AC charging a tow vehicle while driving
- Thread starter wb9wb
- Start date
mep1811
Gentleman Adventurer
I've had great results with the "Toad Charger" . It delivers a 10 amp charge to the trailer battery.
TOAD-CHARGE Dinghy Vehicle Battery Charger/Maintainer
Automatic Battery Charger/Maintainer for Motorhomes
www.lslproducts.net
mep1811
Gentleman Adventurer
This is another system I'm testing out. This system is also a 10 amp charger.
rvibrake.com
The reason I changed from the "Toad Charger" was the connectors to the charging modular were very fragile and the wires pulled out very easily. I see now that was changed.
Towed Battery Charger Plus for flat towing
RVi Towed Battery Charger Plus, charge line replacement for flat towing a vehicle. Great peace of mind for the towed battery while towing a car behind a motorhome. Often used with RVibrake. TBC+
rvibrake.com
The reason I changed from the "Toad Charger" was the connectors to the charging modular were very fragile and the wires pulled out very easily. I see now that was changed.
PhillySMB
Member
Most campervans, and I assume most motorhomes in general, have their house batteries charge from the engine alternator through a battery isolator with no issues. My extended-body Sportsmobile has at least a 15-foot cable run from the engine compartment to a three-AGM battery bank in the rear of the van, and has always charged fine just from driving (we rarely plug-in while traveling, even up to a month on the road). As others have said, you will get some drop with a longer cable run, but proper cable sizing should mitigate that. Or, install solar?
AC charging via an inverter doesn’t make a whole lot of sense to me, as you are losing efficiency converting 12v DC alternator current to AC to run the charger and then back again to DC to charge the battery. A trickle charger is just that... a slow maintenance charge meant for long-term storage and not day to day recharging.
Consider also adding a AC-DC converter/charger, which takes AC from shore power and converts it to DC for running all your DC items, plus charges your battery. These are very common on pop-up trailers and the like, and can usually be found used pretty cheap, too. See if you have an RV junkyard near you and you’ll find a ton of them. Then just try to plug in every few days to top off batteries; you can find plug-in opportunities at lots of places, not just pay campsites.
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AC charging via an inverter doesn’t make a whole lot of sense to me, as you are losing efficiency converting 12v DC alternator current to AC to run the charger and then back again to DC to charge the battery. A trickle charger is just that... a slow maintenance charge meant for long-term storage and not day to day recharging.
Consider also adding a AC-DC converter/charger, which takes AC from shore power and converts it to DC for running all your DC items, plus charges your battery. These are very common on pop-up trailers and the like, and can usually be found used pretty cheap, too. See if you have an RV junkyard near you and you’ll find a ton of them. Then just try to plug in every few days to top off batteries; you can find plug-in opportunities at lots of places, not just pay campsites.
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cool. thanks. I'll check into it.
My current setup is different from what I'm planning on setting up. yes the DC to AC back to DC has a cost. The term trickle charger might not be accurate in this case. It has a trickle feature after charging at a full rate. I will check out what is available in the junk yard.
thanks
shade
Well-known member
they sell models that do up to 8 amps , but offer the same desufator features of a trickle charger.
currently the 1.5amp version seems to work for me.
Have not read the whole thread.
OP: Yes, although it is a redneck engineering kludge, you can do this safely, just put fuses or CBs on both ends of your AC extension cord.
A quality proper deep cycling bank in the trailer should be maintained by a quality shore power charger, not less than $2-300.
Say 200+Ah, 30A minimum for FLA, 60A better assuming AGM.
The connection between your inverter
also needs to be quality, PSW sized at least 20% above what the charger requires
and the Starter circuit should be heavy-duty quality boat cable of sufficient gauge and short as possible.
____
Using a single DCDC unit like Sterling's would be much better, more flexible, but yes requires thicker wiring back to the Starter circuit.
OP: Yes, although it is a redneck engineering kludge, you can do this safely, just put fuses or CBs on both ends of your AC extension cord.
A quality proper deep cycling bank in the trailer should be maintained by a quality shore power charger, not less than $2-300.
Say 200+Ah, 30A minimum for FLA, 60A better assuming AGM.
The connection between your inverter
also needs to be quality, PSW sized at least 20% above what the charger requires
and the Starter circuit should be heavy-duty quality boat cable of sufficient gauge and short as possible.
____
Using a single DCDC unit like Sterling's would be much better, more flexible, but yes requires thicker wiring back to the Starter circuit.
redneck engineering kludge,, yes, I resemble that remark.. LOL
thanks for the feedback.
Buddha.
Finally in expo white.
A 1.5 amp is very little and is designed to keep an unused battery topped off while in storage, I don't think it's doing much for you. As a comparison my travel trailer came equipped with space for 2 batteries and a 60amp converter(charger).
I am in the same boat as you trying to figure out the best way to charge my trailer batteries while driving. I've looked at the TOAD chargers, and the price is right but I want more than 10 amps I think for my 215ah battery bank.
I've already got the previously mentioned 60amp converter which is a good 4 stage charger and you've got me thinking about getting a 1500w converter and just running a heavy duty extension cord back to the existing charger.
Buddha.
Finally in expo white.
Does anyone know if two of these could be used simultaneously? They are a good price compared to other DC-DC chargers I've been seeing but I think I could use more than 10 amps for my 215ah battery bank.
luthj
Engineer In Residence
That looks like a small voltage sensing relay (no DC-DC conversion).
Buddha.
Finally in expo white.
If I used this to charge my trailer batteries would I put this unit under the hood of the tow vehicle or on the trailer by the trailer batteries?The charger you linked puts out 1.5A, and would take a very long time to charge even a modest capacity house battery once it was used as most people would.
Victron just released a product that would allow you to start from scratch with a much better alternator charge source for your house battery.
New Product: Orion-Tr Smart DC-DC charger - Victron Energy
The new Orion-Tr Smart DC-DC charger is designed for use in dual battery systems in vehicles or boats, where the (smart) alternator and the start battery are used to charge the service battery. The model range is suitable for 12V or 24V systems, and both lead acid and lithium batteries. Why do...www.victronenergy.com
Also, what gauge wire for a ~30' run.
Buddha.
Finally in expo white.
So you're saying it just connects the TOAD batteries to the tow vehicle batteries? It doesn't boost voltage and it wouldn't be what I'm looking for?