Ryobi-Baja 900/700W Generator

AnOldUR

@Marceline, we pulled the 3-way out and replaced it with a 12V compressor fridge. Even so, I was trying to ball park the daily use on the high side rather than underestimate it. I really need to spring for a smart shunt to get a better idea of my actual usage. With less than two weeks to go before an extended trip, I'll probably make due with what I have. Just hoping for some last minute tweaks.

Marceline

AnOldUR said:

@Marceline, we pulled the 3-way out and replaced it with a 12V compressor fridge. Even so, I was trying to ball park the daily use on the high side rather than underestimate it. I really need to spring for a smart shunt to get a better idea of my actual usage. With less than two weeks to go before an extended trip, I'll probably make due with what I have. Just hoping for some last minute tweaks.

In that case, I think that your 40aH may be a reasonable daily power budget.  Try to open the fridge as infrequently as possible. Maybe put the beer in an ice bucket. 

rfuss928

Keep in mind the charging requirements of the batteries and realize that the last 10-20% of the capacity is achieved with slow absorption charging usually at about 1-2% of rated capacity for many hours.  Off grid battery banks  typically operate in the ~50-80% capacity range to enable bulk charging rates when power is available (solar or generator).   In most cases it is not practical to expect to recover batteries to 100% SOC with limited time regardless of amps available.  As an example, you certainly cannot bring a 200 ah battery from 50% to 100% in 2 hours even if you have a 50 amp source.  Not even in 4 hours with a 25 amp source.  Absorption/saturation is a slow process.  On the other hand, from 50% to 80% could likely be achieved in 2 hours with a 30 amp source.
To get the most out of generator run time you should find a charger that can come close to the 700 watt capability of the Baja generator - over 50 amps at 12 volts.  Size your battery bank for adequate capacity between charging at ~30% of maximum rating.
My experience with a WFCO 25amp converter is that it will bulk charge depleted batteries at or above its rated 25 amp rate but quickly switches to a lower rate as charge condition of the batteries rise.  

Dutch061

One other comment regarding the allowable charge rate, it varies by battery chemistry and the total Ah capacity.

Example, most SLA or AGM recommend 15 to 20% (check the manufacturers information for yours) of the Ah capacity, so 200 Ah would be able to take up to 40 Amps.

Battleborn can take up to 50% of the Ah, so 200 Ah can would be able to take up to 100 Amps. Other lithium may be the same, again check the manufacturers information. The other benefit of BB, is they will take the maximum charge up to around 95% SOC, so less time at lower amps to finish.

Brad

AnOldUR

rfuss928 said:

My experience with a WFCO 25amp converter is that it will bulk charge depleted batteries at or above its rated 25 amp rate but quickly switches to a lower rate as charge condition of the batteries rise.  

While testing the Baja's ability to charge through the WFCO my batteries were above 80% SOC. Do I need to be concerned that the WFCO will try to pull more amps than the Baja can provide when the batteries are closer to 50%? My fear is that if the WFCO tries to draw 25 amps from the Baja it will overload and the generator will shut down. If that is a problem, will using a NOCO going directly to the battery be the only solution?

rfuss928

AnOldUR said:

. Do I need to be concerned that the WFCO will try to pull more amps than the Baja can provide when the batteries are closer to 50%? My fear is that if the WFCO tries to draw 25 amps from the Baja it will overload and the generator will shut down. If that is a problem, will using a NOCO going directly to the battery be the solution?

The Baja's 700 watt output should easily keep up with the WFCO demand.  Lets estimate the charging output at 25amps @ 15 volts.  That's 375 watts - only about half the capability of the Baja.  Even if the WFCO was only 80% efficient (probably closer to 95%) in converting the 120vac to DC charging current you would still be well with in the generators rating.

AnOldUR

Thanks @rfuss928. Dummy me was thinking the 25A was at 120V.

AnOldUR

Back from our trip and we only ran the generator a few times, but glad we had it for backup when the weather was not solar friendly. We did have one really hot day in a Walmart parking lot with temperatures over 100 degrees. It would have been nice to run the air conditioner, but later in the evening it rained and cooled down enough for sleeping.