What would you do?

[grizzzman]

Hi all
First a bit of history. I have been boondocking for more then 35 years, 15 of it in rv's. Up to this last year, my RV's have been motorhomes.
The last two had gen-sets and large cabling from the start battery. As we tend to be nomadic, the coach batteries "mostly" stayed well charged.
We really never relied on the gen-set for charging (it had a WFCO converter) Watching paint dry would be faster . Anyways we bought a trailer.
Comparitly it uses the most power, power jack,electric slide out,electric awning, TV, DVD entertainment center and of course the wonderful parasitic
draws the manufacturer thinks we should just accept To that I added an inverter, electric levelers, satellite radio. Then add phones, tablets
and bluetooth speaker's..... Well you get the idea
I believe in two charging source's (I have 640 watts of solar) but the 25ish feet of 10awg (2.59mm) charge wire from the truck is.......well......a bit of a joke so this where the question come's in. (I'm not intrusted in a gen-set)

Thanks for your time

[JohnM]

Hi Griz,
The biggest problem we have over here, is every second person has his ideas on how things should be done. Realising we have different power usage and travel modes.
I have a converted school bus, 7 m long with a front mounted diesel engine and tow a Suzuki Jimny, on a trailer, I have little of the mod cons use blocks of wood to level up, no slide outs, we have TV, microwave oven washing machine, cooking is by LPG as is my hot water.
we travel relatively short distances per day, and tend to try and stop for longer times when we find some where we like, a trip of six months might cover over 8.000 km (5000 miles) and take 6 months, mostly all of that time spent free camping.
We have 480 w of solar panels on the roof and run off 300 ah of batteries, we have a 2000 w inverter which we use when we need AC power for the washing machine microwave etc, we have a 300 w small inverter which we use to run the computers, charge phones etc.
my system relies mainly on the solar input and in most cases that is more than adequate for the purpose however I have a 20 a DC to DC battery charger that runs from the motor battery / alternator. as well as ac/dc battery chargers that can be run from shore power or a generator as needed. I also run power back to the toad, to a 100 ah battery to run the fridge freezer, this is connected by 8 mm twin cable connected with anderson plugs, this is also connected through a Dc DC charger.
The advantages of the Dc Dc charger is that in my case the motor batteries on the bus are 24 v where as the house batteries are 12v the charger converts the 24 v to what is required to charge the batters with a proper charging regime, however conversely, the charger is able to boost the power to the toad battery to make up for any voltage drop through the cabling, as well as ensuring the correct charging regime.
Like you I believe in two or more means of charging batteries is a must. I think the DC DC charger will fit your needs as it does mine. I have AGM batteries but believe my system can be modified to lithium.
I hope I haven't confused you too much with my ramblings.

[JohnM]

Hi Grizz, the following is an except from an article here "https://www.caravanworld.com.au/feature ... -explained"
the one sect I disagree with is using the inbuilt solar regulator, I believe the KISS principal, in having separate components, that way if one unit fails you are still mobile.

A DC-DC charger is effectively a smart-charger for your 12V system. It isolates the house battery system from the alternator, so that the vehicle’s computer management system sees it as something like a set of lights. At the same time, it boosts the charge at the house battery from as little as 9V back up to 14.4V (or higher, if required) to maximise charging capacity, delivering it in stepped form, like your smart mains charger, achieving close to 100 per cent charge after a day’s driving.

Most DC-DC chargers also act as solar regulators, relocating what’s traditionally been a separate item on your solar panel to a better position – adjacent to the house battery. And these are no ordinary regulators, but maximum power point trackers (MPPT) that optimise your solar panels’ performance.

Most DC-DC chargers draw a higher rate of amperage from the alternator than would be supplied if you let the alternator ‘push’ down the cable. This can be up to 40A or more per hour, quickly replenishing the house battery system.

Complete battery management systems (BMS) are new to the market and incorporate a mains charger, a DC-DC charger and MPPT solar regulator.

These generally come with a high-tech battery monitoring panel and, while expensive, are simple to install, requiring no post-manufacturer wiring between multiple units.

DC-DC chargers benefit from 6B&S/13.5mm² cabling (the conductor, not the conductor plus insulation, which is how most cable is sold). They work with smaller cable, but as the voltage drop through smaller cable increases, the heat produced reduces its conductivity, forcing the charger to work harder, drawing more current and increasing heat. This can continue to the point where the demand exceeds the alternator’s capacity to supply. The energy dissipates as heat is wasted.

