Charging AGM batteries direct of vehicle

[nzlongfellow]

Can I damage my AGM batteries if I charge direct off my vehicle with jumper leads?
I only have solar and a "not so quiet" generator.
Can I connect jumpers to my vehicle and charge that way as an idling vehicle is much quieter.
I need to get a full charge into them once and for all.

[Flybob]

You will be wasting time and gas/diesel. Your TV will do little if any charging during idle. Get additional panels and a good controller.

[nzlongfellow]

Originally Posted by nzlongfellow

Can I damage my AGM batteries if I charge direct off my vehicle with jumper leads?
I only have solar and a "not so quiet" generator.
Can I connect jumpers to my vehicle and charge that way as an idling vehicle is much quieter.
I need to get a full charge into them once and for all.

Fitted a battery monitor now so I can see what the Solar input is.

I have 4 x 160W (640W) but have yet to get above 105 AHrs on a good day.

[rk06382]

Originally Posted by nzlongfellow

Fitted a battery monitor now so I can see what the Solar input is.

I have 4 x 160W (640W) but have yet to get above 105 AHrs on a good day.

What Solar Charge Controller are you using? Is it programed for AGM batteries?

[Bluepill]

Most modern vehicles can easily output 30 amps or more at idle. Just don't run any demanding loads in the vehicle, such as A/C, rear defogger, headlights. I don't do this in hot weather, but in cooler weather I have no problem idling for a few hours with the hood open. Just verify that your alternator output does't exceed 14.4 volts.

It is a great way to recharge in "No Generator" campgrounds.

Info here:

https://batteryuniversity.com/index...._glass_mat_agm

[babock]

Depends on the vehicle because of the wire size. For example, my Ford F-150 has a 14 gauge wire going to the 7 pin connector. Nothing but a trickle charge in this case.

You will never get 30A unless you change out the wire to 4 gauge and use a separate connector.

[trees]

If you get a DCC battery charger. The one I bought (Amazon) will charge at 7-1/2 ah rate. Clamp input to truck battery and output to trailer battery. The charger has the same high quality charge cycle as the AC chargers. The charger will change the output voltage for best charge rate despite what the input (truck) battery voltage is. Also, if the source battery is low it will interrupt charge with low voltage light. It's an intelligent charger.

Actually, I find this is the best of both worlds. We put an AGM battery in truck since the battery will recharge fast and we do typically go on tips during day. At night before bed will set the DC to DC charger up for long 8 hr charge cycle. It will fully charge the trailer battery overnight. This is something solar is very poor at. Use this device for the slow and low amperage stage of battery charge. The long cycle just isn't possible with generator or solar. A generator or solar is good for bulk charge, but not so good for the long slow charge rate to fully charge the lead acid batteries necessary for optimal battery life. Works like a charm. Also, with this setup your good to go with old fashion lead acid in trailer (golf cart). I think the DCC was $79. Oh, no need to idle engine.

[Splitshaft]

Here is how I would do it if we are talking about charging travel trailer batteries of any type from a tow vehicle. I would replace the stock alternator with a 200-amp alternator, unless a 200-amp alternator is already installed. Then I would install a 1,500-watt inverter in the tow vehicle and plug the TT into the inverter and use a multi stage converter to charge the batteries or safe multistage battery charger. My 220-amp GM alternator will charge over 100 amps into the coach batteries. My Ford 200-amp alternator maintained 13.2 volts at the engine battery operating my 1,000-watt inverter to charge our TT batteries for about an hour on those cold snowy nights when we had no hookups so we could power the furnace though the night. When it comes to burring a little gas, or freezing your backside off, I’ll burn the gas. During the day, I use a Honda EU2000i for battery charging, very quiet and runs almost 8 hours on about a gallon of gas to charge my batteries near full. AGM batteries are very difficult to damage. They are some of the toughest and best made lead acid batteries money can buy and the reason I use flooded batteries instead. The only way to achieve 100-percent charge is over 24-48 hours of charging. The last 5-10 percent of lead acid battery charging is very slow. The best option is to add another battery and use them between 40 and 90-percent charge levels or less when camping and fully charge them on shore power rather than try to achieve a full battery charge off the grid.

[camaraderie]

You need to pull in somewhere with pedestal electric and get a full overnight charge from your converter on those. Charging regularly to less than 100% will lead to a progressive loss of capacity and eventually early death. This is not something you can do once a month...if the camper is in use you need to fully charge at LEAST once a week. A full charge on a 50% depleted battery will take about 6 hours from a 3 stage charger rated at 20% of your battery bank amp hours...more if the charger is smaller.
I don't think charging off your engine alternator/battery is a good plan as AGM's need to be finished at low amp's & voltage to get to 100% ...but you may want to use the engine to get it mostly charged...then rely on solar or your generator for the last couple of hours.

[tosh99]

I have an AGM battery in my trailer and in my tow vehicle.


