technology.

When I realized that I could buy a 4.5 to 5 star rated smart charger for half of what a decent battery would cost —- it was an easy decision.

Picked up a Ampeak with the screen that tells me exactly where the battery is in the process, and what to do next.  Plus it has the choices of various types of batteries and charging Amps.

Mine was $58 shipped on the Ampeak eBay store, last November.

Works very well so far on 4 different types of batteries that I use on a regular basis —- trailer, camper, boat, DR weed-eater, standby generator.

Am finishing up replacing the power converter in our cabover camper with a new 4-stage smart converter this morning.

Yesterday, I needed to remove the old single stage converter, strip out the fuse panel and a bunch of unnecessary wiring, rewire the old fuse panel into the new system, and test.  Got it all done —- will button the job up this morning.

Many of these devices do not come with any directions whatsoever —- so it was a process of figuring out AC, DC, wiring, eliminating the GFCI in the 5 receptacle circuit, all appliances, and the circuit breaker panel.  So it took a little longer.

Some folks with no electrical experience would likely have an impossible time doing this job.  It would just require a $400 labor charge at the RV dealer.

But, now I understand and have verified all of the systems for the fridge/freezer, furnace, lighting, water pump, DC side with fuses, and AC side with shore power and breakers.  The stove and H/W heater are stand alone LP units.

The new converter is a smart unit with a 4-stage charging system to keep the 12V battery up to snuff and at full capacity.

Best, Fred

[Keta]

No or poor manuals seem to be popular today. 

[Gobi King]

Nice charger Fred,

The "Recon" feature is a life saver IMHO,

I use that feature once a month or two on my vehicle/boat batts,
My batts are the most neglected batts east of the Mississippi. Full charge > recon (runs for 1.5 days), batts have lasted 10 years or so on average.