Installing the charger near the house battery overcomes much of that voltage drop, while adhering to the manufacturer-recommended minimum clearance assists in dissipating heat.

DC-DC chargers increase the likelihood of your batteries arriving in camp at close to a full charge, minimises damage to your house battery system from over discharging and, in my opinion, should be fitted as mandatory or at least offered as an option on every camper and caravan sold in Australia.

[native pepper]

Grizzman, you'll find with most Rv people, there are many different setups for various reasons preference and skill level. We have 2 dc-dc chargers on the bus, one is a 60amp 24v-12v which runs from the bus alternator through a redarc to a 24v x60amp battery pack, then from their to the 24v-12v dc charger and into our gel batteries. The other one is a 15amp 12v-12vdc and chargers from the gel to the veggie oil fuel pumps running on a 9v battery situated beside the fuel pumps.

We can also switch the 24v-12v charger to a lifepo4 controller if needed. This was set up because of the unknown quality of lifepo4, as lifepo4 is nothing like lead acid and even the 460w of solar we've had for years keeps 480amp lifepo4 pack fully charged quickly most days and alternator charging of lifepo4 has only been used a few times in the dead of winter with no sun for a couple of days. Whats' good is we can fire up the bus to charge the system and using veggie oil, it costs nothing and any smell is of fish and chips, or curry. It's Always a good laugh to see people looking round trying to find where the fish and chip smell is coming from way out in the bush as we go past in a small town or arrive where others are camped

As we are putting in A/C in the next couple of weeks, we are installing 1000w of solar to cope with that energy drain increase and all the other electric gizmo's we are finding we can use with lifepo4. Got the A/C the other day, but have sent them back as they sent the wrong ones, we got standard A/C when we ordered inverter A/C. So the install will be another few weeks away with the holiday break.

[grizzzman]

Hi ya John
Nice set up you have there.

"The biggest problem we have over here, is every second person has his ideas on how things should be done. Realising we have different power usage and travel modes."

True, but don't you think it may be beneficial to get differing points of view? I like you're idea of a DC to DC charger. That tech is not real common here,
But I think Sterling power sells them. I will take look. I to see Lifepo4 batteries in my future.

Thanks

[bagmaker]

Hi Grizz,
If battery power is the aim then the basis should be solar. You cannot have enough, fill up the roofspace with panels.

[grizzzman]

Hi native pepper

To funny people looking for a burger store
Do have a link to your "lifepo4 controller" by chance?

Thanks

[grizzzman]

Thanks for the link John. Good info.

https://www.caravanworld.com.au/feature ... -explained

[grizzzman]

Hi Grizz,
If battery power is the aim then the basis should be solar. You cannot have enough, fill up the roofspace with panels.

I can not argue with you're thoughts there!

Thanks bagmaker

[native pepper]

Hi native pepper

To funny people looking for a burger store
Do have a link to your "lifepo4 controller" by chance?

Thanks

They are called chip shops or take away shops over here.

I'm a member of buyer group, we had them make specifically for lifepo4 when we found the only ones who made them was my late mates company, who only make them for their own lifepo4 installations. So got them made for us and we buy a bulk lot when we need them, they are wonderful for lifepo4 and can't understand why manufactures are sticking with and claiming their expensive lead acid controllers are fine with lifepo4, when they use float, equalisation and temp controls. Those parameters will reduce the life of your cells to about 5-8 years, according to the research and testing I've seen. Yet to run into anyone else who has a dedicated lifpeo4 controller on the road, most use other methods to control them that work for them.

To me it's the life span that counts and my 120amp portable lifepo4 pack is over 8 years old and still provides 100% energy, until we got the controllers used my mates BMS design and active balancers, but that BMS only bled the cells, rather than equalise them and my mate was working on an active equaliser when he died. His kids finished the design and decided to get them made in china, not long after they got their first batch, their equaliser design appeared on ebay cheaper than they had paid for them. So they are available and work well, as for the controllers, surprised they haven't appeared as well. Think it's because everyone is lead acid orientated and the equalisers work on lead acid series connected batteries and aren't a threat to the established market. But dedicated lifepo4 controllers are a big threat to the monopoly of the lead acid regime, as they have so much tied up in lead acid and are desperate to cling to the past.