When we're not camping, I remove the trailer battery and charge it with a marine "on board" type charger. It will charge it up fairly fast (usually with a few hours) and maintain the charge until I need the battery for the next outing.

[nzlongfellow]

My situation is thus.
The TT has
- 4 x 160W solar panels connected to a Zamp Solar PWM solar charger controller.
- 1 x 3000W generator.
- 1 x 2000W Inverter/ Charger.
- 4 x 210Ahr AGM 6Volt batteries.

The TT was imported by us into New Zealand where shore power is 230V so cannot connect to shore power.

I am getting a Max of 16Amps at present for about 5hrs a day being late winter.

The generator is a Firman sold as a "quiet" unit but far from it so I can't run it in the camp ground after to get batteries up to 100%.
OK you say about now I'm kinda screwed.

I was looking to use the Ford Ranger 850W alternator to slow charge while traveling.
Looking to have to hookup to shore power through a step down transformer which is not what "freedom living" is about.

[JLeising]

Re: the imported New Zealand TT:
Would a 120 to 240 volt transformer work? One example:
https://www.amazon.com/LiteFuze-LT-5...t_sims?ie=UTF8

Lots of options on Amazon at various power and price points.

[rk06382]

Originally Posted by nzlongfellow

My situation is thus.
The TT has
- 4 x 160W solar panels connected to a Zamp Solar PWM solar charger controller.
- 1 x 3000W generator.
- 1 x 2000W Inverter/ Charger.
- 4 x 210Ahr AGM 6Volt batteries.

The TT was imported by us into New Zealand where shore power is 230V so cannot connect to shore power.

I am getting a Max of 16Amps at present for about 5hrs a day being late winter.

The generator is a Firman sold as a "quiet" unit but far from it so I can't run it in the camp ground after to get batteries up to 100%.
OK you say about now I'm kinda screwed.

I was looking to use the Ford Ranger 850W alternator to slow charge while traveling.
Looking to have to hookup to shore power through a step down transformer which is not what "freedom living" is about.

Replace your PWM with a MPPT solar charge controller. See:

https://www.youtube.com/watch?v=wmyuxKmlBCk

My roof:


I have six 100 watt rigid panels in parallel to avoid the shading of vents & A/C on my roof. Last time I boondocked, I saw a peak of 340 watts & 24 amps going into the batteries. I am not able get data loger to work on my EPever TRIRON 40a MPPT Solar Charge Controller. Tech support from China is a pain. I worked with them to get the bluetooth module to work. I am replacing it with a Victron 50a MPPT. (see below)

You should have your panels in parallel. See:

https://www.youtube.com/watch?v=ofo1HQyGG8s

I just installed a Victron BMV-712 Battery Monitor and plan to upgrade from a 40a MPPT to a Victron SmartSolar MPPT 100/50 Solar Charge Controller. Both have bluetooth and can network with each other to share data.

Bottom line: Squeeze as much power as you can out of your solar panels. With your 640 Watts you should have at least a 50 amp MPPT.

[nzlongfellow]

Thanks Robert. Excellent info. I installed the 712 correctly yesterday so I can monitor what's happening.
Certainly not getting Solar output into batteries.
As we are permanent living we need to get it right.
Cheers
Dennis

[camaraderie]

I wouldn't expect you to get much solar output relative to rated wattage in NZ in your winter as you re about the same latitude south as our southern new england as far as sun angles of incidence go. Not terrible but not great either. Panel wattage daily output is rated typically for the equivalent of 6 hours of sunlight at 90 degree incidence to the panels...and you won't be getting that in the winter...and that is on clear days. Anyway nothing to do about that.
Since we now know you can't plug into 120V receptacles to power your coach/converter/charger...it doesn't seem you need to get a transformer...since the only thing you really need is a way to fully charge 4 batteries so they can power your electrical needs...why not get a local current 3 stage battery charger/converter that you can simply use for charging? Nothing else in the coach would ever see 240V since your 12V battery system would power your AC needs through your inverter. You could use up to 90 amps of charging current.Just disconnect from the coach electric system converter and use the shoreside to charge up...then let the sun top you off. At 50% discharge you'll be trying to put back 220 amp hours so a few hours followed by sunshine should do the trick quietly and without major investments. Check out the IOTA DLS55 with smart IQ 4 stage charging. Something like this would be a good choice and protect your batts...while plugging directly into any household current source.
We lived aboard our boat in some 240V places with a 120V electric system and I was never happy with the transformers as a solution...chewed up several plugs and anything motorized doesn't really perform well (like AC).
Anyway...good luck with it all. When and if the batteries finally fail...you might think about some Wet Cells which are a lot less sensitive to abuse in dry camping situations.


https://www.iotaengineering.com/dls24055.htm

[nzlongfellow]

Great info. I'll digest it. Many thanks.